Add Redis source code for testing

1 files changed, 2340 insertions, 0 deletions

diff --git a/examples/redis-unstable/src/dict.c b/examples/redis-unstable/src/dict.c
new file mode 100644
index 0000000..d0885ff
--- /dev/null
+++ b/examples/redis-unstable/src/dict.c
@@ -0,0 +1,2340 @@
+/* Hash Tables Implementation.
+ *
+ * This file implements in memory hash tables with insert/del/replace/find/
+ * get-random-element operations. Hash tables will auto resize if needed
+ * tables of power of two in size are used, collisions are handled by
+ * chaining. See the source code for more information... :)
+ *
+ * Copyright (c) 2006-Present, Redis Ltd.
+ * All rights reserved.
+ *
+ * Licensed under your choice of (a) the Redis Source Available License 2.0
+ * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
+ * GNU Affero General Public License v3 (AGPLv3).
+ */
+
+#include "fmacros.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdarg.h>
+#include <limits.h>
+#include <sys/time.h>
+#include <stddef.h>
+
+#include "dict.h"
+#include "zmalloc.h"
+#include "redisassert.h"
+#include "monotonic.h"
+#include "util.h"
+
+/* Using dictSetResizeEnabled() we make possible to disable
+ * resizing and rehashing of the hash table as needed. This is very important
+ * for Redis, as we use copy-on-write and don't want to move too much memory
+ * around when there is a child performing saving operations.
+ *
+ * Note that even when dict_can_resize is set to DICT_RESIZE_AVOID, not all
+ * resizes are prevented:
+ *  - A hash table is still allowed to expand if the ratio between the number
+ *    of elements and the buckets >= dict_force_resize_ratio.
+ *  - A hash table is still allowed to shrink if the ratio between the number
+ *    of elements and the buckets <= 1 / (HASHTABLE_MIN_FILL * dict_force_resize_ratio). */
+static dictResizeEnable dict_can_resize = DICT_RESIZE_ENABLE;
+static unsigned int dict_force_resize_ratio = 4;
+
+/* -------------------------- types ----------------------------------------- */
+struct dictEntry {
+    struct dictEntry *next;  /* Must be first */
+    void *key;               /* Must be second */
+    union {
+        void *val;
+        uint64_t u64;
+        int64_t s64;
+        double d;
+    } v;
+};
+
+typedef struct dictEntryNoValue {
+    dictEntry *next; /* Must be first */
+    void *key;       /* Must be second */
+} dictEntryNoValue;
+
+static_assert(offsetof(dictEntry, next) == offsetof(dictEntryNoValue, next), "dictEntry & dictEntryNoValue next not aligned");
+static_assert(offsetof(dictEntry, key) == offsetof(dictEntryNoValue, key), "dictEntry & dictEntryNoValue key not aligned");
+
+/* -------------------------- private prototypes ---------------------------- */
+
+static int _dictExpandIfNeeded(dict *d);
+static void _dictShrinkIfNeeded(dict *d);
+static void _dictRehashStepIfNeeded(dict *d, uint64_t visitedIdx);
+static signed char _dictNextExp(unsigned long size);
+static int _dictInit(dict *d, dictType *type);
+static dictEntryLink dictGetNextLink(dictEntry *de);
+static void dictSetNext(dictEntry *de, dictEntry *next);
+static int dictDefaultCompare(dictCmpCache *cache, const void *key1, const void *key2);
+static dictEntryLink dictFindLinkInternal(dict *d, const void *key, dictEntryLink *bucket);
+dictEntryLink dictFindLinkForInsert(dict *d, const void *key, dictEntry **existing);
+static dictEntry *dictInsertKeyAtLink(dict *d, void *key __stored_key, dictEntryLink link);
+
+/* -------------------------- unused  --------------------------- */
+void dictSetSignedIntegerVal(dictEntry *de, int64_t val);
+int64_t dictGetSignedIntegerVal(const dictEntry *de);
+double dictIncrDoubleVal(dictEntry *de, double val);
+void *dictEntryMetadata(dictEntry *de);
+int64_t dictIncrSignedIntegerVal(dictEntry *de, int64_t val);
+
+/* -------------------------- misc inline functions -------------------------------- */
+
+typedef int (*keyCmpFunc)(dictCmpCache *cache, const void *key1, const void *key2);
+static inline keyCmpFunc dictGetCmpFunc(dict *d) {
+    if (d->type->keyCompare)
+        return d->type->keyCompare;
+    return dictDefaultCompare;
+}
+
+static const void *dictStoredKey2Key(dict *d, const void *key __stored_key) {
+    return (d->type->keyFromStoredKey) ? d->type->keyFromStoredKey(key) : key;
+}
+
+/* -------------------------- hash functions -------------------------------- */
+
+static uint8_t dict_hash_function_seed[16];
+
+void dictSetHashFunctionSeed(uint8_t *seed) {
+    memcpy(dict_hash_function_seed,seed,sizeof(dict_hash_function_seed));
+}
+
+/* The default hashing function uses SipHash implementation
+ * in siphash.c. */
+
+uint64_t siphash(const uint8_t *in, const size_t inlen, const uint8_t *k);
+uint64_t siphash_nocase(const uint8_t *in, const size_t inlen, const uint8_t *k);
+
+uint64_t dictGenHashFunction(const void *key, size_t len) {
+    return siphash(key, len, dict_hash_function_seed);
+}
+
+uint64_t dictGenCaseHashFunction(const unsigned char *buf, size_t len) {
+    return siphash_nocase(buf,len,dict_hash_function_seed);
+}
+
+/* --------------------- dictEntry pointer bit tricks ----------------------  */
+
+/* The 3 least significant bits in a pointer to a dictEntry determines what the
+ * pointer actually points to. If the least bit is set, it's a key. Otherwise,
+ * the bit pattern of the least 3 significant bits mark the kind of entry. */
+
+#define ENTRY_PTR_MASK        7 /* 111 */
+#define ENTRY_PTR_NORMAL      0 /* 000 : If a pointer to an entry with value. */
+#define ENTRY_PTR_IS_ODD_KEY  1 /* XX1 : If a pointer to odd key address (must be 1). */
+#define ENTRY_PTR_IS_EVEN_KEY 2 /* 010 : If a pointer to even key address. (must be 2 or 4). */
+#define ENTRY_PTR_UNUSED      4 /* 100 : Unused. */
+
+/* Returns 1 if the entry pointer is a pointer to a key, rather than to an
+ * allocated entry. Returns 0 otherwise. */
+static inline int entryIsKey(const dictEntry *de) {
+    return ((uintptr_t)de & (ENTRY_PTR_IS_ODD_KEY | ENTRY_PTR_IS_EVEN_KEY));
+}
+
+/* Returns 1 if the pointer is actually a pointer to a dictEntry struct. Returns
+ * 0 otherwise. */
+static inline int entryIsNormal(const dictEntry *de) {
+    return ((uintptr_t)(void *)de & ENTRY_PTR_MASK) == ENTRY_PTR_NORMAL;
+}
+
+/* Creates an entry without a value field. */
+static inline dictEntry *createEntryNoValue(void *key __stored_key, dictEntry *next) {
+    dictEntryNoValue *entry = zmalloc(sizeof(*entry));
+    entry->key = key;
+    entry->next = next;
+    return (dictEntry *) entry;
+}
+
+static inline dictEntry *encodeMaskedPtr(const void *ptr, unsigned int bits) {
+    assert(((uintptr_t)ptr & ENTRY_PTR_MASK) == 0);
+    return (dictEntry *)(void *)((uintptr_t)ptr | bits);
+}
+
+static inline void *decodeMaskedPtr(const dictEntry *de) {
+    return (void *)((uintptr_t)(void *)de & ~ENTRY_PTR_MASK);
+}
+
+/* Encode a key pointer for storage in a no_value dict bucket.
+ * For odd keys (like SDS strings), the key can be stored directly.
+ * For even keys, we need to tag it with ENTRY_PTR_IS_EVEN_KEY. */
+static inline dictEntry *encodeEntryKey(dict *d, void *key) {
+    if (d->type->keys_are_odd) {
+        debugAssert(((uintptr_t)key & ENTRY_PTR_IS_ODD_KEY) == ENTRY_PTR_IS_ODD_KEY);
+        return key;
+    } else {
+        return encodeMaskedPtr(key, ENTRY_PTR_IS_EVEN_KEY);
+    }
+}
+
+/* Decodes the pointer to an entry without value, when you know it is an entry
+ * without value. Hint: Use entryIsNoValue to check. */
+static inline dictEntryNoValue *decodeEntryNoValue(const dictEntry *de) {
+    return decodeMaskedPtr(de);
+}
+
+/* Returns 1 if the entry has a value field and 0 otherwise. */
+static inline int entryHasValue(const dictEntry *de) {
+    return entryIsNormal(de);
+}
+
+/* ----------------------------- API implementation ------------------------- */
+
+/* Reset hash table parameters already initialized with _dictInit()*/
+static void _dictReset(dict *d, int htidx)
+{
+    d->ht_table[htidx] = NULL;
+    d->ht_size_exp[htidx] = -1;
+    d->ht_used[htidx] = 0;
+}
+
+/* Create a new hash table */
+dict *dictCreate(dictType *type)
+{
+    size_t metasize = type->dictMetadataBytes ? type->dictMetadataBytes(NULL) : 0;
+    dict *d = zmalloc(sizeof(*d)+metasize);
+    if (metasize > 0) {
+        memset(dictMetadata(d), 0, metasize);
+    }
+    _dictInit(d,type);
+    return d;
+}
+
+/* Change dictType of dict to another one with metadata support
+ * Rest of dictType's values must stay the same */
+void dictTypeAddMeta(dict **d, dictType *typeWithMeta) {
+    /* Verify new dictType is compatible with the old one */
+    dictType toCmp = *typeWithMeta;
+    /* Ignore 'dictMetadataBytes' and 'onDictRelease' in comparison */
+    toCmp.dictMetadataBytes = (*d)->type->dictMetadataBytes;
+    toCmp.onDictRelease = (*d)->type->onDictRelease;
+    assert(memcmp((*d)->type, &toCmp, sizeof(dictType)) == 0); /* The rest of the dictType fields must be the same */
+
+    *d = zrealloc(*d, sizeof(dict) + typeWithMeta->dictMetadataBytes(*d));
+    (*d)->type = typeWithMeta;
+}
+
+/* Initialize the hash table */
+int _dictInit(dict *d, dictType *type)
+{
+    _dictReset(d, 0);
+    _dictReset(d, 1);
+    d->type = type;
+    d->rehashidx = -1;
+    d->pauserehash = 0;
+    d->pauseAutoResize = 0;
+    return DICT_OK;
+}
+
+/* Resize or create the hash table,
+ * when malloc_failed is non-NULL, it'll avoid panic if malloc fails (in which case it'll be set to 1).
+ * Returns DICT_OK if resize was performed, and DICT_ERR if skipped. */
+int _dictResize(dict *d, unsigned long size, int* malloc_failed)
+{
+    if (malloc_failed) *malloc_failed = 0;
+
+    /* We can't rehash twice if rehashing is ongoing. */
+    assert(!dictIsRehashing(d));
+
+    /* the new hash table */
+    dictEntry **new_ht_table;
+    unsigned long new_ht_used;
+    signed char new_ht_size_exp = _dictNextExp(size);
+
+    /* Detect overflows */
+    size_t newsize = DICTHT_SIZE(new_ht_size_exp);
+    if (newsize < size || newsize * sizeof(dictEntry*) < newsize)
+        return DICT_ERR;
+
+    /* Rehashing to the same table size is not useful. */
+    if (new_ht_size_exp == d->ht_size_exp[0]) return DICT_ERR;
+
+    /* Allocate the new hash table and initialize all pointers to NULL */
+    if (malloc_failed) {
+        new_ht_table = ztrycalloc(newsize*sizeof(dictEntry*));
+        *malloc_failed = new_ht_table == NULL;
+        if (*malloc_failed)
+            return DICT_ERR;
+    } else
+        new_ht_table = zcalloc(newsize*sizeof(dictEntry*));
+
+    new_ht_used = 0;
+
+    /* Prepare a second hash table for incremental rehashing.
+     * We do this even for the first initialization, so that we can trigger the
+     * rehashingStarted more conveniently, we will clean it up right after. */
+    d->ht_size_exp[1] = new_ht_size_exp;
+    d->ht_used[1] = new_ht_used;
+    d->ht_table[1] = new_ht_table;
+    d->rehashidx = 0;
+    if (d->type->rehashingStarted) d->type->rehashingStarted(d);
+    if (d->type->bucketChanged)
+        d->type->bucketChanged(d, DICTHT_SIZE(d->ht_size_exp[1]));
+
+    /* Is this the first initialization or is the first hash table empty? If so
+     * it's not really a rehashing, we can just set the first hash table so that
+     * it can accept keys. */
+    if (d->ht_table[0] == NULL || d->ht_used[0] == 0) {
+        if (d->type->rehashingCompleted) d->type->rehashingCompleted(d);
+        if (d->type->bucketChanged)
+            d->type->bucketChanged(d, -(long long)DICTHT_SIZE(d->ht_size_exp[0]));
+        if (d->ht_table[0]) zfree(d->ht_table[0]);
+        d->ht_size_exp[0] = new_ht_size_exp;
+        d->ht_used[0] = new_ht_used;
+        d->ht_table[0] = new_ht_table;
+        _dictReset(d, 1);
+        d->rehashidx = -1;
+        return DICT_OK;
+    }
+
+    /* Force a full rehashing of the dictionary */
+    if (d->type->force_full_rehash) {
+        while (dictRehash(d, 1000)) {
+            /* Continue rehashing */
+        }
+    }
+    return DICT_OK;
+}
+
+int _dictExpand(dict *d, unsigned long size, int* malloc_failed) {
+    /* the size is invalid if it is smaller than the size of the hash table 
+     * or smaller than the number of elements already inside the hash table */
+    if (dictIsRehashing(d) || d->ht_used[0] > size || DICTHT_SIZE(d->ht_size_exp[0]) >= size)
+        return DICT_ERR;
+    return _dictResize(d, size, malloc_failed);
+}
+
+/* return DICT_ERR if expand was not performed */
+int dictExpand(dict *d, unsigned long size) {
+    return _dictExpand(d, size, NULL);
+}
+
+/* return DICT_ERR if expand failed due to memory allocation failure */
+int dictTryExpand(dict *d, unsigned long size) {
+    int malloc_failed = 0;
+    _dictExpand(d, size, &malloc_failed);
+    return malloc_failed? DICT_ERR : DICT_OK;
+}
+
+/* return DICT_ERR if shrink was not performed */
+int dictShrink(dict *d, unsigned long size) {
+    /* the size is invalid if it is bigger than the size of the hash table
+     * or smaller than the number of elements already inside the hash table */
+    if (dictIsRehashing(d) || d->ht_used[0] > size || DICTHT_SIZE(d->ht_size_exp[0]) <= size)
+        return DICT_ERR;
+    return _dictResize(d, size, NULL);
+}
+
+/* Helper function for `dictRehash` and `dictBucketRehash` which rehashes all the keys
+ * in a bucket at index `idx` from the old to the new hash HT. */
+static void rehashEntriesInBucketAtIndex(dict *d, uint64_t idx) {
+    dictEntry *de = d->ht_table[0][idx];
+    uint64_t h;
+    dictEntry *nextde;
+    while (de) {
+        nextde = dictGetNext(de);
+        void *storedKey = dictGetKey(de);
+        /* Get the index in the new hash table */
+        if (d->ht_size_exp[1] > d->ht_size_exp[0]) {
+            const void *key = dictStoredKey2Key(d, storedKey);
+            h = dictGetHash(d, key) & DICTHT_SIZE_MASK(d->ht_size_exp[1]);
+        } else {
+            /* We're shrinking the table. The tables sizes are powers of
+             * two, so we simply mask the bucket index in the larger table
+             * to get the bucket index in the smaller table. */
+            h = idx & DICTHT_SIZE_MASK(d->ht_size_exp[1]);
+        }
+        if (d->type->no_value) {
+            if (!d->ht_table[1][h]) {
+                /* The destination bucket is empty, allowing the key to be stored 
+                 * directly without allocating a dictEntry. If an old entry was 
+                 * previously allocated, free its memory. */                
+                if (!entryIsKey(de)) zfree(decodeMaskedPtr(de));
+                
+                de = encodeEntryKey(d, storedKey);
+                
+            } else if (entryIsKey(de)) {
+                /* We don't have an allocated entry but we need one. */
+                de = createEntryNoValue(storedKey, d->ht_table[1][h]);
+            } else {
+                dictSetNext(de, d->ht_table[1][h]);
+            }
+        } else {
+            dictSetNext(de, d->ht_table[1][h]);
+        }
+        d->ht_table[1][h] = de;
+        d->ht_used[0]--;
+        d->ht_used[1]++;
+        de = nextde;
+    }
+    d->ht_table[0][idx] = NULL;
+}
+
+/* This checks if we already rehashed the whole table and if more rehashing is required */
+static int dictCheckRehashingCompleted(dict *d) {
+    if (d->ht_used[0] != 0) return 0;
+    
+    if (d->type->rehashingCompleted) d->type->rehashingCompleted(d);
+    if (d->type->bucketChanged)
+        d->type->bucketChanged(d, -(long long)DICTHT_SIZE(d->ht_size_exp[0]));
+    zfree(d->ht_table[0]);
+    /* Copy the new ht onto the old one */
+    d->ht_table[0] = d->ht_table[1];
+    d->ht_used[0] = d->ht_used[1];
+    d->ht_size_exp[0] = d->ht_size_exp[1];
+    _dictReset(d, 1);
+    d->rehashidx = -1;
+    return 1;
+}
+
+/* Performs N steps of incremental rehashing. Returns 1 if there are still
+ * keys to move from the old to the new hash table, otherwise 0 is returned.
+ *
+ * Note that a rehashing step consists in moving a bucket (that may have more
+ * than one key as we use chaining) from the old to the new hash table, however
+ * since part of the hash table may be composed of empty spaces, it is not
+ * guaranteed that this function will rehash even a single bucket, since it
+ * will visit at max N*10 empty buckets in total, otherwise the amount of
+ * work it does would be unbound and the function may block for a long time. */
+int dictRehash(dict *d, int n) {
+    int empty_visits = n*10; /* Max number of empty buckets to visit. */
+    unsigned long s0 = DICTHT_SIZE(d->ht_size_exp[0]);
+    unsigned long s1 = DICTHT_SIZE(d->ht_size_exp[1]);
+    if (dict_can_resize == DICT_RESIZE_FORBID || !dictIsRehashing(d)) return 0;
+    /* If dict_can_resize is DICT_RESIZE_AVOID, we want to avoid rehashing. 
+     * - If expanding, the threshold is dict_force_resize_ratio which is 4.
+     * - If shrinking, the threshold is 1 / (HASHTABLE_MIN_FILL * dict_force_resize_ratio) which is 1/32. */
+    if (dict_can_resize == DICT_RESIZE_AVOID && 
+        ((s1 > s0 && s1 < dict_force_resize_ratio * s0) ||
+         (s1 < s0 && s0 < HASHTABLE_MIN_FILL * dict_force_resize_ratio * s1)))
+    {
+        return 0;
+    }
+
+    while(n-- && d->ht_used[0] != 0) {
+        /* Note that rehashidx can't overflow as we are sure there are more
+         * elements because ht[0].used != 0 */
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) > (unsigned long)d->rehashidx);
+        while(d->ht_table[0][d->rehashidx] == NULL) {
+            d->rehashidx++;
+            if (--empty_visits == 0) return 1;
+        }
+        /* Move all the keys in this bucket from the old to the new hash HT */
+        rehashEntriesInBucketAtIndex(d, d->rehashidx);
+        d->rehashidx++;
+    }
+
+    return !dictCheckRehashingCompleted(d);
+}
+
+long long timeInMilliseconds(void) {
+    struct timeval tv;
+
+    gettimeofday(&tv,NULL);
+    return (((long long)tv.tv_sec)*1000)+(tv.tv_usec/1000);
+}
+
+/* Rehash in us+"delta" microseconds. The value of "delta" is larger
+ * than 0, and is smaller than 1000 in most cases. The exact upper bound
+ * depends on the running time of dictRehash(d,100).*/
+int dictRehashMicroseconds(dict *d, uint64_t us) {
+    if (d->pauserehash > 0) return 0;
+
+    monotime timer;
+    elapsedStart(&timer);
+    int rehashes = 0;
+
+    while(dictRehash(d,100)) {
+        rehashes += 100;
+        if (elapsedUs(timer) >= us) break;
+    }
+    return rehashes;
+}
+
+/* This function performs just a step of rehashing, and only if hashing has
+ * not been paused for our hash table. When we have iterators in the
+ * middle of a rehashing we can't mess with the two hash tables otherwise
+ * some elements can be missed or duplicated.
+ *
+ * This function is called by common lookup or update operations in the
+ * dictionary so that the hash table automatically migrates from H1 to H2
+ * while it is actively used. */
+static void _dictRehashStep(dict *d) {
+    if (d->pauserehash == 0) dictRehash(d,1);
+}
+
+/* Performs rehashing on a single bucket. */
+int _dictBucketRehash(dict *d, uint64_t idx) {
+    if (d->pauserehash != 0) return 0;
+    unsigned long s0 = DICTHT_SIZE(d->ht_size_exp[0]);
+    unsigned long s1 = DICTHT_SIZE(d->ht_size_exp[1]);
+    if (dict_can_resize == DICT_RESIZE_FORBID || !dictIsRehashing(d)) return 0;
+    /* If dict_can_resize is DICT_RESIZE_AVOID, we want to avoid rehashing. 
+     * - If expanding, the threshold is dict_force_resize_ratio which is 4.
+     * - If shrinking, the threshold is 1 / (HASHTABLE_MIN_FILL * dict_force_resize_ratio) which is 1/32. */
+    if (dict_can_resize == DICT_RESIZE_AVOID && 
+        ((s1 > s0 && s1 < dict_force_resize_ratio * s0) ||
+         (s1 < s0 && s0 < HASHTABLE_MIN_FILL * dict_force_resize_ratio * s1)))
+    {
+        return 0;
+    }
+    rehashEntriesInBucketAtIndex(d, idx);
+    dictCheckRehashingCompleted(d);
+    return 1;
+}
+
+/* Add an element to the target hash table */
+int dictAdd(dict *d, void *key __stored_key, void *val)
+{
+    dictEntry *entry = dictAddRaw(d,key,NULL);
+
+    if (!entry) return DICT_ERR;
+    if (!d->type->no_value) dictSetVal(d, entry, val);
+    return DICT_OK;
+}
+
+int dictCompareKeys(dict *d, const void *key1, const void *key2) {
+    dictCmpCache cache = {0};
+    keyCmpFunc cmpFunc = dictGetCmpFunc(d);
+    return cmpFunc(&cache, key1, key2);
+}
+
+/* Low level add or find:
+ * This function adds the entry but instead of setting a value returns the
+ * dictEntry structure to the user, that will make sure to fill the value
+ * field as they wish.
+ *
+ * This function is also directly exposed to the user API to be called
+ * mainly in order to store non-pointers inside the hash value, example:
+ *
+ * entry = dictAddRaw(dict,mykey,NULL);
+ * if (entry != NULL) dictSetSignedIntegerVal(entry,1000);
+ *
+ * Return values:
+ *
+ * If key already exists NULL is returned, and "*existing" is populated
+ * with the existing entry if existing is not NULL.
+ *
+ * If key was added, the hash entry is returned to be manipulated by the caller.
+ */
+dictEntry *dictAddRaw(dict *d, void *key __stored_key, dictEntry **existing)
+{
+    /* Get the position for the new key or NULL if the key already exists. */
+    void *position = dictFindLinkForInsert(d, dictStoredKey2Key(d, key), existing);
+    if (!position) return NULL;
+
+    /* Dup the key if necessary. */
+    if (d->type->keyDup) key = d->type->keyDup(d, key);
+
+    return dictInsertKeyAtLink(d, key, position);
+}
+
+/* Adds a key in the dict's hashtable at the link returned by a preceding
+ * call to dictFindLinkForInsert(). This is a low level function which allows
+ * splitting dictAddRaw in two parts. Normally, dictAddRaw or dictAdd should be
+ * used instead. It assumes that dictExpandIfNeeded() was called before. */
+dictEntry *dictInsertKeyAtLink(dict *d, void *key __stored_key, dictEntryLink link) {
+    dictEntryLink bucket = link; /* It's a bucket, but the API hides that. */
+    dictEntry *entry;
+    /* If rehashing is ongoing, we insert in table 1, otherwise in table 0.
+     * Assert that the provided bucket is the right table. */
+    int htidx = dictIsRehashing(d) ? 1 : 0;
+    assert(bucket >= &d->ht_table[htidx][0] &&
+           bucket <= &d->ht_table[htidx][DICTHT_SIZE_MASK(d->ht_size_exp[htidx])]);
+    if (d->type->no_value) {
+        if (!*bucket) {
+            /* We can store the key directly in the destination bucket without 
+             * allocating dictEntry.
+             */
+            entry = encodeEntryKey(d, key);
+            assert(entryIsKey(entry));
+        } else {
+            /* Allocate an entry without value. */
+            entry = createEntryNoValue(key, *bucket);
+        }
+    } else {
+        /* Allocate the memory and store the new entry.
+         * Insert the element in top, with the assumption that in a database
+         * system it is more likely that recently added entries are accessed
+         * more frequently. */
+        entry = zmalloc(sizeof(*entry));
+        assert(entryIsNormal(entry)); /* Check alignment of allocation */
+        entry->key = key;
+        entry->next = *bucket;
+    }
+    *bucket = entry;
+    d->ht_used[htidx]++;
+
+    return entry;
+}
+
+/* Add or Overwrite:
+ * Add an element, discarding the old value if the key already exists.
+ * Return 1 if the key was added from scratch, 0 if there was already an
+ * element with such key and dictReplace() just performed a value update
+ * operation. */
+int dictReplace(dict *d, void *key __stored_key, void *val)
+{
+    dictEntry *entry, *existing;
+
+    /* Try to add the element. If the key
+     * does not exists dictAdd will succeed. */
+    entry = dictAddRaw(d,key,&existing);
+    if (entry) {
+        dictSetVal(d, entry, val);
+        return 1;
+    }
+
+    /* Set the new value and free the old one. Note that it is important
+     * to do that in this order, as the value may just be exactly the same
+     * as the previous one. In this context, think to reference counting,
+     * you want to increment (set), and then decrement (free), and not the
+     * reverse. */
+    void *oldval = dictGetVal(existing);
+    dictSetVal(d, existing, val);
+    if (d->type->valDestructor)
+        d->type->valDestructor(d, oldval);
+    return 0;
+}
+
+/* Add or Find:
+ * dictAddOrFind() is simply a version of dictAddRaw() that always
+ * returns the hash entry of the specified key, even if the key already
+ * exists and can't be added (in that case the entry of the already
+ * existing key is returned.)
+ *
+ * See dictAddRaw() for more information. */
+dictEntry *dictAddOrFind(dict *d, void *key __stored_key) {
+    dictEntry *entry, *existing;
+    entry = dictAddRaw(d,key,&existing);
+    return entry ? entry : existing;
+}
+
+/* Search and remove an element. This is a helper function for
+ * dictDelete() and dictUnlink(), please check the top comment
+ * of those functions. */
+static dictEntry *dictGenericDelete(dict *d, const void *key, int nofree) {
+    dictCmpCache cmpCache = {0};
+    uint64_t h, idx;
+    dictEntry *he, *prevHe;
+    int table;
+
+    /* dict is empty */
+    if (dictSize(d) == 0) return NULL;
+
+    h = dictGetHash(d, key);
+    idx = h & DICTHT_SIZE_MASK(d->ht_size_exp[0]);
+
+    /* Rehash the hash table if needed */
+    _dictRehashStepIfNeeded(d,idx);
+
+    keyCmpFunc cmpFunc = dictGetCmpFunc(d);
+
+    for (table = 0; table <= 1; table++) {
+        if (table == 0 && (long)idx < d->rehashidx) continue;
+        idx = h & DICTHT_SIZE_MASK(d->ht_size_exp[table]);
+        he = d->ht_table[table][idx];
+        prevHe = NULL;
+        while(he) {
+            const void *he_key = dictStoredKey2Key(d, dictGetKey(he));
+            if (key == he_key || cmpFunc(&cmpCache, key, he_key)) {
+                /* Unlink the element from the list */
+                if (prevHe)
+                    dictSetNext(prevHe, dictGetNext(he));
+                else
+                    d->ht_table[table][idx] = dictGetNext(he);
+                if (!nofree) {
+                    dictFreeUnlinkedEntry(d, he);
+                }
+                d->ht_used[table]--;
+                _dictShrinkIfNeeded(d);
+                return he;
+            }
+            prevHe = he;
+            he = dictGetNext(he);
+        }
+        if (!dictIsRehashing(d)) break;
+    }
+    return NULL; /* not found */
+}
+
+/* Remove an element, returning DICT_OK on success or DICT_ERR if the
+ * element was not found. */
+int dictDelete(dict *ht, const void *key) {
+    return dictGenericDelete(ht,key,0) ? DICT_OK : DICT_ERR;
+}
+
+/* Remove an element from the table, but without actually releasing
+ * the key, value and dictionary entry. The dictionary entry is returned
+ * if the element was found (and unlinked from the table), and the user
+ * should later call `dictFreeUnlinkedEntry()` with it in order to release it.
+ * Otherwise if the key is not found, NULL is returned.
+ *
+ * This function is useful when we want to remove something from the hash
+ * table but want to use its value before actually deleting the entry.
+ * Without this function the pattern would require two lookups:
+ *
+ *  entry = dictFind(...);
+ *  // Do something with entry
+ *  dictDelete(dictionary,entry);
+ *
+ * Thanks to this function it is possible to avoid this, and use
+ * instead:
+ *
+ * entry = dictUnlink(dictionary,entry);
+ * // Do something with entry
+ * dictFreeUnlinkedEntry(entry); // <- This does not need to lookup again.
+ */
+dictEntry *dictUnlink(dict *d, const void *key) {
+    return dictGenericDelete(d,key,1);
+}
+
+/* You need to call this function to really free the entry after a call
+ * to dictUnlink(). It's safe to call this function with 'he' = NULL. */
+void dictFreeUnlinkedEntry(dict *d, dictEntry *he) {
+    if (he == NULL) return;
+    dictFreeKey(d, he);
+    dictFreeVal(d, he);
+    if (!entryIsKey(he)) zfree(decodeMaskedPtr(he));
+}
+
+/* Destroy an entire dictionary */
+int _dictClear(dict *d, int htidx, void(callback)(dict*)) {
+    unsigned long i;
+
+    /* Free all the elements */
+    for (i = 0; i < DICTHT_SIZE(d->ht_size_exp[htidx]) && d->ht_used[htidx] > 0; i++) {
+        dictEntry *he, *nextHe;
+        /* Callback will be called once for every 65535 deletions. Beware,
+         * if dict has less than 65535 items, it will not be called at all.*/
+        if (callback && i != 0 && (i & 65535) == 0) callback(d);
+
+        if ((he = d->ht_table[htidx][i]) == NULL) continue;
+        while(he) {
+            nextHe = dictGetNext(he);
+            dictFreeKey(d, he);
+            dictFreeVal(d, he);
+            if (!entryIsKey(he)) zfree(decodeMaskedPtr(he));
+            d->ht_used[htidx]--;
+            he = nextHe;
+        }
+    }
+    /* Free the table and the allocated cache structure */
+    zfree(d->ht_table[htidx]);
+    /* Re-initialize the table */
+    _dictReset(d, htidx);
+    return DICT_OK; /* never fails */
+}
+
+/* Clear & Release the hash table */
+void dictRelease(dict *d)
+{
+    /* Someone may be monitoring a dict that started rehashing, before
+     * destroying the dict fake completion. */
+    if (dictIsRehashing(d) && d->type->rehashingCompleted)
+        d->type->rehashingCompleted(d);
+
+    /* Subtract the size of all buckets. */
+    if (d->type->bucketChanged)
+        d->type->bucketChanged(d, -(long long)dictBuckets(d));
+
+    if (d->type->onDictRelease)
+        d->type->onDictRelease(d);
+
+    _dictClear(d,0,NULL);
+    _dictClear(d,1,NULL);
+    zfree(d);
+}
+
+/* Finds a given key. Like dictFindLink(), yet search bucket even if dict is empty. 
+ * 
+ * Returns dictEntryLink reference if found. Otherwise, return NULL.
+ * 
+ * bucket - return pointer to bucket that the key was mapped. unless dict is empty.
+ */
+static dictEntryLink dictFindLinkInternal(dict *d, const void *key, dictEntryLink *bucket) {
+    dictCmpCache cmpCache = {0};
+    dictEntryLink link;
+    uint64_t idx;
+    int table;
+    
+    if (bucket) {
+        *bucket = NULL;
+    } else {
+        /* If dict is empty and no need to find bucket, return NULL */
+        if (dictSize(d) == 0) return NULL; 
+    }
+
+    const uint64_t hash = dictGetHash(d, key);
+    idx = hash & DICTHT_SIZE_MASK(d->ht_size_exp[0]);
+    keyCmpFunc cmpFunc = dictGetCmpFunc(d);
+
+    /* Rehash the hash table if needed */
+    _dictRehashStepIfNeeded(d,idx);
+
+    int tables = (dictIsRehashing(d)) ? 2 : 1;
+    for (table = 0; table < tables; table++) {
+        if (table == 0 && (long)idx < d->rehashidx) continue;
+        idx = hash & DICTHT_SIZE_MASK(d->ht_size_exp[table]);
+
+        link = &(d->ht_table[table][idx]);
+        if (bucket) *bucket = link;
+        while(link && *link) {
+            const void *visitedKey = dictStoredKey2Key(d, dictGetKey(*link));
+
+            if (key == visitedKey || cmpFunc( &cmpCache, key, visitedKey))                
+                return link;
+
+            link = dictGetNextLink(*link);
+        }
+    }
+    return NULL;
+}
+
+dictEntry *dictFind(dict *d, const void *key)
+{
+    dictEntryLink link = dictFindLink(d, key, NULL);
+    return (link) ? *link : NULL;
+}
+
+/* Finds the dictEntry using pointer and pre-calculated hash.
+ * oldkey is a dead pointer and should not be accessed.
+ * the hash value should be provided using dictGetHash.
+ * no string / key comparison is performed.
+ * return value is a pointer to the dictEntry if found, or NULL if not found. */
+dictEntry *dictFindByHashAndPtr(dict *d, const void *oldptr, const uint64_t hash) {
+    dictEntry *he;
+    unsigned long idx, table;
+
+    if (dictSize(d) == 0) return NULL; /* dict is empty */
+    for (table = 0; table <= 1; table++) {
+        idx = hash & DICTHT_SIZE_MASK(d->ht_size_exp[table]);
+        if (table == 0 && (long)idx < d->rehashidx) continue;
+        he = d->ht_table[table][idx];
+        while(he) {
+            if (oldptr == dictGetKey(he))
+                return he;
+            he = dictGetNext(he);
+        }
+        if (!dictIsRehashing(d)) return NULL;
+    }
+    return NULL;
+}
+
+/* Find a key and return its dictEntryLink reference. Otherwise, return NULL
+ * 
+ * A dictEntryLink pointer being used to find preceding dictEntry of searched item. 
+ * It is Useful for deletion, addition, unlinking and updating, especially for 
+ * dict configured with 'no_value'. In such cases returning only `dictEntry` from 
+ * a lookup may be insufficient since it might be opt-out to be the object itself. 
+ * By locating preceding dictEntry (dictEntryLink) these ops can be properly handled. 
+ * 
+ * After calling link = dictFindLink(...), any necessary updates based on returned 
+ * link or bucket must be performed immediately after by calling dictSetKeyAtLink() 
+ * without any intervening operations on given dict. Otherwise, `dictEntryLink` may 
+ * become invalid. Example with kvobj of replacing key with new key:
+ * 
+ *      link = dictFindLink(d, key, &bucket, 0);
+ *      ... Do something, but don't modify the dict ...
+ *      // assert(link != NULL);
+ *      dictSetKeyAtLink(d, kv, &link, 0);
+ *      
+ * To add new value (If no space for the new key, dict will be expanded by
+ * dictSetKeyAtLink() and bucket will be looked up again.):
+ *   
+ *      link = dictFindLink(d, key, &bucket);
+ *      ... Do something, but don't modify the dict ...
+ *      // assert(link == NULL);
+ *      dictSetKeyAtLink(d, kv, &bucket, 1);
+ *  
+ *  bucket - return link to bucket that the key was mapped. unless dict is empty.
+ */
+dictEntryLink dictFindLink(dict *d, const void *key, dictEntryLink *bucket) {
+    if (bucket) *bucket = NULL;
+    if (unlikely(dictSize(d) == 0))
+        return NULL;
+    
+    return dictFindLinkInternal(d, key, bucket);
+}
+
+/* Set the key with link 
+ *
+ * link:    - When `newItem` is set, `link` points to the bucket of the key.
+ *          - When `newItem` is not set, `link` points to the link of the key.
+ *          - If *link is NULL, dictFindLink() will be called to locate the key.
+ *          - On return, get updated, by need, to the inserted key. 
+ *
+ * newItem: 1 = Add a key with a new dictEntry.
+ *          0 = Set a key to an existing dictEntry. 
+ */
+void dictSetKeyAtLink(dict *d, void *key __stored_key, dictEntryLink *link, int newItem) {
+    dictEntryLink dummy = NULL;
+    if (link == NULL) link = &dummy;
+    void *addedKey = (d->type->keyDup) ? d->type->keyDup(d, key) : key;
+    
+    if (newItem) {
+        signed char snap[2] = {d->ht_size_exp[0], d->ht_size_exp[1] };
+
+        /* Make room if needed for the new key */
+        dictExpandIfNeeded(d);
+        
+        /* Lookup key's link if tables reallocated or if given link is set to NULL */
+        if (snap[0] != d->ht_size_exp[0] || snap[1] != d->ht_size_exp[1] || *link == NULL) {
+            dictEntryLink bucket;
+            /* Bypass dictFindLink() to search bucket even if dict is empty!!! */
+            *link = dictFindLinkInternal(d, dictStoredKey2Key(d, key), &bucket);
+            assert(bucket != NULL);
+            assert(*link == NULL);
+            *link = bucket; /* On newItem the link should be the bucket */
+        }
+        dictInsertKeyAtLink(d, addedKey, *link);
+        return;
+    } 
+    
+    /* Setting key of existing dictEntry (newItem == 0)*/
+    
+    if (*link == NULL) {
+        *link = dictFindLink(d, key, NULL);
+        assert(*link != NULL);
+    }
+    
+    dictEntry **de = *link;
+    if (entryIsKey(*de)) {
+        /* `de` opt-out to be actually a key. Replace key but keep the lsb flags */
+        *de = encodeEntryKey(d, addedKey);
+    } else {
+        /* either dictEntry or dictEntryNoValue */
+        (*de)->key = addedKey;
+    }
+}
+
+void *dictFetchValue(dict *d, const void *key) {
+    dictEntry *he;
+
+    he = dictFind(d,key);
+    return he ? dictGetVal(he) : NULL;
+}
+
+/* Find an element from the table. A link is returned if the element is found, and
+ * the user should later call `dictTwoPhaseUnlinkFree` with it in order to unlink
+ * and release it. Otherwise if the key is not found, NULL is returned. These two
+ * functions should be used in pair.
+ * `dictTwoPhaseUnlinkFind` pauses rehash and `dictTwoPhaseUnlinkFree` resumes rehash.
+ *
+ * We can use like this:
+ *
+ * dictEntryLink link = dictTwoPhaseUnlinkFind(db->dict,key->ptr, &table);
+ * // Do something, but we can't modify the dict
+ * dictTwoPhaseUnlinkFree(db->dict, link, table); // We don't need to lookup again
+ *
+ * If we want to find an entry before delete this entry, this an optimization to avoid
+ * dictFind followed by dictDelete. i.e. the first API is a find, and it gives some info
+ * to the second one to avoid repeating the lookup
+ */
+dictEntryLink dictTwoPhaseUnlinkFind(dict *d, const void *key, int *table_index) {
+    dictCmpCache cmpCache = {0};
+    uint64_t h, idx, table;
+
+    if (dictSize(d) == 0) return NULL; /* dict is empty */
+    if (dictIsRehashing(d)) _dictRehashStep(d);
+
+    h = dictGetHash(d, key);    
+    keyCmpFunc cmpFunc = dictGetCmpFunc(d);
+
+    for (table = 0; table <= 1; table++) {
+        idx = h & DICTHT_SIZE_MASK(d->ht_size_exp[table]);
+        if (table == 0 && (long)idx < d->rehashidx) continue;
+        dictEntry **ref = &d->ht_table[table][idx];
+        while (ref && *ref) {
+            const void *de_key = dictStoredKey2Key(d, dictGetKey(*ref));
+            if (key == de_key || cmpFunc(&cmpCache, key, de_key)) {
+                *table_index = table;
+                dictPauseRehashing(d);
+                return ref;
+            }
+            ref = dictGetNextLink(*ref);
+        }
+        if (!dictIsRehashing(d)) return NULL;
+    }
+    return NULL;
+}
+
+void dictTwoPhaseUnlinkFree(dict *d, dictEntryLink plink, int table_index) {
+    if (plink == NULL || *plink == NULL) return;
+    dictEntry *de = *plink;
+    d->ht_used[table_index]--;
+
+    *plink = dictGetNext(de);
+    dictFreeKey(d, de);
+    dictFreeVal(d, de);
+    if (!entryIsKey(de)) zfree(decodeMaskedPtr(de));
+    _dictShrinkIfNeeded(d);
+    dictResumeRehashing(d);
+}
+
+void dictSetKey(dict *d, dictEntry* de, void *key __stored_key) {
+    assert(!d->type->no_value);
+    if (d->type->keyDup)
+        de->key = d->type->keyDup(d, key);
+    else
+        de->key = key;
+}
+
+void dictSetVal(dict *d, dictEntry *de, void *val) {
+    assert(entryHasValue(de));
+    de->v.val = d->type->valDup ? d->type->valDup(d, val) : val;
+}
+
+void dictSetSignedIntegerVal(dictEntry *de, int64_t val) {
+    assert(entryHasValue(de));
+    de->v.s64 = val;
+}
+
+void dictSetUnsignedIntegerVal(dictEntry *de, uint64_t val) {
+    assert(entryHasValue(de));
+    de->v.u64 = val;
+}
+
+void dictSetDoubleVal(dictEntry *de, double val) {
+    assert(entryHasValue(de));
+    de->v.d = val;
+}
+
+int64_t dictIncrSignedIntegerVal(dictEntry *de, int64_t val) {
+    assert(entryHasValue(de));
+    return de->v.s64 += val;
+}
+
+uint64_t dictIncrUnsignedIntegerVal(dictEntry *de, uint64_t val) {
+    assert(entryHasValue(de));
+    return de->v.u64 += val;
+}
+
+double dictIncrDoubleVal(dictEntry *de, double val) {
+    assert(entryHasValue(de));
+    return de->v.d += val;
+}
+
+int dictEntryIsKey(const dictEntry *de) {
+    return entryIsKey(de);
+}
+
+void *dictGetKey(const dictEntry *de) {
+    /* if entryIsKey() */
+    if ((uintptr_t)de & ENTRY_PTR_IS_ODD_KEY) return (void *) de;
+    if ((uintptr_t)de & ENTRY_PTR_IS_EVEN_KEY) return decodeMaskedPtr(de);    
+    /* Regular entry */
+    return de->key;
+}
+
+void *dictGetVal(const dictEntry *de) {
+    assert(entryHasValue(de));
+    return de->v.val;
+}
+
+int64_t dictGetSignedIntegerVal(const dictEntry *de) {
+    assert(entryHasValue(de));
+    return de->v.s64;
+}
+
+uint64_t dictGetUnsignedIntegerVal(const dictEntry *de) {
+    assert(entryHasValue(de));
+    return de->v.u64;
+}
+
+double dictGetDoubleVal(const dictEntry *de) {
+    assert(entryHasValue(de));
+    return de->v.d;
+}
+
+/* Returns a mutable reference to the value as a double within the entry. */
+double *dictGetDoubleValPtr(dictEntry *de) {
+    assert(entryHasValue(de));
+    return &de->v.d;
+}
+
+/* Returns the 'next' field of the entry or NULL if the entry doesn't have a
+ * 'next' field. */
+dictEntry *dictGetNext(const dictEntry *de) {
+    if (entryIsKey(de)) return NULL; /* there's no next */
+    /* Must come after entryIsKey() check */
+    return de->next;
+}
+
+/* Returns a pointer to the 'next' field in the entry or NULL if the entry
+ * doesn't have a next field. */
+static dictEntryLink dictGetNextLink(dictEntry *de) {
+    if (entryIsKey(de)) return NULL;
+    /* Must come after entryIsKey() check */
+    return &de->next;
+}
+
+static void dictSetNext(dictEntry *de, dictEntry *next) {
+    assert(!entryIsKey(de));
+    /* dictEntryNoValue & dictEntry are layout-compatible */
+    de->next = next;
+}
+
+/* Returns the memory usage in bytes of the dict, excluding the size of the keys
+ * and values. */
+size_t dictMemUsage(const dict *d) {
+    return dictSize(d) * sizeof(dictEntry) +
+        dictBuckets(d) * sizeof(dictEntry*);
+}
+
+size_t dictEntryMemUsage(int noValueDict) {
+    return (noValueDict) ? sizeof(dictEntryNoValue) :sizeof(dictEntry);
+}
+
+/* A fingerprint is a 64 bit number that represents the state of the dictionary
+ * at a given time, it's just a few dict properties xored together.
+ * When an unsafe iterator is initialized, we get the dict fingerprint, and check
+ * the fingerprint again when the iterator is released.
+ * If the two fingerprints are different it means that the user of the iterator
+ * performed forbidden operations against the dictionary while iterating. */
+unsigned long long dictFingerprint(dict *d) {
+    unsigned long long integers[6], hash = 0;
+    int j;
+
+    integers[0] = (long) d->ht_table[0];
+    integers[1] = d->ht_size_exp[0];
+    integers[2] = d->ht_used[0];
+    integers[3] = (long) d->ht_table[1];
+    integers[4] = d->ht_size_exp[1];
+    integers[5] = d->ht_used[1];
+
+    /* We hash N integers by summing every successive integer with the integer
+     * hashing of the previous sum. Basically:
+     *
+     * Result = hash(hash(hash(int1)+int2)+int3) ...
+     *
+     * This way the same set of integers in a different order will (likely) hash
+     * to a different number. */
+    for (j = 0; j < 6; j++) {
+        hash += integers[j];
+        /* For the hashing step we use Tomas Wang's 64 bit integer hash. */
+        hash = (~hash) + (hash << 21); // hash = (hash << 21) - hash - 1;
+        hash = hash ^ (hash >> 24);
+        hash = (hash + (hash << 3)) + (hash << 8); // hash * 265
+        hash = hash ^ (hash >> 14);
+        hash = (hash + (hash << 2)) + (hash << 4); // hash * 21
+        hash = hash ^ (hash >> 28);
+        hash = hash + (hash << 31);
+    }
+    return hash;
+}
+
+void dictInitIterator(dictIterator *iter, dict *d)
+{
+    iter->d = d;
+    iter->table = 0;
+    iter->index = -1;
+    iter->safe = 0;
+    iter->entry = NULL;
+    iter->nextEntry = NULL;
+}
+
+void dictInitSafeIterator(dictIterator *iter, dict *d)
+{
+    dictInitIterator(iter, d);
+    iter->safe = 1;
+}
+
+void dictResetIterator(dictIterator *iter)
+{
+    if (!(iter->index == -1 && iter->table == 0)) {
+        if (iter->safe)
+            dictResumeRehashing(iter->d);
+        else
+            assert(iter->fingerprint == dictFingerprint(iter->d));
+    }
+}
+
+dictIterator *dictGetIterator(dict *d)
+{
+    dictIterator *iter = zmalloc(sizeof(*iter));
+    dictInitIterator(iter, d);
+    return iter;
+}
+
+dictIterator *dictGetSafeIterator(dict *d) {
+    dictIterator *i = dictGetIterator(d);
+
+    i->safe = 1;
+    return i;
+}
+
+dictEntry *dictNext(dictIterator *iter)
+{
+    while (1) {
+        if (iter->entry == NULL) {
+            if (iter->index == -1 && iter->table == 0) {
+                if (iter->safe)
+                    dictPauseRehashing(iter->d);
+                else
+                    iter->fingerprint = dictFingerprint(iter->d);
+
+                /* skip the rehashed slots in table[0] */
+                if (dictIsRehashing(iter->d)) {
+                    iter->index = iter->d->rehashidx - 1;
+                }
+            }
+            iter->index++;
+            if (iter->index >= (long) DICTHT_SIZE(iter->d->ht_size_exp[iter->table])) {
+                if (dictIsRehashing(iter->d) && iter->table == 0) {
+                    iter->table++;
+                    iter->index = 0;
+                } else {
+                    break;
+                }
+            }
+            iter->entry = iter->d->ht_table[iter->table][iter->index];
+        } else {
+            iter->entry = iter->nextEntry;
+        }
+        if (iter->entry) {
+            /* We need to save the 'next' here, the iterator user
+             * may delete the entry we are returning. */
+            iter->nextEntry = dictGetNext(iter->entry);
+            return iter->entry;
+        }
+    }
+    return NULL;
+}
+
+void dictReleaseIterator(dictIterator *iter)
+{
+    dictResetIterator(iter);
+    zfree(iter);
+}
+
+/* Return a random entry from the hash table. Useful to
+ * implement randomized algorithms */
+dictEntry *dictGetRandomKey(dict *d)
+{
+    dictEntry *he, *orighe;
+    unsigned long h;
+    int listlen, listele;
+
+    if (dictSize(d) == 0) return NULL;
+    if (dictIsRehashing(d)) _dictRehashStep(d);
+    if (dictIsRehashing(d)) {
+        unsigned long s0 = DICTHT_SIZE(d->ht_size_exp[0]);
+        do {
+            /* We are sure there are no elements in indexes from 0
+             * to rehashidx-1 */
+            h = d->rehashidx + (randomULong() % (dictBuckets(d) - d->rehashidx));
+            he = (h >= s0) ? d->ht_table[1][h - s0] : d->ht_table[0][h];
+        } while(he == NULL);
+    } else {
+        unsigned long m = DICTHT_SIZE_MASK(d->ht_size_exp[0]);
+        do {
+            h = randomULong() & m;
+            he = d->ht_table[0][h];
+        } while(he == NULL);
+    }
+
+    /* Now we found a non empty bucket, but it is a linked
+     * list and we need to get a random element from the list.
+     * The only sane way to do so is counting the elements and
+     * select a random index. */
+    listlen = 0;
+    orighe = he;
+    while(he) {
+        he = dictGetNext(he);
+        listlen++;
+    }
+    listele = random() % listlen;
+    he = orighe;
+    while(listele--) he = dictGetNext(he);
+    return he;
+}
+
+/* This function samples the dictionary to return a few keys from random
+ * locations.
+ *
+ * It does not guarantee to return all the keys specified in 'count', nor
+ * it does guarantee to return non-duplicated elements, however it will make
+ * some effort to do both things.
+ *
+ * Returned pointers to hash table entries are stored into 'des' that
+ * points to an array of dictEntry pointers. The array must have room for
+ * at least 'count' elements, that is the argument we pass to the function
+ * to tell how many random elements we need.
+ *
+ * The function returns the number of items stored into 'des', that may
+ * be less than 'count' if the hash table has less than 'count' elements
+ * inside, or if not enough elements were found in a reasonable amount of
+ * steps.
+ *
+ * Note that this function is not suitable when you need a good distribution
+ * of the returned items, but only when you need to "sample" a given number
+ * of continuous elements to run some kind of algorithm or to produce
+ * statistics. However the function is much faster than dictGetRandomKey()
+ * at producing N elements. */
+unsigned int dictGetSomeKeys(dict *d, dictEntry **des, unsigned int count) {
+    unsigned long j; /* internal hash table id, 0 or 1. */
+    unsigned long tables; /* 1 or 2 tables? */
+    unsigned long stored = 0, maxsizemask;
+    unsigned long maxsteps;
+
+    if (dictSize(d) < count) count = dictSize(d);
+    maxsteps = count*10;
+
+    /* Try to do a rehashing work proportional to 'count'. */
+    for (j = 0; j < count; j++) {
+        if (dictIsRehashing(d))
+            _dictRehashStep(d);
+        else
+            break;
+    }
+
+    tables = dictIsRehashing(d) ? 2 : 1;
+    maxsizemask = DICTHT_SIZE_MASK(d->ht_size_exp[0]);
+    if (tables > 1 && maxsizemask < DICTHT_SIZE_MASK(d->ht_size_exp[1]))
+        maxsizemask = DICTHT_SIZE_MASK(d->ht_size_exp[1]);
+
+    /* Pick a random point inside the larger table. */
+    unsigned long i = randomULong() & maxsizemask;
+    unsigned long emptylen = 0; /* Continuous empty entries so far. */
+    while(stored < count && maxsteps--) {
+        for (j = 0; j < tables; j++) {
+            /* Invariant of the dict.c rehashing: up to the indexes already
+             * visited in ht[0] during the rehashing, there are no populated
+             * buckets, so we can skip ht[0] for indexes between 0 and idx-1. */
+            if (tables == 2 && j == 0 && i < (unsigned long) d->rehashidx) {
+                /* Moreover, if we are currently out of range in the second
+                 * table, there will be no elements in both tables up to
+                 * the current rehashing index, so we jump if possible.
+                 * (this happens when going from big to small table). */
+                if (i >= DICTHT_SIZE(d->ht_size_exp[1]))
+                    i = d->rehashidx;
+                else
+                    continue;
+            }
+            if (i >= DICTHT_SIZE(d->ht_size_exp[j])) continue; /* Out of range for this table. */
+            dictEntry *he = d->ht_table[j][i];
+
+            /* Count contiguous empty buckets, and jump to other
+             * locations if they reach 'count' (with a minimum of 5). */
+            if (he == NULL) {
+                emptylen++;
+                if (emptylen >= 5 && emptylen > count) {
+                    i = randomULong() & maxsizemask;
+                    emptylen = 0;
+                }
+            } else {
+                emptylen = 0;
+                while (he) {
+                    /* Collect all the elements of the buckets found non empty while iterating.
+                     * To avoid the issue of being unable to sample the end of a long chain,
+                     * we utilize the Reservoir Sampling algorithm to optimize the sampling process.
+                     * This means that even when the maximum number of samples has been reached,
+                     * we continue sampling until we reach the end of the chain.
+                     * See https://en.wikipedia.org/wiki/Reservoir_sampling. */
+                    if (stored < count) {
+                        des[stored] = he;
+                    } else {
+                        unsigned long r = randomULong() % (stored + 1);
+                        if (r < count) des[r] = he;
+                    }
+
+                    he = dictGetNext(he);
+                    stored++;
+                }
+                if (stored >= count) goto end;
+            }
+        }
+        i = (i+1) & maxsizemask;
+    }
+
+end:
+    return stored > count ? count : stored;
+}
+
+
+/* Reallocate the dictEntry, key and value allocations in a bucket using the
+ * provided allocation functions in order to defrag them. */
+static void dictDefragBucket(dict *d, dictEntry **bucketref, dictDefragFunctions *defragfns) {
+    dictDefragAllocFunction *defragalloc = defragfns->defragAlloc;
+    dictDefragAllocFunction *defragkey = defragfns->defragKey;
+    dictDefragAllocFunction *defragval = defragfns->defragVal;
+    while (bucketref && *bucketref) {
+        dictEntry *de = *bucketref, *newde = NULL;
+        void *newkey = defragkey ? defragkey(dictGetKey(de)) : NULL;
+
+        if (d->type->no_value) {
+            if (entryIsKey(de)) {
+                if (newkey) *bucketref = encodeEntryKey(d, newkey);
+            } else {
+                dictEntryNoValue *entry = decodeEntryNoValue(de), *newentry;
+                if ((newentry = defragalloc(entry))) {
+                    newde = (dictEntry *) newentry;
+                    entry = newentry;
+                }
+                if (newkey) entry->key = newkey;
+            }
+        } else {
+            void *newval = defragval ? defragval(dictGetVal(de)) : NULL;
+            assert(entryIsNormal(de));
+            newde = defragalloc(de);
+            if (newde) de = newde;
+            if (newkey) de->key = newkey;
+            if (newval) de->v.val = newval;
+        }
+        if (newde) {
+            *bucketref = newde;
+        }
+        bucketref = dictGetNextLink(*bucketref);
+    }
+}
+
+/* This is like dictGetRandomKey() from the POV of the API, but will do more
+ * work to ensure a better distribution of the returned element.
+ *
+ * This function improves the distribution because the dictGetRandomKey()
+ * problem is that it selects a random bucket, then it selects a random
+ * element from the chain in the bucket. However elements being in different
+ * chain lengths will have different probabilities of being reported. With
+ * this function instead what we do is to consider a "linear" range of the table
+ * that may be constituted of N buckets with chains of different lengths
+ * appearing one after the other. Then we report a random element in the range.
+ * In this way we smooth away the problem of different chain lengths. */
+#define GETFAIR_NUM_ENTRIES 15
+dictEntry *dictGetFairRandomKey(dict *d) {
+    dictEntry *entries[GETFAIR_NUM_ENTRIES];
+    unsigned int count = dictGetSomeKeys(d,entries,GETFAIR_NUM_ENTRIES);
+    /* Note that dictGetSomeKeys() may return zero elements in an unlucky
+     * run() even if there are actually elements inside the hash table. So
+     * when we get zero, we call the true dictGetRandomKey() that will always
+     * yield the element if the hash table has at least one. */
+    if (count == 0) return dictGetRandomKey(d);
+    unsigned int idx = rand() % count;
+    return entries[idx];
+}
+
+/* Function to reverse bits. Algorithm from:
+ * http://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel */
+static unsigned long rev(unsigned long v) {
+    unsigned long s = CHAR_BIT * sizeof(v); // bit size; must be power of 2
+    unsigned long mask = ~0UL;
+    while ((s >>= 1) > 0) {
+        mask ^= (mask << s);
+        v = ((v >> s) & mask) | ((v << s) & ~mask);
+    }
+    return v;
+}
+
+/* dictScan() is used to iterate over the elements of a dictionary.
+ *
+ * Iterating works the following way:
+ *
+ * 1) Initially you call the function using a cursor (v) value of 0.
+ * 2) The function performs one step of the iteration, and returns the
+ *    new cursor value you must use in the next call.
+ * 3) When the returned cursor is 0, the iteration is complete.
+ *
+ * The function guarantees all elements present in the
+ * dictionary get returned between the start and end of the iteration.
+ * However it is possible some elements get returned multiple times.
+ *
+ * For every element returned, the callback argument 'fn' is
+ * called with 'privdata' as first argument and the dictionary entry
+ * 'de' as second argument.
+ *
+ * HOW IT WORKS.
+ *
+ * The iteration algorithm was designed by Pieter Noordhuis.
+ * The main idea is to increment a cursor starting from the higher order
+ * bits. That is, instead of incrementing the cursor normally, the bits
+ * of the cursor are reversed, then the cursor is incremented, and finally
+ * the bits are reversed again.
+ *
+ * This strategy is needed because the hash table may be resized between
+ * iteration calls.
+ *
+ * dict.c hash tables are always power of two in size, and they
+ * use chaining, so the position of an element in a given table is given
+ * by computing the bitwise AND between Hash(key) and SIZE-1
+ * (where SIZE-1 is always the mask that is equivalent to taking the rest
+ *  of the division between the Hash of the key and SIZE).
+ *
+ * For example if the current hash table size is 16, the mask is
+ * (in binary) 1111. The position of a key in the hash table will always be
+ * the last four bits of the hash output, and so forth.
+ *
+ * WHAT HAPPENS IF THE TABLE CHANGES IN SIZE?
+ *
+ * If the hash table grows, elements can go anywhere in one multiple of
+ * the old bucket: for example let's say we already iterated with
+ * a 4 bit cursor 1100 (the mask is 1111 because hash table size = 16).
+ *
+ * If the hash table will be resized to 64 elements, then the new mask will
+ * be 111111. The new buckets you obtain by substituting in ??1100
+ * with either 0 or 1 can be targeted only by keys we already visited
+ * when scanning the bucket 1100 in the smaller hash table.
+ *
+ * By iterating the higher bits first, because of the inverted counter, the
+ * cursor does not need to restart if the table size gets bigger. It will
+ * continue iterating using cursors without '1100' at the end, and also
+ * without any other combination of the final 4 bits already explored.
+ *
+ * Similarly when the table size shrinks over time, for example going from
+ * 16 to 8, if a combination of the lower three bits (the mask for size 8
+ * is 111) were already completely explored, it would not be visited again
+ * because we are sure we tried, for example, both 0111 and 1111 (all the
+ * variations of the higher bit) so we don't need to test it again.
+ *
+ * WAIT... YOU HAVE *TWO* TABLES DURING REHASHING!
+ *
+ * Yes, this is true, but we always iterate the smaller table first, then
+ * we test all the expansions of the current cursor into the larger
+ * table. For example if the current cursor is 101 and we also have a
+ * larger table of size 16, we also test (0)101 and (1)101 inside the larger
+ * table. This reduces the problem back to having only one table, where
+ * the larger one, if it exists, is just an expansion of the smaller one.
+ *
+ * LIMITATIONS
+ *
+ * This iterator is completely stateless, and this is a huge advantage,
+ * including no additional memory used.
+ *
+ * The disadvantages resulting from this design are:
+ *
+ * 1) It is possible we return elements more than once. However this is usually
+ *    easy to deal with in the application level.
+ * 2) The iterator must return multiple elements per call, as it needs to always
+ *    return all the keys chained in a given bucket, and all the expansions, so
+ *    we are sure we don't miss keys moving during rehashing.
+ * 3) The reverse cursor is somewhat hard to understand at first, but this
+ *    comment is supposed to help.
+ */
+unsigned long dictScan(dict *d,
+                       unsigned long v,
+                       dictScanFunction *fn,
+                       void *privdata)
+{
+    return dictScanDefrag(d, v, fn, NULL, privdata);
+}
+
+void dictScanDefragBucket(dict *d,dictScanFunction *fn,
+                          dictDefragFunctions *defragfns,
+                          void *privdata,
+                          dictEntry **bucketref) {
+    dictEntry **plink, *de, *next;
+
+    /* Emit entries at bucket */
+    if (defragfns) dictDefragBucket(d, bucketref, defragfns);
+
+    de = *bucketref;
+    plink = bucketref;
+    while (de) {
+        next = dictGetNext(de);
+        fn(privdata, de, plink);
+
+        if (!next) break; /* if last element, break */
+
+        /* if `*plink` still pointing to 'de', then it means that the 
+         * visited item wasn't deleted by fn() */
+        if (*plink == de)            
+            plink = &(de->next);
+
+        de = next;
+    }
+}
+
+/* Like dictScan, but additionally reallocates the memory used by the dict
+ * entries using the provided allocation function. This feature was added for
+ * the active defrag feature.
+ *
+ * The 'defragfns' callbacks are called with a pointer to memory that callback
+ * can reallocate. The callbacks should return a new memory address or NULL,
+ * where NULL means that no reallocation happened and the old memory is still
+ * valid. */
+unsigned long dictScanDefrag(dict *d,
+                             unsigned long v,
+                             dictScanFunction *fn,
+                             dictDefragFunctions *defragfns,
+                             void *privdata)
+{
+    int htidx0, htidx1;
+    unsigned long m0, m1;
+
+    if (dictSize(d) == 0) return 0;
+
+    /* This is needed in case the scan callback tries to do dictFind or alike. */
+    dictPauseRehashing(d);
+
+    if (!dictIsRehashing(d)) {
+        htidx0 = 0;
+        m0 = DICTHT_SIZE_MASK(d->ht_size_exp[htidx0]);
+        dictScanDefragBucket(d, fn, defragfns, privdata, &d->ht_table[htidx0][v & m0]);
+
+        /* Set unmasked bits so incrementing the reversed cursor
+         * operates on the masked bits */
+        v |= ~m0;
+
+        /* Increment the reverse cursor */
+        v = rev(v);
+        v++;
+        v = rev(v);
+
+    } else {
+        htidx0 = 0;
+        htidx1 = 1;
+
+        /* Make sure t0 is the smaller and t1 is the bigger table */
+        if (DICTHT_SIZE(d->ht_size_exp[htidx0]) > DICTHT_SIZE(d->ht_size_exp[htidx1])) {
+            htidx0 = 1;
+            htidx1 = 0;
+        }
+
+        m0 = DICTHT_SIZE_MASK(d->ht_size_exp[htidx0]);
+        m1 = DICTHT_SIZE_MASK(d->ht_size_exp[htidx1]);
+
+        dictScanDefragBucket(d, fn, defragfns, privdata, &d->ht_table[htidx0][v & m0]);
+
+        /* Iterate over indices in larger table that are the expansion
+         * of the index pointed to by the cursor in the smaller table */
+        do {
+            dictScanDefragBucket(d, fn, defragfns, privdata, &d->ht_table[htidx1][v & m1]);
+
+            /* Increment the reverse cursor not covered by the smaller mask.*/
+            v |= ~m1;
+            v = rev(v);
+            v++;
+            v = rev(v);
+
+            /* Continue while bits covered by mask difference is non-zero */
+        } while (v & (m0 ^ m1));
+    }
+
+    dictResumeRehashing(d);
+
+    return v;
+}
+
+/* ------------------------- private functions ------------------------------ */
+
+/* Because we may need to allocate huge memory chunk at once when dict
+ * resizes, we will check this allocation is allowed or not if the dict
+ * type has resizeAllowed member function. */
+static int dictTypeResizeAllowed(dict *d, size_t size) {
+    if (d->type->resizeAllowed == NULL) return 1;
+    return d->type->resizeAllowed(
+                    DICTHT_SIZE(_dictNextExp(size)) * sizeof(dictEntry*),
+                    (double)d->ht_used[0] / DICTHT_SIZE(d->ht_size_exp[0]));
+}
+
+/* Returning DICT_OK indicates a successful expand or the dictionary is undergoing rehashing, 
+ * and there is nothing else we need to do about this dictionary currently. While DICT_ERR indicates
+ * that expand has not been triggered (may be try shrinking?)*/
+int dictExpandIfNeeded(dict *d) {
+    /* Incremental rehashing already in progress. Return. */
+    if (dictIsRehashing(d)) return DICT_OK;
+
+    /* If the hash table is empty expand it to the initial size. */
+    if (DICTHT_SIZE(d->ht_size_exp[0]) == 0) {
+        dictExpand(d, DICT_HT_INITIAL_SIZE);
+        return DICT_OK;
+    }
+
+    /* If we reached the 1:1 ratio, and we are allowed to resize the hash
+     * table (global setting) or we should avoid it but the ratio between
+     * elements/buckets is over the "safe" threshold, we resize doubling
+     * the number of buckets. */
+    if ((dict_can_resize == DICT_RESIZE_ENABLE &&
+         d->ht_used[0] >= DICTHT_SIZE(d->ht_size_exp[0])) ||
+        (dict_can_resize != DICT_RESIZE_FORBID &&
+         d->ht_used[0] >= dict_force_resize_ratio * DICTHT_SIZE(d->ht_size_exp[0])))
+    {
+        if (dictTypeResizeAllowed(d, d->ht_used[0] + 1))
+            dictExpand(d, d->ht_used[0] + 1);
+        return DICT_OK;
+    }
+    return DICT_ERR;
+}
+
+/* Expand the hash table if needed (OK=Expanded, ERR=Not expanded) */
+static int _dictExpandIfNeeded(dict *d) {
+    /* Automatic resizing is disallowed. Return */
+    if (d->pauseAutoResize > 0) return DICT_ERR;
+    
+    return dictExpandIfNeeded(d);
+}
+
+/* Returning DICT_OK indicates a successful shrinking or the dictionary is undergoing rehashing, 
+ * and there is nothing else we need to do about this dictionary currently. While DICT_ERR indicates
+ * that shrinking has not been triggered (may be try expanding?)*/
+int dictShrinkIfNeeded(dict *d) {
+    /* Incremental rehashing already in progress. Return. */
+    if (dictIsRehashing(d)) return DICT_OK;
+    
+    /* If the size of hash table is DICT_HT_INITIAL_SIZE, don't shrink it. */
+    if (DICTHT_SIZE(d->ht_size_exp[0]) <= DICT_HT_INITIAL_SIZE) return DICT_OK;
+
+    /* If we reached below 1:8 elements/buckets ratio, and we are allowed to resize
+     * the hash table (global setting) or we should avoid it but the ratio is below 1:32,
+     * we'll trigger a resize of the hash table. */
+    if ((dict_can_resize == DICT_RESIZE_ENABLE &&
+         d->ht_used[0] * HASHTABLE_MIN_FILL <= DICTHT_SIZE(d->ht_size_exp[0])) ||
+        (dict_can_resize != DICT_RESIZE_FORBID &&
+         d->ht_used[0] * HASHTABLE_MIN_FILL * dict_force_resize_ratio <= DICTHT_SIZE(d->ht_size_exp[0])))
+    {
+        if (dictTypeResizeAllowed(d, d->ht_used[0]))
+            dictShrink(d, d->ht_used[0]);
+        return DICT_OK;
+    }
+    return DICT_ERR;
+}
+
+static void _dictShrinkIfNeeded(dict *d) 
+{
+    /* Automatic resizing is disallowed. Return */
+    if (d->pauseAutoResize > 0) return;
+
+    dictShrinkIfNeeded(d);
+}
+
+static void _dictRehashStepIfNeeded(dict *d, uint64_t visitedIdx) {
+    if ((!dictIsRehashing(d)) || (d->pauserehash != 0))
+        return;
+    /* rehashing not in progress if rehashidx == -1 */
+    if ((long)visitedIdx >= d->rehashidx && d->ht_table[0][visitedIdx]) {
+        /* If we have a valid hash entry at `idx` in ht0, we perform
+         * rehash on the bucket at `idx` (being more CPU cache friendly) */
+        _dictBucketRehash(d, visitedIdx);
+    } else {
+        /* If the hash entry is not in ht0, we rehash the buckets based
+         * on the rehashidx (not CPU cache friendly). */
+        dictRehash(d,1);
+    }
+}
+
+/* Our hash table capability is a power of two */
+static signed char _dictNextExp(unsigned long size)
+{
+    if (size <= DICT_HT_INITIAL_SIZE) return DICT_HT_INITIAL_EXP;
+    if (size >= LONG_MAX) return (8*sizeof(long)-1);
+
+    return 8*sizeof(long) - __builtin_clzl(size-1);
+}
+
+/* Finds and returns the link within the dict where the provided key should
+ * be inserted using dictInsertKeyAtLink() if the key does not already exist in
+ * the dict. If the key exists in the dict, NULL is returned and the optional
+ * 'existing' entry pointer is populated, if provided. */
+dictEntryLink dictFindLinkForInsert(dict *d, const void *key, dictEntry **existing) {
+    unsigned long idx, table;
+    dictCmpCache cmpCache = {0};
+    dictEntry *he;
+    uint64_t hash = dictGetHash(d, key);
+    if (existing) *existing = NULL;
+    idx = hash & DICTHT_SIZE_MASK(d->ht_size_exp[0]);
+
+    /* Rehash the hash table if needed */
+    _dictRehashStepIfNeeded(d,idx);
+
+    /* Expand the hash table if needed */
+    _dictExpandIfNeeded(d);
+    keyCmpFunc cmpFunc = dictGetCmpFunc(d);
+
+    for (table = 0; table <= 1; table++) {
+        if (table == 0 && (long)idx < d->rehashidx) continue; 
+        idx = hash & DICTHT_SIZE_MASK(d->ht_size_exp[table]);
+        /* Search if this slot does not already contain the given key */
+        he = d->ht_table[table][idx];
+        while(he) {
+            const void *he_key = dictStoredKey2Key(d, dictGetKey(he));            
+            if (key == he_key || cmpFunc(&cmpCache, key, he_key)) {
+                if (existing) *existing = he;
+                return NULL;
+            }
+            he = dictGetNext(he);
+        }
+        if (!dictIsRehashing(d)) break;
+    }
+
+    /* If we are in the process of rehashing the hash table, the bucket is
+     * always returned in the context of the second (new) hash table. */
+    dictEntry **bucket = &d->ht_table[dictIsRehashing(d) ? 1 : 0][idx];
+    return bucket;
+}
+
+
+void dictEmpty(dict *d, void(callback)(dict*)) {
+    /* Someone may be monitoring a dict that started rehashing, before
+     * destroying the dict fake completion. */
+    if (dictIsRehashing(d) && d->type->rehashingCompleted)
+        d->type->rehashingCompleted(d);
+
+    /* Subtract the size of all buckets. */
+    if (d->type->bucketChanged)
+        d->type->bucketChanged(d, -(long long)dictBuckets(d));
+
+    _dictClear(d,0,callback);
+    _dictClear(d,1,callback);
+    d->rehashidx = -1;
+    d->pauserehash = 0;
+    d->pauseAutoResize = 0;
+}
+
+void dictSetResizeEnabled(dictResizeEnable enable) {
+    dict_can_resize = enable;
+}
+
+/* Compiler inlines this for internal calls within dict.c (verified with -O3). */
+uint64_t dictGetHash(dict *d, const void *key) {
+    return d->type->hashFunction(key);
+}
+
+/* Provides the old and new ht size for a given dictionary during rehashing. This method
+ * should only be invoked during initialization/rehashing. */
+void dictRehashingInfo(dict *d, unsigned long long *from_size, unsigned long long *to_size) {
+    /* Invalid method usage if rehashing isn't ongoing. */
+    assert(dictIsRehashing(d));
+    *from_size = DICTHT_SIZE(d->ht_size_exp[0]);
+    *to_size = DICTHT_SIZE(d->ht_size_exp[1]);
+}
+
+/* ------------------------------- Debugging ---------------------------------*/
+#define DICT_STATS_VECTLEN 50
+void dictFreeStats(dictStats *stats) {
+    zfree(stats->clvector);
+    zfree(stats);
+}
+
+void dictCombineStats(dictStats *from, dictStats *into) {
+    into->buckets += from->buckets;
+    into->maxChainLen = (from->maxChainLen > into->maxChainLen) ? from->maxChainLen : into->maxChainLen;
+    into->totalChainLen += from->totalChainLen;
+    into->htSize += from->htSize;
+    into->htUsed += from->htUsed;
+    for (int i = 0; i < DICT_STATS_VECTLEN; i++) {
+        into->clvector[i] += from->clvector[i];
+    }
+}
+
+dictStats *dictGetStatsHt(dict *d, int htidx, int full) {
+    unsigned long *clvector = zcalloc(sizeof(unsigned long) * DICT_STATS_VECTLEN);
+    dictStats *stats = zcalloc(sizeof(dictStats));
+    stats->htidx = htidx;
+    stats->clvector = clvector;
+    stats->htSize = DICTHT_SIZE(d->ht_size_exp[htidx]);
+    stats->htUsed = d->ht_used[htidx];
+    if (!full) return stats;
+    /* Compute stats. */
+    for (unsigned long i = 0; i < DICTHT_SIZE(d->ht_size_exp[htidx]); i++) {
+        dictEntry *he;
+
+        if (d->ht_table[htidx][i] == NULL) {
+            clvector[0]++;
+            continue;
+        }
+        stats->buckets++;
+        /* For each hash entry on this slot... */
+        unsigned long chainlen = 0;
+        he = d->ht_table[htidx][i];
+        while(he) {
+            chainlen++;
+            he = dictGetNext(he);
+        }
+        clvector[(chainlen < DICT_STATS_VECTLEN) ? chainlen : (DICT_STATS_VECTLEN-1)]++;
+        if (chainlen > stats->maxChainLen) stats->maxChainLen = chainlen;
+        stats->totalChainLen += chainlen;
+    }
+
+    return stats;
+}
+
+/* Generates human readable stats. */
+size_t dictGetStatsMsg(char *buf, size_t bufsize, dictStats *stats, int full) {
+    if (stats->htUsed == 0) {
+        return snprintf(buf,bufsize,
+            "Hash table %d stats (%s):\n"
+            "No stats available for empty dictionaries\n",
+            stats->htidx, (stats->htidx == 0) ? "main hash table" : "rehashing target");
+    }
+    size_t l = 0;
+    l += snprintf(buf + l, bufsize - l,
+                  "Hash table %d stats (%s):\n"
+                  " table size: %lu\n"
+                  " number of elements: %lu\n",
+                  stats->htidx, (stats->htidx == 0) ? "main hash table" : "rehashing target",
+                  stats->htSize, stats->htUsed);
+    if (full) {
+        l += snprintf(buf + l, bufsize - l,
+                      " different slots: %lu\n"
+                      " max chain length: %lu\n"
+                      " avg chain length (counted): %.02f\n"
+                      " avg chain length (computed): %.02f\n"
+                      " Chain length distribution:\n",
+                      stats->buckets, stats->maxChainLen,
+                      (float) stats->totalChainLen / stats->buckets, (float) stats->htUsed / stats->buckets);
+
+        for (unsigned long i = 0; i < DICT_STATS_VECTLEN - 1; i++) {
+            if (stats->clvector[i] == 0) continue;
+            if (l >= bufsize) break;
+            l += snprintf(buf + l, bufsize - l,
+                          "   %ld: %ld (%.02f%%)\n",
+                          i, stats->clvector[i], ((float) stats->clvector[i] / stats->htSize) * 100);
+        }
+    }
+
+    /* Make sure there is a NULL term at the end. */
+    buf[bufsize-1] = '\0';
+    /* Unlike snprintf(), return the number of characters actually written. */
+    return strlen(buf);
+}
+
+void dictGetStats(char *buf, size_t bufsize, dict *d, int full) {
+    size_t l;
+    char *orig_buf = buf;
+    size_t orig_bufsize = bufsize;
+
+    dictStats *mainHtStats = dictGetStatsHt(d, 0, full);
+    l = dictGetStatsMsg(buf, bufsize, mainHtStats, full);
+    dictFreeStats(mainHtStats);
+    buf += l;
+    bufsize -= l;
+    if (dictIsRehashing(d) && bufsize > 0) {
+        dictStats *rehashHtStats = dictGetStatsHt(d, 1, full);
+        dictGetStatsMsg(buf, bufsize, rehashHtStats, full);
+        dictFreeStats(rehashHtStats);
+    }
+    /* Make sure there is a NULL term at the end. */
+    orig_buf[orig_bufsize-1] = '\0';
+}
+
+static int dictDefaultCompare(dictCmpCache *cache, const void *key1, const void *key2) {
+    (void)(cache); /*unused*/
+    return key1 == key2;
+}
+
+/* ------------------------------- Benchmark ---------------------------------*/
+
+#ifdef REDIS_TEST
+#include "testhelp.h"
+
+#define UNUSED(V) ((void) V)
+#define TEST(name) printf("test — %s\n", name);
+
+uint64_t hashCallback(const void *key) {
+    return dictGenHashFunction((unsigned char*)key, strlen((char*)key));
+}
+
+int compareCallback(dictCmpCache *cache, const void *key1, const void *key2) {
+    int l1,l2;
+    UNUSED(cache);
+
+    l1 = strlen((char*)key1);
+    l2 = strlen((char*)key2);
+    if (l1 != l2) return 0;
+    return memcmp(key1, key2, l1) == 0;
+}
+
+void freeCallback(dict *d, void *val) {
+    UNUSED(d);
+
+    zfree(val);
+}
+
+char *stringFromLongLong(long long value) {
+    char buf[32];
+    int len;
+    char *s;
+
+    len = snprintf(buf,sizeof(buf),"%lld",value);
+    s = zmalloc(len+1);
+    memcpy(s, buf, len);
+    s[len] = '\0';
+    return s;
+}
+
+char *stringFromSubstring(void) {
+    #define LARGE_STRING_SIZE 10000
+    #define MIN_STRING_SIZE 100
+    #define MAX_STRING_SIZE 500
+    static char largeString[LARGE_STRING_SIZE + 1];
+    static int init = 0;
+    if (init == 0) {
+        /* Generate a large string */
+        for (size_t i = 0; i < LARGE_STRING_SIZE; i++) {
+            /* Random printable ASCII character (33 to 126) */
+            largeString[i] = 33 + (rand() % 94);
+        }
+        /* Null-terminate the large string */
+        largeString[LARGE_STRING_SIZE] = '\0';
+        init = 1;
+    }
+    /* Randomly choose a size between minSize and maxSize */
+    size_t substringSize = MIN_STRING_SIZE + (rand() % (MAX_STRING_SIZE - MIN_STRING_SIZE + 1));
+    size_t startIndex = rand() % (LARGE_STRING_SIZE - substringSize + 1);
+    /* Allocate memory for the substring (+1 for null terminator) */
+    char *s = zmalloc(substringSize + 1);
+    memcpy(s, largeString + startIndex, substringSize); // Copy the substring
+    s[substringSize] = '\0'; // Null-terminate the string
+    return s;
+}
+
+dictType BenchmarkDictType = {
+    hashCallback,
+    NULL,
+    NULL,
+    compareCallback,
+    freeCallback,
+    NULL,
+    NULL
+};
+
+#define start_benchmark() start = timeInMilliseconds()
+#define end_benchmark(msg) do { \
+    elapsed = timeInMilliseconds()-start; \
+    printf(msg ": %ld items in %lld ms\n", count, elapsed); \
+} while(0)
+
+/* ./redis-server test dict [<count> | --accurate] */
+int dictTest(int argc, char **argv, int flags) {
+    long j;
+    long long start, elapsed;
+    int retval;
+    dict *d = dictCreate(&BenchmarkDictType);
+    dictEntry* de = NULL;
+    dictEntry* existing = NULL;
+    long count = 0;
+    unsigned long new_dict_size, current_dict_used, remain_keys;
+    int accurate = (flags & REDIS_TEST_ACCURATE);
+
+    if (argc == 4) {
+        if (accurate) {
+            count = 5000000;
+        } else {
+            count = strtol(argv[3],NULL,10);
+        }
+    } else {
+        count = 5000;
+    }
+
+    TEST("Add 16 keys and verify dict resize is ok") {
+        dictSetResizeEnabled(DICT_RESIZE_ENABLE);
+        for (j = 0; j < 16; j++) {
+            retval = dictAdd(d,stringFromLongLong(j),(void*)j);
+            assert(retval == DICT_OK);
+        }
+        while (dictIsRehashing(d)) dictRehashMicroseconds(d,1000);
+        assert(dictSize(d) == 16);
+        assert(dictBuckets(d) == 16);
+    }
+
+    TEST("Use DICT_RESIZE_AVOID to disable the dict resize and pad to (dict_force_resize_ratio * 16)") {
+        /* Use DICT_RESIZE_AVOID to disable the dict resize, and pad
+         * the number of keys to (dict_force_resize_ratio * 16), so we can satisfy
+         * dict_force_resize_ratio in next test. */
+        dictSetResizeEnabled(DICT_RESIZE_AVOID);
+        for (j = 16; j < (long)dict_force_resize_ratio * 16; j++) {
+            retval = dictAdd(d,stringFromLongLong(j),(void*)j);
+            assert(retval == DICT_OK);
+        }
+        current_dict_used = dict_force_resize_ratio * 16;
+        assert(dictSize(d) == current_dict_used);
+        assert(dictBuckets(d) == 16);
+    }
+
+    TEST("Add one more key, trigger the dict resize") {
+        retval = dictAdd(d,stringFromLongLong(current_dict_used),(void*)(current_dict_used));
+        assert(retval == DICT_OK);
+        current_dict_used++;
+        new_dict_size = 1UL << _dictNextExp(current_dict_used);
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == 16);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == new_dict_size);
+
+        /* Wait for rehashing. */
+        dictSetResizeEnabled(DICT_RESIZE_ENABLE);
+        while (dictIsRehashing(d)) dictRehashMicroseconds(d,1000);
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == new_dict_size);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == 0);
+    }
+
+    TEST("Delete keys until we can trigger shrink in next test") {
+        /* Delete keys until we can satisfy (1 / HASHTABLE_MIN_FILL) in the next test. */
+        for (j = new_dict_size / HASHTABLE_MIN_FILL + 1; j < (long)current_dict_used; j++) {
+            char *key = stringFromLongLong(j);
+            retval = dictDelete(d, key);
+            zfree(key);
+            assert(retval == DICT_OK);
+        }
+        current_dict_used = new_dict_size / HASHTABLE_MIN_FILL + 1;
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == new_dict_size);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == 0);
+    }
+
+    TEST("Delete one more key, trigger the dict resize") {
+        current_dict_used--;
+        char *key = stringFromLongLong(current_dict_used);
+        retval = dictDelete(d, key);
+        zfree(key);
+        unsigned long oldDictSize = new_dict_size;
+        new_dict_size = 1UL << _dictNextExp(current_dict_used);
+        assert(retval == DICT_OK);
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == oldDictSize);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == new_dict_size);
+
+        /* Wait for rehashing. */
+        while (dictIsRehashing(d)) dictRehashMicroseconds(d,1000);
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == new_dict_size);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == 0);
+    }
+
+    TEST("Empty the dictionary and add 128 keys") {
+        dictEmpty(d, NULL);
+        for (j = 0; j < 128; j++) {
+            retval = dictAdd(d,stringFromLongLong(j),(void*)j);
+            assert(retval == DICT_OK);
+        }
+        while (dictIsRehashing(d)) dictRehashMicroseconds(d,1000);
+        assert(dictSize(d) == 128);
+        assert(dictBuckets(d) == 128);
+    }
+
+    TEST("Use DICT_RESIZE_AVOID to disable the dict resize and reduce to 3") {
+        /* Use DICT_RESIZE_AVOID to disable the dict reset, and reduce
+         * the number of keys until we can trigger shrinking in next test. */
+        dictSetResizeEnabled(DICT_RESIZE_AVOID);
+        remain_keys = DICTHT_SIZE(d->ht_size_exp[0]) / (HASHTABLE_MIN_FILL * dict_force_resize_ratio) + 1;
+        for (j = remain_keys; j < 128; j++) {
+            char *key = stringFromLongLong(j);
+            retval = dictDelete(d, key);
+            zfree(key);
+            assert(retval == DICT_OK);
+        }
+        current_dict_used = remain_keys;
+        assert(dictSize(d) == remain_keys);
+        assert(dictBuckets(d) == 128);
+    }
+
+    TEST("Delete one more key, trigger the dict resize") {
+        current_dict_used--;
+        char *key = stringFromLongLong(current_dict_used);
+        retval = dictDelete(d, key);
+        zfree(key);
+        new_dict_size = 1UL << _dictNextExp(current_dict_used);
+        assert(retval == DICT_OK);
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == 128);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == new_dict_size);
+
+        /* Wait for rehashing. */
+        dictSetResizeEnabled(DICT_RESIZE_ENABLE);
+        while (dictIsRehashing(d)) dictRehashMicroseconds(d,1000);
+        assert(dictSize(d) == current_dict_used);
+        assert(DICTHT_SIZE(d->ht_size_exp[0]) == new_dict_size);
+        assert(DICTHT_SIZE(d->ht_size_exp[1]) == 0);
+    }
+
+    TEST("Restore to original state") {
+        dictEmpty(d, NULL);
+        dictSetResizeEnabled(DICT_RESIZE_ENABLE);
+    }
+    srand(12345);
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        /* Create a dynamically allocated substring */
+        char *key = stringFromSubstring();
+
+        /* Insert the range directly from the large string */
+        de = dictAddRaw(d, key, &existing);
+        assert(de != NULL || existing != NULL);
+        /* If key already exists NULL is returned so we need to free the temp key string */
+        if (de == NULL) zfree(key);
+    }
+    end_benchmark("Inserting random substrings (100-500B) from large string with symbols");
+    assert((long)dictSize(d) <= count);
+    dictEmpty(d, NULL);
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        retval = dictAdd(d,stringFromLongLong(j),(void*)j);
+        assert(retval == DICT_OK);
+    }
+    end_benchmark("Inserting via dictAdd() non existing");
+    assert((long)dictSize(d) == count);
+
+    dictEmpty(d, NULL);
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        de = dictAddRaw(d,stringFromLongLong(j),NULL);
+        assert(de != NULL);
+    }
+    end_benchmark("Inserting via dictAddRaw() non existing");
+    assert((long)dictSize(d) == count);
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        void *key = stringFromLongLong(j);
+        de = dictAddRaw(d,key,&existing);
+        assert(existing != NULL);
+        zfree(key);
+    }
+    end_benchmark("Inserting via dictAddRaw() existing (no insertion)");
+    assert((long)dictSize(d) == count);
+
+    /* Wait for rehashing. */
+    while (dictIsRehashing(d)) {
+        dictRehashMicroseconds(d,100*1000);
+    }
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        char *key = stringFromLongLong(j);
+        dictEntry *de = dictFind(d,key);
+        assert(de != NULL);
+        zfree(key);
+    }
+    end_benchmark("Linear access of existing elements");
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        char *key = stringFromLongLong(j);
+        dictEntry *de = dictFind(d,key);
+        assert(de != NULL);
+        zfree(key);
+    }
+    end_benchmark("Linear access of existing elements (2nd round)");
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        char *key = stringFromLongLong(rand() % count);
+        dictEntry *de = dictFind(d,key);
+        assert(de != NULL);
+        zfree(key);
+    }
+    end_benchmark("Random access of existing elements");
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        dictEntry *de = dictGetRandomKey(d);
+        assert(de != NULL);
+    }
+    end_benchmark("Accessing random keys");
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        char *key = stringFromLongLong(rand() % count);
+        key[0] = 'X';
+        dictEntry *de = dictFind(d,key);
+        assert(de == NULL);
+        zfree(key);
+    }
+    end_benchmark("Accessing missing");
+
+    start_benchmark();
+    for (j = 0; j < count; j++) {
+        char *key = stringFromLongLong(j);
+        retval = dictDelete(d,key);
+        assert(retval == DICT_OK);
+        key[0] += 17; /* Change first number to letter. */
+        retval = dictAdd(d,key,(void*)j);
+        assert(retval == DICT_OK);
+    }
+    end_benchmark("Removing and adding");
+    dictRelease(d);
+
+    TEST("Use dict without values (no_value=1)") {
+        dictType dt = BenchmarkDictType;
+        dt.no_value = 1;
+
+        /* Allocate array of size count and fill it with keys (stringFromLongLong(j) */
+        char **lookupKeys = zmalloc(sizeof(char*) * count);
+        for (long j = 0; j < count; j++)
+            lookupKeys[j] = stringFromLongLong(j);
+
+
+        /* Add keys without values. */
+        dict *d = dictCreate(&dt);
+        for (j = 0; j < count; j++) {
+            retval = dictAdd(d,lookupKeys[j],NULL);
+            assert(retval == DICT_OK);
+        }
+
+        /* Now, we should be able to find the keys. */
+        for (j = 0; j < count; j++) {
+            dictEntry *de = dictFind(d,lookupKeys[j]);
+            assert(de != NULL);
+        }
+
+        /* Find non exists keys. */
+        for (j = 0; j < count; j++) {
+            /* Temporarily override first char of key */
+            char tmp = lookupKeys[j][0];
+            lookupKeys[j][0] = 'X';
+            dictEntry *de = dictFind(d,lookupKeys[j]);
+            lookupKeys[j][0] = tmp;
+            assert(de == NULL);
+        }
+
+        dictRelease(d);
+        zfree(lookupKeys);
+    }
+
+    TEST("Test dictFindLink() functionality") {
+        dictType dt = BenchmarkDictType;
+        dict *d = dictCreate(&dt);
+        
+        /* find in empty dict */
+        dictEntryLink link = dictFindLink(d, "key", NULL);
+        assert(link == NULL);
+
+        /* Add keys to dict and test */
+        for (j = 0; j < 10; j++) {
+            /* Add another key to dict */
+            char *key = stringFromLongLong(j);
+            retval = dictAdd(d, key, (void*)j);
+            assert(retval == DICT_OK);
+            /* find existing keys with dictFindLink() */
+            dictEntryLink link = dictFindLink(d, key, NULL);
+            assert(link != NULL);
+            assert(*link != NULL);
+            assert(dictGetKey(*link) != NULL);
+            
+            /* Test that the key found is the correct one */
+            void *foundKey = dictGetKey(*link);
+            assert(compareCallback( NULL, foundKey, key));
+
+            /* Test finding a non-existing key */
+            char *nonExistingKey = stringFromLongLong(j + 10);
+            link = dictFindLink(d, nonExistingKey, NULL);
+            assert(link == NULL);
+
+            /* Test with bucket parameter */
+            dictEntryLink bucket = NULL;
+            link = dictFindLink(d, key, &bucket);
+            assert(link != NULL);
+            assert(bucket != NULL);
+
+            /* Test bucket parameter with non-existing key */
+            link = dictFindLink(d, nonExistingKey, &bucket);
+            assert(link == NULL);
+            assert(bucket != NULL); /* Bucket should still be set even for non-existing keys */
+
+            /* Clean up */
+            zfree(nonExistingKey);
+        }
+
+        dictRelease(d);
+    }
+
+    return 0;
+}
+#endif