1 files changed, 1217 insertions, 0 deletions

diff --git a/examples/redis-unstable/src/zmalloc.c b/examples/redis-unstable/src/zmalloc.c
new file mode 100644
index 0000000..21d5749
--- /dev/null
+++ b/examples/redis-unstable/src/zmalloc.c
@@ -0,0 +1,1217 @@
+/* zmalloc - total amount of allocated memory aware version of malloc()
+ *
+ * Copyright (c) 2009-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 "config.h"
+#include "solarisfixes.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#ifdef __linux__
+#include <sys/mman.h>
+#endif
+
+/* This function provide us access to the original libc free(). This is useful
+ * for instance to free results obtained by backtrace_symbols(). We need
+ * to define this function before including zmalloc.h that may shadow the
+ * free implementation if we use jemalloc or another non standard allocator. */
+void zlibc_free(void *ptr) {
+    free(ptr);
+}
+
+#include <string.h>
+#include "zmalloc.h"
+#include "atomicvar.h"
+#include "redisassert.h"
+
+#define UNUSED(x) ((void)(x))
+
+#ifdef HAVE_MALLOC_SIZE
+#define PREFIX_SIZE (0)
+#else
+/* Use at least 8 bytes alignment on all systems. */
+#if SIZE_MAX < 0xffffffffffffffffull
+#define PREFIX_SIZE 8
+#else
+#define PREFIX_SIZE (sizeof(size_t))
+#endif
+#endif
+
+/* When using the libc allocator, use a minimum allocation size to match the
+ * jemalloc behavior that doesn't return NULL in this case.
+ */
+#define MALLOC_MIN_SIZE(x) ((x) > 0 ? (x) : sizeof(long))
+
+/* Explicitly override malloc/free etc when using tcmalloc. */
+#if defined(USE_TCMALLOC)
+#define malloc(size) tc_malloc(size)
+#define calloc(count,size) tc_calloc(count,size)
+#define realloc(ptr,size) tc_realloc(ptr,size)
+#define free(ptr) tc_free(ptr)
+/* Explicitly override malloc/free etc when using jemalloc. */
+#elif defined(USE_JEMALLOC)
+#define malloc(size) je_malloc(size)
+#define calloc(count,size) je_calloc(count,size)
+#define realloc(ptr,size) je_realloc(ptr,size)
+#define free(ptr) je_free(ptr)
+#define mallocx(size,flags) je_mallocx(size,flags)
+#define rallocx(ptr,size,flags) je_rallocx(ptr,size,flags)
+#define dallocx(ptr,flags) je_dallocx(ptr,flags)
+#if defined(HAVE_ALLOC_WITH_USIZE)
+void *je_malloc_with_usize(size_t size, size_t *usize);
+void *je_calloc_with_usize(size_t num, size_t size, size_t *usize);
+void *je_realloc_with_usize(void *ptr, size_t size, size_t *old_usize, size_t *new_usize);
+void je_free_with_usize(void *ptr, size_t *usize);
+#define malloc_with_usize(size,usize) je_malloc_with_usize(size,usize)
+#define calloc_with_usize(num,size,usize) je_calloc_with_usize(num,size,usize)
+#define realloc_with_usize(ptr,size,old_usize,new_usize) je_realloc_with_usize(ptr,size,old_usize,new_usize)
+#define free_with_usize(ptr,usize) je_free_with_usize(ptr,usize)
+#endif
+#endif
+
+#define MAX_THREADS 16 /* Keep it a power of 2 so we can use '&' instead of '%'. */
+#define THREAD_MASK (MAX_THREADS - 1)
+#define PEAK_CHECK_THRESHOLD (1024 * 100) /* 100KB */
+
+typedef struct used_memory_entry {
+    redisAtomic long long used_memory;
+    redisAtomic long long last_peak_check;
+    char padding[CACHE_LINE_SIZE - sizeof(long long) - sizeof(long long)];
+} used_memory_entry;
+
+static __attribute__((aligned(CACHE_LINE_SIZE))) used_memory_entry used_memory[MAX_THREADS];
+static redisAtomic size_t num_active_threads = 0;
+static redisAtomic size_t zmalloc_peak = 0;
+static redisAtomic time_t zmalloc_peak_time = 0;
+static __thread long my_thread_index = -1;
+
+static inline void init_my_thread_index(void) {
+    if (unlikely(my_thread_index == -1)) {
+        atomicGetIncr(num_active_threads, my_thread_index, 1);
+        my_thread_index &= THREAD_MASK;
+    }
+}
+
+static void update_zmalloc_stat_alloc(long long bytes_delta) {
+    init_my_thread_index();
+
+    /* Per-thread allocation counter and the last counter value at which we ran a
+     * global peak check (throttles how often we call zmalloc_used_memory()). */
+    long long thread_used, thread_last_peak_check_used;
+    atomicIncrGet(used_memory[my_thread_index].used_memory, thread_used, bytes_delta);
+    atomicGet(used_memory[my_thread_index].last_peak_check, thread_last_peak_check_used);
+
+    /* Only run the (expensive) global used/peak check after this thread's
+     * allocation counter has advanced enough since the last check. */
+    if (unlikely(thread_used - thread_last_peak_check_used > PEAK_CHECK_THRESHOLD)) {
+        /* Snapshot of global used memory across all threads. */
+        size_t used_mem = zmalloc_used_memory();
+
+        /* Current published global peak. */
+        size_t published_peak;
+        atomicGet(zmalloc_peak, published_peak);
+
+        if (used_mem > published_peak) {
+            /* Try to publish `used_mem` as the new global peak.
+             *
+             * Another thread may update `zmalloc_peak` concurrently. Use a CAS loop:
+             * on failure, `old_peak` is refreshed with the latest peak value, and we
+             * retry only while our snapshot still exceeds it. */
+            size_t old_peak = published_peak;
+            while (used_mem > old_peak && !atomicCompareExchange(size_t, zmalloc_peak, old_peak, used_mem)) {
+                /* CAS failed: `old_peak` now holds the current `zmalloc_peak`. */
+            }
+
+            /* If we raised the peak, record when it was reached. */
+            if (used_mem > old_peak) {
+                atomicSet(zmalloc_peak_time, time(NULL));
+            }
+        }
+
+        /* Record the thread counter value at which we last ran a global peak check,
+         * to throttle future checks for this thread. */
+        atomicSet(used_memory[my_thread_index].last_peak_check, thread_used);
+    }
+}
+
+static void update_zmalloc_stat_free(long long num) {
+    init_my_thread_index();
+    atomicDecr(used_memory[my_thread_index].used_memory, num);
+}
+
+static void zmalloc_default_oom(size_t size) {
+    fprintf(stderr, "zmalloc: Out of memory trying to allocate %zu bytes\n",
+        size);
+    fflush(stderr);
+    abort();
+}
+
+static void (*zmalloc_oom_handler)(size_t) = zmalloc_default_oom;
+
+#ifdef HAVE_MALLOC_SIZE
+void *extend_to_usable(void *ptr, size_t size) {
+    UNUSED(size);
+    return ptr;
+}
+#endif
+
+/* Try allocating memory, and return NULL if failed.
+ * '*usable' is set to the usable size if non NULL. */
+static inline void *ztrymalloc_usable_internal(size_t size, size_t *usable) {
+    /* Possible overflow, return NULL, so that the caller can panic or handle a failed allocation. */
+    if (size >= SIZE_MAX/2) return NULL;
+#ifdef HAVE_ALLOC_WITH_USIZE
+    void *ptr = malloc_with_usize(MALLOC_MIN_SIZE(size)+PREFIX_SIZE, &size);
+#else
+    void *ptr = malloc(MALLOC_MIN_SIZE(size)+PREFIX_SIZE);
+#endif
+    if (!ptr) return NULL;
+#ifdef HAVE_ALLOC_WITH_USIZE
+    update_zmalloc_stat_alloc(size);
+    if (usable) *usable = size;
+    return ptr;
+#elif HAVE_MALLOC_SIZE
+    size = zmalloc_size(ptr);
+    update_zmalloc_stat_alloc(size);
+    if (usable) *usable = size;
+    return ptr;
+#else
+    size = MALLOC_MIN_SIZE(size);
+    *((size_t*)ptr) = size;
+    update_zmalloc_stat_alloc(size+PREFIX_SIZE);
+    if (usable) *usable = size;
+    return (char*)ptr+PREFIX_SIZE;
+#endif
+}
+
+void *ztrymalloc_usable(size_t size, size_t *usable) {
+    size_t usable_size = 0;
+    void *ptr = ztrymalloc_usable_internal(size, &usable_size);
+#ifdef HAVE_MALLOC_SIZE
+    ptr = extend_to_usable(ptr, usable_size);
+#endif
+    if (usable) *usable = usable_size;
+    return ptr;
+}
+
+/* Allocate memory or panic */
+void *zmalloc(size_t size) {
+    void *ptr = ztrymalloc_usable_internal(size, NULL);
+    if (!ptr) zmalloc_oom_handler(size);
+    return ptr;
+}
+
+/* Try allocating memory, and return NULL if failed. */
+void *ztrymalloc(size_t size) {
+    void *ptr = ztrymalloc_usable_internal(size, NULL);
+    return ptr;
+}
+
+/* Allocate memory or panic.
+ * '*usable' is set to the usable size if non NULL. */
+void *zmalloc_usable(size_t size, size_t *usable) {
+    size_t usable_size = 0;
+    void *ptr = ztrymalloc_usable_internal(size, &usable_size);
+    if (!ptr) zmalloc_oom_handler(size);
+#ifdef HAVE_MALLOC_SIZE
+    if (ptr) ptr = extend_to_usable(ptr, usable_size);
+#endif
+    if (usable) *usable = usable_size;
+    return ptr;
+}
+
+#if defined(USE_JEMALLOC)
+void *zmalloc_with_flags(size_t size, int flags) {
+    if (size >= SIZE_MAX/2) zmalloc_oom_handler(size);
+    void *ptr = mallocx(size+PREFIX_SIZE, flags);
+    if (!ptr) zmalloc_oom_handler(size);
+    update_zmalloc_stat_alloc(zmalloc_size(ptr));
+    return ptr;
+}
+
+void *zrealloc_with_flags(void *ptr, size_t size, int flags) {
+    /* Not allocating anything, just redirect to free. */
+    if (size == 0 && ptr != NULL) {
+        zfree_with_flags(ptr, flags);
+        return NULL;
+    }
+
+    /* Not freeing anything, just redirect to malloc. */
+    if (ptr == NULL)
+        return zmalloc_with_flags(size, flags);
+
+    /* Possible overflow, return NULL, so that the caller can panic or handle a failed allocation. */
+    if (size >= SIZE_MAX/2) {
+        zfree_with_flags(ptr, flags);
+        zmalloc_oom_handler(size);
+        return NULL;
+    }
+
+    size_t oldsize = zmalloc_size(ptr);
+    void *newptr = rallocx(ptr, size, flags);
+    if (newptr == NULL) {
+        zmalloc_oom_handler(size);
+        return NULL;
+    }
+
+    update_zmalloc_stat_free(oldsize);
+    size = zmalloc_size(newptr);
+    update_zmalloc_stat_alloc(size);
+    return newptr;
+}
+
+void zfree_with_flags(void *ptr, int flags) {
+    if (ptr == NULL) return;
+    update_zmalloc_stat_free(zmalloc_size(ptr));
+    dallocx(ptr, flags);
+}
+#endif
+
+/* Allocation and free functions that bypass the thread cache
+ * and go straight to the allocator arena bins.
+ * Currently implemented only for jemalloc. Used for online defragmentation. */
+#if (defined(USE_JEMALLOC) && defined(HAVE_DEFRAG))
+void *zmalloc_no_tcache(size_t size) {
+    if (size >= SIZE_MAX/2) zmalloc_oom_handler(size);
+    void *ptr = mallocx(size+PREFIX_SIZE, MALLOCX_TCACHE_NONE);
+    if (!ptr) zmalloc_oom_handler(size);
+    update_zmalloc_stat_alloc(zmalloc_size(ptr));
+    return ptr;
+}
+
+void zfree_no_tcache(void *ptr) {
+    if (ptr == NULL) return;
+    update_zmalloc_stat_free(zmalloc_size(ptr));
+    dallocx(ptr, MALLOCX_TCACHE_NONE);
+}
+#endif
+
+/* Try allocating memory and zero it, and return NULL if failed.
+ * '*usable' is set to the usable size if non NULL. */
+static inline void *ztrycalloc_usable_internal(size_t size, size_t *usable) {
+    /* Possible overflow, return NULL, so that the caller can panic or handle a failed allocation. */
+    if (size >= SIZE_MAX/2) return NULL;
+#ifdef HAVE_ALLOC_WITH_USIZE
+    void *ptr = calloc_with_usize(1, MALLOC_MIN_SIZE(size)+PREFIX_SIZE, &size);
+#else
+    void *ptr = calloc(1, MALLOC_MIN_SIZE(size)+PREFIX_SIZE);
+#endif
+    if (ptr == NULL) return NULL;
+
+#ifdef HAVE_ALLOC_WITH_USIZE
+    update_zmalloc_stat_alloc(size);
+    if (usable) *usable = size;
+    return ptr;
+#elif HAVE_MALLOC_SIZE
+    size = zmalloc_size(ptr);
+    update_zmalloc_stat_alloc(size);
+    if (usable) *usable = size;
+    return ptr;
+#else
+    size = MALLOC_MIN_SIZE(size);
+    *((size_t*)ptr) = size;
+    update_zmalloc_stat_alloc(size+PREFIX_SIZE);
+    if (usable) *usable = size;
+    return (char*)ptr+PREFIX_SIZE;
+#endif
+}
+
+void *ztrycalloc_usable(size_t size, size_t *usable) {
+    size_t usable_size = 0;
+    void *ptr = ztrycalloc_usable_internal(size, &usable_size);
+#ifdef HAVE_MALLOC_SIZE
+    ptr = extend_to_usable(ptr, usable_size);
+#endif
+    if (usable) *usable = usable_size;
+    return ptr;
+}
+
+/* Allocate memory and zero it or panic.
+ * We need this wrapper to have a calloc compatible signature */
+void *zcalloc_num(size_t num, size_t size) {
+    /* Ensure that the arguments to calloc(), when multiplied, do not wrap.
+     * Division operations are susceptible to divide-by-zero errors so we also check it. */
+    if ((size == 0) || (num > SIZE_MAX/size)) {
+        zmalloc_oom_handler(SIZE_MAX);
+        return NULL;
+    }
+    void *ptr = ztrycalloc_usable_internal(num*size, NULL);
+    if (!ptr) zmalloc_oom_handler(num*size);
+    return ptr;
+}
+
+/* Allocate memory and zero it or panic */
+void *zcalloc(size_t size) {
+    void *ptr = ztrycalloc_usable_internal(size, NULL);
+    if (!ptr) zmalloc_oom_handler(size);
+    return ptr;
+}
+
+/* Try allocating memory, and return NULL if failed. */
+void *ztrycalloc(size_t size) {
+    void *ptr = ztrycalloc_usable_internal(size, NULL);
+    return ptr;
+}
+
+/* Allocate memory or panic.
+ * '*usable' is set to the usable size if non NULL. */
+void *zcalloc_usable(size_t size, size_t *usable) {
+    size_t usable_size = 0;
+    void *ptr = ztrycalloc_usable_internal(size, &usable_size);
+    if (!ptr) zmalloc_oom_handler(size);
+#ifdef HAVE_MALLOC_SIZE
+    ptr = extend_to_usable(ptr, usable_size);
+#endif
+    if (usable) *usable = usable_size;
+    return ptr;
+}
+
+/* Try reallocating memory, and return NULL if failed.
+ * '*usable' is set to the usable size if non NULL
+ * '*old_usable' is set to the previous usable size if non NULL. */
+static inline void *ztryrealloc_usable_internal(void *ptr, size_t size, size_t *usable, size_t *old_usable) {
+#ifndef HAVE_MALLOC_SIZE
+    void *realptr;
+#endif
+    size_t oldsize, dummy;
+    void *newptr;
+
+    if (!usable) usable = &dummy;
+    if (!old_usable) old_usable = &dummy;
+
+    /* not allocating anything, just redirect to free. */
+    if (size == 0 && ptr != NULL) {
+        zfree_usable(ptr, &oldsize);
+        *usable = 0;
+        *old_usable = oldsize;
+        return NULL;
+    }
+    /* Not freeing anything, just redirect to malloc. */
+    if (ptr == NULL) {
+        *old_usable = 0;
+        return ztrymalloc_usable(size, usable);
+    }
+
+    /* Possible overflow, return NULL, so that the caller can panic or handle a failed allocation. */
+    if (size >= SIZE_MAX/2) {
+        zfree_usable(ptr, &oldsize);
+        *usable = 0;
+        *old_usable = oldsize;
+        return NULL;
+    }
+#ifdef HAVE_ALLOC_WITH_USIZE
+    newptr = realloc_with_usize(ptr, size, &oldsize, &size);
+    if (newptr == NULL) {
+        *usable = 0;
+        *old_usable = oldsize;
+        return NULL;
+    }
+    update_zmalloc_stat_free(oldsize);
+    update_zmalloc_stat_alloc(size);
+    *usable = size;
+    *old_usable = oldsize;
+    return newptr;
+#elif HAVE_MALLOC_SIZE
+    oldsize = zmalloc_size(ptr);
+    newptr = realloc(ptr,size);
+    if (newptr == NULL) {
+        *usable = 0;
+        *old_usable = oldsize;
+        return NULL;
+    }
+
+    update_zmalloc_stat_free(oldsize);
+    size = zmalloc_size(newptr);
+    update_zmalloc_stat_alloc(size);
+    *usable = size;
+    *old_usable = oldsize;
+    return newptr;
+#else
+    realptr = (char*)ptr-PREFIX_SIZE;
+    oldsize = *((size_t*)realptr);
+    newptr = realloc(realptr,size+PREFIX_SIZE);
+    if (newptr == NULL) {
+        *usable = 0;
+        *old_usable = oldsize;
+        return NULL;
+    }
+
+    *((size_t*)newptr) = size;
+    update_zmalloc_stat_free(oldsize);
+    update_zmalloc_stat_alloc(size);
+    *usable = size;
+    *old_usable = oldsize;
+    return (char*)newptr+PREFIX_SIZE;
+#endif
+}
+
+void *ztryrealloc_usable(void *ptr, size_t size, size_t *usable, size_t *old_usable) {
+    size_t usable_size = 0;
+    ptr = ztryrealloc_usable_internal(ptr, size, &usable_size, old_usable);
+#ifdef HAVE_MALLOC_SIZE
+    ptr = extend_to_usable(ptr, usable_size);
+#endif
+    if (usable) *usable = usable_size;
+    return ptr;
+}
+
+/* Reallocate memory and zero it or panic */
+void *zrealloc(void *ptr, size_t size) {
+    ptr = ztryrealloc_usable_internal(ptr, size, NULL, NULL);
+    if (!ptr && size != 0) zmalloc_oom_handler(size);
+    return ptr;
+}
+
+/* Try Reallocating memory, and return NULL if failed. */
+void *ztryrealloc(void *ptr, size_t size) {
+    ptr = ztryrealloc_usable_internal(ptr, size, NULL, NULL);
+    return ptr;
+}
+
+/* Reallocate memory or panic.
+ * '*old_usable' is set to the previous usable size if non NULL
+ * '*usable' is set to the usable size if non NULL. */
+void *zrealloc_usable(void *ptr, size_t size, size_t *usable, size_t *old_usable) {
+    size_t usable_size = 0;
+    ptr = ztryrealloc_usable(ptr, size, &usable_size, old_usable);
+    if (!ptr && size != 0) zmalloc_oom_handler(size);
+#ifdef HAVE_MALLOC_SIZE
+    ptr = extend_to_usable(ptr, usable_size);
+#endif
+    if (usable) *usable = usable_size;
+    return ptr;
+}
+
+/* Provide zmalloc_size() for systems where this function is not provided by
+ * malloc itself, given that in that case we store a header with this
+ * information as the first bytes of every allocation. */
+#ifndef HAVE_MALLOC_SIZE
+size_t zmalloc_size(void *ptr) {
+    void *realptr = (char*)ptr-PREFIX_SIZE;
+    size_t size = *((size_t*)realptr);
+    return size+PREFIX_SIZE;
+}
+size_t zmalloc_usable_size(void *ptr) {
+    return zmalloc_size(ptr)-PREFIX_SIZE;
+}
+#endif
+
+void zfree(void *ptr) {
+    if (ptr == NULL) return;
+
+#ifdef HAVE_ALLOC_WITH_USIZE
+    size_t oldsize;
+    free_with_usize(ptr, &oldsize);
+    update_zmalloc_stat_free(oldsize);
+#elif HAVE_MALLOC_SIZE
+    update_zmalloc_stat_free(zmalloc_size(ptr));
+    free(ptr);
+#else
+    size_t oldsize;
+    void *realptr = (char*)ptr-PREFIX_SIZE;
+    oldsize = *((size_t*)realptr);
+    update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
+    free(realptr);
+#endif
+}
+
+/* Similar to zfree, '*usable' is set to the usable size being freed. */
+void zfree_usable(void *ptr, size_t *usable) {
+    size_t oldsize;
+#ifndef HAVE_MALLOC_SIZE
+    void *realptr;
+#endif
+
+    if (ptr == NULL) {
+        if (usable) *usable = 0;
+        return;
+    }
+
+#ifdef HAVE_ALLOC_WITH_USIZE
+    free_with_usize(ptr, &oldsize);
+    update_zmalloc_stat_free(oldsize);
+#elif HAVE_MALLOC_SIZE
+    update_zmalloc_stat_free(oldsize = zmalloc_size(ptr));
+    free(ptr);
+#else
+    realptr = (char*)ptr-PREFIX_SIZE;
+    oldsize = *((size_t*)realptr);
+    update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
+    free(realptr);
+#endif
+    if (usable) *usable = oldsize;
+}
+
+char *zstrdup_usable(const char *s, size_t *usable) {
+    size_t l = strlen(s)+1;
+    char *p = zmalloc_usable(l, usable);
+
+    memcpy(p,s,l);
+    return p;
+}
+
+char *zstrdup(const char *s) {
+    return zstrdup_usable(s, NULL);
+}
+
+size_t zmalloc_used_memory(void) {
+    size_t local_num_active_threads;
+    long long total_mem = 0;
+    atomicGet(num_active_threads,local_num_active_threads);
+    if (local_num_active_threads > MAX_THREADS) {
+        local_num_active_threads = MAX_THREADS;
+    }
+    for (size_t i = 0; i < local_num_active_threads; ++i) {
+        long long thread_used_mem;
+        atomicGet(used_memory[i].used_memory, thread_used_mem);
+        total_mem += thread_used_mem;
+    }
+    return total_mem;
+}
+
+size_t zmalloc_get_peak_memory(void) {
+    size_t peak;
+    atomicGet(zmalloc_peak, peak);
+    return peak;
+}
+
+time_t zmalloc_get_peak_memory_time(void) {
+    time_t t;
+    atomicGet(zmalloc_peak_time, t);
+    return t;
+}
+
+void zmalloc_set_oom_handler(void (*oom_handler)(size_t)) {
+    zmalloc_oom_handler = oom_handler;
+}
+
+/* Use 'MADV_DONTNEED' to release memory to operating system quickly.
+ * We do that in a fork child process to avoid CoW when the parent modifies
+ * these shared pages. */
+void zmadvise_dontneed(void *ptr) {
+#if defined(USE_JEMALLOC) && defined(__linux__)
+    static size_t page_size = 0;
+    if (page_size == 0) page_size = sysconf(_SC_PAGESIZE);
+    size_t page_size_mask = page_size - 1;
+
+    size_t real_size = zmalloc_size(ptr);
+    if (real_size < page_size) return;
+
+    /* We need to align the pointer upwards according to page size, because
+     * the memory address is increased upwards and we only can free memory
+     * based on page. */
+    char *aligned_ptr = (char *)(((size_t)ptr+page_size_mask) & ~page_size_mask);
+    real_size -= (aligned_ptr-(char*)ptr);
+    if (real_size >= page_size) {
+        madvise((void *)aligned_ptr, real_size&~page_size_mask, MADV_DONTNEED);
+    }
+#else
+    (void)(ptr);
+#endif
+}
+
+/* Get the RSS information in an OS-specific way.
+ *
+ * WARNING: the function zmalloc_get_rss() is not designed to be fast
+ * and may not be called in the busy loops where Redis tries to release
+ * memory expiring or swapping out objects.
+ *
+ * For this kind of "fast RSS reporting" usages use instead the
+ * function RedisEstimateRSS() that is a much faster (and less precise)
+ * version of the function. */
+
+#if defined(HAVE_PROC_STAT)
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#endif
+
+/* Get the i'th field from "/proc/self/stat" note i is 1 based as appears in the 'proc' man page */
+int get_proc_stat_ll(int i, long long *res) {
+#if defined(HAVE_PROC_STAT)
+    char buf[4096];
+    int fd, l;
+    char *p, *x;
+
+    if ((fd = open("/proc/self/stat",O_RDONLY)) == -1) return 0;
+    if ((l = read(fd,buf,sizeof(buf)-1)) <= 0) {
+        close(fd);
+        return 0;
+    }
+    close(fd);
+    buf[l] = '\0';
+    if (buf[l-1] == '\n') buf[l-1] = '\0';
+
+    /* Skip pid and process name (surrounded with parentheses) */
+    p = strrchr(buf, ')');
+    if (!p) return 0;
+    p++;
+    while (*p == ' ') p++;
+    if (*p == '\0') return 0;
+    i -= 3;
+    if (i < 0) return 0;
+
+    while (p && i--) {
+        p = strchr(p, ' ');
+        if (p) p++;
+        else return 0;
+    }
+    x = strchr(p,' ');
+    if (x) *x = '\0';
+
+    *res = strtoll(p,&x,10);
+    if (*x != '\0') return 0;
+    return 1;
+#else
+    UNUSED(i);
+    UNUSED(res);
+    return 0;
+#endif
+}
+
+#if defined(HAVE_PROC_STAT)
+size_t zmalloc_get_rss(void) {
+    int page = sysconf(_SC_PAGESIZE);
+    long long rss;
+
+    /* RSS is the 24th field in /proc/<pid>/stat */
+    if (!get_proc_stat_ll(24, &rss)) return 0;
+    rss *= page;
+    return rss;
+}
+#elif defined(HAVE_TASKINFO)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <mach/task.h>
+#include <mach/mach_init.h>
+
+size_t zmalloc_get_rss(void) {
+    task_t task = MACH_PORT_NULL;
+    struct task_basic_info t_info;
+    mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;
+
+    if (task_for_pid(current_task(), getpid(), &task) != KERN_SUCCESS)
+        return 0;
+    task_info(task, TASK_BASIC_INFO, (task_info_t)&t_info, &t_info_count);
+
+    return t_info.resident_size;
+}
+#elif defined(__FreeBSD__) || defined(__DragonFly__)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+
+size_t zmalloc_get_rss(void) {
+    struct kinfo_proc info;
+    size_t infolen = sizeof(info);
+    int mib[4];
+    mib[0] = CTL_KERN;
+    mib[1] = KERN_PROC;
+    mib[2] = KERN_PROC_PID;
+    mib[3] = getpid();
+
+    if (sysctl(mib, 4, &info, &infolen, NULL, 0) == 0)
+#if defined(__FreeBSD__)
+        return (size_t)info.ki_rssize * getpagesize();
+#else
+        return (size_t)info.kp_vm_rssize * getpagesize();
+#endif
+
+    return 0L;
+}
+#elif defined(__NetBSD__) || defined(__OpenBSD__)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
+#if defined(__OpenBSD__)
+#define kinfo_proc2 kinfo_proc
+#define KERN_PROC2 KERN_PROC
+#define __arraycount(a) (sizeof(a) / sizeof(a[0]))
+#endif
+
+size_t zmalloc_get_rss(void) {
+    struct kinfo_proc2 info;
+    size_t infolen = sizeof(info);
+    int mib[6];
+    mib[0] = CTL_KERN;
+    mib[1] = KERN_PROC2;
+    mib[2] = KERN_PROC_PID;
+    mib[3] = getpid();
+    mib[4] = sizeof(info);
+    mib[5] = 1;
+    if (sysctl(mib, __arraycount(mib), &info, &infolen, NULL, 0) == 0)
+        return (size_t)info.p_vm_rssize * getpagesize();
+
+    return 0L;
+}
+#elif defined(__HAIKU__)
+#include <OS.h>
+
+size_t zmalloc_get_rss(void) {
+    area_info info;
+    thread_info th;
+    size_t rss = 0;
+    ssize_t cookie = 0;
+
+    if (get_thread_info(find_thread(0), &th) != B_OK)
+        return 0;
+
+    while (get_next_area_info(th.team, &cookie, &info) == B_OK)
+        rss += info.ram_size;
+
+    return rss;
+}
+#elif defined(HAVE_PSINFO)
+#include <unistd.h>
+#include <sys/procfs.h>
+#include <fcntl.h>
+
+size_t zmalloc_get_rss(void) {
+    struct prpsinfo info;
+    char filename[256];
+    int fd;
+
+    snprintf(filename,256,"/proc/%ld/psinfo",(long) getpid());
+
+    if ((fd = open(filename,O_RDONLY)) == -1) return 0;
+    if (ioctl(fd, PIOCPSINFO, &info) == -1) {
+        close(fd);
+        return 0;
+    }
+
+    close(fd);
+    return info.pr_rssize;
+}
+#else
+size_t zmalloc_get_rss(void) {
+    /* If we can't get the RSS in an OS-specific way for this system just
+     * return the memory usage we estimated in zmalloc()..
+     *
+     * Fragmentation will appear to be always 1 (no fragmentation)
+     * of course... */
+    return zmalloc_used_memory();
+}
+#endif
+
+#if defined(USE_JEMALLOC)
+
+/* Compute the total memory wasted in fragmentation of inside small arena bins.
+ * Done by summing the memory in unused regs in all slabs of all small bins.
+ *
+ * Pass in arena to get the information of the specified arena, otherwise pass
+ * in MALLCTL_ARENAS_ALL to get all. */
+size_t zmalloc_get_frag_smallbins_by_arena(unsigned int arena) {
+    unsigned nbins;
+    size_t sz, frag = 0;
+
+    /* Pre-convert mallctl paths to MIB for better performance.
+     * This eliminates snprintf and string parsing overhead in the loop. */
+    size_t bin_size_mib[8], bin_nregs_mib[8], curregs_mib[8], curslabs_mib[8];
+    size_t bin_size_miblen = 8, bin_nregs_miblen = 8, curregs_miblen = 8, curslabs_miblen = 8;
+
+    sz = sizeof(unsigned);
+    assert(!je_mallctl("arenas.nbins", &nbins, &sz, NULL, 0));
+
+    /* Convert all patterns to MIB (required before using je_mallctlbymib) */
+    assert(!je_mallctlnametomib("arenas.bin.0.size", bin_size_mib, &bin_size_miblen));
+    assert(!je_mallctlnametomib("arenas.bin.0.nregs", bin_nregs_mib, &bin_nregs_miblen));
+    assert(!je_mallctlnametomib("stats.arenas.0.bins.0.curregs", curregs_mib, &curregs_miblen));
+    assert(!je_mallctlnametomib("stats.arenas.0.bins.0.curslabs", curslabs_mib, &curslabs_miblen));
+
+    for (unsigned j = 0; j < nbins; j++) {
+        size_t curregs, curslabs, reg_size;
+        uint32_t nregs;
+
+        /* The size of the current bin */
+        bin_size_mib[2] = j;
+        sz = sizeof(size_t);
+        assert(!je_mallctlbymib(bin_size_mib, bin_size_miblen, &reg_size, &sz, NULL, 0));
+
+        /* Number of used regions in the bin */
+        curregs_mib[2] = arena;
+        curregs_mib[4] = j;
+        sz = sizeof(size_t);
+        assert(!je_mallctlbymib(curregs_mib, curregs_miblen, &curregs, &sz, NULL, 0));
+
+        /* Number of regions per slab */
+        bin_nregs_mib[2] = j;
+        sz = sizeof(uint32_t);
+        assert(!je_mallctlbymib(bin_nregs_mib, bin_nregs_miblen, &nregs, &sz, NULL, 0));
+
+        /* Number of current slabs in the bin */
+        curslabs_mib[2] = arena;
+        curslabs_mib[4] = j;
+        sz = sizeof(size_t);
+        assert(!je_mallctlbymib(curslabs_mib, curslabs_miblen, &curslabs, &sz, NULL, 0));
+
+        /* Calculate the fragmentation bytes for the current bin and add it to the total. */
+        frag += ((nregs * curslabs) - curregs) * reg_size;
+    }
+
+    return frag;
+}
+
+/* Compute the total memory wasted in fragmentation of inside small arena bins.
+ * Done by summing the memory in unused regs in all slabs of all small bins. */
+size_t zmalloc_get_frag_smallbins(void) {
+    return zmalloc_get_frag_smallbins_by_arena(MALLCTL_ARENAS_ALL);
+}
+
+/* Get memory allocation information from allocator.
+ *
+ * refresh_stats indicates whether to refresh cached statistics.
+ * For the meaning of the other parameters, please refer to the function implementation
+ * and INFO's allocator_* in redis-doc. */
+int zmalloc_get_allocator_info(int refresh_stats, size_t *allocated, size_t *active, size_t *resident,
+                               size_t *retained, size_t *muzzy, size_t *frag_smallbins_bytes)
+{
+    size_t sz;
+    *allocated = *resident = *active = 0;
+
+    /* Update the statistics cached by mallctl. */
+    if (refresh_stats) {
+        uint64_t epoch = 1;
+        sz = sizeof(epoch);
+        je_mallctl("epoch", &epoch, &sz, &epoch, sz);
+    }
+
+    sz = sizeof(size_t);
+    /* Unlike RSS, this does not include RSS from shared libraries and other non
+     * heap mappings. */
+    je_mallctl("stats.resident", resident, &sz, NULL, 0);
+    /* Unlike resident, this doesn't not include the pages jemalloc reserves
+     * for re-use (purge will clean that). */
+    je_mallctl("stats.active", active, &sz, NULL, 0);
+    /* Unlike zmalloc_used_memory, this matches the stats.resident by taking
+     * into account all allocations done by this process (not only zmalloc). */
+    je_mallctl("stats.allocated", allocated, &sz, NULL, 0);
+
+    /* Retained memory is memory released by `madvised(..., MADV_DONTNEED)`, which is not part
+     * of RSS or mapped memory, and doesn't have a strong association with physical memory in the OS.
+     * It is still part of the VM-Size, and may be used again in later allocations. */
+    if (retained) {
+        *retained = 0;
+        je_mallctl("stats.retained", retained, &sz, NULL, 0);
+    }
+
+    /* Unlike retained, Muzzy representats memory released with `madvised(..., MADV_FREE)`.
+     * These pages will show as RSS for the process, until the OS decides to re-use them. */
+    if (muzzy) {
+        char buf[100];
+        size_t pmuzzy, page;
+        snprintf(buf, sizeof(buf), "stats.arenas.%u.pmuzzy", MALLCTL_ARENAS_ALL);
+        assert(!je_mallctl(buf, &pmuzzy, &sz, NULL, 0));
+        assert(!je_mallctl("arenas.page", &page, &sz, NULL, 0));
+        *muzzy = pmuzzy * page;
+    }
+
+    /* Total size of consumed meomry in unused regs in small bins (AKA external fragmentation). */
+    *frag_smallbins_bytes = zmalloc_get_frag_smallbins();
+    return 1;
+}
+
+/* Get the specified arena memory allocation information from allocator.
+ *
+ * refresh_stats indicates whether to refresh cached statistics.
+ * For the meaning of the other parameters, please refer to the function implementation
+ * and INFO's allocator_* in redis-doc. */
+int zmalloc_get_allocator_info_by_arena(unsigned int arena, int refresh_stats, size_t *allocated,
+                                        size_t *active, size_t *resident, size_t *frag_smallbins_bytes)
+{
+    char buf[100];
+    size_t sz;
+    *allocated = *resident = *active = 0;
+
+    /* Update the statistics cached by mallctl. */
+    if (refresh_stats) {
+        uint64_t epoch = 1;
+        sz = sizeof(epoch);
+        je_mallctl("epoch", &epoch, &sz, &epoch, sz);
+    }
+
+    sz = sizeof(size_t);
+    /* Unlike RSS, this does not include RSS from shared libraries and other non
+     * heap mappings. */
+    snprintf(buf, sizeof(buf), "stats.arenas.%u.small.resident", arena);
+    je_mallctl(buf, resident, &sz, NULL, 0);
+    /* Unlike resident, this doesn't not include the pages jemalloc reserves
+     * for re-use (purge will clean that). */
+    size_t pactive, page;
+    snprintf(buf, sizeof(buf), "stats.arenas.%u.pactive", arena);
+    assert(!je_mallctl(buf, &pactive, &sz, NULL, 0));
+    assert(!je_mallctl("arenas.page", &page, &sz, NULL, 0));
+    *active = pactive * page;
+    /* Unlike zmalloc_used_memory, this matches the stats.resident by taking
+     * into account all allocations done by this process (not only zmalloc). */
+    size_t small_allcated, large_allacted;
+    snprintf(buf, sizeof(buf), "stats.arenas.%u.small.allocated", arena);
+    assert(!je_mallctl(buf, &small_allcated, &sz, NULL, 0));
+    *allocated += small_allcated;
+    snprintf(buf, sizeof(buf), "stats.arenas.%u.large.allocated", arena);
+    assert(!je_mallctl(buf, &large_allacted, &sz, NULL, 0));
+    *allocated += large_allacted;
+
+    /* Total size of consumed meomry in unused regs in small bins (AKA external fragmentation). */
+    *frag_smallbins_bytes = zmalloc_get_frag_smallbins_by_arena(arena);
+    return 1;
+}
+
+
+void set_jemalloc_bg_thread(int enable) {
+    /* let jemalloc do purging asynchronously, required when there's no traffic 
+     * after flushdb */
+    char val = !!enable;
+    je_mallctl("background_thread", NULL, 0, &val, 1);
+}
+
+int jemalloc_purge(void) {
+    /* return all unused (reserved) pages to the OS */
+    char tmp[32];
+    unsigned narenas = 0;
+    size_t sz = sizeof(unsigned);
+    if (!je_mallctl("arenas.narenas", &narenas, &sz, NULL, 0)) {
+        snprintf(tmp, sizeof(tmp), "arena.%u.purge", narenas);
+        if (!je_mallctl(tmp, NULL, 0, NULL, 0))
+            return 0;
+    }
+    return -1;
+}
+
+#else
+
+int zmalloc_get_allocator_info(int refresh_stats, size_t *allocated, size_t *active, size_t *resident,
+                               size_t *retained, size_t *muzzy, size_t *frag_smallbins_bytes)
+{
+    UNUSED(refresh_stats);
+    *allocated = *resident = *active = *frag_smallbins_bytes = 0;
+    if (retained) *retained = 0;
+    if (muzzy) *muzzy = 0;
+    return 1;
+}
+
+int zmalloc_get_allocator_info_by_arena(unsigned int arena, int refresh_stats, size_t *allocated,
+                                        size_t *active, size_t *resident, size_t *frag_smallbins_bytes)
+{
+    UNUSED(arena);
+    UNUSED(refresh_stats);
+    *allocated = *resident = *active = *frag_smallbins_bytes = 0;
+    return 1;
+}
+
+
+void set_jemalloc_bg_thread(int enable) {
+    ((void)(enable));
+}
+
+int jemalloc_purge(void) {
+    return 0;
+}
+
+#endif
+
+#if defined(__APPLE__)
+/* For proc_pidinfo() used later in zmalloc_get_smap_bytes_by_field().
+ * Note that this file cannot be included in zmalloc.h because it includes
+ * a Darwin queue.h file where there is a "LIST_HEAD" macro (!) defined
+ * conficting with Redis user code. */
+#include <libproc.h>
+#endif
+
+/* Get the sum of the specified field (converted form kb to bytes) in
+ * /proc/self/smaps. The field must be specified with trailing ":" as it
+ * apperas in the smaps output.
+ *
+ * If a pid is specified, the information is extracted for such a pid,
+ * otherwise if pid is -1 the information is reported is about the
+ * current process.
+ *
+ * Example: zmalloc_get_smap_bytes_by_field("Rss:",-1);
+ */
+#if defined(HAVE_PROC_SMAPS)
+size_t zmalloc_get_smap_bytes_by_field(char *field, long pid) {
+    char line[1024];
+    size_t bytes = 0;
+    int flen = strlen(field);
+    FILE *fp;
+
+    if (pid == -1) {
+        fp = fopen("/proc/self/smaps","r");
+    } else {
+        char filename[128];
+        snprintf(filename,sizeof(filename),"/proc/%ld/smaps",pid);
+        fp = fopen(filename,"r");
+    }
+
+    if (!fp) return 0;
+    while(fgets(line,sizeof(line),fp) != NULL) {
+        if (strncmp(line,field,flen) == 0) {
+            char *p = strchr(line,'k');
+            if (p) {
+                *p = '\0';
+                bytes += strtol(line+flen,NULL,10) * 1024;
+            }
+        }
+    }
+    fclose(fp);
+    return bytes;
+}
+#else
+/* Get sum of the specified field from libproc api call.
+ * As there are per page value basis we need to convert
+ * them accordingly.
+ *
+ * Note that AnonHugePages is a no-op as THP feature
+ * is not supported in this platform
+ */
+size_t zmalloc_get_smap_bytes_by_field(char *field, long pid) {
+#if defined(__APPLE__)
+    struct proc_regioninfo pri;
+    if (pid == -1) pid = getpid();
+    if (proc_pidinfo(pid, PROC_PIDREGIONINFO, 0, &pri,
+                     PROC_PIDREGIONINFO_SIZE) == PROC_PIDREGIONINFO_SIZE)
+    {
+        int pagesize = getpagesize();
+        if (!strcmp(field, "Private_Dirty:")) {
+            return (size_t)pri.pri_pages_dirtied * pagesize;
+        } else if (!strcmp(field, "Rss:")) {
+            return (size_t)pri.pri_pages_resident * pagesize;
+        } else if (!strcmp(field, "AnonHugePages:")) {
+            return 0;
+        }
+    }
+    return 0;
+#endif
+    ((void) field);
+    ((void) pid);
+    return 0;
+}
+#endif
+
+/* Return the total number bytes in pages marked as Private Dirty.
+ *
+ * Note: depending on the platform and memory footprint of the process, this
+ * call can be slow, exceeding 1000ms!
+ */
+size_t zmalloc_get_private_dirty(long pid) {
+    return zmalloc_get_smap_bytes_by_field("Private_Dirty:",pid);
+}
+
+/* Returns the size of physical memory (RAM) in bytes.
+ * It looks ugly, but this is the cleanest way to achieve cross platform results.
+ * Cleaned up from:
+ *
+ * http://nadeausoftware.com/articles/2012/09/c_c_tip_how_get_physical_memory_size_system
+ *
+ * Note that this function:
+ * 1) Was released under the following CC attribution license:
+ *    http://creativecommons.org/licenses/by/3.0/deed.en_US.
+ * 2) Was originally implemented by David Robert Nadeau.
+ * 3) Was modified for Redis by Matt Stancliff.
+ * 4) This note exists in order to comply with the original license.
+ */
+size_t zmalloc_get_memory_size(void) {
+#if defined(__unix__) || defined(__unix) || defined(unix) || \
+    (defined(__APPLE__) && defined(__MACH__))
+#if defined(CTL_HW) && (defined(HW_MEMSIZE) || defined(HW_PHYSMEM64))
+    int mib[2];
+    mib[0] = CTL_HW;
+#if defined(HW_MEMSIZE)
+    mib[1] = HW_MEMSIZE;            /* OSX. --------------------- */
+#elif defined(HW_PHYSMEM64)
+    mib[1] = HW_PHYSMEM64;          /* NetBSD, OpenBSD. --------- */
+#endif
+    int64_t size = 0;               /* 64-bit */
+    size_t len = sizeof(size);
+    if (sysctl( mib, 2, &size, &len, NULL, 0) == 0)
+        return (size_t)size;
+    return 0L;          /* Failed? */
+
+#elif defined(_SC_PHYS_PAGES) && defined(_SC_PAGESIZE)
+    /* FreeBSD, Linux, OpenBSD, and Solaris. -------------------- */
+    return (size_t)sysconf(_SC_PHYS_PAGES) * (size_t)sysconf(_SC_PAGESIZE);
+
+#elif defined(CTL_HW) && (defined(HW_PHYSMEM) || defined(HW_REALMEM))
+    /* DragonFly BSD, FreeBSD, NetBSD, OpenBSD, and OSX. -------- */
+    int mib[2];
+    mib[0] = CTL_HW;
+#if defined(HW_REALMEM)
+    mib[1] = HW_REALMEM;        /* FreeBSD. ----------------- */
+#elif defined(HW_PHYSMEM)
+    mib[1] = HW_PHYSMEM;        /* Others. ------------------ */
+#endif
+    unsigned int size = 0;      /* 32-bit */
+    size_t len = sizeof(size);
+    if (sysctl(mib, 2, &size, &len, NULL, 0) == 0)
+        return (size_t)size;
+    return 0L;          /* Failed? */
+#else
+    return 0L;          /* Unknown method to get the data. */
+#endif
+#else
+    return 0L;          /* Unknown OS. */
+#endif
+}
+
+#ifdef REDIS_TEST
+#include "testhelp.h"
+#include "redisassert.h"
+
+#define TEST(name) printf("test — %s\n", name);
+
+int zmalloc_test(int argc, char **argv, int flags) {
+    void *ptr, *ptr2;
+
+    UNUSED(argc);
+    UNUSED(argv);
+    UNUSED(flags);
+
+    printf("Malloc prefix size: %d\n", (int) PREFIX_SIZE);
+
+    TEST("Initial used memory is 0") {
+        assert(zmalloc_used_memory() == 0);
+    }
+
+    TEST("Allocated 123 bytes") {
+        ptr = zmalloc(123);
+        printf("Allocated 123 bytes; used: %zu\n", zmalloc_used_memory());
+    }
+
+    TEST("Reallocated to 456 bytes") {
+        ptr = zrealloc(ptr, 456);
+        printf("Reallocated to 456 bytes; used: %zu\n", zmalloc_used_memory());
+    }
+
+    TEST("Callocated 123 bytes") {
+        ptr2 = zcalloc(123);
+        printf("Callocated 123 bytes; used: %zu\n", zmalloc_used_memory());
+    }
+
+    TEST("Freed pointers") {
+        zfree(ptr);
+        zfree(ptr2);
+        printf("Freed pointers; used: %zu\n", zmalloc_used_memory());
+    }
+
+    TEST("Allocated 0 bytes") {
+        ptr = zmalloc(0);
+        printf("Allocated 0 bytes; used: %zu\n", zmalloc_used_memory());
+        zfree(ptr);
+    }
+
+    TEST("At the end used memory is 0") {
+        assert(zmalloc_used_memory() == 0);
+    }
+
+    return 0;
+}
+#endif