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Diffstat (limited to 'examples/redis-unstable/src/rax.h')
| -rw-r--r-- | examples/redis-unstable/src/rax.h | 204 |
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diff --git a/examples/redis-unstable/src/rax.h b/examples/redis-unstable/src/rax.h deleted file mode 100644 index db8c463..0000000 --- a/examples/redis-unstable/src/rax.h +++ /dev/null | |||
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| 1 | /* Rax -- A radix tree implementation. | ||
| 2 | * | ||
| 3 | * Copyright (c) 2017-Present, Redis Ltd. | ||
| 4 | * All rights reserved. | ||
| 5 | * | ||
| 6 | * Licensed under your choice of (a) the Redis Source Available License 2.0 | ||
| 7 | * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the | ||
| 8 | * GNU Affero General Public License v3 (AGPLv3). | ||
| 9 | */ | ||
| 10 | |||
| 11 | #ifndef RAX_H | ||
| 12 | #define RAX_H | ||
| 13 | |||
| 14 | #include <stdint.h> | ||
| 15 | |||
| 16 | /* Representation of a radix tree as implemented in this file, that contains | ||
| 17 | * the strings "foo", "foobar" and "footer" after the insertion of each | ||
| 18 | * word. When the node represents a key inside the radix tree, we write it | ||
| 19 | * between [], otherwise it is written between (). | ||
| 20 | * | ||
| 21 | * This is the vanilla representation: | ||
| 22 | * | ||
| 23 | * (f) "" | ||
| 24 | * \ | ||
| 25 | * (o) "f" | ||
| 26 | * \ | ||
| 27 | * (o) "fo" | ||
| 28 | * \ | ||
| 29 | * [t b] "foo" | ||
| 30 | * / \ | ||
| 31 | * "foot" (e) (a) "foob" | ||
| 32 | * / \ | ||
| 33 | * "foote" (r) (r) "fooba" | ||
| 34 | * / \ | ||
| 35 | * "footer" [] [] "foobar" | ||
| 36 | * | ||
| 37 | * However, this implementation implements a very common optimization where | ||
| 38 | * successive nodes having a single child are "compressed" into the node | ||
| 39 | * itself as a string of characters, each representing a next-level child, | ||
| 40 | * and only the link to the node representing the last character node is | ||
| 41 | * provided inside the representation. So the above representation is turned | ||
| 42 | * into: | ||
| 43 | * | ||
| 44 | * ["foo"] "" | ||
| 45 | * | | ||
| 46 | * [t b] "foo" | ||
| 47 | * / \ | ||
| 48 | * "foot" ("er") ("ar") "foob" | ||
| 49 | * / \ | ||
| 50 | * "footer" [] [] "foobar" | ||
| 51 | * | ||
| 52 | * However this optimization makes the implementation a bit more complex. | ||
| 53 | * For instance if a key "first" is added in the above radix tree, a | ||
| 54 | * "node splitting" operation is needed, since the "foo" prefix is no longer | ||
| 55 | * composed of nodes having a single child one after the other. This is the | ||
| 56 | * above tree and the resulting node splitting after this event happens: | ||
| 57 | * | ||
| 58 | * | ||
| 59 | * (f) "" | ||
| 60 | * / | ||
| 61 | * (i o) "f" | ||
| 62 | * / \ | ||
| 63 | * "firs" ("rst") (o) "fo" | ||
| 64 | * / \ | ||
| 65 | * "first" [] [t b] "foo" | ||
| 66 | * / \ | ||
| 67 | * "foot" ("er") ("ar") "foob" | ||
| 68 | * / \ | ||
| 69 | * "footer" [] [] "foobar" | ||
| 70 | * | ||
| 71 | * Similarly after deletion, if a new chain of nodes having a single child | ||
| 72 | * is created (the chain must also not include nodes that represent keys), | ||
| 73 | * it must be compressed back into a single node. | ||
| 74 | * | ||
| 75 | */ | ||
| 76 | |||
| 77 | #define RAX_NODE_MAX_SIZE ((1<<29)-1) | ||
| 78 | typedef struct raxNode { | ||
| 79 | uint32_t iskey:1; /* Does this node contain a key? */ | ||
| 80 | uint32_t isnull:1; /* Associated value is NULL (don't store it). */ | ||
| 81 | uint32_t iscompr:1; /* Node is compressed. */ | ||
| 82 | uint32_t size:29; /* Number of children, or compressed string len. */ | ||
| 83 | /* Data layout is as follows: | ||
| 84 | * | ||
| 85 | * If node is not compressed we have 'size' bytes, one for each children | ||
| 86 | * character, and 'size' raxNode pointers, point to each child node. | ||
| 87 | * Note how the character is not stored in the children but in the | ||
| 88 | * edge of the parents: | ||
| 89 | * | ||
| 90 | * [header iscompr=0][abc][a-ptr][b-ptr][c-ptr](value-ptr?) | ||
| 91 | * | ||
| 92 | * if node is compressed (iscompr bit is 1) the node has 1 child. | ||
| 93 | * In that case the 'size' bytes of the string stored immediately at | ||
| 94 | * the start of the data section, represent a sequence of successive | ||
| 95 | * nodes linked one after the other, for which only the last one in | ||
| 96 | * the sequence is actually represented as a node, and pointed to by | ||
| 97 | * the current compressed node. | ||
| 98 | * | ||
| 99 | * [header iscompr=1][xyz][z-ptr](value-ptr?) | ||
| 100 | * | ||
| 101 | * Both compressed and not compressed nodes can represent a key | ||
| 102 | * with associated data in the radix tree at any level (not just terminal | ||
| 103 | * nodes). | ||
| 104 | * | ||
| 105 | * If the node has an associated key (iskey=1) and is not NULL | ||
| 106 | * (isnull=0), then after the raxNode pointers pointing to the | ||
| 107 | * children, an additional value pointer is present (as you can see | ||
| 108 | * in the representation above as "value-ptr" field). | ||
| 109 | */ | ||
| 110 | unsigned char data[]; | ||
| 111 | } raxNode; | ||
| 112 | |||
| 113 | typedef struct rax { | ||
| 114 | raxNode *head; | ||
| 115 | uint64_t numele; | ||
| 116 | uint64_t numnodes; | ||
| 117 | size_t *alloc_size; | ||
| 118 | void *metadata[]; | ||
| 119 | } rax; | ||
| 120 | |||
| 121 | /* Stack data structure used by raxLowWalk() in order to, optionally, return | ||
| 122 | * a list of parent nodes to the caller. The nodes do not have a "parent" | ||
| 123 | * field for space concerns, so we use the auxiliary stack when needed. */ | ||
| 124 | #define RAX_STACK_STATIC_ITEMS 32 | ||
| 125 | typedef struct raxStack { | ||
| 126 | void **stack; /* Points to static_items or an heap allocated array. */ | ||
| 127 | size_t items, maxitems; /* Number of items contained and total space. */ | ||
| 128 | /* Up to RAXSTACK_STACK_ITEMS items we avoid to allocate on the heap | ||
| 129 | * and use this static array of pointers instead. */ | ||
| 130 | void *static_items[RAX_STACK_STATIC_ITEMS]; | ||
| 131 | int oom; /* True if pushing into this stack failed for OOM at some point. */ | ||
| 132 | } raxStack; | ||
| 133 | |||
| 134 | /* Optional callback used for iterators and be notified on each rax node, | ||
| 135 | * including nodes not representing keys. If the callback returns true | ||
| 136 | * the callback changed the node pointer in the iterator structure, and the | ||
| 137 | * iterator implementation will have to replace the pointer in the radix tree | ||
| 138 | * internals. This allows the callback to reallocate the node to perform | ||
| 139 | * very special operations, normally not needed by normal applications. | ||
| 140 | * | ||
| 141 | * This callback is used to perform very low level analysis of the radix tree | ||
| 142 | * structure, scanning each possible node (but the root node), or in order to | ||
| 143 | * reallocate the nodes to reduce the allocation fragmentation (this is the | ||
| 144 | * Redis application for this callback). | ||
| 145 | * | ||
| 146 | * This is currently only supported in forward iterations (raxNext) */ | ||
| 147 | typedef int (*raxNodeCallback)(raxNode **noderef, void *privdata); | ||
| 148 | |||
| 149 | /* Radix tree iterator state is encapsulated into this data structure. */ | ||
| 150 | #define RAX_ITER_STATIC_LEN 128 | ||
| 151 | #define RAX_ITER_JUST_SEEKED (1<<0) /* Iterator was just seeked. Return current | ||
| 152 | element for the first iteration and | ||
| 153 | clear the flag. */ | ||
| 154 | #define RAX_ITER_EOF (1<<1) /* End of iteration reached. */ | ||
| 155 | #define RAX_ITER_SAFE (1<<2) /* Safe iterator, allows operations while | ||
| 156 | iterating. But it is slower. */ | ||
| 157 | typedef struct raxIterator { | ||
| 158 | int flags; | ||
| 159 | rax *rt; /* Radix tree we are iterating. */ | ||
| 160 | unsigned char *key; /* The current string. */ | ||
| 161 | void *data; /* Data associated to this key. */ | ||
| 162 | size_t key_len; /* Current key length. */ | ||
| 163 | size_t key_max; /* Max key len the current key buffer can hold. */ | ||
| 164 | unsigned char key_static_string[RAX_ITER_STATIC_LEN]; | ||
| 165 | raxNode *node; /* Current node. Only for unsafe iteration. */ | ||
| 166 | raxStack stack; /* Stack used for unsafe iteration. */ | ||
| 167 | raxNodeCallback node_cb; /* Optional node callback. Normally set to NULL. */ | ||
| 168 | void *privdata; /* Optional private data for node callback. */ | ||
| 169 | } raxIterator; | ||
| 170 | |||
| 171 | /* Exported API. */ | ||
| 172 | rax *raxNew(void); | ||
| 173 | rax *raxNewWithMetadata(int metaSize, size_t *alloc_size); | ||
| 174 | int raxInsert(rax *rax, unsigned char *s, size_t len, void *data, void **old); | ||
| 175 | int raxTryInsert(rax *rax, unsigned char *s, size_t len, void *data, void **old); | ||
| 176 | int raxRemove(rax *rax, unsigned char *s, size_t len, void **old); | ||
| 177 | int raxFind(rax *rax, unsigned char *s, size_t len, void **value); | ||
| 178 | void raxFree(rax *rax); | ||
| 179 | void raxFreeWithCallback(rax *rax, void (*free_callback)(void*)); | ||
| 180 | void raxFreeWithCbAndContext(rax *rax, | ||
| 181 | void (*free_callback)(void *item, void *ctx), | ||
| 182 | void *ctx); | ||
| 183 | void raxStart(raxIterator *it, rax *rt); | ||
| 184 | int raxSeek(raxIterator *it, const char *op, unsigned char *ele, size_t len); | ||
| 185 | int raxNext(raxIterator *it); | ||
| 186 | int raxPrev(raxIterator *it); | ||
| 187 | int raxRandomWalk(raxIterator *it, size_t steps); | ||
| 188 | int raxCompare(raxIterator *iter, const char *op, unsigned char *key, size_t key_len); | ||
| 189 | void raxStop(raxIterator *it); | ||
| 190 | int raxEOF(raxIterator *it); | ||
| 191 | void raxShow(rax *rax); | ||
| 192 | uint64_t raxSize(rax *rax); | ||
| 193 | unsigned long raxTouch(raxNode *n); | ||
| 194 | void raxSetDebugMsg(int onoff); | ||
| 195 | |||
| 196 | /* Internal API. May be used by the node callback in order to access rax nodes | ||
| 197 | * in a low level way, so this function is exported as well. */ | ||
| 198 | void raxSetData(raxNode *n, void *data); | ||
| 199 | |||
| 200 | #ifdef REDIS_TEST | ||
| 201 | int raxTest(int argc, char *argv[], int flags); | ||
| 202 | #endif | ||
| 203 | |||
| 204 | #endif | ||
