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-rw-r--r--src/trie.c258
1 files changed, 97 insertions, 161 deletions
diff --git a/src/trie.c b/src/trie.c
index 4bbdf13..808953e 100644
--- a/src/trie.c
+++ b/src/trie.c
@@ -1,18 +1,5 @@
-/****************************************************************************
- * bfs *
- * Copyright (C) 2019-2022 Tavian Barnes <tavianator@tavianator.com> *
- * *
- * Permission to use, copy, modify, and/or distribute this software for any *
- * purpose with or without fee is hereby granted. *
- * *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF *
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR *
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES *
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN *
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF *
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
- ****************************************************************************/
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
/**
* This is an implementation of a "qp trie," as documented at
@@ -94,31 +81,29 @@
* and insert intermediate singleton "jump" nodes when necessary.
*/
+#include "prelude.h"
#include "trie.h"
-#include "config.h"
-#include <assert.h>
-#include <limits.h>
-#include <stdbool.h>
+#include "alloc.h"
+#include "bit.h"
+#include "diag.h"
+#include "list.h"
#include <stdint.h>
-#include <stdlib.h>
#include <string.h>
-#if __has_attribute(target_clones) && (__i386__ || __x86_64__)
-# define TARGET_CLONES_POPCNT __attribute__((target_clones("popcnt", "default")))
-#else
-# define TARGET_CLONES_POPCNT
-#endif
+bfs_static_assert(CHAR_WIDTH == 8);
-#if CHAR_BIT != 8
-# error "This trie implementation assumes 8-bit bytes."
+#if __i386__ || __x86_64__
+# define trie_clones attr(target_clones("popcnt", "default"))
+#else
+# define trie_clones
#endif
/** Number of bits for the sparse array bitmap, aka the range of a nibble. */
-#define BITMAP_BITS 16
+#define BITMAP_WIDTH 16
/** The number of remaining bits in a word, to hold the offset. */
-#define OFFSET_BITS (sizeof(size_t)*CHAR_BIT - BITMAP_BITS)
+#define OFFSET_WIDTH (SIZE_WIDTH - BITMAP_WIDTH)
/** The highest representable offset (only 64k on a 32-bit architecture). */
-#define OFFSET_MAX (((size_t)1 << OFFSET_BITS) - 1)
+#define OFFSET_MAX (((size_t)1 << OFFSET_WIDTH) - 1)
/**
* An internal node of the trie.
@@ -129,13 +114,13 @@ struct trie_node {
* Bit i will be set if a child exists at logical index i, and its index
* into the array will be popcount(bitmap & ((1 << i) - 1)).
*/
- size_t bitmap : BITMAP_BITS;
+ size_t bitmap : BITMAP_WIDTH;
/**
* The offset into the key in nibbles. This is relative to the parent
* node, to support offsets larger than OFFSET_MAX.
*/
- size_t offset : OFFSET_BITS;
+ size_t offset : OFFSET_WIDTH;
/**
* Flexible array of children. Each pointer uses the lowest bit as a
@@ -152,53 +137,35 @@ static bool trie_is_leaf(uintptr_t ptr) {
/** Decode a pointer to a leaf. */
static struct trie_leaf *trie_decode_leaf(uintptr_t ptr) {
- assert(trie_is_leaf(ptr));
+ bfs_assert(trie_is_leaf(ptr));
return (struct trie_leaf *)(ptr ^ 1);
}
/** Encode a pointer to a leaf. */
static uintptr_t trie_encode_leaf(const struct trie_leaf *leaf) {
uintptr_t ptr = (uintptr_t)leaf ^ 1;
- assert(trie_is_leaf(ptr));
+ bfs_assert(trie_is_leaf(ptr));
return ptr;
}
/** Decode a pointer to an internal node. */
static struct trie_node *trie_decode_node(uintptr_t ptr) {
- assert(!trie_is_leaf(ptr));
+ bfs_assert(!trie_is_leaf(ptr));
return (struct trie_node *)ptr;
}
/** Encode a pointer to an internal node. */
static uintptr_t trie_encode_node(const struct trie_node *node) {
uintptr_t ptr = (uintptr_t)node;
- assert(!trie_is_leaf(ptr));
+ bfs_assert(!trie_is_leaf(ptr));
return ptr;
}
void trie_init(struct trie *trie) {
trie->root = 0;
- trie->head = NULL;
- trie->tail = NULL;
-}
-
-/** Check if a number is a power of two. */
-static bool is_power_of_two(size_t n) {
- return (n & (n - 1)) == 0;
-}
-
-/** Compute the popcount (Hamming weight) of a bitmap. */
-static unsigned int trie_popcount(unsigned int n) {
-#if __GNUC__
- return __builtin_popcount(n);
-#else
- // See https://en.wikipedia.org/wiki/Hamming_weight#Efficient_implementation
- n -= (n >> 1) & 0x5555;
- n = (n & 0x3333) + ((n >> 2) & 0x3333);
- n = (n + (n >> 4)) & 0x0F0F;
- n = (n + (n >> 8)) & 0xFF;
- return n;
-#endif
+ LIST_INIT(trie);
+ VARENA_INIT(&trie->nodes, struct trie_node, children);
+ VARENA_INIT(&trie->leaves, struct trie_leaf, key);
}
/** Extract the nibble at a certain offset from a byte sequence. */
@@ -223,7 +190,7 @@ static unsigned char trie_key_nibble(const void *key, size_t offset) {
* that case, the first mismatch between the key and the representative will be
* the depth at which to make a new branch to insert the key.
*/
-TARGET_CLONES_POPCNT
+trie_clones
static struct trie_leaf *trie_representative(const struct trie *trie, const void *key, size_t length) {
uintptr_t ptr = trie->root;
if (!ptr) {
@@ -239,9 +206,10 @@ static struct trie_leaf *trie_representative(const struct trie *trie, const void
if ((offset >> 1) < length) {
unsigned char nibble = trie_key_nibble(key, offset);
unsigned int bit = 1U << nibble;
- if (node->bitmap & bit) {
- index = trie_popcount(node->bitmap & (bit - 1));
- }
+ // bits = bitmap & bit ? bitmap & (bit - 1) : 0
+ unsigned int mask = -!!(node->bitmap & bit);
+ unsigned int bits = node->bitmap & (bit - 1) & mask;
+ index = count_ones(bits);
}
ptr = node->children[index];
}
@@ -302,7 +270,7 @@ static bool trie_check_prefix(struct trie_leaf *leaf, size_t skip, const char *k
}
}
-TARGET_CLONES_POPCNT
+trie_clones
static struct trie_leaf *trie_find_prefix_impl(const struct trie *trie, const char *key) {
uintptr_t ptr = trie->root;
if (!ptr) {
@@ -330,7 +298,7 @@ static struct trie_leaf *trie_find_prefix_impl(const struct trie *trie, const ch
unsigned char nibble = trie_key_nibble(key, offset);
unsigned int bit = 1U << nibble;
if (node->bitmap & bit) {
- unsigned int index = trie_popcount(node->bitmap & (bit - 1));
+ unsigned int index = count_ones(node->bitmap & (bit - 1));
ptr = node->children[index];
} else {
return best;
@@ -351,21 +319,13 @@ struct trie_leaf *trie_find_prefix(const struct trie *trie, const char *key) {
/** Create a new leaf, holding a copy of the given key. */
static struct trie_leaf *trie_leaf_alloc(struct trie *trie, const void *key, size_t length) {
- struct trie_leaf *leaf = malloc(BFS_FLEX_SIZEOF(struct trie_leaf, key, length));
+ struct trie_leaf *leaf = varena_alloc(&trie->leaves, length);
if (!leaf) {
return NULL;
}
- leaf->prev = trie->tail;
- leaf->next = NULL;
-
- if (leaf->prev) {
- leaf->prev->next = leaf;
- } else {
- trie->head = leaf;
- }
-
- trie->tail = leaf;
+ LIST_ITEM_INIT(leaf);
+ LIST_APPEND(trie, leaf);
leaf->value = NULL;
leaf->length = length;
@@ -376,49 +336,33 @@ static struct trie_leaf *trie_leaf_alloc(struct trie *trie, const void *key, siz
/** Free a leaf. */
static void trie_leaf_free(struct trie *trie, struct trie_leaf *leaf) {
- if (leaf->prev) {
- leaf->prev->next = leaf->next;
- } else {
- trie->head = leaf->next;
- }
-
- if (leaf->next) {
- leaf->next->prev = leaf->prev;
- } else {
- trie->tail = leaf->prev;
- }
-
- free(leaf);
+ LIST_REMOVE(trie, leaf);
+ varena_free(&trie->leaves, leaf, leaf->length);
}
-/** Compute the size of a trie node with a certain number of children. */
-static size_t trie_node_size(unsigned int size) {
- // Empty nodes aren't supported
- assert(size > 0);
- // Node size must be a power of two
- assert(is_power_of_two(size));
+/** Create a new node. */
+static struct trie_node *trie_node_alloc(struct trie *trie, size_t size) {
+ bfs_assert(has_single_bit(size));
+ return varena_alloc(&trie->nodes, size);
+}
- return BFS_FLEX_SIZEOF(struct trie_node, children, size);
+/** Reallocate a trie node. */
+static struct trie_node *trie_node_realloc(struct trie *trie, struct trie_node *node, size_t old_size, size_t new_size) {
+ bfs_assert(has_single_bit(old_size));
+ bfs_assert(has_single_bit(new_size));
+ return varena_realloc(&trie->nodes, node, old_size, new_size);
}
-#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-# define TRIE_BSWAP(n) (n)
-#elif defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
-# if __SIZEOF_SIZE_T__ == 8
-# define TRIE_BSWAP(n) __builtin_bswap64(n)
-# elif __SIZEOF_SIZE_T__ == 4
-# define TRIE_BSWAP(n) __builtin_bswap32(n)
-# endif
-#endif
+/** Free a node. */
+static void trie_node_free(struct trie *trie, struct trie_node *node, size_t size) {
+ bfs_assert(size == (size_t)count_ones(node->bitmap));
+ varena_free(&trie->nodes, node, size);
+}
-#ifdef TRIE_BSWAP
-# if __SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__
-# define TRIE_CTZ(n) __builtin_ctzll(n)
-# elif __SIZEOF_SIZE_T__ == __SIZEOF_LONG__
-# define TRIE_CTZ(n) __builtin_ctzl(n)
-# elif __SIZEOF_SIZE_T__ == __SIZEOF_INT__
-# define TRIE_CTZ(n) __builtin_ctz(n)
-# endif
+#if ENDIAN_NATIVE == ENDIAN_LITTLE
+# define TRIE_BSWAP(n) (n)
+#elif ENDIAN_NATIVE == ENDIAN_BIG
+# define TRIE_BSWAP(n) bswap(n)
#endif
/** Find the offset of the first nibble that differs between two keys. */
@@ -441,10 +385,10 @@ static size_t trie_mismatch(const struct trie_leaf *rep, const void *key, size_t
memcpy(&key_chunk, key_bytes + i, sizeof(key_chunk));
if (rep_chunk != key_chunk) {
-#ifdef TRIE_CTZ
+#ifdef TRIE_BSWAP
size_t diff = TRIE_BSWAP(rep_chunk ^ key_chunk);
i *= 2;
- i += TRIE_CTZ(diff) / 4;
+ i += trailing_zeros(diff) / 4;
return i;
#else
break;
@@ -484,14 +428,14 @@ static size_t trie_mismatch(const struct trie_leaf *rep, const void *key, size_t
* | Z
* +--->...
*/
-TARGET_CLONES_POPCNT
+trie_clones
static struct trie_leaf *trie_node_insert(struct trie *trie, uintptr_t *ptr, struct trie_leaf *leaf, unsigned char nibble) {
struct trie_node *node = trie_decode_node(*ptr);
- unsigned int size = trie_popcount(node->bitmap);
+ unsigned int size = count_ones(node->bitmap);
// Double the capacity every power of two
- if (is_power_of_two(size)) {
- node = realloc(node, trie_node_size(2 * size));
+ if (has_single_bit(size)) {
+ node = trie_node_realloc(trie, node, size, 2 * size);
if (!node) {
trie_leaf_free(trie, leaf);
return NULL;
@@ -502,10 +446,10 @@ static struct trie_leaf *trie_node_insert(struct trie *trie, uintptr_t *ptr, str
unsigned int bit = 1U << nibble;
// The child must not already be present
- assert(!(node->bitmap & bit));
+ bfs_assert(!(node->bitmap & bit));
node->bitmap |= bit;
- unsigned int target = trie_popcount(node->bitmap & (bit - 1));
+ unsigned int target = count_ones(node->bitmap & (bit - 1));
for (size_t i = size; i > target; --i) {
node->children[i] = node->children[i - 1];
}
@@ -538,12 +482,12 @@ static struct trie_leaf *trie_node_insert(struct trie *trie, uintptr_t *ptr, str
* | Y
* +--->key
*/
-static uintptr_t *trie_jump(uintptr_t *ptr, const char *key, size_t *offset) {
+static uintptr_t *trie_jump(struct trie *trie, uintptr_t *ptr, const char *key, size_t *offset) {
// We only ever need to jump to leaf nodes, since internal nodes are
// guaranteed to be within OFFSET_MAX anyway
- assert(trie_is_leaf(*ptr));
+ bfs_assert(trie_is_leaf(*ptr));
- struct trie_node *node = malloc(trie_node_size(1));
+ struct trie_node *node = trie_node_alloc(trie, 1);
if (!node) {
return NULL;
}
@@ -579,9 +523,9 @@ static uintptr_t *trie_jump(uintptr_t *ptr, const char *key, size_t *offset) {
static struct trie_leaf *trie_split(struct trie *trie, uintptr_t *ptr, struct trie_leaf *leaf, struct trie_leaf *rep, size_t offset, size_t mismatch) {
unsigned char key_nibble = trie_key_nibble(leaf->key, mismatch);
unsigned char rep_nibble = trie_key_nibble(rep->key, mismatch);
- assert(key_nibble != rep_nibble);
+ bfs_assert(key_nibble != rep_nibble);
- struct trie_node *node = malloc(trie_node_size(2));
+ struct trie_node *node = trie_node_alloc(trie, 2);
if (!node) {
trie_leaf_free(trie, leaf);
return NULL;
@@ -607,7 +551,7 @@ struct trie_leaf *trie_insert_str(struct trie *trie, const char *key) {
return trie_insert_mem(trie, key, strlen(key) + 1);
}
-TARGET_CLONES_POPCNT
+trie_clones
static struct trie_leaf *trie_insert_mem_impl(struct trie *trie, const void *key, size_t length) {
struct trie_leaf *rep = trie_representative(trie, key, length);
size_t mismatch = trie_mismatch(rep, key, length);
@@ -637,17 +581,17 @@ static struct trie_leaf *trie_insert_mem_impl(struct trie *trie, const void *key
unsigned char nibble = trie_key_nibble(key, offset);
unsigned int bit = 1U << nibble;
if (node->bitmap & bit) {
- assert(offset < mismatch);
- unsigned int index = trie_popcount(node->bitmap & (bit - 1));
+ bfs_assert(offset < mismatch);
+ unsigned int index = count_ones(node->bitmap & (bit - 1));
ptr = &node->children[index];
} else {
- assert(offset == mismatch);
+ bfs_assert(offset == mismatch);
return trie_node_insert(trie, ptr, leaf, nibble);
}
}
while (mismatch - offset > OFFSET_MAX) {
- ptr = trie_jump(ptr, key, &offset);
+ ptr = trie_jump(trie, ptr, key, &offset);
if (!ptr) {
trie_leaf_free(trie, leaf);
return NULL;
@@ -667,10 +611,10 @@ static void trie_free_singletons(struct trie *trie, uintptr_t ptr) {
struct trie_node *node = trie_decode_node(ptr);
// Make sure the bitmap is a power of two, i.e. it has just one child
- assert(is_power_of_two(node->bitmap));
+ bfs_assert(has_single_bit(node->bitmap));
ptr = node->children[0];
- free(node);
+ trie_node_free(trie, node, 1);
}
trie_leaf_free(trie, trie_decode_leaf(ptr));
@@ -693,7 +637,7 @@ static void trie_free_singletons(struct trie *trie, uintptr_t ptr) {
* v
* other
*/
-static int trie_collapse_node(uintptr_t *parent, struct trie_node *parent_node, unsigned int child_index) {
+static int trie_collapse_node(struct trie *trie, uintptr_t *parent, struct trie_node *parent_node, unsigned int child_index) {
uintptr_t other = parent_node->children[child_index ^ 1];
if (!trie_is_leaf(other)) {
struct trie_node *other_node = trie_decode_node(other);
@@ -705,11 +649,11 @@ static int trie_collapse_node(uintptr_t *parent, struct trie_node *parent_node,
}
*parent = other;
- free(parent_node);
+ trie_node_free(trie, parent_node, 1);
return 0;
}
-TARGET_CLONES_POPCNT
+trie_clones
static void trie_remove_impl(struct trie *trie, struct trie_leaf *leaf) {
uintptr_t *child = &trie->root;
uintptr_t *parent = NULL;
@@ -718,16 +662,16 @@ static void trie_remove_impl(struct trie *trie, struct trie_leaf *leaf) {
while (!trie_is_leaf(*child)) {
struct trie_node *node = trie_decode_node(*child);
offset += node->offset;
- assert((offset >> 1) < leaf->length);
+ bfs_assert((offset >> 1) < leaf->length);
unsigned char nibble = trie_key_nibble(leaf->key, offset);
unsigned int bit = 1U << nibble;
unsigned int bitmap = node->bitmap;
- assert(bitmap & bit);
- unsigned int index = trie_popcount(bitmap & (bit - 1));
+ bfs_assert(bitmap & bit);
+ unsigned int index = count_ones(bitmap & (bit - 1));
// Advance the parent pointer, unless this node had only one child
- if (!is_power_of_two(bitmap)) {
+ if (!has_single_bit(bitmap)) {
parent = child;
child_bit = bit;
child_index = index;
@@ -736,7 +680,7 @@ static void trie_remove_impl(struct trie *trie, struct trie_leaf *leaf) {
child = &node->children[index];
}
- assert(trie_decode_leaf(*child) == leaf);
+ bfs_assert(trie_decode_leaf(*child) == leaf);
if (!parent) {
trie_free_singletons(trie, trie->root);
@@ -749,18 +693,18 @@ static void trie_remove_impl(struct trie *trie, struct trie_leaf *leaf) {
trie_free_singletons(trie, *child);
node->bitmap ^= child_bit;
- unsigned int parent_size = trie_popcount(node->bitmap);
- assert(parent_size > 0);
- if (parent_size == 1 && trie_collapse_node(parent, node, child_index) == 0) {
+ unsigned int parent_size = count_ones(node->bitmap);
+ bfs_assert(parent_size > 0);
+ if (parent_size == 1 && trie_collapse_node(trie, parent, node, child_index) == 0) {
return;
}
if (child_index < parent_size) {
- memmove(child, child + 1, (parent_size - child_index)*sizeof(*child));
+ memmove(child, child + 1, (parent_size - child_index) * sizeof(*child));
}
- if (is_power_of_two(parent_size)) {
- node = realloc(node, trie_node_size(parent_size));
+ if (has_single_bit(parent_size)) {
+ node = trie_node_realloc(trie, node, 2 * parent_size, parent_size);
if (node) {
*parent = trie_encode_node(node);
}
@@ -771,23 +715,15 @@ void trie_remove(struct trie *trie, struct trie_leaf *leaf) {
trie_remove_impl(trie, leaf);
}
-/** Free an encoded pointer to a node. */
-TARGET_CLONES_POPCNT
-static void free_trie_ptr(uintptr_t ptr) {
- if (trie_is_leaf(ptr)) {
- free(trie_decode_leaf(ptr));
- } else {
- struct trie_node *node = trie_decode_node(ptr);
- size_t size = trie_popcount(node->bitmap);
- for (size_t i = 0; i < size; ++i) {
- free_trie_ptr(node->children[i]);
- }
- free(node);
- }
+void trie_clear(struct trie *trie) {
+ trie->root = 0;
+ LIST_INIT(trie);
+
+ varena_clear(&trie->leaves);
+ varena_clear(&trie->nodes);
}
void trie_destroy(struct trie *trie) {
- if (trie->root) {
- free_trie_ptr(trie->root);
- }
+ varena_destroy(&trie->leaves);
+ varena_destroy(&trie->nodes);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-10 11:12:12 +0000