| 0,0 → 1,542 |
|---|
| /* cairo - a vector graphics library with display and print output |
| * |
| * Copyright © 2004 Red Hat, Inc. |
| * Copyright © 2005 Red Hat, Inc. |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it either under the terms of the GNU Lesser General Public |
| * License version 2.1 as published by the Free Software Foundation |
| * (the "LGPL") or, at your option, under the terms of the Mozilla |
| * Public License Version 1.1 (the "MPL"). If you do not alter this |
| * notice, a recipient may use your version of this file under either |
| * the MPL or the LGPL. |
| * |
| * You should have received a copy of the LGPL along with this library |
| * in the file COPYING-LGPL-2.1; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA |
| * You should have received a copy of the MPL along with this library |
| * in the file COPYING-MPL-1.1 |
| * |
| * The contents of this file are subject to the Mozilla Public License |
| * Version 1.1 (the "License"); you may not use this file except in |
| * compliance with the License. You may obtain a copy of the License at |
| * http://www.mozilla.org/MPL/ |
| * |
| * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY |
| * OF ANY KIND, either express or implied. See the LGPL or the MPL for |
| * the specific language governing rights and limitations. |
| * |
| * The Original Code is the cairo graphics library. |
| * |
| * The Initial Developer of the Original Code is Red Hat, Inc. |
| * |
| * Contributor(s): |
| * Keith Packard <keithp@keithp.com> |
| * Graydon Hoare <graydon@redhat.com> |
| * Carl Worth <cworth@cworth.org> |
| */ |
| |
| #include "cairoint.h" |
| #include "cairo-error-private.h" |
| |
| /* |
| * An entry can be in one of three states: |
| * |
| * FREE: Entry has never been used, terminates all searches. |
| * Appears in the table as a %NULL pointer. |
| * |
| * DEAD: Entry had been live in the past. A dead entry can be reused |
| * but does not terminate a search for an exact entry. |
| * Appears in the table as a pointer to DEAD_ENTRY. |
| * |
| * LIVE: Entry is currently being used. |
| * Appears in the table as any non-%NULL, non-DEAD_ENTRY pointer. |
| */ |
| |
| #define DEAD_ENTRY ((cairo_hash_entry_t *) 0x1) |
| |
| #define ENTRY_IS_FREE(entry) ((entry) == NULL) |
| #define ENTRY_IS_DEAD(entry) ((entry) == DEAD_ENTRY) |
| #define ENTRY_IS_LIVE(entry) ((entry) > DEAD_ENTRY) |
| |
| /* We expect keys will not be destroyed frequently, so our table does not |
| * contain any explicit shrinking code nor any chain-coalescing code for |
| * entries randomly deleted by memory pressure (except during rehashing, of |
| * course). These assumptions are potentially bad, but they make the |
| * implementation straightforward. |
| * |
| * Revisit later if evidence appears that we're using excessive memory from |
| * a mostly-dead table. |
| * |
| * This table is open-addressed with double hashing. Each table size is a |
| * prime chosen to be a little more than double the high water mark for a |
| * given arrangement, so the tables should remain < 50% full. The table |
| * size makes for the "first" hash modulus; a second prime (2 less than the |
| * first prime) serves as the "second" hash modulus, which is co-prime and |
| * thus guarantees a complete permutation of table indices. |
| * |
| * This structure, and accompanying table, is borrowed/modified from the |
| * file xserver/render/glyph.c in the freedesktop.org x server, with |
| * permission (and suggested modification of doubling sizes) by Keith |
| * Packard. |
| */ |
| |
| typedef struct _cairo_hash_table_arrangement { |
| unsigned long high_water_mark; |
| unsigned long size; |
| unsigned long rehash; |
| } cairo_hash_table_arrangement_t; |
| |
| static const cairo_hash_table_arrangement_t hash_table_arrangements [] = { |
| { 16, 43, 41 }, |
| { 32, 73, 71 }, |
| { 64, 151, 149 }, |
| { 128, 283, 281 }, |
| { 256, 571, 569 }, |
| { 512, 1153, 1151 }, |
| { 1024, 2269, 2267 }, |
| { 2048, 4519, 4517 }, |
| { 4096, 9013, 9011 }, |
| { 8192, 18043, 18041 }, |
| { 16384, 36109, 36107 }, |
| { 32768, 72091, 72089 }, |
| { 65536, 144409, 144407 }, |
| { 131072, 288361, 288359 }, |
| { 262144, 576883, 576881 }, |
| { 524288, 1153459, 1153457 }, |
| { 1048576, 2307163, 2307161 }, |
| { 2097152, 4613893, 4613891 }, |
| { 4194304, 9227641, 9227639 }, |
| { 8388608, 18455029, 18455027 }, |
| { 16777216, 36911011, 36911009 }, |
| { 33554432, 73819861, 73819859 }, |
| { 67108864, 147639589, 147639587 }, |
| { 134217728, 295279081, 295279079 }, |
| { 268435456, 590559793, 590559791 } |
| }; |
| |
| #define NUM_HASH_TABLE_ARRANGEMENTS ARRAY_LENGTH (hash_table_arrangements) |
| |
| struct _cairo_hash_table { |
| cairo_hash_keys_equal_func_t keys_equal; |
| |
| const cairo_hash_table_arrangement_t *arrangement; |
| cairo_hash_entry_t **entries; |
| |
| unsigned long live_entries; |
| unsigned long iterating; /* Iterating, no insert, no resize */ |
| }; |
| |
| /** |
| * _cairo_hash_table_create: |
| * @keys_equal: a function to return %TRUE if two keys are equal |
| * |
| * Creates a new hash table which will use the keys_equal() function |
| * to compare hash keys. Data is provided to the hash table in the |
| * form of user-derived versions of #cairo_hash_entry_t. A hash entry |
| * must be able to hold both a key (including a hash code) and a |
| * value. Sometimes only the key will be necessary, (as in |
| * _cairo_hash_table_remove), and other times both a key and a value |
| * will be necessary, (as in _cairo_hash_table_insert). |
| * |
| * See #cairo_hash_entry_t for more details. |
| * |
| * Return value: the new hash table or %NULL if out of memory. |
| **/ |
| cairo_hash_table_t * |
| _cairo_hash_table_create (cairo_hash_keys_equal_func_t keys_equal) |
| { |
| cairo_hash_table_t *hash_table; |
| |
| hash_table = malloc (sizeof (cairo_hash_table_t)); |
| if (unlikely (hash_table == NULL)) { |
| _cairo_error_throw (CAIRO_STATUS_NO_MEMORY); |
| return NULL; |
| } |
| |
| hash_table->keys_equal = keys_equal; |
| |
| hash_table->arrangement = &hash_table_arrangements[0]; |
| |
| hash_table->entries = calloc (hash_table->arrangement->size, |
| sizeof(cairo_hash_entry_t *)); |
| if (unlikely (hash_table->entries == NULL)) { |
| _cairo_error_throw (CAIRO_STATUS_NO_MEMORY); |
| free (hash_table); |
| return NULL; |
| } |
| |
| hash_table->live_entries = 0; |
| hash_table->iterating = 0; |
| |
| return hash_table; |
| } |
| |
| /** |
| * _cairo_hash_table_destroy: |
| * @hash_table: an empty hash table to destroy |
| * |
| * Immediately destroys the given hash table, freeing all resources |
| * associated with it. |
| * |
| * WARNING: The hash_table must have no live entries in it before |
| * _cairo_hash_table_destroy is called. It is a fatal error otherwise, |
| * and this function will halt. The rationale for this behavior is to |
| * avoid memory leaks and to avoid needless complication of the API |
| * with destroy notifiy callbacks. |
| * |
| * WARNING: The hash_table must have no running iterators in it when |
| * _cairo_hash_table_destroy is called. It is a fatal error otherwise, |
| * and this function will halt. |
| **/ |
| void |
| _cairo_hash_table_destroy (cairo_hash_table_t *hash_table) |
| { |
| /* The hash table must be empty. Otherwise, halt. */ |
| assert (hash_table->live_entries == 0); |
| /* No iterators can be running. Otherwise, halt. */ |
| assert (hash_table->iterating == 0); |
| |
| free (hash_table->entries); |
| hash_table->entries = NULL; |
| |
| free (hash_table); |
| } |
| |
| static cairo_hash_entry_t ** |
| _cairo_hash_table_lookup_unique_key (cairo_hash_table_t *hash_table, |
| cairo_hash_entry_t *key) |
| { |
| unsigned long table_size, i, idx, step; |
| cairo_hash_entry_t **entry; |
| |
| table_size = hash_table->arrangement->size; |
| idx = key->hash % table_size; |
| |
| entry = &hash_table->entries[idx]; |
| if (! ENTRY_IS_LIVE (*entry)) |
| return entry; |
| |
| i = 1; |
| step = key->hash % hash_table->arrangement->rehash; |
| if (step == 0) |
| step = 1; |
| do { |
| idx += step; |
| if (idx >= table_size) |
| idx -= table_size; |
| |
| entry = &hash_table->entries[idx]; |
| if (! ENTRY_IS_LIVE (*entry)) |
| return entry; |
| } while (++i < table_size); |
| |
| ASSERT_NOT_REACHED; |
| return NULL; |
| } |
| |
| /** |
| * _cairo_hash_table_resize: |
| * @hash_table: a hash table |
| * |
| * Resize the hash table if the number of entries has gotten much |
| * bigger or smaller than the ideal number of entries for the current |
| * size. |
| * |
| * Return value: %CAIRO_STATUS_SUCCESS if successful or |
| * %CAIRO_STATUS_NO_MEMORY if out of memory. |
| **/ |
| static cairo_status_t |
| _cairo_hash_table_resize (cairo_hash_table_t *hash_table) |
| { |
| cairo_hash_table_t tmp; |
| unsigned long new_size, i; |
| |
| /* This keeps the hash table between 25% and 50% full. */ |
| unsigned long high = hash_table->arrangement->high_water_mark; |
| unsigned long low = high >> 2; |
| |
| if (hash_table->live_entries >= low && hash_table->live_entries <= high) |
| return CAIRO_STATUS_SUCCESS; |
| |
| tmp = *hash_table; |
| |
| if (hash_table->live_entries > high) |
| { |
| tmp.arrangement = hash_table->arrangement + 1; |
| /* This code is being abused if we can't make a table big enough. */ |
| assert (tmp.arrangement - hash_table_arrangements < |
| NUM_HASH_TABLE_ARRANGEMENTS); |
| } |
| else /* hash_table->live_entries < low */ |
| { |
| /* Can't shrink if we're at the smallest size */ |
| if (hash_table->arrangement == &hash_table_arrangements[0]) |
| return CAIRO_STATUS_SUCCESS; |
| tmp.arrangement = hash_table->arrangement - 1; |
| } |
| |
| new_size = tmp.arrangement->size; |
| tmp.entries = calloc (new_size, sizeof (cairo_hash_entry_t*)); |
| if (unlikely (tmp.entries == NULL)) |
| return _cairo_error (CAIRO_STATUS_NO_MEMORY); |
| |
| for (i = 0; i < hash_table->arrangement->size; ++i) { |
| if (ENTRY_IS_LIVE (hash_table->entries[i])) { |
| *_cairo_hash_table_lookup_unique_key (&tmp, hash_table->entries[i]) |
| = hash_table->entries[i]; |
| } |
| } |
| |
| free (hash_table->entries); |
| hash_table->entries = tmp.entries; |
| hash_table->arrangement = tmp.arrangement; |
| |
| return CAIRO_STATUS_SUCCESS; |
| } |
| |
| /** |
| * _cairo_hash_table_lookup: |
| * @hash_table: a hash table |
| * @key: the key of interest |
| * |
| * Performs a lookup in @hash_table looking for an entry which has a |
| * key that matches @key, (as determined by the keys_equal() function |
| * passed to _cairo_hash_table_create). |
| * |
| * Return value: the matching entry, of %NULL if no match was found. |
| **/ |
| void * |
| _cairo_hash_table_lookup (cairo_hash_table_t *hash_table, |
| cairo_hash_entry_t *key) |
| { |
| cairo_hash_entry_t *entry; |
| unsigned long table_size, i, idx, step; |
| |
| table_size = hash_table->arrangement->size; |
| idx = key->hash % table_size; |
| |
| entry = hash_table->entries[idx]; |
| if (ENTRY_IS_LIVE (entry)) { |
| if (hash_table->keys_equal (key, entry)) |
| return entry; |
| } else if (ENTRY_IS_FREE (entry)) |
| return NULL; |
| |
| i = 1; |
| step = key->hash % hash_table->arrangement->rehash; |
| if (step == 0) |
| step = 1; |
| do { |
| idx += step; |
| if (idx >= table_size) |
| idx -= table_size; |
| |
| entry = hash_table->entries[idx]; |
| if (ENTRY_IS_LIVE (entry)) { |
| if (hash_table->keys_equal (key, entry)) |
| return entry; |
| } else if (ENTRY_IS_FREE (entry)) |
| return NULL; |
| } while (++i < table_size); |
| |
| return NULL; |
| } |
| |
| /** |
| * _cairo_hash_table_random_entry: |
| * @hash_table: a hash table |
| * @predicate: a predicate function. |
| * |
| * Find a random entry in the hash table satisfying the given |
| * @predicate. |
| * |
| * We use the same algorithm as the lookup algorithm to walk over the |
| * entries in the hash table in a pseudo-random order. Walking |
| * linearly would favor entries following gaps in the hash table. We |
| * could also call rand() repeatedly, which works well for almost-full |
| * tables, but degrades when the table is almost empty, or predicate |
| * returns %TRUE for most entries. |
| * |
| * Return value: a random live entry or %NULL if there are no entries |
| * that match the given predicate. In particular, if predicate is |
| * %NULL, a %NULL return value indicates that the table is empty. |
| **/ |
| void * |
| _cairo_hash_table_random_entry (cairo_hash_table_t *hash_table, |
| cairo_hash_predicate_func_t predicate) |
| { |
| cairo_hash_entry_t *entry; |
| unsigned long hash; |
| unsigned long table_size, i, idx, step; |
| |
| assert (predicate != NULL); |
| |
| table_size = hash_table->arrangement->size; |
| hash = rand (); |
| idx = hash % table_size; |
| |
| entry = hash_table->entries[idx]; |
| if (ENTRY_IS_LIVE (entry) && predicate (entry)) |
| return entry; |
| |
| i = 1; |
| step = hash % hash_table->arrangement->rehash; |
| if (step == 0) |
| step = 1; |
| do { |
| idx += step; |
| if (idx >= table_size) |
| idx -= table_size; |
| |
| entry = hash_table->entries[idx]; |
| if (ENTRY_IS_LIVE (entry) && predicate (entry)) |
| return entry; |
| } while (++i < table_size); |
| |
| return NULL; |
| } |
| |
| /** |
| * _cairo_hash_table_insert: |
| * @hash_table: a hash table |
| * @key_and_value: an entry to be inserted |
| * |
| * Insert the entry #key_and_value into the hash table. |
| * |
| * WARNING: There must not be an existing entry in the hash table |
| * with a matching key. |
| * |
| * WARNING: It is a fatal error to insert an element while |
| * an iterator is running |
| * |
| * Instead of using insert to replace an entry, consider just editing |
| * the entry obtained with _cairo_hash_table_lookup. Or if absolutely |
| * necessary, use _cairo_hash_table_remove first. |
| * |
| * Return value: %CAIRO_STATUS_SUCCESS if successful or |
| * %CAIRO_STATUS_NO_MEMORY if insufficient memory is available. |
| **/ |
| cairo_status_t |
| _cairo_hash_table_insert (cairo_hash_table_t *hash_table, |
| cairo_hash_entry_t *key_and_value) |
| { |
| cairo_status_t status; |
| |
| /* Insert is illegal while an iterator is running. */ |
| assert (hash_table->iterating == 0); |
| |
| hash_table->live_entries++; |
| status = _cairo_hash_table_resize (hash_table); |
| if (unlikely (status)) { |
| /* abort the insert... */ |
| hash_table->live_entries--; |
| return status; |
| } |
| |
| *_cairo_hash_table_lookup_unique_key (hash_table, |
| key_and_value) = key_and_value; |
| |
| return CAIRO_STATUS_SUCCESS; |
| } |
| |
| static cairo_hash_entry_t ** |
| _cairo_hash_table_lookup_exact_key (cairo_hash_table_t *hash_table, |
| cairo_hash_entry_t *key) |
| { |
| unsigned long table_size, i, idx, step; |
| cairo_hash_entry_t **entry; |
| |
| table_size = hash_table->arrangement->size; |
| idx = key->hash % table_size; |
| |
| entry = &hash_table->entries[idx]; |
| if (*entry == key) |
| return entry; |
| |
| i = 1; |
| step = key->hash % hash_table->arrangement->rehash; |
| if (step == 0) |
| step = 1; |
| do { |
| idx += step; |
| if (idx >= table_size) |
| idx -= table_size; |
| |
| entry = &hash_table->entries[idx]; |
| if (*entry == key) |
| return entry; |
| } while (++i < table_size); |
| |
| ASSERT_NOT_REACHED; |
| return NULL; |
| } |
| /** |
| * _cairo_hash_table_remove: |
| * @hash_table: a hash table |
| * @key: key of entry to be removed |
| * |
| * Remove an entry from the hash table which points to @key. |
| * |
| * Return value: %CAIRO_STATUS_SUCCESS if successful or |
| * %CAIRO_STATUS_NO_MEMORY if out of memory. |
| **/ |
| void |
| _cairo_hash_table_remove (cairo_hash_table_t *hash_table, |
| cairo_hash_entry_t *key) |
| { |
| *_cairo_hash_table_lookup_exact_key (hash_table, key) = DEAD_ENTRY; |
| hash_table->live_entries--; |
| |
| /* Check for table resize. Don't do this when iterating as this will |
| * reorder elements of the table and cause the iteration to potentially |
| * skip some elements. */ |
| if (hash_table->iterating == 0) { |
| /* This call _can_ fail, but only in failing to allocate new |
| * memory to shrink the hash table. It does leave the table in a |
| * consistent state, and we've already succeeded in removing the |
| * entry, so we don't examine the failure status of this call. */ |
| _cairo_hash_table_resize (hash_table); |
| } |
| } |
| |
| /** |
| * _cairo_hash_table_foreach: |
| * @hash_table: a hash table |
| * @hash_callback: function to be called for each live entry |
| * @closure: additional argument to be passed to @hash_callback |
| * |
| * Call @hash_callback for each live entry in the hash table, in a |
| * non-specified order. |
| * |
| * Entries in @hash_table may be removed by code executed from @hash_callback. |
| * |
| * Entries may not be inserted to @hash_table, nor may @hash_table |
| * be destroyed by code executed from @hash_callback. The relevant |
| * functions will halt in these cases. |
| **/ |
| void |
| _cairo_hash_table_foreach (cairo_hash_table_t *hash_table, |
| cairo_hash_callback_func_t hash_callback, |
| void *closure) |
| { |
| unsigned long i; |
| cairo_hash_entry_t *entry; |
| |
| /* Mark the table for iteration */ |
| ++hash_table->iterating; |
| for (i = 0; i < hash_table->arrangement->size; i++) { |
| entry = hash_table->entries[i]; |
| if (ENTRY_IS_LIVE(entry)) |
| hash_callback (entry, closure); |
| } |
| /* If some elements were deleted during the iteration, |
| * the table may need resizing. Just do this every time |
| * as the check is inexpensive. |
| */ |
| if (--hash_table->iterating == 0) { |
| /* Should we fail to shrink the hash table, it is left unaltered, |
| * and we don't need to propagate the error status. */ |
| _cairo_hash_table_resize (hash_table); |
| } |
| } |