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-rw-r--r--util/cairo-script/cairo-script-hash.c483
1 files changed, 483 insertions, 0 deletions
diff --git a/util/cairo-script/cairo-script-hash.c b/util/cairo-script/cairo-script-hash.c
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+++ b/util/cairo-script/cairo-script-hash.c
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+/* 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>
+ * Karl Tomlinson <karlt+@karlt.net>, Mozilla Corporation
+ */
+
+#include "cairo-script-private.h"
+
+#include <stdlib.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 ((csi_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)
+
+
+/* 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.
+ */
+
+static const csi_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)
+
+/**
+ * _csi_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 #csi_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
+ * _csi_hash_table_remove), and other times both a key and a value
+ * will be necessary, (as in _csi_hash_table_insert).
+ *
+ * See #csi_hash_entry_t for more details.
+ *
+ * Return value: the new hash table or %NULL if out of memory.
+ **/
+csi_status_t
+_csi_hash_table_init (csi_hash_table_t *hash_table,
+ csi_hash_keys_equal_func_t keys_equal)
+{
+ hash_table->keys_equal = keys_equal;
+
+ hash_table->arrangement = &hash_table_arrangements[0];
+
+ hash_table->entries = calloc (hash_table->arrangement->size,
+ sizeof(csi_hash_entry_t *));
+ if (hash_table->entries == NULL)
+ return _csi_error (CAIRO_STATUS_NO_MEMORY);
+
+ hash_table->live_entries = 0;
+ hash_table->used_entries = 0;
+ hash_table->iterating = 0;
+
+ return CSI_STATUS_SUCCESS;
+}
+
+/**
+ * _csi_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
+ * _csi_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
+ * _csi_hash_table_destroy is called. It is a fatal error otherwise,
+ * and this function will halt.
+ **/
+void
+_csi_hash_table_fini (csi_hash_table_t *hash_table)
+{
+ free (hash_table->entries);
+}
+
+static csi_hash_entry_t **
+_csi_hash_table_lookup_unique_key (csi_hash_table_t *hash_table,
+ csi_hash_entry_t *key)
+{
+ unsigned long table_size, i, idx, step;
+ csi_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);
+
+ return NULL;
+}
+
+/**
+ * _csi_hash_table_manage:
+ * @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, or control the number of dead entries by moving the entries
+ * within the table.
+ *
+ * Return value: %CAIRO_STATUS_SUCCESS if successful or
+ * %CAIRO_STATUS_NO_MEMORY if out of memory.
+ **/
+static csi_status_t
+_csi_hash_table_manage (csi_hash_table_t *hash_table)
+{
+ csi_hash_table_t tmp;
+ csi_boolean_t realloc = TRUE;
+ unsigned long i;
+
+ /* This keeps the size of the hash table between 2 and approximately 8
+ * times the number of live entries and keeps the proportion of free
+ * entries (search-terminations) > 25%.
+ */
+ unsigned long high = hash_table->arrangement->high_water_mark;
+ unsigned long low = high >> 2;
+ unsigned long max_used = high + high / 2;
+
+ 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. */
+ } else if (hash_table->live_entries < low &&
+ /* Can't shrink if we're at the smallest size */
+ hash_table->arrangement != &hash_table_arrangements[0])
+ {
+ tmp.arrangement = hash_table->arrangement - 1;
+ }
+ else if (hash_table->used_entries > max_used)
+ {
+ /* Clean out dead entries to prevent lookups from becoming too slow. */
+ for (i = 0; i < hash_table->arrangement->size; ++i) {
+ if (ENTRY_IS_DEAD (hash_table->entries[i]))
+ hash_table->entries[i] = NULL;
+ }
+ hash_table->used_entries = hash_table->live_entries;
+
+ /* There is no need to reallocate but some entries may need to be
+ * moved. Typically the proportion of entries needing to be moved is
+ * small, but, if the moving should leave a large number of dead
+ * entries, they will be cleaned out next time this code is
+ * executed. */
+ realloc = FALSE;
+ }
+ else
+ {
+ return CAIRO_STATUS_SUCCESS;
+ }
+
+ if (realloc) {
+ tmp.entries = calloc (tmp.arrangement->size,
+ sizeof (csi_hash_entry_t*));
+ if (tmp.entries == NULL)
+ return _csi_error (CAIRO_STATUS_NO_MEMORY);
+
+ hash_table->used_entries = 0;
+ }
+
+ for (i = 0; i < hash_table->arrangement->size; ++i) {
+ csi_hash_entry_t *entry, **pos;
+
+ entry = hash_table->entries[i];
+ if (ENTRY_IS_LIVE (entry)) {
+ hash_table->entries[i] = DEAD_ENTRY;
+
+ pos = _csi_hash_table_lookup_unique_key (&tmp, entry);
+ if (ENTRY_IS_FREE (*pos))
+ hash_table->used_entries++;
+
+ *pos = entry;
+ }
+ }
+
+ if (realloc) {
+ free (hash_table->entries);
+ hash_table->entries = tmp.entries;
+ hash_table->arrangement = tmp.arrangement;
+ }
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+/**
+ * _csi_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 _csi_hash_table_create).
+ *
+ * Return value: the matching entry, of %NULL if no match was found.
+ **/
+void *
+_csi_hash_table_lookup (csi_hash_table_t *hash_table,
+ csi_hash_entry_t *key)
+{
+ csi_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 ((*entry)->hash == key->hash && 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 ((*entry)->hash == key->hash &&
+ hash_table->keys_equal (key, *entry))
+ {
+ return *entry;
+ }
+ } else if (ENTRY_IS_FREE (*entry))
+ return NULL;
+ } while (++i < table_size);
+
+ return NULL;
+}
+
+/**
+ * _csi_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 _csi_hash_table_lookup. Or if absolutely
+ * necessary, use _csi_hash_table_remove first.
+ *
+ * Return value: %CAIRO_STATUS_SUCCESS if successful or
+ * %CAIRO_STATUS_NO_MEMORY if insufficient memory is available.
+ **/
+csi_status_t
+_csi_hash_table_insert (csi_hash_table_t *hash_table,
+ csi_hash_entry_t *key_and_value)
+{
+ csi_status_t status;
+ csi_hash_entry_t **entry;
+
+ hash_table->live_entries++;
+ status = _csi_hash_table_manage (hash_table);
+ if (_csi_unlikely (status)) {
+ /* abort the insert... */
+ hash_table->live_entries--;
+ return status;
+ }
+
+ entry = _csi_hash_table_lookup_unique_key (hash_table,
+ key_and_value);
+ if (ENTRY_IS_FREE (*entry))
+ hash_table->used_entries++;
+
+ *entry = key_and_value;
+ return CAIRO_STATUS_SUCCESS;
+}
+
+static csi_hash_entry_t **
+_csi_hash_table_lookup_exact_key (csi_hash_table_t *hash_table,
+ csi_hash_entry_t *key)
+{
+ unsigned long table_size, i, idx, step;
+ csi_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);
+
+ return NULL;
+}
+/**
+ * _csi_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
+_csi_hash_table_remove (csi_hash_table_t *hash_table,
+ csi_hash_entry_t *key)
+{
+ *_csi_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. */
+ _csi_hash_table_manage (hash_table);
+ }
+}
+
+/**
+ * _csi_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
+_csi_hash_table_foreach (csi_hash_table_t *hash_table,
+ csi_hash_callback_func_t hash_callback,
+ void *closure)
+{
+ unsigned long i;
+ csi_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. */
+ _csi_hash_table_manage (hash_table);
+ }
+}
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