[igt-dev] [PATCH i-g-t v30 03/39] lib/igt_map: Adopt Mesa hash table

Zbigniew Kempczyński zbigniew.kempczynski at intel.com
Fri Apr 2 09:38:08 UTC 2021


From: Dominik Grzegorzek <dominik.grzegorzek at intel.com>

The _search function has been changed to return a pointer to
the stored data instead of the entry struct. The _search_entry function,
which acts as the original search has been added. Additionally _remove function
has an optional delete_function param, to make it more usable.

For more information, see:
http://cgit.freedesktop.org/~anholt/hash_table/tree/README

Signed-off-by: Dominik Grzegorzek <dominik.grzegorzek at intel.com>
Cc: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Jason Ekstrand <jason at jlekstrand.net>
---
 .../igt-gpu-tools/igt-gpu-tools-docs.xml      |   1 +
 lib/Makefile.sources                          |   2 +
 lib/igt_map.c                                 | 502 ++++++++++++++++++
 lib/igt_map.h                                 | 174 ++++++
 lib/meson.build                               |   1 +
 5 files changed, 680 insertions(+)
 create mode 100644 lib/igt_map.c
 create mode 100644 lib/igt_map.h

diff --git a/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml b/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
index 9c9aa8f1d..bf5ac5428 100644
--- a/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
+++ b/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
@@ -33,6 +33,7 @@
     <xi:include href="xml/igt_kmod.xml"/>
     <xi:include href="xml/igt_kms.xml"/>
     <xi:include href="xml/igt_list.xml"/>
+    <xi:include href="xml/igt_map.xml"/>
     <xi:include href="xml/igt_pm.xml"/>
     <xi:include href="xml/igt_primes.xml"/>
     <xi:include href="xml/igt_rand.xml"/>
diff --git a/lib/Makefile.sources b/lib/Makefile.sources
index 4f6389f8a..84fd7b49c 100644
--- a/lib/Makefile.sources
+++ b/lib/Makefile.sources
@@ -48,6 +48,8 @@ lib_source_list =	 	\
 	igt_infoframe.h		\
 	igt_list.c		\
 	igt_list.h		\
+	igt_map.c		\
+	igt_map.h		\
 	igt_matrix.c		\
 	igt_matrix.h		\
 	igt_params.c		\
diff --git a/lib/igt_map.c b/lib/igt_map.c
new file mode 100644
index 000000000..da8713a18
--- /dev/null
+++ b/lib/igt_map.c
@@ -0,0 +1,502 @@
+/*
+ * Copyright © 2009, 2021 Intel Corporation
+ * Copyright © 1988-2004 Keith Packard and Bart Massey.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Except as contained in this notice, the names of the authors
+ * or their institutions shall not be used in advertising or
+ * otherwise to promote the sale, use or other dealings in this
+ * Software without prior written authorization from the
+ * authors.
+ *
+ * Authors:
+ *    Eric Anholt <eric at anholt.net>
+ *    Keith Packard <keithp at keithp.com>
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "igt_map.h"
+
+#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0]))
+
+/*
+ * From Knuth -- a good choice for hash/rehash values is p, p-2 where
+ * p and p-2 are both prime.  These tables are sized to have an extra 10%
+ * free to avoid exponential performance degradation as the hash table fills
+ */
+
+static const uint32_t deleted_key_value;
+static const void *deleted_key = &deleted_key_value;
+
+static const struct {
+	uint32_t max_entries, size, rehash;
+} hash_sizes[] = {
+	{ 2,		5,		3	  },
+	{ 4,		7,		5	  },
+	{ 8,		13,		11	  },
+	{ 16,		19,		17	  },
+	{ 32,		43,		41        },
+	{ 64,		73,		71        },
+	{ 128,		151,		149       },
+	{ 256,		283,		281       },
+	{ 512,		571,		569       },
+	{ 1024,		1153,		1151      },
+	{ 2048,		2269,		2267      },
+	{ 4096,		4519,		4517      },
+	{ 8192,		9013,		9011      },
+	{ 16384,	18043,		18041     },
+	{ 32768,	36109,		36107     },
+	{ 65536,	72091,		72089     },
+	{ 131072,	144409,		144407    },
+	{ 262144,	288361,		288359    },
+	{ 524288,	576883,		576881    },
+	{ 1048576,	1153459,	1153457   },
+	{ 2097152,	2307163,	2307161   },
+	{ 4194304,	4613893,	4613891   },
+	{ 8388608,	9227641,	9227639   },
+	{ 16777216,	18455029,	18455027  },
+	{ 33554432,	36911011,	36911009  },
+	{ 67108864,	73819861,	73819859  },
+	{ 134217728,	147639589,	147639587 },
+	{ 268435456,	295279081,	295279079 },
+	{ 536870912,	590559793,	590559791 },
+	{ 1073741824,	1181116273,	1181116271},
+	{ 2147483648ul,	2362232233ul,	2362232231ul}
+};
+
+static int
+entry_is_free(const struct igt_map_entry *entry)
+{
+	return entry->key == NULL;
+}
+
+static int
+entry_is_deleted(const struct igt_map_entry *entry)
+{
+	return entry->key == deleted_key;
+}
+
+static int
+entry_is_present(const struct igt_map_entry *entry)
+{
+	return entry->key != NULL && entry->key != deleted_key;
+}
+
+/**
+ * igt_map_create:
+ * @hash_function: function that maps key to 32b hash
+ * @key_equals_function: function that compares given hashes
+ *
+ * Function creates a map and initializes it with given @hash_function and
+ * @key_equals_function.
+ *
+ * Returns: pointer to just created map
+ */
+struct igt_map *
+igt_map_create(uint32_t (*hash_function)(const void *key),
+	       int (*key_equals_function)(const void *a, const void *b))
+{
+	struct igt_map *map;
+
+	map = malloc(sizeof(*map));
+	if (map == NULL)
+		return NULL;
+
+	map->size_index = 0;
+	map->size = hash_sizes[map->size_index].size;
+	map->rehash = hash_sizes[map->size_index].rehash;
+	map->max_entries = hash_sizes[map->size_index].max_entries;
+	map->hash_function = hash_function;
+	map->key_equals_function = key_equals_function;
+	map->table = calloc(map->size, sizeof(*map->table));
+	map->entries = 0;
+	map->deleted_entries = 0;
+
+	if (map->table == NULL) {
+		free(map);
+		return NULL;
+	}
+
+	return map;
+}
+
+/**
+ * igt_map_destroy:
+ * @map: igt_map pointer
+ * @delete_function: function that frees data in igt_map_entry
+ *
+ * Frees the given hash table. If @delete_function is passed, it gets called
+ * on each entry present before freeing.
+ */
+void
+igt_map_destroy(struct igt_map *map,
+		void (*delete_function)(struct igt_map_entry *entry))
+{
+	if (!map)
+		return;
+
+	if (delete_function) {
+		struct igt_map_entry *entry;
+
+		igt_map_foreach(map, entry) {
+			delete_function(entry);
+		}
+	}
+	free(map->table);
+	free(map);
+}
+
+/**
+ * igt_map_search:
+ * @map: igt_map pointer
+ * @key: pointer to searched key
+ *
+ * Finds a map entry's data with the given @key.
+ *
+ * Returns: data pointer if the entry was found, %NULL otherwise.
+ * Note that it may be modified by the user.
+ */
+void *
+igt_map_search(struct igt_map *map, const void *key)
+{
+	uint32_t hash = map->hash_function(key);
+	struct igt_map_entry *entry;
+
+	entry = igt_map_search_pre_hashed(map, hash, key);
+	return entry ? entry->data : NULL;
+}
+
+/**
+ * igt_map_search_entry:
+ * @map: igt_map pointer
+ * @key: pointer to searched key
+ *
+ * Finds a map entry with the given @key.
+ *
+ * Returns: map entry or %NULL if no entry is found.
+ * Note that the data pointer may be modified by the user.
+ */
+struct igt_map_entry *
+igt_map_search_entry(struct igt_map *map, const void *key)
+{
+	uint32_t hash = map->hash_function(key);
+
+	return igt_map_search_pre_hashed(map, hash, key);
+}
+
+/**
+ * igt_map_search_pre_hashed:
+ * @map: igt_map pointer
+ * @hash: hash of @key
+ * @key: pointer to searched key
+ *
+ * Finds a map entry with the given @key and @hash of that key.
+ *
+ * Returns: map entry or %NULL if no entry is found.
+ * Note that the data pointer may be modified by the user.
+ */
+struct igt_map_entry *
+igt_map_search_pre_hashed(struct igt_map *map, uint32_t hash,
+			  const void *key)
+{
+	uint32_t start_hash_address = hash % map->size;
+	uint32_t hash_address = start_hash_address;
+
+	do {
+		uint32_t double_hash;
+
+		struct igt_map_entry *entry = map->table + hash_address;
+
+		if (entry_is_free(entry)) {
+			return NULL;
+		} else if (entry_is_present(entry) && entry->hash == hash) {
+			if (map->key_equals_function(key, entry->key)) {
+				return entry;
+			}
+		}
+
+		double_hash = 1 + hash % map->rehash;
+
+		hash_address = (hash_address + double_hash) % map->size;
+	} while (hash_address != start_hash_address);
+
+	return NULL;
+}
+
+static void
+igt_map_rehash(struct igt_map *map, int new_size_index)
+{
+	struct igt_map old_map;
+	struct igt_map_entry *table, *entry;
+
+	if (new_size_index >= ARRAY_SIZE(hash_sizes))
+		return;
+
+	table = calloc(hash_sizes[new_size_index].size, sizeof(*map->table));
+	if (table == NULL)
+		return;
+
+	old_map = *map;
+
+	map->table = table;
+	map->size_index = new_size_index;
+	map->size = hash_sizes[map->size_index].size;
+	map->rehash = hash_sizes[map->size_index].rehash;
+	map->max_entries = hash_sizes[map->size_index].max_entries;
+	map->entries = 0;
+	map->deleted_entries = 0;
+
+	igt_map_foreach(&old_map, entry) {
+		igt_map_insert_pre_hashed(map, entry->hash,
+					     entry->key, entry->data);
+	}
+
+	free(old_map.table);
+}
+
+/**
+ * igt_map_insert:
+ * @map: igt_map pointer
+ * @data: data to be store
+ * @key: pointer to searched key
+ *
+ * Inserts the @data indexed by given @key into the map. If the @map already
+ * contains an entry with the @key, it will be replaced. To avoid memory leaks,
+ * perform a search before inserting.
+ *
+ * Note that insertion may rearrange the table on a resize or rehash,
+ * so previously found hash entries are no longer valid after this function.
+ *
+ * Returns: pointer to just inserted entry
+ */
+struct igt_map_entry *
+igt_map_insert(struct igt_map *map, const void *key, void *data)
+{
+	uint32_t hash = map->hash_function(key);
+
+	/* Make sure nobody tries to add one of the magic values as a
+	 * key. If you need to do so, either do so in a wrapper, or
+	 * store keys with the magic values separately in the struct
+	 * igt_map.
+	 */
+	assert(key != NULL);
+
+	return igt_map_insert_pre_hashed(map, hash, key, data);
+}
+
+/**
+ * igt_map_insert_pre_hashed:
+ * @map: igt_map pointer
+ * @hash: hash of @key
+ * @data: data to be store
+ * @key: pointer to searched key
+ *
+ * Inserts the @data indexed by given @key and @hash of that @key into the map.
+ * If the @map already contains an entry with the @key, it will be replaced.
+ * To avoid memory leaks, perform a search before inserting.
+ *
+ * Note that insertion may rearrange the table on a resize or rehash,
+ * so previously found hash entries are no longer valid after this function.
+ *
+ * Returns: pointer to just inserted entry
+ */
+struct igt_map_entry *
+igt_map_insert_pre_hashed(struct igt_map *map, uint32_t hash,
+			  const void *key, void *data)
+{
+	uint32_t start_hash_address, hash_address;
+	struct igt_map_entry *available_entry = NULL;
+
+	if (map->entries >= map->max_entries) {
+		igt_map_rehash(map, map->size_index + 1);
+	} else if (map->deleted_entries + map->entries >= map->max_entries) {
+		igt_map_rehash(map, map->size_index);
+	}
+
+	start_hash_address = hash % map->size;
+	hash_address = start_hash_address;
+	do {
+		struct igt_map_entry *entry = map->table + hash_address;
+		uint32_t double_hash;
+
+		if (!entry_is_present(entry)) {
+			/* Stash the first available entry we find */
+			if (available_entry == NULL)
+				available_entry = entry;
+			if (entry_is_free(entry))
+				break;
+		}
+
+		/* Implement replacement when another insert happens
+		 * with a matching key.  This is a relatively common
+		 * feature of hash tables, with the alternative
+		 * generally being "insert the new value as well, and
+		 * return it first when the key is searched for".
+		 *
+		 * Note that the hash table doesn't have a delete
+		 * callback.  If freeing of old data pointers is
+		 * required to avoid memory leaks, perform a search
+		 * before inserting.
+		 */
+		if (!entry_is_deleted(entry) &&
+		    entry->hash == hash &&
+		    map->key_equals_function(key, entry->key)) {
+			entry->key = key;
+			entry->data = data;
+			return entry;
+		}
+
+
+		double_hash = 1 + hash % map->rehash;
+
+		hash_address = (hash_address + double_hash) % map->size;
+	} while (hash_address != start_hash_address);
+
+	if (available_entry) {
+		if (entry_is_deleted(available_entry))
+			map->deleted_entries--;
+		available_entry->hash = hash;
+		available_entry->key = key;
+		available_entry->data = data;
+		map->entries++;
+		return available_entry;
+	}
+
+	/* We could hit here if a required resize failed. An unchecked-malloc
+	 * application could ignore this result.
+	 */
+	return NULL;
+}
+
+/**
+ * igt_map_remove:
+ * @map: igt_map pointer
+ * @key: pointer to searched key
+ * @delete_function: function that frees data in igt_map_entry
+ *
+ * Function searches for an entry with a given @key, and removes it from
+ * the map. If @delete_function is passed, it will be called on removed entry.
+ *
+ * If the caller has previously found a struct igt_map_entry pointer,
+ * (from calling igt_map_search() or remembering it from igt_map_insert()),
+ * then igt_map_remove_entry() can be called instead to avoid an extra search.
+ */
+void
+igt_map_remove(struct igt_map *map, const void *key,
+		void (*delete_function)(struct igt_map_entry *entry))
+{
+	struct igt_map_entry *entry;
+
+	entry = igt_map_search_entry(map, key);
+	if (delete_function)
+		delete_function(entry);
+
+	igt_map_remove_entry(map, entry);
+}
+
+/**
+ * igt_map_remove_entry:
+ * @map: igt_map pointer
+ * @entry: pointer to map entry
+ *
+ * Function deletes the given hash entry.
+ *
+ * Note that deletion doesn't otherwise modify the table, so an iteration over
+ * the map deleting entries is safe.
+ */
+void
+igt_map_remove_entry(struct igt_map *map, struct igt_map_entry *entry)
+{
+	if (!entry)
+		return;
+
+	entry->key = deleted_key;
+	map->entries--;
+	map->deleted_entries++;
+}
+
+/**
+ * igt_map_next_entry:
+ * @map: igt_map pointer
+ * @entry: pointer to map entry, %NULL for the first map entry
+ *
+ * This function is an iterator over the hash table.
+ * Note that an iteration over the table is O(table_size) not O(entries).
+ *
+ * Returns: pointer to the next entry
+ */
+struct igt_map_entry *
+igt_map_next_entry(struct igt_map *map, struct igt_map_entry *entry)
+{
+	if (entry == NULL)
+		entry = map->table;
+	else
+		entry = entry + 1;
+
+	for (; entry != map->table + map->size; entry++) {
+		if (entry_is_present(entry)) {
+			return entry;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * igt_map_random_entry:
+ * @map: igt_map pointer
+ * @predicate: filtering entries function
+ *
+ * Functions returns random entry from the map. This may be useful in
+ * implementing random replacement (as opposed to just removing everything)
+ * in caches based on this hash table implementation. @predicate may be used to
+ * filter entries, or may be set to %NULL for no filtering.
+ *
+ * Returns: pointer to the randomly chosen map entry
+ */
+struct igt_map_entry *
+igt_map_random_entry(struct igt_map *map,
+		     int (*predicate)(struct igt_map_entry *entry))
+{
+	struct igt_map_entry *entry;
+	uint32_t i = random() % map->size;
+
+	if (map->entries == 0)
+		return NULL;
+
+	for (entry = map->table + i; entry != map->table + map->size; entry++) {
+		if (entry_is_present(entry) &&
+		    (!predicate || predicate(entry))) {
+			return entry;
+		}
+	}
+
+	for (entry = map->table; entry != map->table + i; entry++) {
+		if (entry_is_present(entry) &&
+		    (!predicate || predicate(entry))) {
+			return entry;
+		}
+	}
+
+	return NULL;
+}
diff --git a/lib/igt_map.h b/lib/igt_map.h
new file mode 100644
index 000000000..cadcd6e35
--- /dev/null
+++ b/lib/igt_map.h
@@ -0,0 +1,174 @@
+/*
+ * Copyright © 2009,2021 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Eric Anholt <eric at anholt.net>
+ *
+ */
+
+#ifndef IGT_MAP_H
+#define IGT_MAP_H
+
+#include <inttypes.h>
+
+/**
+ * SECTION:igt_map
+ * @short_description: a linear-reprobing hashmap implementation
+ * @title: IGT Map
+ * @include: igt_map.h
+ *
+ * Implements an open-addressing, linear-reprobing hash table.
+ *
+ * For more information, see:
+ * http://cgit.freedesktop.org/~anholt/hash_table/tree/README
+ *
+ * Example usage:
+ *
+ *|[<!-- language="C" -->
+ * #define GOLDEN_RATIO_PRIME_32 0x9e370001UL
+ *
+ * static inline uint32_t hash_identifier(const void *val)
+ * {
+ *	uint32_t hash = *(uint32_t *) val;
+ *
+ *	hash = hash * GOLDEN_RATIO_PRIME_32;
+ *	return hash;
+ * }
+ *
+ * static int equal_identifiers(const void *a, const void *b)
+ * {
+ *	uint32_t *key1 = (uint32_t *) a, *key2 = (uint32_t *) b;
+ *
+ *	return *key1 == *key2;
+ * }
+ *
+ * static void free_func(struct igt_map_entry *entry)
+ * {
+ * 	free(entry->data);
+ * }
+ *
+ * struct igt_map *map;
+ *
+ * struct record {
+ *      int foo;
+ *      uint32_t unique_identifier;
+ * };
+ *
+ * struct record *r1, r2, *record;
+ * struct igt_map_entry *entry;
+ *
+ * r1 = malloc(sizeof(struct record));
+ * map = igt_map_create(hash_identifier, equal_identifiers);
+ * igt_map_insert(map, &r1->unique_identifier, r1);
+ * igt_map_insert(map, &r2.unique_identifier, &r2);
+ *
+ * igt_map_foreach(map, entry) {
+ * 	record = entry->data;
+ * 	printf("key: %u, foo: %d\n", *(uint32_t *) entry->key, record->foo);
+ * }
+ *
+ * record = igt_map_search(map, &r1->unique_identifier);
+ * entry = igt_map_search_entry(map, &r2.unique_identifier);
+ *
+ * igt_map_remove(map, &r1->unique_identifier, free_func);
+ * igt_map_remove_entry(map, entry);
+ *
+ *  igt_map_destroy(map, NULL);
+ * ]|
+ */
+
+struct igt_map_entry {
+	uint32_t hash;
+	const void *key;
+	void *data;
+};
+
+struct igt_map {
+	struct igt_map_entry *table;
+	uint32_t (*hash_function)(const void *key);
+	int (*key_equals_function)(const void *a, const void *b);
+	uint32_t size;
+	uint32_t rehash;
+	uint32_t max_entries;
+	uint32_t size_index;
+	uint32_t entries;
+	uint32_t deleted_entries;
+};
+
+struct igt_map *
+igt_map_create(uint32_t (*hash_function)(const void *key),
+	       int (*key_equals_function)(const void *a, const void *b));
+void
+igt_map_destroy(struct igt_map *map,
+		void (*delete_function)(struct igt_map_entry *entry));
+
+struct igt_map_entry *
+igt_map_insert(struct igt_map *map, const void *key, void *data);
+
+void *
+igt_map_search(struct igt_map *map, const void *key);
+
+struct igt_map_entry *
+igt_map_search_entry(struct igt_map *map, const void *key);
+
+void
+igt_map_remove(struct igt_map *map, const void *key,
+	       void (*delete_function)(struct igt_map_entry *entry));
+
+void
+igt_map_remove_entry(struct igt_map *map, struct igt_map_entry *entry);
+
+struct igt_map_entry *
+igt_map_next_entry(struct igt_map *map, struct igt_map_entry *entry);
+
+struct igt_map_entry *
+igt_map_random_entry(struct igt_map *map,
+		     int (*predicate)(struct igt_map_entry *entry));
+/**
+ * igt_map_foreach
+ * @map: igt_map pointer
+ * @entry: igt_map_entry pointer
+ *
+ * Macro is a loop, which iterates through each map entry. Inside a
+ * loop block current element is accessible by the @entry pointer.
+ *
+ * This foreach function is safe against deletion (which just replaces
+ * an entry's data with the deleted marker), but not against insertion
+ * (which may rehash the table, making entry a dangling pointer).
+ */
+#define igt_map_foreach(map, entry)				\
+	for (entry = igt_map_next_entry(map, NULL);		\
+	     entry != NULL;					\
+	     entry = igt_map_next_entry(map, entry))
+
+/* Alternate interfaces to reduce repeated calls to hash function. */
+struct igt_map_entry *
+igt_map_search_pre_hashed(struct igt_map *map,
+			     uint32_t hash,
+			     const void *key);
+
+struct igt_map_entry *
+igt_map_insert_pre_hashed(struct igt_map *map,
+			     uint32_t hash,
+			     const void *key, void *data);
+
+#endif
diff --git a/lib/meson.build b/lib/meson.build
index 672b42062..7254faeac 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -61,6 +61,7 @@ lib_sources = [
 	'igt_core.c',
 	'igt_draw.c',
 	'igt_list.c',
+	'igt_map.c',
 	'igt_pm.c',
 	'igt_dummyload.c',
 	'uwildmat/uwildmat.c',
-- 
2.26.0



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