[Mesa-dev] Fwd: Re: [PATCH 06/14] util: Make a copy of the existing hash table implementation

Thomas Helland thomashelland90 at gmail.com
Mon Jan 2 12:16:50 UTC 2017


---------- Forwarded message ----------
From: "Thomas Helland" <thomashelland90 at gmail.com>
Date: Jan 2, 2017 1:16 PM
Subject: Re: [Mesa-dev] [PATCH 06/14] util: Make a copy of the existing
hash table implementation
To: "Vladislav Egorov" <vegorov180 at gmail.com>
Cc:

Thanks!

I was thinking that this data structure would have a name.
I'll keep that in mind if I take the route of this series.
If I follow Connor's suggestion a multimap would not be needed,
so then I'll probably just stowe away the implementation and forget it.


On Jan 2, 2017 11:49 AM, "Vladislav Egorov" <vegorov180 at gmail.com> wrote:

I think this data structure is known as multimap (in STL it's named
std::unordered_multimap, in Scala it's MultiMap, in Apache Commons it's
MultiValueMap and so on).

https://en.wikipedia.org/wiki/Multimap

01.01.2017 21:37, Thomas Helland пишет:

---
>   src/util/Makefile.sources           |   2 +
>   src/util/non_replacing_hash_table.c | 504 ++++++++++++++++++++++++++++++
> ++++++
>   src/util/non_replacing_hash_table.h | 159 ++++++++++++
>   3 files changed, 665 insertions(+)
>   create mode 100644 src/util/non_replacing_hash_table.c
>   create mode 100644 src/util/non_replacing_hash_table.h
>
> diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
> index b24611a363..6d7f0884fb 100644
> --- a/src/util/Makefile.sources
> +++ b/src/util/Makefile.sources
> @@ -20,6 +20,8 @@ MESA_UTIL_FILES :=    \
>         macros.h \
>         mesa-sha1.c \
>         mesa-sha1.h \
> +       non_replacing_hash_table.c \
> +       non_replacing_hash_table.h \
>         ralloc.c \
>         ralloc.h \
>         register_allocate.c \
> diff --git a/src/util/non_replacing_hash_table.c
> b/src/util/non_replacing_hash_table.c
> new file mode 100644
> index 0000000000..1730b1ee0d
> --- /dev/null
> +++ b/src/util/non_replacing_hash_table.c
> @@ -0,0 +1,504 @@
> +/*
> + * Copyright © 2009,2012 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>
> + */
> +
> +/**
> + * Implements an open-addressing, linear-reprobing hash table.
> + *
> + * For more information, see:
> + *
> + * http://cgit.freedesktop.org/~anholt/hash_table/tree/README
> + */
> +
> +#include <stdlib.h>
> +#include <string.h>
> +#include <assert.h>
> +
> +#include "non_replacing_hash_table.h"
> +#include "ralloc.h"
> +#include "macros.h"
> +
> +static const uint32_t deleted_key_value;
> +
> +/**
> + * 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 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 hash_entry *entry)
> +{
> +   return entry->key == NULL;
> +}
> +
> +static int
> +entry_is_deleted(const struct hash_table *ht, struct hash_entry *entry)
> +{
> +   return entry->key == ht->deleted_key;
> +}
> +
> +static int
> +entry_is_present(const struct hash_table *ht, struct hash_entry *entry)
> +{
> +   return entry->key != NULL && entry->key != ht->deleted_key;
> +}
> +
> +struct hash_table *
> +_mesa_hash_table_create(void *mem_ctx,
> +                        uint32_t (*key_hash_function)(const void *key),
> +                        bool (*key_equals_function)(const void *a,
> +                                                    const void *b))
> +{
> +   struct hash_table *ht;
> +
> +   ht = ralloc(mem_ctx, struct hash_table);
> +   if (ht == NULL)
> +      return NULL;
> +
> +   ht->size_index = 0;
> +   ht->size = hash_sizes[ht->size_index].size;
> +   ht->rehash = hash_sizes[ht->size_index].rehash;
> +   ht->max_entries = hash_sizes[ht->size_index].max_entries;
> +   ht->key_hash_function = key_hash_function;
> +   ht->key_equals_function = key_equals_function;
> +   ht->table = rzalloc_array(ht, struct hash_entry, ht->size);
> +   ht->entries = 0;
> +   ht->deleted_entries = 0;
> +   ht->deleted_key = &deleted_key_value;
> +
> +   if (ht->table == NULL) {
> +      ralloc_free(ht);
> +      return NULL;
> +   }
> +
> +   return ht;
> +}
> +
> +/**
> + * Frees the given hash table.
> + *
> + * If delete_function is passed, it gets called on each entry present
> before
> + * freeing.
> + */
> +void
> +_mesa_hash_table_destroy(struct hash_table *ht,
> +                         void (*delete_function)(struct hash_entry
> *entry))
> +{
> +   if (!ht)
> +      return;
> +
> +   if (delete_function) {
> +      struct hash_entry *entry;
> +
> +      hash_table_foreach(ht, entry) {
> +         delete_function(entry);
> +      }
> +   }
> +   ralloc_free(ht);
> +}
> +
> +/**
> + * Deletes all entries of the given hash table without deleting the table
> + * itself or changing its structure.
> + *
> + * If delete_function is passed, it gets called on each entry present.
> + */
> +void
> +_mesa_hash_table_clear(struct hash_table *ht,
> +                       void (*delete_function)(struct hash_entry *entry))
> +{
> +   struct hash_entry *entry;
> +
> +   for (entry = ht->table; entry != ht->table + ht->size; entry++) {
> +      if (entry->key == NULL)
> +         continue;
> +
> +      if (delete_function != NULL && entry->key != ht->deleted_key)
> +         delete_function(entry);
> +
> +      entry->key = NULL;
> +   }
> +
> +   ht->entries = 0;
> +   ht->deleted_entries = 0;
> +}
> +
> +/** Sets the value of the key pointer used for deleted entries in the
> table.
> + *
> + * The assumption is that usually keys are actual pointers, so we use a
> + * default value of a pointer to an arbitrary piece of storage in the
> library.
> + * But in some cases a consumer wants to store some other sort of value
> in the
> + * table, like a uint32_t, in which case that pointer may conflict with
> one of
> + * their valid keys.  This lets that user select a safe value.
> + *
> + * This must be called before any keys are actually deleted from the
> table.
> + */
> +void
> +_mesa_hash_table_set_deleted_key(struct hash_table *ht, const void
> *deleted_key)
> +{
> +   ht->deleted_key = deleted_key;
> +}
> +
> +static struct hash_entry *
> +hash_table_search(struct hash_table *ht, uint32_t hash, const void *key)
> +{
> +   uint32_t start_hash_address = hash % ht->size;
> +   uint32_t hash_address = start_hash_address;
> +
> +   do {
> +      uint32_t double_hash;
> +
> +      struct hash_entry *entry = ht->table + hash_address;
> +
> +      if (entry_is_free(entry)) {
> +         return NULL;
> +      } else if (entry_is_present(ht, entry) && entry->hash == hash) {
> +         if (ht->key_equals_function(key, entry->key)) {
> +            return entry;
> +         }
> +      }
> +
> +      double_hash = 1 + hash % ht->rehash;
> +
> +      hash_address = (hash_address + double_hash) % ht->size;
> +   } while (hash_address != start_hash_address);
> +
> +   return NULL;
> +}
> +
> +/**
> + * Finds a hash table entry with the given key and hash of that key.
> + *
> + * Returns NULL if no entry is found.  Note that the data pointer may be
> + * modified by the user.
> + */
> +struct hash_entry *
> +_mesa_hash_table_search(struct hash_table *ht, const void *key)
> +{
> +   assert(ht->key_hash_function);
> +   return hash_table_search(ht, ht->key_hash_function(key), key);
> +}
> +
> +struct hash_entry *
> +_mesa_hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash,
> +                                  const void *key)
> +{
> +   assert(ht->key_hash_function == NULL || hash ==
> ht->key_hash_function(key));
> +   return hash_table_search(ht, hash, key);
> +}
> +
> +static struct hash_entry *
> +hash_table_insert(struct hash_table *ht, uint32_t hash,
> +                  const void *key, void *data);
> +
> +static void
> +_mesa_hash_table_rehash(struct hash_table *ht, unsigned new_size_index)
> +{
> +   struct hash_table old_ht;
> +   struct hash_entry *table, *entry;
> +
> +   if (new_size_index >= ARRAY_SIZE(hash_sizes))
> +      return;
> +
> +   table = rzalloc_array(ht, struct hash_entry,
> +                         hash_sizes[new_size_index].size);
> +   if (table == NULL)
> +      return;
> +
> +   old_ht = *ht;
> +
> +   ht->table = table;
> +   ht->size_index = new_size_index;
> +   ht->size = hash_sizes[ht->size_index].size;
> +   ht->rehash = hash_sizes[ht->size_index].rehash;
> +   ht->max_entries = hash_sizes[ht->size_index].max_entries;
> +   ht->entries = 0;
> +   ht->deleted_entries = 0;
> +
> +   hash_table_foreach(&old_ht, entry) {
> +      hash_table_insert(ht, entry->hash, entry->key, entry->data);
> +   }
> +
> +   ralloc_free(old_ht.table);
> +}
> +
> +static struct hash_entry *
> +hash_table_insert(struct hash_table *ht, uint32_t hash,
> +                  const void *key, void *data)
> +{
> +   uint32_t start_hash_address, hash_address;
> +   struct hash_entry *available_entry = NULL;
> +
> +   assert(key != NULL);
> +
> +   if (ht->entries >= ht->max_entries) {
> +      _mesa_hash_table_rehash(ht, ht->size_index + 1);
> +   } else if (ht->deleted_entries + ht->entries >= ht->max_entries) {
> +      _mesa_hash_table_rehash(ht, ht->size_index);
> +   }
> +
> +   start_hash_address = hash % ht->size;
> +   hash_address = start_hash_address;
> +   do {
> +      struct hash_entry *entry = ht->table + hash_address;
> +      uint32_t double_hash;
> +
> +      if (!entry_is_present(ht, 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(ht, entry) &&
> +          entry->hash == hash &&
> +          ht->key_equals_function(key, entry->key)) {
> +         entry->key = key;
> +         entry->data = data;
> +         return entry;
> +      }
> +
> +
> +      double_hash = 1 + hash % ht->rehash;
> +
> +      hash_address = (hash_address + double_hash) % ht->size;
> +   } while (hash_address != start_hash_address);
> +
> +   if (available_entry) {
> +      if (entry_is_deleted(ht, available_entry))
> +         ht->deleted_entries--;
> +      available_entry->hash = hash;
> +      available_entry->key = key;
> +      available_entry->data = data;
> +      ht->entries++;
> +      return available_entry;
> +   }
> +
> +   /* We could hit here if a required resize failed. An unchecked-malloc
> +    * application could ignore this result.
> +    */
> +   return NULL;
> +}
> +
> +/**
> + * Inserts the key with the given hash into the table.
> + *
> + * Note that insertion may rearrange the table on a resize or rehash,
> + * so previously found hash_entries are no longer valid after this
> function.
> + */
> +struct hash_entry *
> +_mesa_hash_table_insert(struct hash_table *ht, const void *key, void
> *data)
> +{
> +   assert(ht->key_hash_function);
> +   return hash_table_insert(ht, ht->key_hash_function(key), key, data);
> +}
> +
> +struct hash_entry *
> +_mesa_hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash,
> +                                   const void *key, void *data)
> +{
> +   assert(ht->key_hash_function == NULL || hash ==
> ht->key_hash_function(key));
> +   return hash_table_insert(ht, hash, key, data);
> +}
> +
> +/**
> + * This function deletes the given hash table entry.
> + *
> + * Note that deletion doesn't otherwise modify the table, so an iteration
> over
> + * the table deleting entries is safe.
> + */
> +void
> +_mesa_hash_table_remove(struct hash_table *ht,
> +                        struct hash_entry *entry)
> +{
> +   if (!entry)
> +      return;
> +
> +   entry->key = ht->deleted_key;
> +   ht->entries--;
> +   ht->deleted_entries++;
> +}
> +
> +/**
> + * This function is an iterator over the hash table.
> + *
> + * Pass in NULL for the first entry, as in the start of a for loop.  Note
> that
> + * an iteration over the table is O(table_size) not O(entries).
> + */
> +struct hash_entry *
> +_mesa_hash_table_next_entry(struct hash_table *ht,
> +                            struct hash_entry *entry)
> +{
> +   if (entry == NULL)
> +      entry = ht->table;
> +   else
> +      entry = entry + 1;
> +
> +   for (; entry != ht->table + ht->size; entry++) {
> +      if (entry_is_present(ht, entry)) {
> +         return entry;
> +      }
> +   }
> +
> +   return NULL;
> +}
> +
> +/**
> + * Returns a random entry from the hash table.
> + *
> + * 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.
> + */
> +struct hash_entry *
> +_mesa_hash_table_random_entry(struct hash_table *ht,
> +                              bool (*predicate)(struct hash_entry *entry))
> +{
> +   struct hash_entry *entry;
> +   uint32_t i = rand() % ht->size;
> +
> +   if (ht->entries == 0)
> +      return NULL;
> +
> +   for (entry = ht->table + i; entry != ht->table + ht->size; entry++) {
> +      if (entry_is_present(ht, entry) &&
> +          (!predicate || predicate(entry))) {
> +         return entry;
> +      }
> +   }
> +
> +   for (entry = ht->table; entry != ht->table + i; entry++) {
> +      if (entry_is_present(ht, entry) &&
> +          (!predicate || predicate(entry))) {
> +         return entry;
> +      }
> +   }
> +
> +   return NULL;
> +}
> +
> +
> +/**
> + * Quick FNV-1a hash implementation based on:
> + * http://www.isthe.com/chongo/tech/comp/fnv/
> + *
> + * FNV-1a is not be the best hash out there -- Jenkins's lookup3 is
> supposed
> + * to be quite good, and it probably beats FNV.  But FNV has the advantage
> + * that it involves almost no code.  For an improvement on both, see Paul
> + * Hsieh's http://www.azillionmonkeys.com/qed/hash.html
> + */
> +uint32_t
> +_mesa_hash_data(const void *data, size_t size)
> +{
> +   return _mesa_fnv32_1a_accumulate_block(_mesa_fnv32_1a_offset_bias,
> +                                          data, size);
> +}
> +
> +/** FNV-1a string hash implementation */
> +uint32_t
> +_mesa_hash_string(const char *key)
> +{
> +   uint32_t hash = _mesa_fnv32_1a_offset_bias;
> +
> +   while (*key != 0) {
> +      hash = _mesa_fnv32_1a_accumulate(hash, *key);
> +      key++;
> +   }
> +
> +   return hash;
> +}
> +
> +/**
> + * String compare function for use as the comparison callback in
> + * _mesa_hash_table_create().
> + */
> +bool
> +_mesa_key_string_equal(const void *a, const void *b)
> +{
> +   return strcmp(a, b) == 0;
> +}
> +
> +bool
> +_mesa_key_pointer_equal(const void *a, const void *b)
> +{
> +   return a == b;
> +}
> diff --git a/src/util/non_replacing_hash_table.h
> b/src/util/non_replacing_hash_table.h
> new file mode 100644
> index 0000000000..b35ee871bb
> --- /dev/null
> +++ b/src/util/non_replacing_hash_table.h
> @@ -0,0 +1,159 @@
> +/*
> + * Copyright © 2009,2012 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 _HASH_TABLE_H
> +#define _HASH_TABLE_H
> +
> +#include <stdlib.h>
> +#include <inttypes.h>
> +#include <stdbool.h>
> +#include "c99_compat.h"
> +#include "macros.h"
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +struct hash_entry {
> +   uint32_t hash;
> +   const void *key;
> +   void *data;
> +};
> +
> +struct hash_table {
> +   struct hash_entry *table;
> +   uint32_t (*key_hash_function)(const void *key);
> +   bool (*key_equals_function)(const void *a, const void *b);
> +   const void *deleted_key;
> +   uint32_t size;
> +   uint32_t rehash;
> +   uint32_t max_entries;
> +   uint32_t size_index;
> +   uint32_t entries;
> +   uint32_t deleted_entries;
> +};
> +
> +struct hash_table *
> +_mesa_hash_table_create(void *mem_ctx,
> +                        uint32_t (*key_hash_function)(const void *key),
> +                        bool (*key_equals_function)(const void *a,
> +                                                    const void *b));
> +void _mesa_hash_table_destroy(struct hash_table *ht,
> +                              void (*delete_function)(struct hash_entry
> *entry));
> +void _mesa_hash_table_clear(struct hash_table *ht,
> +                            void (*delete_function)(struct hash_entry
> *entry));
> +void _mesa_hash_table_set_deleted_key(struct hash_table *ht,
> +                                      const void *deleted_key);
> +
> +static inline uint32_t _mesa_hash_table_num_entries(struct hash_table
> *ht)
> +{
> +   return ht->entries;
> +}
> +
> +struct hash_entry *
> +_mesa_hash_table_insert(struct hash_table *ht, const void *key, void
> *data);
> +struct hash_entry *
> +_mesa_hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash,
> +                                   const void *key, void *data);
> +struct hash_entry *
> +_mesa_hash_table_search(struct hash_table *ht, const void *key);
> +struct hash_entry *
> +_mesa_hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash,
> +                                  const void *key);
> +void _mesa_hash_table_remove(struct hash_table *ht,
> +                             struct hash_entry *entry);
> +
> +struct hash_entry *_mesa_hash_table_next_entry(struct hash_table *ht,
> +                                               struct hash_entry *entry);
> +struct hash_entry *
> +_mesa_hash_table_random_entry(struct hash_table *ht,
> +                              bool (*predicate)(struct hash_entry
> *entry));
> +
> +uint32_t _mesa_hash_data(const void *data, size_t size);
> +uint32_t _mesa_hash_string(const char *key);
> +bool _mesa_key_string_equal(const void *a, const void *b);
> +bool _mesa_key_pointer_equal(const void *a, const void *b);
> +
> +static inline uint32_t _mesa_key_hash_string(const void *key)
> +{
> +   return _mesa_hash_string((const char *)key);
> +}
> +
> +static inline uint32_t _mesa_hash_pointer(const void *pointer)
> +{
> +   return _mesa_hash_data(&pointer, sizeof(pointer));
> +}
> +
> +enum {
> +   _mesa_fnv32_1a_offset_bias = 2166136261u,
> +};
> +
> +static inline uint32_t
> +_mesa_fnv32_1a_accumulate_block(uint32_t hash, const void *data, size_t
> size)
> +{
> +   const uint8_t *bytes = (const uint8_t *)data;
> +
> +   while (size-- != 0) {
> +      hash ^= *bytes;
> +      hash = hash * 0x01000193;
> +      bytes++;
> +   }
> +
> +   return hash;
> +}
> +
> +#define _mesa_fnv32_1a_accumulate(hash, expr) \
> +   _mesa_fnv32_1a_accumulate_block(hash, &(expr), sizeof(expr))
> +
> +/**
> + * 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 hash_table_foreach(ht, entry)                   \
> +   for (entry = _mesa_hash_table_next_entry(ht, NULL);  \
> +        entry != NULL;                                  \
> +        entry = _mesa_hash_table_next_entry(ht, entry))
> +
> +static inline void
> +hash_table_call_foreach(struct hash_table *ht,
> +                        void (*callback)(const void *key,
> +                                         void *data,
> +                                         void *closure),
> +                        void *closure)
> +{
> +   struct hash_entry *entry;
> +
> +   hash_table_foreach(ht, entry)
> +      callback(entry->key, entry->data, closure);
> +}
> +
> +#ifdef __cplusplus
> +} /* extern C */
> +#endif
> +
> +#endif /* _HASH_TABLE_H */
>
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