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/**
* \file hash.h
* Generic hash table.
*/
/*
* Mesa 3-D graphics library
*
* Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
*
* 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 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.
*/
#ifndef HASH_H
#define HASH_H
#include "glheader.h"
#include "util/imports.h"
#include "c11/threads.h"
/**
* Magic GLuint object name that gets stored outside of the struct hash_table.
*
* The hash table needs a particular pointer to be the marker for a key that
* was deleted from the table, along with NULL for the "never allocated in the
* table" marker. Legacy GL allows any GLuint to be used as a GL object name,
* and we use a 1:1 mapping from GLuints to key pointers, so we need to be
* able to track a GLuint that happens to match the deleted key outside of
* struct hash_table. We tell the hash table to use "1" as the deleted key
* value, so that we test the deleted-key-in-the-table path as best we can.
*/
#define DELETED_KEY_VALUE 1
/** @{
* Mapping from our use of GLuint as both the key and the hash value to the
* hash_table.h API
*
* There exist many integer hash functions, designed to avoid collisions when
* the integers are spread across key space with some patterns. In GL, the
* pattern (in the case of glGen*()ed object IDs) is that the keys are unique
* contiguous integers starting from 1. Because of that, we just use the key
* as the hash value, to minimize the cost of the hash function. If objects
* are never deleted, we will never see a collision in the table, because the
* table resizes itself when it approaches full, and thus key % table_size ==
* key.
*
* The case where we could have collisions for genned objects would be
* something like: glGenBuffers(&a, 100); glDeleteBuffers(&a + 50, 50);
* glGenBuffers(&b, 100), because objects 1-50 and 101-200 are allocated at
* the end of that sequence, instead of 1-150. So far it doesn't appear to be
* a problem.
*/
static inline bool
uint_key_compare(const void *a, const void *b)
{
return a == b;
}
static inline uint32_t
uint_hash(GLuint id)
{
return id;
}
static inline uint32_t
uint_key_hash(const void *key)
{
return uint_hash((uintptr_t)key);
}
static inline void *
uint_key(GLuint id)
{
return (void *)(uintptr_t) id;
}
/** @} */
/**
* The hash table data structure.
*/
struct _mesa_HashTable {
struct hash_table *ht;
GLuint MaxKey; /**< highest key inserted so far */
mtx_t Mutex; /**< mutual exclusion lock */
GLboolean InDeleteAll; /**< Debug check */
/** Value that would be in the table for DELETED_KEY_VALUE. */
void *deleted_key_data;
};
extern struct _mesa_HashTable *_mesa_NewHashTable(void);
extern void _mesa_DeleteHashTable(struct _mesa_HashTable *table);
extern void *_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key);
extern void _mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data);
extern void _mesa_HashRemove(struct _mesa_HashTable *table, GLuint key);
/**
* Lock the hash table mutex.
*
* This function should be used when multiple objects need
* to be looked up in the hash table, to avoid having to lock
* and unlock the mutex each time.
*
* \param table the hash table.
*/
static inline void
_mesa_HashLockMutex(struct _mesa_HashTable *table)
{
assert(table);
mtx_lock(&table->Mutex);
}
/**
* Unlock the hash table mutex.
*
* \param table the hash table.
*/
static inline void
_mesa_HashUnlockMutex(struct _mesa_HashTable *table)
{
assert(table);
mtx_unlock(&table->Mutex);
}
extern void *_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key);
extern void _mesa_HashInsertLocked(struct _mesa_HashTable *table,
GLuint key, void *data);
extern void _mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key);
extern void
_mesa_HashDeleteAll(struct _mesa_HashTable *table,
void (*callback)(GLuint key, void *data, void *userData),
void *userData);
extern void
_mesa_HashWalk(const struct _mesa_HashTable *table,
void (*callback)(GLuint key, void *data, void *userData),
void *userData);
extern void
_mesa_HashWalkLocked(const struct _mesa_HashTable *table,
void (*callback)(GLuint key, void *data, void *userData),
void *userData);
extern void _mesa_HashPrint(const struct _mesa_HashTable *table);
extern GLuint _mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys);
extern GLuint
_mesa_HashNumEntries(const struct _mesa_HashTable *table);
extern void _mesa_test_hash_functions(void);
#endif
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