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/**

 * \file hash.c

 * Generic hash table.

 *

 * Used for display lists, texture objects, vertex/fragment programs,

 * buffer objects, etc.  The hash functions are thread-safe.

 *

 * \note key=0 is illegal.

 *

 * \author Brian Paul

 */

/*

 * 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.

 */

#include "glheader.h"

#include "imports.h"

#include "hash.h"

#include "util/hash_table.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

/**

 * 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 */

   mtx_t WalkMutex;            /**< for _mesa_HashWalk() */

   GLboolean InDeleteAll;                /**< Debug check */

   /** Value that would be in the table for DELETED_KEY_VALUE. */

   void *deleted_key_data;

};

/** @{

 * 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 bool

uint_key_compare(const void *a, const void *b)

{

   return a == b;

}

static uint32_t

uint_hash(GLuint id)

{

   return id;

}

static uint32_t

uint_key_hash(const void *key)

{

   return uint_hash((uintptr_t)key);

}

static void *

uint_key(GLuint id)

{

   return (void *)(uintptr_t) id;

}

/** @} */

/**

 * Create a new hash table.

 *

 * \return pointer to a new, empty hash table.

 */

struct _mesa_HashTable *

_mesa_NewHashTable(void)

{

   struct _mesa_HashTable *table = CALLOC_STRUCT(_mesa_HashTable);

   if (table) {

      table->ht = _mesa_hash_table_create(NULL, uint_key_hash,

                                          uint_key_compare);

      if (table->ht == NULL) {

         free(table);

         _mesa_error_no_memory(__func__);

         return NULL;

      }

      _mesa_hash_table_set_deleted_key(table->ht, uint_key(DELETED_KEY_VALUE));

      mtx_init(&table->Mutex, mtx_plain);

      mtx_init(&table->WalkMutex, mtx_plain);

   }

   else {

      _mesa_error_no_memory(__func__);

   }

   return table;

}

/**

 * Delete a hash table.

 * Frees each entry on the hash table and then the hash table structure itself.

 * Note that the caller should have already traversed the table and deleted

 * the objects in the table (i.e. We don't free the entries' data pointer).

 *

 * \param table the hash table to delete.

 */

void

_mesa_DeleteHashTable(struct _mesa_HashTable *table)

{

   assert(table);

   if (_mesa_hash_table_next_entry(table->ht, NULL) != NULL) {

      _mesa_problem(NULL, "In _mesa_DeleteHashTable, found non-freed data");

   }

   _mesa_hash_table_destroy(table->ht, NULL);

   mtx_destroy(&table->Mutex);

   mtx_destroy(&table->WalkMutex);

   free(table);

}

/**

 * Lookup an entry in the hash table, without locking.

 * \sa _mesa_HashLookup

 */

static inline void *

_mesa_HashLookup_unlocked(struct _mesa_HashTable *table, GLuint key)

{

   const struct hash_entry *entry;

   assert(table);

   assert(key);

   if (key == DELETED_KEY_VALUE)

      return table->deleted_key_data;

   entry = _mesa_hash_table_search(table->ht, uint_key(key));

   if (!entry)

      return NULL;

   return entry->data;

}

/**

 * Lookup an entry in the hash table.

 *

 * \param table the hash table.

 * \param key the key.

 *

 * \return pointer to user's data or NULL if key not in table

 */

void *

_mesa_HashLookup(struct _mesa_HashTable *table, GLuint key)

{

   void *res;

   assert(table);

   mtx_lock(&table->Mutex);

   res = _mesa_HashLookup_unlocked(table, key);

   mtx_unlock(&table->Mutex);

   return res;

}

/**

 * Lookup an entry in the hash table without locking the mutex.

 *

 * The hash table mutex must be locked manually by calling

 * _mesa_HashLockMutex() before calling this function.

 *

 * \param table the hash table.

 * \param key the key.

 *

 * \return pointer to user's data or NULL if key not in table

 */

void *

_mesa_HashLookupLocked(struct _mesa_HashTable *table, GLuint key)

{

   return _mesa_HashLookup_unlocked(table, 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.

 */

void

_mesa_HashLockMutex(struct _mesa_HashTable *table)

{

   assert(table);

   mtx_lock(&table->Mutex);

}

/**

 * Unlock the hash table mutex.

 *

 * \param table the hash table.

 */

void

_mesa_HashUnlockMutex(struct _mesa_HashTable *table)

{

   assert(table);

   mtx_unlock(&table->Mutex);

}

static inline void

_mesa_HashInsert_unlocked(struct _mesa_HashTable *table, GLuint key, void *data)

{

   uint32_t hash = uint_hash(key);

   struct hash_entry *entry;

   assert(table);

   assert(key);

   if (key > table->MaxKey)

      table->MaxKey = key;

   if (key == DELETED_KEY_VALUE) {

      table->deleted_key_data = data;

   } else {

      entry = _mesa_hash_table_search_pre_hashed(table->ht, hash, uint_key(key));

      if (entry) {

         entry->data = data;

      } else {

         _mesa_hash_table_insert_pre_hashed(table->ht, hash, uint_key(key), data);

      }

   }

}

/**

 * Insert a key/pointer pair into the hash table without locking the mutex.

 * If an entry with this key already exists we'll replace the existing entry.

 *

 * The hash table mutex must be locked manually by calling

 * _mesa_HashLockMutex() before calling this function.

 *

 * \param table the hash table.

 * \param key the key (not zero).

 * \param data pointer to user data.

 */

void

_mesa_HashInsertLocked(struct _mesa_HashTable *table, GLuint key, void *data)

{

   _mesa_HashInsert_unlocked(table, key, data);

}

/**

 * Insert a key/pointer pair into the hash table.

 * If an entry with this key already exists we'll replace the existing entry.

 *

 * \param table the hash table.

 * \param key the key (not zero).

 * \param data pointer to user data.

 */

void

_mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data)

{

   assert(table);

   mtx_lock(&table->Mutex);

   _mesa_HashInsert_unlocked(table, key, data);

   mtx_unlock(&table->Mutex);

}

/**

 * Remove an entry from the hash table.

 *

 * \param table the hash table.

 * \param key key of entry to remove.

 *

 * While holding the hash table's lock, searches the entry with the matching

 * key and unlinks it.

 */

void

_mesa_HashRemove(struct _mesa_HashTable *table, GLuint key)

{

   struct hash_entry *entry;

   assert(table);

   assert(key);

   /* have to check this outside of mutex lock */

   if (table->InDeleteAll) {

      _mesa_problem(NULL, "_mesa_HashRemove illegally called from "

                    "_mesa_HashDeleteAll callback function");

      return;

   }

   mtx_lock(&table->Mutex);

   if (key == DELETED_KEY_VALUE) {

      table->deleted_key_data = NULL;

   } else {

      entry = _mesa_hash_table_search(table->ht, uint_key(key));

      _mesa_hash_table_remove(table->ht, entry);

   }

   mtx_unlock(&table->Mutex);

}

/**

 * Delete all entries in a hash table, but don't delete the table itself.

 * Invoke the given callback function for each table entry.

 *

 * \param table  the hash table to delete

 * \param callback  the callback function

 * \param userData  arbitrary pointer to pass along to the callback

 *                  (this is typically a struct gl_context pointer)

 */

void

_mesa_HashDeleteAll(struct _mesa_HashTable *table,

                    void (*callback)(GLuint key, void *data, void *userData),

                    void *userData)

{

   struct hash_entry *entry;

   assert(table);

   assert(callback);

   mtx_lock(&table->Mutex);

   table->InDeleteAll = GL_TRUE;

   hash_table_foreach(table->ht, entry) {

      callback((uintptr_t)entry->key, entry->data, userData);

      _mesa_hash_table_remove(table->ht, entry);

   }

   if (table->deleted_key_data) {

      callback(DELETED_KEY_VALUE, table->deleted_key_data, userData);

      table->deleted_key_data = NULL;

   }

   table->InDeleteAll = GL_FALSE;

   mtx_unlock(&table->Mutex);

}

/**

 * Clone all entries in a hash table, into a new table.

 *

 * \param table  the hash table to clone

 */

struct _mesa_HashTable *

_mesa_HashClone(const struct _mesa_HashTable *table)

{

   /* cast-away const */

   struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table;

   struct hash_entry *entry;

   struct _mesa_HashTable *clonetable;

   assert(table);

   mtx_lock(&table2->Mutex);

   clonetable = _mesa_NewHashTable();

   assert(clonetable);

   hash_table_foreach(table->ht, entry) {

      _mesa_HashInsert(clonetable, (GLint)(uintptr_t)entry->key, entry->data);

   }

   mtx_unlock(&table2->Mutex);

   return clonetable;

}

/**

 * Walk over all entries in a hash table, calling callback function for each.

 * Note: we use a separate mutex in this function to avoid a recursive

 * locking deadlock (in case the callback calls _mesa_HashRemove()) and to

 * prevent multiple threads/contexts from getting tangled up.

 * A lock-less version of this function could be used when the table will

 * not be modified.

 * \param table  the hash table to walk

 * \param callback  the callback function

 * \param userData  arbitrary pointer to pass along to the callback

 *                  (this is typically a struct gl_context pointer)

 */

void

_mesa_HashWalk(const struct _mesa_HashTable *table,

               void (*callback)(GLuint key, void *data, void *userData),

               void *userData)

{

   /* cast-away const */

   struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table;

   struct hash_entry *entry;

   assert(table);

   assert(callback);

   mtx_lock(&table2->WalkMutex);

   hash_table_foreach(table->ht, entry) {

      callback((uintptr_t)entry->key, entry->data, userData);

   }

   if (table->deleted_key_data)

      callback(DELETED_KEY_VALUE, table->deleted_key_data, userData);

   mtx_unlock(&table2->WalkMutex);

}

static void

debug_print_entry(GLuint key, void *data, void *userData)

{

   _mesa_debug(NULL, "%u %p\n", key, data);

}

/**

 * Dump contents of hash table for debugging.

 *

 * \param table the hash table.

 */

void

_mesa_HashPrint(const struct _mesa_HashTable *table)

{

   if (table->deleted_key_data)

      debug_print_entry(DELETED_KEY_VALUE, table->deleted_key_data, NULL);

   _mesa_HashWalk(table, debug_print_entry, NULL);

}

/**

 * Find a block of adjacent unused hash keys.

 *

 * \param table the hash table.

 * \param numKeys number of keys needed.

 *

 * \return Starting key of free block or 0 if failure.

 *

 * If there are enough free keys between the maximum key existing in the table

 * (_mesa_HashTable::MaxKey) and the maximum key possible, then simply return

 * the adjacent key. Otherwise do a full search for a free key block in the

 * allowable key range.

 */

GLuint

_mesa_HashFindFreeKeyBlock(struct _mesa_HashTable *table, GLuint numKeys)

{

   const GLuint maxKey = ~((GLuint) 0) - 1;

   mtx_lock(&table->Mutex);

   if (maxKey - numKeys > table->MaxKey) {

      /* the quick solution */

      mtx_unlock(&table->Mutex);

      return table->MaxKey + 1;

   }

   else {

      /* the slow solution */

      GLuint freeCount = 0;

      GLuint freeStart = 1;

      GLuint key;

      for (key = 1; key != maxKey; key++) {

	 if (_mesa_HashLookup_unlocked(table, key)) {

	    /* darn, this key is already in use */

	    freeCount = 0;

	    freeStart = key+1;

	 }

	 else {

	    /* this key not in use, check if we've found enough */

	    freeCount++;

	    if (freeCount == numKeys) {

               mtx_unlock(&table->Mutex);

	       return freeStart;

	    }

	 }

      }

      /* cannot allocate a block of numKeys consecutive keys */

      mtx_unlock(&table->Mutex);

      return 0;

   }

}

/**

 * Return the number of entries in the hash table.

 */

GLuint

_mesa_HashNumEntries(const struct _mesa_HashTable *table)

{

   struct hash_entry *entry;

   GLuint count = 0;

   if (table->deleted_key_data)

      count++;

   hash_table_foreach(table->ht, entry)

      count++;

   return count;

}