mesa/main/hash.c

/**
 * \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 "errors.h"
#include "glheader.h"
#include "hash.h"
#include "util/hash_table.h"
#include "util/u_memory.h"
#include "util/u_idalloc.h"


/**
 * 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));
      simple_mtx_init(&table->Mutex, 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);
   if (table->id_alloc) {
      util_idalloc_fini(table->id_alloc);
      free(table->id_alloc);
   }

   simple_mtx_destroy(&table->Mutex);
   free(table);
}

static void init_name_reuse(struct _mesa_HashTable *table)
{
   assert(_mesa_hash_table_num_entries(table->ht) == 0);
   table->id_alloc = MALLOC_STRUCT(util_idalloc);
   util_idalloc_init(table->id_alloc, 8);
   ASSERTED GLuint reserve0 = util_idalloc_alloc(table->id_alloc);
   assert (reserve0 == 0);
}

void
_mesa_HashEnableNameReuse(struct _mesa_HashTable *table)
{
   _mesa_HashLockMutex(table);
   init_name_reuse(table);
   _mesa_HashUnlockMutex(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_pre_hashed(table->ht,
                                              uint_hash(key),
                                              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;
   _mesa_HashLockMutex(table);
   res = _mesa_HashLookup_unlocked(table, key);
   _mesa_HashUnlockMutex(table);
   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);
}


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.
 * \param isGenName true if the key has been generated by a HashFindFreeKey* function
 */
void
_mesa_HashInsertLocked(struct _mesa_HashTable *table, GLuint key, void *data,
                       GLboolean isGenName)
{
   _mesa_HashInsert_unlocked(table, key, data);
   if (!isGenName && table->id_alloc)
      util_idalloc_reserve(table->id_alloc, key);
}


/**
 * 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.
 * \param isGenName true if the key has been generated by a HashFindFreeKey* function
 */
void
_mesa_HashInsert(struct _mesa_HashTable *table, GLuint key, void *data,
                 GLboolean isGenName)
{
   _mesa_HashLockMutex(table);
   _mesa_HashInsert_unlocked(table, key, data);
   if (!isGenName && table->id_alloc)
      util_idalloc_reserve(table->id_alloc, key);
   _mesa_HashUnlockMutex(table);
}


/**
 * 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.
 */
static inline void
_mesa_HashRemove_unlocked(struct _mesa_HashTable *table, GLuint key)
{
   struct hash_entry *entry;

   assert(table);
   assert(key);

   #ifndef NDEBUG
   /* assert if _mesa_HashRemove illegally called from _mesa_HashDeleteAll
    * callback function. Have to check this outside of mutex lock.
    */
   assert(!table->InDeleteAll);
   #endif

   if (key == DELETED_KEY_VALUE) {
      table->deleted_key_data = NULL;
   } else {
      entry = _mesa_hash_table_search_pre_hashed(table->ht,
                                                 uint_hash(key),
                                                 uint_key(key));
      _mesa_hash_table_remove(table->ht, entry);
   }

   if (table->id_alloc)
      util_idalloc_free(table->id_alloc, key);
}


void
_mesa_HashRemoveLocked(struct _mesa_HashTable *table, GLuint key)
{
   _mesa_HashRemove_unlocked(table, key);
}

void
_mesa_HashRemove(struct _mesa_HashTable *table, GLuint key)
{
   _mesa_HashLockMutex(table);
   _mesa_HashRemove_unlocked(table, key);
   _mesa_HashUnlockMutex(table);
}

/**
 * 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)(void *data, void *userData),
                    void *userData)
{
   assert(callback);
   _mesa_HashLockMutex(table);
   #ifndef NDEBUG
   table->InDeleteAll = GL_TRUE;
   #endif
   hash_table_foreach(table->ht, entry) {
      callback(entry->data, userData);
      _mesa_hash_table_remove(table->ht, entry);
   }
   if (table->deleted_key_data) {
      callback(table->deleted_key_data, userData);
      table->deleted_key_data = NULL;
   }
   if (table->id_alloc) {
      util_idalloc_fini(table->id_alloc);
      free(table->id_alloc);
      init_name_reuse(table);
   }
   #ifndef NDEBUG
   table->InDeleteAll = GL_FALSE;
   #endif
   table->MaxKey = 0;
   _mesa_HashUnlockMutex(table);
}


/**
 * Walk over all entries in a hash table, calling callback function for each.
 * \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)
 */
static void
hash_walk_unlocked(const struct _mesa_HashTable *table,
                   void (*callback)(void *data, void *userData),
                   void *userData)
{
   assert(table);
   assert(callback);

   hash_table_foreach(table->ht, entry) {
      callback(entry->data, userData);
   }
   if (table->deleted_key_data)
      callback(table->deleted_key_data, userData);
}


void
_mesa_HashWalk(const struct _mesa_HashTable *table,
               void (*callback)(void *data, void *userData),
               void *userData)
{
   /* cast-away const */
   struct _mesa_HashTable *table2 = (struct _mesa_HashTable *) table;

   _mesa_HashLockMutex(table2);
   hash_walk_unlocked(table, callback, userData);
   _mesa_HashUnlockMutex(table2);
}

void
_mesa_HashWalkLocked(const struct _mesa_HashTable *table,
               void (*callback)(void *data, void *userData),
               void *userData)
{
   hash_walk_unlocked(table, callback, userData);
}

/**
 * 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)
      _mesa_debug(NULL, "%u %p\n", DELETED_KEY_VALUE, table->deleted_key_data);

   hash_table_foreach(table->ht, entry) {
      _mesa_debug(NULL, "%u %p\n", (unsigned)(uintptr_t) entry->key,
                  entry->data);
   }
}


/**
 * 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;
   if (table->id_alloc && numKeys == 1) {
      return util_idalloc_alloc(table->id_alloc);
   } else if (maxKey - numKeys > table->MaxKey) {
      /* the quick solution */
      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) {
	       return freeStart;
	    }
	 }
      }
      /* cannot allocate a block of numKeys consecutive keys */
      return 0;
   }
}


bool
_mesa_HashFindFreeKeys(struct _mesa_HashTable *table, GLuint* keys, GLuint numKeys)
{
   if (!table->id_alloc) {
      GLuint first = _mesa_HashFindFreeKeyBlock(table, numKeys);
      for (int i = 0; i < numKeys; i++) {
         keys[i] = first + i;
      }
      return first != 0;
   }

   for (int i = 0; i < numKeys; i++) {
      keys[i] = util_idalloc_alloc(table->id_alloc);
   }

   return true;
}


/**
 * Return the number of entries in the hash table.
 */
GLuint
_mesa_HashNumEntries(const struct _mesa_HashTable *table)
{
   GLuint count = 0;

   if (table->deleted_key_data)
      count++;

   count += _mesa_hash_table_num_entries(table->ht);

   return count;
}