2002-12-24 Havoc Pennington <hp@pobox.com>

	* glib/dbus-gthread.c: fix include

	* glib/dbus-glib.h: rename DBusMessageHandler for now.
	I think glib API needs to change, though, as you don't
	want to use DBusMessageFunction, you want to use the
	DBusMessageHandler object. Probably
	dbus_connection_open_with_g_main_loop()
	and dbus_connection_setup_g_main_loop() or something like that
	(but think of better names...) that just create a connection
	that has watch/timeout functions etc. already set up.

	* dbus/dbus-connection.c
	(dbus_connection_send_message_with_reply): new function just to
	show how the message handler helps us deal with replies.

	* dbus/dbus-list.c (_dbus_list_remove_last): new function

	* dbus/dbus-string.c (_dbus_string_test): free a string that
	wasn't

	* dbus/dbus-hash.c: use memory pools for the hash entries
	(rebuild_table): be more paranoid about overflow, and
	shrink table when we can
	(_dbus_hash_test): reduce number of sprintfs and write
	valid C89. Add tests for case where we grow and then
	shrink the hash table.

	* dbus/dbus-mempool.h, dbus/dbus-mempool.c: memory pools

	* dbus/dbus-connection.c (dbus_connection_register_handler)
	(dbus_connection_unregister_handler): new functions

	* dbus/dbus-message.c (dbus_message_get_name): new

	* dbus/dbus-list.c: fix docs typo

	* dbus/dbus-message-handler.h, dbus/dbus-message-handler.c:
	an object representing a handler for messages.

1 files changed, 454 insertions, 0 deletions

diff --git a/dbus/dbus-mempool.c b/dbus/dbus-mempool.c
new file mode 100644
index 00000000..a3aa086d
--- /dev/null
+++ b/dbus/dbus-mempool.c
@@ -0,0 +1,454 @@
+/* -*- mode: C; c-file-style: "gnu" -*- */
+/* dbus-mempool.h Memory pools
+ * 
+ * Copyright (C) 2002  Red Hat, Inc.
+ *
+ * Licensed under the Academic Free License version 1.2
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include "dbus-mempool.h"
+
+/**
+ * @defgroup DBusMemPool memory pools
+ * @ingroup  DBusInternals
+ * @brief DBusMemPool object
+ *
+ * Types and functions related to DBusMemPool.  A memory pool is used
+ * to decrease memory fragmentation/overhead and increase speed for
+ * blocks of small uniformly-sized objects. The main point is to avoid
+ * the overhead of a malloc block for each small object, speed is
+ * secondary.
+ */
+
+/**
+ * @defgroup DBusMemPoolInternals Memory pool implementation details
+ * @ingroup  DBusInternals
+ * @brief DBusMemPool implementation details
+ *
+ * The guts of DBusMemPool.
+ *
+ * @{
+ */
+
+/**
+ * typedef so DBusFreedElement struct can refer to itself.
+ */
+typedef struct DBusFreedElement DBusFreedElement;
+
+/**
+ * struct representing an element on the free list.
+ * We just cast freed elements to this so we can
+ * make a list out of them.
+ */
+struct DBusFreedElement
+{
+  DBusFreedElement *next; /**< next element of the free list */
+};
+
+/**
+ * The dummy size of the variable-length "elements"
+ * field in DBusMemBlock
+ */
+#define ELEMENT_PADDING 4
+
+/**
+ * Typedef for DBusMemBlock so the struct can recursively
+ * point to itself.
+ */
+typedef struct DBusMemBlock DBusMemBlock;
+
+/**
+ * DBusMemBlock object represents a single malloc()-returned
+ * block that gets chunked up into objects in the memory pool.
+ */
+struct DBusMemBlock
+{
+  DBusMemBlock *next;  /**< next block in the list, which is already used up;
+                        *   only saved so we can free all the blocks
+                        *   when we free the mem pool.
+                        */
+
+  int used_so_far;     /**< bytes of this block already allocated as elements. */
+  
+  unsigned char elements[ELEMENT_PADDING]; /**< the block data, actually allocated to required size */
+};
+
+/**
+ * Internals fields of DBusMemPool
+ */
+struct DBusMemPool
+{
+  int element_size;                /**< size of a single object in the pool */
+  int block_size;                  /**< size of most recently allocated block */
+  unsigned int zero_elements : 1;  /**< whether to zero-init allocated elements */
+
+  DBusFreedElement *free_elements; /**< a free list of elements to recycle */
+  DBusMemBlock *blocks;            /**< blocks of memory from malloc() */
+};
+
+/** @} */
+
+/**
+ * @addtogroup DBusMemPool
+ *
+ * @{
+ */
+
+/**
+ * @typedef DBusMemPool
+ *
+ * Opaque object representing a memory pool. Memory pools allow
+ * avoiding per-malloc-block memory overhead when allocating a lot of
+ * small objects that are all the same size. They are slightly
+ * faster than calling malloc() also.
+ */
+
+/**
+ * Creates a new memory pool, or returns #NULL on failure.  Objects in
+ * the pool must be at least sizeof(void*) bytes each, due to the way
+ * memory pools work. To avoid creating 64 bit problems, this means at
+ * least 8 bytes on all platforms, unless you are 4 bytes on 32-bit
+ * and 8 bytes on 64-bit.
+ *
+ * @param element_size size of an element allocated from the pool.
+ * @param zero_elements whether to zero-initialize elements
+ * @returns the new pool or #NULL
+ */
+DBusMemPool*
+_dbus_mem_pool_new (int element_size,
+                    dbus_bool_t zero_elements)
+{
+  DBusMemPool *pool;
+
+  pool = dbus_new0 (DBusMemPool, 1);
+  if (pool == NULL)
+    return NULL;
+
+  /* these assertions are equivalent but the first is more clear
+   * to programmers that see it fail.
+   */
+  _dbus_assert (element_size >= (int) sizeof (void*));
+  _dbus_assert (element_size >= (int) sizeof (DBusFreedElement));
+  
+  pool->element_size = element_size;
+  pool->zero_elements = zero_elements != FALSE;
+
+  /* pick a size for the first block; it increases
+   * for each block we need to allocate. This is
+   * actually half the initial block size
+   * since _dbus_mem_pool_alloc() unconditionally
+   * doubles it prior to creating a new block.
+   */
+  pool->block_size = element_size * 8;
+
+  _dbus_assert ((pool->block_size %
+                 pool->element_size) == 0);
+  
+  return pool;
+}
+
+/**
+ * Frees a memory pool (and all elements allocated from it).
+ *
+ * @param pool the memory pool.
+ */
+void
+_dbus_mem_pool_free (DBusMemPool *pool)
+{
+  DBusMemBlock *block;
+
+  block = pool->blocks;
+  while (block != NULL)
+    {
+      DBusMemBlock *next = block->next;
+
+      dbus_free (block);
+
+      block = next;
+    }
+
+  dbus_free (pool);
+}
+
+/**
+ * Allocates an object from the memory pool.
+ * The object must be freed with _dbus_mem_pool_dealloc().
+ *
+ * @param pool the memory pool
+ * @returns the allocated object or #NULL if no memory.
+ */
+void*
+_dbus_mem_pool_alloc (DBusMemPool *pool)
+{
+  if (pool->free_elements)
+    {
+      DBusFreedElement *element = pool->free_elements;
+
+      pool->free_elements = pool->free_elements->next;
+
+      if (pool->zero_elements)
+        memset (element, '\0', pool->element_size);
+      
+      return element;
+    }
+  else
+    {
+      void *element;
+      
+      if (pool->blocks == NULL ||
+          pool->blocks->used_so_far == pool->block_size)
+        {
+          /* Need a new block */
+          DBusMemBlock *block;
+          int alloc_size;
+
+          if (pool->block_size <= _DBUS_INT_MAX / 4) /* avoid overflow */
+            {
+              /* use a larger block size for our next block */
+              pool->block_size *= 2;
+              _dbus_assert ((pool->block_size %
+                             pool->element_size) == 0);
+            }
+
+          alloc_size = sizeof (DBusMemBlock) - ELEMENT_PADDING + pool->block_size;
+          
+          if (pool->zero_elements)
+            block = dbus_malloc0 (alloc_size);
+          else
+            block = dbus_malloc (alloc_size);
+
+          if (block == NULL)
+            return NULL;
+
+          block->used_so_far = 0;
+          block->next = pool->blocks;
+          pool->blocks = block;
+        }
+      
+      element = &pool->blocks->elements[pool->blocks->used_so_far];
+
+      pool->blocks->used_so_far += pool->element_size;
+
+      return element;
+    }
+}
+
+/**
+ * Deallocates an object previously created with
+ * _dbus_mem_pool_alloc(). The previous object
+ * must have come from this same pool.
+ * @param pool the memory pool
+ * @param element the element earlier allocated.
+ */
+void
+_dbus_mem_pool_dealloc (DBusMemPool *pool,
+                        void        *element)
+{
+  DBusFreedElement *freed;
+
+  freed = element;
+  freed->next = pool->free_elements;
+  pool->free_elements = freed;
+}
+
+/** @} */
+
+#ifdef DBUS_BUILD_TESTS
+#include "dbus-test.h"
+#include <stdio.h>
+#include <time.h>
+
+static void
+time_for_size (int size)
+{
+  int i;
+  int j;
+  clock_t start;
+  clock_t end;
+#define FREE_ARRAY_SIZE 512
+#define N_ITERATIONS FREE_ARRAY_SIZE * 512
+  void *to_free[FREE_ARRAY_SIZE];
+  DBusMemPool *pool;
+
+  printf ("Timings for size %d\n", size);
+  
+  printf (" malloc\n");
+  
+  start = clock ();
+  
+  i = 0;
+  j = 0;
+  while (i < N_ITERATIONS)
+    {
+      to_free[j] = dbus_malloc (size);
+      _dbus_assert (to_free[j] != NULL); /* in a real app of course this is wrong */
+
+      ++j;
+
+      if (j == FREE_ARRAY_SIZE)
+        {
+          j = 0;
+          while (j < FREE_ARRAY_SIZE)
+            {
+              dbus_free (to_free[j]);
+              ++j;
+            }
+
+          j = 0;
+        }
+      
+      ++i;
+    }
+
+  end = clock ();
+
+  printf ("  created/destroyed %d elements in %g seconds\n",
+          N_ITERATIONS, (end - start) / (double) CLOCKS_PER_SEC);
+
+
+
+  printf (" mempools\n");
+  
+  start = clock ();
+
+  pool = _dbus_mem_pool_new (size, FALSE);
+  
+  i = 0;
+  j = 0;
+  while (i < N_ITERATIONS)
+    {
+      to_free[j] = _dbus_mem_pool_alloc (pool); 
+      _dbus_assert (to_free[j] != NULL);  /* in a real app of course this is wrong */
+
+      ++j;
+
+      if (j == FREE_ARRAY_SIZE)
+        {
+          j = 0;
+          while (j < FREE_ARRAY_SIZE)
+            {
+              _dbus_mem_pool_dealloc (pool, to_free[j]);
+              ++j;
+            }
+
+          j = 0;
+        }
+      
+      ++i;
+    }
+
+  _dbus_mem_pool_free (pool);
+  
+  end = clock ();
+
+  printf ("  created/destroyed %d elements in %g seconds\n",
+          N_ITERATIONS, (end - start) / (double) CLOCKS_PER_SEC);
+
+  printf (" zeroed malloc\n");
+    
+  start = clock ();
+  
+  i = 0;
+  j = 0;
+  while (i < N_ITERATIONS)
+    {
+      to_free[j] = dbus_malloc0 (size);
+      _dbus_assert (to_free[j] != NULL); /* in a real app of course this is wrong */
+
+      ++j;
+
+      if (j == FREE_ARRAY_SIZE)
+        {
+          j = 0;
+          while (j < FREE_ARRAY_SIZE)
+            {
+              dbus_free (to_free[j]);
+              ++j;
+            }
+
+          j = 0;
+        }
+      
+      ++i;
+    }
+
+  end = clock ();
+
+  printf ("  created/destroyed %d elements in %g seconds\n",
+          N_ITERATIONS, (end - start) / (double) CLOCKS_PER_SEC);
+  
+  printf (" zeroed mempools\n");
+  
+  start = clock ();
+
+  pool = _dbus_mem_pool_new (size, TRUE);
+  
+  i = 0;
+  j = 0;
+  while (i < N_ITERATIONS)
+    {
+      to_free[j] = _dbus_mem_pool_alloc (pool); 
+      _dbus_assert (to_free[j] != NULL);  /* in a real app of course this is wrong */
+
+      ++j;
+
+      if (j == FREE_ARRAY_SIZE)
+        {
+          j = 0;
+          while (j < FREE_ARRAY_SIZE)
+            {
+              _dbus_mem_pool_dealloc (pool, to_free[j]);
+              ++j;
+            }
+
+          j = 0;
+        }
+      
+      ++i;
+    }
+
+  _dbus_mem_pool_free (pool);
+  
+  end = clock ();
+
+  printf ("  created/destroyed %d elements in %g seconds\n",
+          N_ITERATIONS, (end - start) / (double) CLOCKS_PER_SEC);
+}
+
+/**
+ * @ingroup DBusMemPoolInternals
+ * Unit test for DBusMemPool
+ * @returns #TRUE on success.
+ */
+dbus_bool_t
+_dbus_mem_pool_test (void)
+{
+  int i;
+  int element_sizes[] = { 4, 8, 16, 50, 124 };
+  
+  i = 0;
+  while (i < _DBUS_N_ELEMENTS (element_sizes))
+    {
+      time_for_size (element_sizes[i]);
+      ++i;
+    }
+  
+  return TRUE;
+}
+
+#endif /* DBUS_BUILD_TESTS */