added ref counting to the buffer pool. also _destroy will clean up the buffer pool mem_chunk if it is the default imp...

Original commit message from CVS:
added ref counting to the buffer pool. also _destroy will clean up the buffer pool mem_chunk if it is the default implementation

gst/gstbufferpool.c

@@ -25,7 +25,7 @@
 
 #include "gstbuffer.h"
 
-static GMutex *default_pool_lock;
+static GMutex *_default_pool_lock;
 static GHashTable *_default_pools;
 
 static GstBuffer* gst_buffer_pool_default_create (GstBufferPool *pool, gpointer user_data);
@@ -35,7 +35,7 @@ void
 _gst_buffer_pool_initialize (void) 
 {
   _default_pools = g_hash_table_new(NULL,NULL);
-  default_pool_lock = g_mutex_new ();
+  _default_pool_lock = g_mutex_new ();
 }
 
 /**
@@ -55,10 +55,97 @@ gst_buffer_pool_new (void)
 
   pool->new_buffer = NULL;
   pool->destroy_buffer = NULL;
+  pool->lock = g_mutex_new ();
+#ifdef HAVE_ATOMIC_H
+  atomic_set (&pool->refcount, 1);
+#else
+  pool->refcount = 1;
+#endif
 
   return pool;
 }
 
+/**
+ * gst_buffer_pool_ref:
+ * @pool: the GstBufferPool to reference
+ *
+ * Increment the refcount of this buffer pool.
+ */
+void 
+gst_buffer_pool_ref (GstBufferPool *pool) 
+{
+  g_return_if_fail (pool != NULL);
+
+  GST_DEBUG(0,"referencing buffer pool %p from %d\n", pool, GST_BUFFER_POOL_REFCOUNT(pool));
+  
+#ifdef HAVE_ATOMIC_H
+  atomic_inc (&(pool->refcount));
+#else
+  g_return_if_fail (pool->refcount > 0);
+  GST_BUFFER_POOL_LOCK (pool);
+  buffer->refcount++;
+  GST_BUFFER_POOL_UNLOCK (pool);
+#endif
+}
+
+/**
+ * gst_buffer_pool_ref_by_count:
+ * @pool: the GstBufferPool to reference
+ * @count: a number
+ *
+ * Increment the refcount of this buffer pool by the given number.
+ */
+void 
+gst_buffer_pool_ref_by_count (GstBufferPool *pool, int count) 
+{
+  g_return_if_fail (pool != NULL);
+  g_return_if_fail (count > 0);
+
+#ifdef HAVE_ATOMIC_H
+  g_return_if_fail (atomic_read (&(pool->refcount)) > 0);
+  atomic_add (count, &(pool->refcount));
+#else
+  g_return_if_fail (pool->refcount > 0);
+  GST_BUFFER_POOL_LOCK (pool);
+  pool->refcount += count;
+  GST_BUFFER_POOL_UNLOCK (pool);
+#endif
+}
+
+/**
+ * gst_buffer_pool_unref:
+ * @pool: the GstBufferPool to unref
+ *
+ * Decrement the refcount of this buffer pool. If the refcount is
+ * zero and the pool is a default implementation, 
+ * the buffer pool will be destroyed.
+ */
+void 
+gst_buffer_pool_unref (GstBufferPool *pool) 
+{
+  gint zero;
+
+  g_return_if_fail (pool != NULL);
+
+  GST_DEBUG(0,"unreferencing buffer pool %p from %d\n", pool, GST_BUFFER_POOL_REFCOUNT(pool));
+
+#ifdef HAVE_ATOMIC_H
+  g_return_if_fail (atomic_read (&(pool->refcount)) > 0);
+  zero = atomic_dec_and_test (&(pool->refcount));
+#else
+  g_return_if_fail (pool->refcount > 0);
+  GST_BUFFER_POOL_LOCK (pool);
+  pool->refcount--;
+  zero = (pool->refcount == 0);
+  GST_BUFFER_POOL_UNLOCK (pool);
+#endif
+
+  /* if we ended up with the refcount at zero, destroy the buffer pool*/
+  if (zero) {
+    gst_buffer_pool_destroy (pool);
+  }
+}
+
 /**
  * gst_buffer_pool_set_create_function:
  * @pool: the pool to set the create function for
@@ -108,8 +195,18 @@ gst_buffer_pool_set_destroy_function (GstBufferPool *pool,
 void 
 gst_buffer_pool_destroy (GstBufferPool *pool) 
 {
+  GMemChunk *data_chunk;
   g_return_if_fail (pool != NULL);
   
+  // if its a default buffer pool, we know how to free the user data
+  if (pool->new_buffer == gst_buffer_pool_default_create &&
+      pool->destroy_buffer == gst_buffer_pool_default_destroy){
+    GST_DEBUG(0,"destroying default buffer pool %p\n", pool);
+    data_chunk = (GMemChunk*)pool->new_user_data;
+    g_mem_chunk_reset(data_chunk);
+    g_free(data_chunk);
+  }
+  
   g_free(pool);
 }
 
@@ -151,23 +248,46 @@ gst_buffer_pool_destroy_buffer (GstBufferPool *pool,
   pool->destroy_buffer (pool, buffer, pool->new_user_data);
 }
 
+/**
+ * gst_buffer_pool_get_default:
+ * @pool: instance of GstBufferPool which is no longer required (or NULL if it doesn't exist)
+ * @buffer_size: the number of bytes this buffer will store
+ * @pool_size: the default number of buffers to be preallocated
+ *
+ * Returns an instance of a buffer pool using the default
+ * implementation.  If a buffer pool instance with the same buffer_size
+ * already exists this will be returned, otherwise a new instance will
+ * be created.
+ * 
+ * Returns: an instance of GstBufferPool
+ */
 GstBufferPool*
-gst_buffer_pool_get_default (guint buffer_size, guint pool_size)
+gst_buffer_pool_get_default (GstBufferPool *oldpool, guint buffer_size, guint pool_size)
 {
   GstBufferPool *pool;
   GMemChunk *data_chunk;
   guint real_buffer_size;
 
-  // check for an existing GstBufferPool with the same buffer_size
+  // round up to the nearest 32 bytes for cache-line and other efficiencies
+  real_buffer_size = (((buffer_size-1) / 32) + 1) * 32;
+  
+  // check for an existing GstBufferPool with the same real_buffer_size
   // (we won't worry about the pool_size)
-  if ((pool = (GstBufferPool*)g_hash_table_lookup(_default_pools,GINT_TO_POINTER(buffer_size)))){
+  g_mutex_lock (_default_pool_lock);
+  pool = (GstBufferPool*)g_hash_table_lookup(_default_pools,GINT_TO_POINTER(real_buffer_size));
+  g_mutex_unlock (_default_pool_lock);
+
+  if (pool != NULL){
+    if (oldpool != pool){
+      gst_buffer_pool_ref(pool);
+
+      if (oldpool != NULL){
+        gst_buffer_pool_unref(oldpool);
+      }
+    }
     return pool;
   }
   
-  // g_print("new buffer pool bytes:%d size:%d\n", buffer_size, pool_size);
-  
-  // round up to the nearest 32 bytes for cache-line and other efficiencies
-  real_buffer_size = ((buffer_size-1 / 32) + 1) * 32;
 
   data_chunk = g_mem_chunk_new ("GstBufferPoolDefault", real_buffer_size, 
     real_buffer_size * pool_size, G_ALLOC_AND_FREE);
@@ -176,7 +296,15 @@ gst_buffer_pool_get_default (guint buffer_size, guint pool_size)
   gst_buffer_pool_set_create_function	(pool, gst_buffer_pool_default_create, data_chunk);
   gst_buffer_pool_set_destroy_function	(pool, gst_buffer_pool_default_destroy, data_chunk);
 
-  g_hash_table_insert(_default_pools,GINT_TO_POINTER(buffer_size),pool);
+  g_mutex_lock (_default_pool_lock);
+  g_hash_table_insert(_default_pools,GINT_TO_POINTER(real_buffer_size),pool);
+  g_mutex_unlock (_default_pool_lock);
+
+  GST_DEBUG(0,"new buffer pool %p bytes:%d size:%d\n", pool, real_buffer_size, pool_size);
+
+  if (oldpool != NULL){
+    gst_buffer_pool_unref(oldpool);
+  }
   return pool;
 }
 
@@ -186,13 +314,14 @@ gst_buffer_pool_default_create (GstBufferPool *pool, gpointer user_data)
   GMemChunk *data_chunk = (GMemChunk*)user_data;
   GstBuffer *buffer;
   
+  gst_buffer_pool_ref(pool);
   buffer = gst_buffer_new();
   GST_BUFFER_FLAG_SET(buffer,GST_BUFFER_DONTFREE);
   buffer->pool = pool;
 
-  g_mutex_lock (default_pool_lock);
+  g_mutex_lock (pool->lock);
   GST_BUFFER_DATA(buffer) = g_mem_chunk_alloc(data_chunk);
-  g_mutex_unlock (default_pool_lock);
+  g_mutex_unlock (pool->lock);
     
   return buffer;
 }
@@ -203,11 +332,12 @@ gst_buffer_pool_default_destroy (GstBufferPool *pool, GstBuffer *buffer, gpointe
   GMemChunk *data_chunk = (GMemChunk*)user_data;
   gpointer data = GST_BUFFER_DATA(buffer);
 
-  g_mutex_lock (default_pool_lock);
+  g_mutex_lock (pool->lock);
   g_mem_chunk_free (data_chunk,data);
-  g_mutex_unlock (default_pool_lock);
+  g_mutex_unlock (pool->lock);
 
   buffer->pool = NULL;
+  gst_buffer_pool_unref(pool);
   gst_buffer_destroy (buffer);
   
 }

gst/gstbufferpool.h

@@ -31,8 +31,9 @@ extern "C" {
 #endif /* __cplusplus */
 
 
-#define GST_BUFFER_POOL(buf) \
-  ((GstBufferPool *)(buf))
+#define GST_BUFFER_POOL(pool) \
+  ((GstBufferPool *)(pool))
+#define GST_BUFFER_POOL_LOCK(pool)	(g_mutex_lock(GST_BUFFER_POOL(pool)->lock))
 
 typedef struct _GstBufferPool GstBufferPool;
 
@@ -40,6 +41,18 @@ typedef GstBuffer*	(*GstBufferPoolCreateFunction) 	(GstBufferPool *pool, gpointe
 typedef void 		(*GstBufferPoolDestroyFunction) (GstBufferPool *pool, GstBuffer *buffer, gpointer user_data);
 
 struct _GstBufferPool {
+  /* locking */
+  GMutex *lock;
+
+  /* refcounting */
+#ifdef HAVE_ATOMIC_H
+  atomic_t refcount;
+#define GST_BUFFER_POOL_REFCOUNT(pool)	(atomic_read(&(GST_BUFFER_POOL((pool))->refcount)))
+#else
+  int refcount;
+#define GST_BUFFER_POOL_REFCOUNT(pool)	(GST_BUFFER_POOL(pool)->refcount)
+#endif
+
   /* will be called when a new buffer is to be created */
   GstBufferPoolCreateFunction new_buffer;
   /* user data to pass with the new_buffer function */
@@ -47,6 +60,7 @@ struct _GstBufferPool {
 
   gpointer destroy_user_data;
   GstBufferPoolDestroyFunction destroy_buffer;
+
 };
 
 void _gst_buffer_pool_initialize (void);
@@ -58,6 +72,11 @@ GstBufferPool*		gst_buffer_pool_new			(void);
 GstBuffer*		gst_buffer_pool_new_buffer		(GstBufferPool *pool);
 void 			gst_buffer_pool_destroy_buffer		(GstBufferPool *pool, GstBuffer *buffer);
 
+/* refcounting */
+void 		gst_buffer_pool_ref			(GstBufferPool *pool);
+void 		gst_buffer_pool_ref_by_count		(GstBufferPool *pool, int count);
+void 		gst_buffer_pool_unref		(GstBufferPool *buffer);
+
 /* setting create and destroy functions */
 void 			gst_buffer_pool_set_create_function	(GstBufferPool *pool, 
 								 GstBufferPoolCreateFunction create, 
@@ -70,7 +89,7 @@ void 			gst_buffer_pool_set_destroy_function	(GstBufferPool *pool,
 void 			gst_buffer_pool_destroy			(GstBufferPool *pool);
 
 /* a default buffer pool implementation */
-GstBufferPool* gst_buffer_pool_get_default (guint buffer_size, guint pool_size);
+GstBufferPool* gst_buffer_pool_get_default (GstBufferPool *oldpool, guint buffer_size, guint pool_size);
 
 #ifdef __cplusplus
 }