Refactored guac_client_alloc_layer(), implement guac_client_free_layer().

libguac/include/client.h

@@ -396,6 +396,22 @@ struct guac_client {
      */
     guac_layer* __last_available_buffer;
 
+    /**
+     * The index of the next available layer.
+     */
+    int __next_layer_index;
+
+    /**
+     * The head pointer of the list of all available (allocated but not used)
+     * layers.
+     */
+    guac_layer* __available_layers;
+
+    /**
+     * Pointer to the last layer in the list of all available layers.
+     */
+    guac_layer* __last_available_layer;
+
     /**
      * The head pointer of the list of all allocated layers, regardless of use
      * status.
@@ -467,14 +483,13 @@ int guac_client_handle_instruction(guac_client* client, guac_instruction* instru
 guac_layer* guac_client_alloc_buffer(guac_client* client);
 
 /**
- * Allocates a new layer. The layer will be given the specified index,
+ * Allocates a new layer. An arbitrary index is automatically assigned
- * even if the layer returned was a previously used (and free'd) layer.
+ * if no existing layer is available for use.
  *
  * @param client The proxy client to allocate the layer buffer for.
- * @param index The index of the layer to allocate.
  * @return The next available layer, or a newly allocated layer.
  */
-guac_layer* guac_client_alloc_layer(guac_client* client, int index);
+guac_layer* guac_client_alloc_layer(guac_client* client);
 
 /**
  * Returns the given buffer to the pool of available buffers, such that it
@@ -485,6 +500,16 @@ guac_layer* guac_client_alloc_layer(guac_client* client, int index);
  */
 void guac_client_free_buffer(guac_client* client, guac_layer* layer);
 
+/**
+ * Returns the given layer to the pool of available layers, such that it
+ * can be reused by any subsequent call to guac_client_allow_layer().
+ *
+ * @param client The proxy client to return the layer to.
+ * @param layer The buffer to return to the pool of available layer.
+ */
+void guac_client_free_layer(guac_client* client, guac_layer* layer);
+
+
 /**
  * Logs an informational message in the log used by the given client. The
  * logger used will normally be defined by guacd (or whichever program loads

libguac/src/client.c

@@ -57,18 +57,37 @@ guac_layer __GUAC_DEFAULT_LAYER = {
 
 const guac_layer* GUAC_DEFAULT_LAYER = &__GUAC_DEFAULT_LAYER;
 
-guac_layer* guac_client_alloc_layer(guac_client* client, int index) {
+guac_layer* guac_client_alloc_layer(guac_client* client) {
 
     guac_layer* allocd_layer;
 
+    /* If available layers, pop off first available layer */
+    if (client->__next_layer_index >= GUAC_BUFFER_POOL_INITIAL_SIZE &&
+            client->__available_layers != NULL) {
+
+        allocd_layer = client->__available_layers;
+        client->__available_layers = client->__available_layers->__next_available;
+        allocd_layer->__next_available = NULL;
+
+        /* If last layer, reset last available layer pointer */
+        if (allocd_layer == client->__last_available_layer)
+            client->__last_available_layer = NULL;
+
+    }
+
+    /* If no available layer, allocate new layer, add to __all_layers list */
+    else {
+
         /* Init new layer */
         allocd_layer = malloc(sizeof(guac_layer));
+        allocd_layer->index = client->__next_layer_index++;
 
         /* Add to __all_layers list */
         allocd_layer->__next = client->__all_layers;
         client->__all_layers = allocd_layer;
 
-    allocd_layer->index = index;
+    }
+
     return allocd_layer;
 
 }
@@ -118,6 +137,16 @@ void guac_client_free_buffer(guac_client* client, guac_layer* layer) {
 
 }
 
+void guac_client_free_layer(guac_client* client, guac_layer* layer) {
+
+    /* Add layer to tail of pool of available layers */
+    if (client->__last_available_layer != NULL)
+        client->__last_available_layer->__next_available = layer;
+
+    client->__last_available_layer = layer;
+
+}
+
 guac_client_plugin* guac_client_plugin_open(const char* protocol) {
 
     guac_client_plugin* plugin;
@@ -222,9 +251,11 @@ guac_client* guac_client_plugin_get_client(guac_client_plugin* plugin,
     client->state = GUAC_CLIENT_RUNNING;
 
     client->__all_layers        = NULL;
-    client->__available_buffers = NULL;
+    client->__available_buffers = client->__last_available_buffer = NULL;
+    client->__available_layers  = client->__last_available_layer  = NULL;
 
     client->__next_buffer_index = -1;
+    client->__next_layer_index  =  1;
 
     if (plugin->init_handler(client, argc, argv) != 0) {
         free(client);