From e82deafc3a75cd51ff3d93069a60c37c334fef5c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?IOhannes=20m=20zm=C3=B6lnig?=
 <zmoelnig@users.sourceforge.net>
Date: Fri, 20 Aug 2010 16:54:42 +0000
Subject: fixed bugs in multithreading code

svn path=/trunk/externals/iem/iemnet/; revision=13871
---
 iemnet_data.c | 166 ++++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 102 insertions(+), 64 deletions(-)

(limited to 'iemnet_data.c')

diff --git a/iemnet_data.c b/iemnet_data.c
index 9969e9a..e671d7d 100644
--- a/iemnet_data.c
+++ b/iemnet_data.c
@@ -203,6 +203,7 @@ struct _iemnet_queue {
 
 
 /* push a  chunk into the queue
+ * this will return the current queue size
  */
 int queue_push(
 	       t_iemnet_queue* const _this,
@@ -211,37 +212,39 @@ int queue_push(
   t_node* tail;
   t_node* n=NULL;
   int size=-1;
-  if(_this) {
-    size=_this->size;
+  if(NULL == _this)return size;
 
-    if(NULL == data) return size;
-    //fprintf(stderr, "pushing %d bytes\n", data->size);
+  pthread_mutex_lock(&_this->mtx);
+  size=_this->size;
+  pthread_mutex_unlock(&_this->mtx);
 
-    n=(t_node*)getbytes(sizeof(t_node));
+  if(NULL == data) return size;
 
-    n->next = 0;
-    n->data = data;
-    pthread_mutex_lock(&_this->mtx);
-    if (! (tail = _this->tail)) {
-      _this->head = n;
-    } else {
-      tail->next = n;
-    }
-    _this->tail = n;
-
-    _this->size+=data->size;
-    size=_this->size;
+  n=(t_node*)getbytes(sizeof(t_node));
 
-    //fprintf(stderr, "pushed %d bytes\n", data->size);
+  n->next = 0;
+  n->data = data;
 
-    pthread_mutex_unlock(&_this->mtx);
-    pthread_cond_signal(&_this->cond);
+  pthread_mutex_lock(&_this->mtx);
+  if (! (tail = _this->tail)) {
+    _this->head = n;
+  } else {
+    tail->next = n;
   }
+  _this->tail = n;
+
+  _this->size+=data->size;
+  size=_this->size;
+
+  // added new chunk, so tell waiting threads that they can pop the data
+  pthread_cond_signal(&_this->cond);
+  pthread_mutex_unlock(&_this->mtx);
+
   return size;
 }
 
 
-/* push a chunk from the queue
+/* pop a chunk from the queue
  * if the queue is empty, this will block until 
  *    something has been pushed
  *   OR the queue is "done" (in which case NULL is returned)
@@ -252,61 +255,93 @@ t_iemnet_chunk* queue_pop_block(
 
   t_node* head=0;
   t_iemnet_chunk*data=0;
-  if(_this) {
-    pthread_mutex_lock(&_this->mtx);
-
-    /* wait until there is something in the queue or the "done" flag is set */
-    while (! (head = _this->head)) {
-      if(_this->done) {
-	pthread_mutex_unlock(&_this->mtx);
-	return NULL;
-      } else {
-	pthread_cond_wait(&_this->cond, &_this->mtx);
-      }
+  if(NULL == _this)return NULL;
+
+  pthread_mutex_lock(&_this->mtx);
+#if 1
+
+  /* if the queue is empty, wait */
+  if(NULL == _this->head) {
+    pthread_cond_wait(&_this->cond, &_this->mtx);
+    /* somebody signaled us, that we should do some work
+     * either the queue has been filled, or we are done...
+     */
+    if(_this->done) {
+      pthread_mutex_unlock(&_this->mtx);
+      return NULL;
     }
+  }
+  /* save the head, below we gonna work on this */
+  head = _this->head;
 
-    if (! (_this->head = head->next)) {
-      _this->tail = 0;
-    }
-    if(head && head->data) {
-      _this->size-=head->data->size;
-    }
+  /* update _this */
+  if (! (_this->head = head->next)) {
+    _this->tail = 0;
+  }
+  if(head && head->data) {
+    _this->size-=head->data->size;
+  }
 
-    pthread_mutex_unlock(&_this->mtx);
-    if(head) {
-      data=head->data;
-      freebytes(head, sizeof(t_node));
-      head=NULL;
+  pthread_mutex_unlock(&_this->mtx);
+#else
+  /* wait until there is something in the queue or the "done" flag is set */
+  while (! (head = _this->head)) {
+    if(_this->done) {
+      pthread_mutex_unlock(&_this->mtx);
+      return NULL;
+    } else {
+      pthread_cond_wait(&_this->cond, &_this->mtx);
     }
   }
+
+  if (! (_this->head = head->next)) {
+    _this->tail = 0;
+  }
+  if(head && head->data) {
+    _this->size-=head->data->size;
+  }
+
+  pthread_mutex_unlock(&_this->mtx);
+#endif
+
+  if(head) {
+    data=head->data;
+    freebytes(head, sizeof(t_node));
+    head=NULL;
+  }
   return data;
 }
-
+/* pop a chunk from the queue
+ * if the queue is empty, this will immediately return NULL
+ * (note that despite of the name this does block for synchronization) 
+ */
 t_iemnet_chunk* queue_pop_noblock(
 				  t_iemnet_queue* const _this
 				  ) {
   t_node* head=0;
   t_iemnet_chunk*data=0;
-  if(_this) {
-    pthread_mutex_lock(&_this->mtx);
-    if (! (head = _this->head)) {
-      // empty head
-      pthread_mutex_unlock(&_this->mtx);
-      return NULL;
-    }
-    if (! (_this->head = head->next)) {
-      _this->tail = 0;
-    }
-    if(head && head->data) {
-      _this->size-=head->data->size;
-    }
+  if(NULL == _this)return NULL;
 
+  pthread_mutex_lock(&_this->mtx);
+  if (! (head = _this->head)) {
+    // empty head
     pthread_mutex_unlock(&_this->mtx);
-    if(head) {
-      data=head->data;
-      freebytes(head, sizeof(t_node));
-      head=NULL;
-    }
+    return NULL;
+  }
+
+  if (! (_this->head = head->next)) {
+    _this->tail = 0;
+  }
+  if(head && head->data) {
+    _this->size-=head->data->size;
+  }
+
+  pthread_mutex_unlock(&_this->mtx);
+
+  if(head) {
+    data=head->data;
+    freebytes(head, sizeof(t_node));
+    head=NULL;
   }
   return data;
 }
@@ -326,12 +361,15 @@ int queue_getsize(t_iemnet_queue* const _this) {
 }
 void queue_finish(t_iemnet_queue* q) {
   DEBUG("queue_finish: %x", q);
-  if(NULL==q) 
-    return;
+  if(NULL==q) return;
+
+  pthread_mutex_lock(&q->mtx);
   q->done=1;
   DEBUG("queue signaling: %x", q);
   pthread_cond_signal(&q->cond);
   DEBUG("queue signaled: %x", q);
+  pthread_mutex_unlock(&q->mtx);
+  DEBUG("queue_finished: %x", q);
 }
 
 void queue_destroy(t_iemnet_queue* q) {
-- 
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