Simplified.

1 files changed, 40 insertions, 35 deletions

diff --git a/daemon/fifo.c b/daemon/fifo.c
index 2754885..9daecdf 100644
--- a/daemon/fifo.c
+++ b/daemon/fifo.c
@@ -1,11 +1,9 @@
 /*
- * fifo.c - syslogd implementation for windows, simple and fast queue
+ * fifo.c - syslogd implementation for windows, just a queue
+ *          for the replacement of glib's queue.
  *
  * Created by Alexander Yaworsky
  *
- * This replacement eliminates strange page faults which were
- * with glib's 2.6.3 queues.
- *
  * THIS SOFTWARE IS NOT COPYRIGHTED
  *
  * This source code is offered for use in the public domain. You may
@@ -24,6 +22,19 @@
 #include <syslog.h>
 #include <syslogd.h>
 
+struct fifo_item
+{
+    struct fifo_item *next;  /* queue is a single-linked list */
+    void *payload;
+};
+
+struct fifo
+{
+    struct fifo_item *first;  /* first pushed item */
+    struct fifo_item *last;   /* last pushed item */
+    int item_count;
+};
+
 /******************************************************************************
  * fifo_create
  *
@@ -32,11 +43,9 @@
 struct fifo* fifo_create()
 {
     struct fifo *ret = g_malloc( sizeof(struct fifo) );
-    struct fifo_item *guard_item= g_malloc( sizeof(struct fifo_item) );
-    ret->first = guard_item;
-    ret->last = guard_item;
-    guard_item->next = NULL;
-    guard_item->payload = NULL;
+    ret->first = NULL;
+    ret->last = NULL;
+    ret->item_count = 0;
     return ret;
 }
 
@@ -61,45 +70,41 @@ void fifo_destroy( struct fifo* queue )
  * fifo_push
  *
  * Add item to queue.
+ * Return TRUE if added item is the first in the queue.
  */
-void fifo_push( struct fifo* queue, void* data )
+gboolean fifo_push( struct fifo* queue, void* data )
 {
     struct fifo_item *item = g_malloc( sizeof(struct fifo_item) );
     item->next = NULL;
     item->payload = data;
-    queue->last->next = item;
+    if( !queue->last )
+        queue->first = item;
+    else
+        queue->last->next = item;
     queue->last = item;
+    return 1 == ++queue->item_count;
 }
 
 /******************************************************************************
  * fifo_pop
  *
  * Extract item from queue.
- * Consider four possible conditions:
- * 1) next == NULL, payload == NULL: there is the only one empty item
- *    in the queue; leave it and return NULL
- * 2) next == NULL, payload != NULL: leave item and return its payload;
- *    set item's payload NULL
- * 3) next != NULL, payload == NULL: queue was empty when a new item was
- *    added; free this item and go to the next one
- * 4) next != NULL, payload != NULL: free item and return its payload
  */
 void* fifo_pop( struct fifo* queue )
 {
-    for(;;)
-    {
-        struct fifo_item *item = queue->first;
-        struct fifo_item *next = InterlockedExchangePointer( &item->next, NULL );
-        void *data = item->payload;
-        item->payload = NULL;
-        if( next )
-        {
-            queue->first = next;
-            g_free( item );
-        }
-        if( data )
-            return data;
-        if( !next )
-            return NULL;
-    }
+    struct fifo_item *item;
+    void *data;
+
+    item = queue->first;
+    if( !item )
+        return NULL;
+
+    queue->first = item->next;
+    if( !queue->first )
+        queue->last = NULL;
+
+    data = item->payload;
+    g_free( item );
+    queue->item_count--;
+    return data;
 }