add shared pool

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/performance/trunk@31457 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,10 +1,16 @@
+2010-10-30 Richard Frith-Macdonald  <rfm@gnu.org>
+
+	* GSThreadPool.h:
+	* GSThreadPool.m:
+	Add new methed to return a shared pool.
+
 2010-09-29 Richard Frith-Macdonald  <rfm@gnu.org>
 
 	* GSLinkedList.h:
 	* GSLinkedList.m:
 	Revise structure and API for greater flexibility.
-	* GSThreadPool.h
+	* GSThreadPool.h:
-	* GSThreadPool.m
+	* GSThreadPool.m:
 	Modify for new linked list api.
 
 2010-09-23 Richard Frith-Macdonald  <rfm@gnu.org>

GSThreadPool.h

@@ -48,6 +48,14 @@
   NSUInteger	processed;
 }
 
+/** Returns an instance intended for sharing between sections of code which
+ * wish to make use of threading by performing operations in other threads,
+ * but which don't mind operations being interleaved with those belonging to
+ * oither sections of code.<br />
+ * Always returns the same instance whenever the method is called.
+ */
++ (GSThreadPool*) sharedPool;
+
 /** Waits until the pool of operations is empty or until the specified
  * timestamp.  Returns YES if the pool was emptied, NO otherwise.
  */

GSThreadPool.m

@@ -57,10 +57,31 @@
 
 @implementation	GSThreadPool
 
+static GSThreadPool	*shared = nil;
+
++ (void) initialize
+{
+  if ([GSThreadPool class] == self)
+    {
+      shared = [self new];
+    }
+}
+
++ (GSThreadPool*) sharedPool
+{
+  return shared;
+}
+
 - (void) dealloc
 {
   GSThreadLink	*link;
 
+  if (self == shared)
+    {
+      [self retain];
+      [NSException raise: NSInternalInconsistencyException
+	format: @"[GSThreadPool-dealloc] attempt to deallocate shared pool"];
+    }
   [poolLock lock];
   [operations release];
   operations = nil;