Changeset 10722 in osm for applications/viewer/jmapviewer/src

Timestamp:

2008-09-16T11:50:59+02:00 (16 years ago)

Author:

stotz

Message:

Sigelton instance creation is now 100% thread safe

File:

• applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/JobDispatcher.java (modified) (1 diff)

applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/JobDispatcher.java

@@ -24 +24 @@
          */
         public static JobDispatcher getInstance() {
-                if (instance == null)
+                // for speed reasons we check if the instance has been created
+                // one time before we enter the synchronized section...
+                if (instance != null)
+                        return instance;
+                synchronized (JobDispatcher.class) {
+                        // ... and for thread safety reasons one time inside the
+                        // synchronized section.
+                        if (instance != null)
+                                return instance;
                         new JobDispatcher();
-                return instance;
+                        return instance;
+                }
         }