Bug 654041 - Add buttons that trigger GC and CC from about:memory. r=vlad,jruderman.

toolkit/components/aboutmemory/content/aboutMemory.js

@@ -40,6 +40,7 @@
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
+const Cu = Components.utils;
 
 // Must use .href here instead of .search because "about:memory" is a
 // non-standard URL.
@@ -73,6 +74,49 @@ function $(n)
   return document.getElementById(n);
 }
 
+function doGlobalGC()
+{
+  Cu.forceGC();
+  update();
+}
+
+function doGlobalGCandCC()
+{
+  window.QueryInterface(Ci.nsIInterfaceRequestor)
+        .getInterface(Ci.nsIDOMWindowUtils)
+        .garbageCollect();
+  update();
+}
+
+// For maximum effect, this returns to the event loop between each
+// notification.  See bug 610166 comment 12 for an explanation.
+// Ideally a single notification would be enough.
+function sendHeapMinNotifications()
+{
+  function runSoon(f)
+  {
+    var tm = Cc["@mozilla.org/thread-manager;1"]
+              .getService(Ci.nsIThreadManager);
+
+    tm.mainThread.dispatch({ run: f }, Ci.nsIThread.DISPATCH_NORMAL);
+  }
+
+  function sendHeapMinNotificationsInner()
+  {
+    var os = Cc["@mozilla.org/observer-service;1"]
+             .getService(Ci.nsIObserverService);
+    os.notifyObservers(null, "memory-pressure", "heap-minimize");
+
+    if (++j < 3)
+      runSoon(sendHeapMinNotificationsInner);
+    else
+      runSoon(update);
+  }
+
+  var j = 0;
+  sendHeapMinNotificationsInner();
+}
+
 /**
  * Top-level function that does the work of generating the page.
  */
@@ -143,6 +187,23 @@ function update()
     }
   }
 
+  // Memory-related actions.
+  const GCDesc = "Do a global garbage collection.";
+  // XXX: once bug 625302 is fixed, should change this button to just do a CC.
+  const CCDesc = "Do a global garbage collection followed by a cycle " +
+                 "collection. (It currently is not possible to do a cycle " +
+                 "collection on its own, see bug 625302.)";
+  const MPDesc = "Send three \"heap-minimize\" notifications in a row.  Each " +
+                 "notification triggers a global garbage collection followed " +
+                 "by a cycle collection, and causes the process to reduce " +
+                 "memory usage in other ways, e.g. by flushing various caches.";
+
+  text += "<div>" +
+    "<button title='" + GCDesc + "' onclick='doGlobalGC()'>GC</button>" +
+    "<button title='" + CCDesc + "' onclick='doGlobalGCandCC()'>GC + CC</button>" +
+    "<button title='" + MPDesc + "' onclick='sendHeapMinNotifications()'>" + "Minimize memory usage</button>" +
+    "</div>";
+
   // Generate verbosity option link at the bottom.
   text += gVerbose
         ? "<span class='option'><a href='about:memory'>Less verbose</a></span>"