michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: "use strict";
michael@0: 
michael@0: var MemoryObserver = {
michael@0:   observe: function mo_observe(aSubject, aTopic, aData) {
michael@0:     if (aTopic == "memory-pressure") {
michael@0:       if (aData != "heap-minimize") {
michael@0:         this.handleLowMemory();
michael@0:       }
michael@0:       // The JS engine would normally GC on this notification, but since we
michael@0:       // disabled that in favor of this method (bug 669346), we should gc here.
michael@0:       // See bug 784040 for when this code was ported from XUL to native Fennec.
michael@0:       this.gc();
michael@0:     } else if (aTopic == "Memory:Dump") {
michael@0:       this.dumpMemoryStats(aData);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   handleLowMemory: function() {
michael@0:     // do things to reduce memory usage here
michael@0:     let tabs = BrowserApp.tabs;
michael@0:     let selected = BrowserApp.selectedTab;
michael@0:     for (let i = 0; i < tabs.length; i++) {
michael@0:       if (tabs[i] != selected) {
michael@0:         this.zombify(tabs[i]);
michael@0:         Telemetry.addData("FENNEC_TAB_ZOMBIFIED", (Date.now() - tabs[i].lastTouchedAt) / 1000);
michael@0:       }
michael@0:     }
michael@0:     Telemetry.addData("FENNEC_LOWMEM_TAB_COUNT", tabs.length);
michael@0:   },
michael@0: 
michael@0:   zombify: function(tab) {
michael@0:     let browser = tab.browser;
michael@0:     let data = browser.__SS_data;
michael@0:     let extra = browser.__SS_extdata;
michael@0: 
michael@0:     // We need this data to correctly create and position the new browser
michael@0:     // If this browser is already a zombie, fallback to the session data
michael@0:     let currentURL = browser.__SS_restore ? data.entries[0].url : browser.currentURI.spec;
michael@0:     let sibling = browser.nextSibling;
michael@0:     let isPrivate = PrivateBrowsingUtils.isWindowPrivate(browser.contentWindow);
michael@0: 
michael@0:     tab.destroy();
michael@0:     tab.create(currentURL, { sibling: sibling, zombifying: true, delayLoad: true, isPrivate: isPrivate });
michael@0: 
michael@0:     // Reattach session store data and flag this browser so it is restored on select
michael@0:     browser = tab.browser;
michael@0:     browser.__SS_data = data;
michael@0:     browser.__SS_extdata = extra;
michael@0:     browser.__SS_restore = true;
michael@0:     browser.setAttribute("pending", "true");
michael@0:   },
michael@0: 
michael@0:   gc: function() {
michael@0:     window.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils).garbageCollect();
michael@0:     Cu.forceGC();
michael@0:   },
michael@0: 
michael@0:   dumpMemoryStats: function(aLabel) {
michael@0:     let memDumper = Cc["@mozilla.org/memory-info-dumper;1"].getService(Ci.nsIMemoryInfoDumper);
michael@0:     memDumper.dumpMemoryInfoToTempDir(aLabel, /* minimize = */ false);
michael@0:   },
michael@0: };