Bug 1372670 - part 3 - add spinEventLoopUntil to nsIThreadManager; r=erahm,florian

addon-sdk/source/lib/sdk/system/child_process/subprocess.js

@@ -28,8 +28,7 @@ function awaitPromise(promise) {
     value = val;
   });
 
-  while (resolved === null)
-    Services.tm.mainThread.processNextEvent(true);
+  Services.tm.spinEventLoopUntil(() => resolved !== null);
 
   if (resolved === true)
     return value;

addon-sdk/source/test/addons/content-permissions/httpd.js

@@ -5175,9 +5175,9 @@ function server(port, basePath)
   srv.registerContentType("sjs", SJS_TYPE);
   srv.start(port);
 
+  gThreadManager.spinEventLoopUntil(() => srv.isStopped());
+
   var thread = gThreadManager.currentThread;
-  while (!srv.isStopped())
-    thread.processNextEvent(true);
 
   // get rid of any pending requests
   while (thread.hasPendingEvents())

addon-sdk/source/test/addons/content-script-messages-latency/httpd.js

@@ -5175,9 +5175,9 @@ function server(port, basePath)
   srv.registerContentType("sjs", SJS_TYPE);
   srv.start(port);
 
+  gThreadManager.spinEventLoopUntil(() => srv.isStopped());
+
   var thread = gThreadManager.currentThread;
-  while (!srv.isStopped())
-    thread.processNextEvent(true);
 
   // get rid of any pending requests
   while (thread.hasPendingEvents())

addon-sdk/source/test/addons/e10s-content/lib/httpd.js

@@ -5176,9 +5176,9 @@ function server(port, basePath)
   srv.registerContentType("sjs", SJS_TYPE);
   srv.start(port);
 
+  gThreadManager.spinEventLoopUntil(() => srv.isStopped());
+
   var thread = gThreadManager.currentThread;
-  while (!srv.isStopped())
-    thread.processNextEvent(true);
 
   // get rid of any pending requests
   while (thread.hasPendingEvents())

addon-sdk/source/test/addons/places/lib/httpd.js

@@ -5175,9 +5175,9 @@ function server(port, basePath)
   srv.registerContentType("sjs", SJS_TYPE);
   srv.start(port);
 
+  gThreadManager.spinEventLoopUntil(() => srv.isStopped());
+
   var thread = gThreadManager.currentThread;
-  while (!srv.isStopped())
-    thread.processNextEvent(true);
 
   // get rid of any pending requests
   while (thread.hasPendingEvents())

addon-sdk/source/test/lib/httpd.js

@@ -5176,9 +5176,9 @@ function server(port, basePath)
   srv.registerContentType("sjs", SJS_TYPE);
   srv.start(port);
 
+  gThreadManager.spinEventLoopUntil(() => srv.isStopped());
+
   var thread = gThreadManager.currentThread;
-  while (!srv.isStopped())
-    thread.processNextEvent(true);
 
   // get rid of any pending requests
   while (thread.hasPendingEvents())

browser/extensions/mortar/host/common/ppapi-runtime.jsm

@@ -915,10 +915,10 @@ class Buffer extends PP_Resource {
 class Flash_MessageLoop extends PP_Resource {
   run() {
     this._running = true;
-    let thread = Cc["@mozilla.org/thread-manager;1"].getService().currentThread;
-    while (this._running) {
-      thread.processNextEvent(true);
-    }
+    let tm = Cc["@mozilla.org/thread-manager;1"].getService();
+    tm.spinEventLoopUntil(() => {
+      return !this._running;
+    });
   }
   quit() {
     this._running = false;

devtools/client/devtools-startup.js

@@ -139,10 +139,10 @@ DevToolsStartup.prototype = {
 
     if (pauseOnStartup) {
       // Spin the event loop until the debugger connects.
-      let thread = Cc["@mozilla.org/thread-manager;1"].getService().currentThread;
-      while (!devtoolsThreadResumed) {
-        thread.processNextEvent(true);
-      }
+      let tm = Cc["@mozilla.org/thread-manager;1"].getService();
+      tm.spinEventLoopUntil(() => {
+        return devtoolsThreadResumed;
+      });
     }
 
     if (cmdLine.state == Ci.nsICommandLine.STATE_REMOTE_AUTO) {

devtools/client/framework/devtools-browser.js

@@ -627,9 +627,9 @@ var gDevToolsBrowser = exports.gDevToolsBrowser = {
       let utils = window.QueryInterface(Ci.nsIInterfaceRequestor)
                          .getInterface(Ci.nsIDOMWindowUtils);
       utils.enterModalState();
-      while (!setupFinished) {
-        tm.currentThread.processNextEvent(true);
-      }
+      tm.spinEventLoopUntil(() => {
+        return setupFinished;
+      });
       utils.leaveModalState();
     };
 

devtools/client/responsive.html/browser/tunnel.js

@@ -163,9 +163,9 @@ function tunnelToInnerBrowser(outer, inner) {
       // The constructor of the new XBL binding is run asynchronously and there is no
       // event to signal its completion.  Spin an event loop to watch for properties that
       // are set by the contructor.
-      while (!outer._remoteWebNavigation) {
-        Services.tm.currentThread.processNextEvent(true);
-      }
+      Services.tm.spinEventLoopUntil(() => {
+        return outer._remoteWebNavigation;
+      });
 
       // Replace the `webNavigation` object with our own version which tries to use
       // mozbrowser APIs where possible.  This replaces the webNavigation object that the

dom/base/test/plugin.js

@@ -20,11 +20,11 @@ function setTestPluginEnabledState(newEnabledState, pluginName) {
     return;
   }
   var plugin = getTestPlugin(pluginName);
-  while (plugin.enabledState != newEnabledState) {
-    // Run a nested event loop to wait for the preference change to
-    // propagate to the child. Yuck!
-    SpecialPowers.Services.tm.currentThread.processNextEvent(true);
-  }
+  // Run a nested event loop to wait for the preference change to
+  // propagate to the child. Yuck!
+  SpecialPowers.Services.tm.spinEventLoopUntil(() => {
+    return plugin.enabledState == newEnabledState;
+  });
   SimpleTest.registerCleanupFunction(function() {
     SpecialPowers.setTestPluginEnabledState(oldEnabledState, pluginName);
   });

dom/browser-element/BrowserElementChildPreload.js

@@ -425,20 +425,19 @@ BrowserElementChild.prototype = {
     win.modalDepth++;
     let origModalDepth = win.modalDepth;
 
-    let thread = Services.tm.currentThread;
     debug("Nested event loop - begin");
-    while (win.modalDepth == origModalDepth && !this._shuttingDown) {
+    Services.tm.spinEventLoopUntil(() => {
       // Bail out of the loop if the inner window changed; that means the
       // window navigated.  Bail out when we're shutting down because otherwise
       // we'll leak our window.
       if (this._tryGetInnerWindowID(win) !== innerWindowID) {
         debug("_waitForResult: Inner window ID changed " +
               "while in nested event loop.");
-        break;
+        return true;
       }
 
-      thread.processNextEvent(/* mayWait = */ true);
-    }
+      return win.modalDepth !== origModalDepth || this._shuttingDown;
+    });
     debug("Nested event loop - finish");
 
     if (win.modalDepth == 0) {

dom/indexedDB/test/unit/test_transaction_lifetimes_nested.js

@@ -26,9 +26,9 @@ function* testSteps()
   let transaction2;
 
   let comp = this.window ? SpecialPowers.wrap(Components) : Components;
-  let thread = comp.classes["@mozilla.org/thread-manager;1"]
-                   .getService(comp.interfaces.nsIThreadManager)
-                   .currentThread;
+  let tm = comp.classes["@mozilla.org/thread-manager;1"]
+               .getService(comp.interfaces.nsIThreadManager);
+  let thread = tm.currentThread;
 
   let eventHasRun;
 
@@ -38,9 +38,7 @@ function* testSteps()
     transaction2 = db.transaction("foo");
   }, Components.interfaces.nsIThread.DISPATCH_NORMAL);
 
-  while (!eventHasRun) {
-    thread.processNextEvent(false);
-  }
+  tm.spinEventLoopUntil(() => eventHasRun);
 
   ok(transaction2, "Non-null transaction2");
 

dom/plugins/test/mochitest/plugin-utils.js

@@ -28,11 +28,11 @@ function getTestPlugin(pluginName) {
 function setTestPluginEnabledState(newEnabledState, pluginName) {
   var oldEnabledState = SpecialPowers.setTestPluginEnabledState(newEnabledState, pluginName);
   var plugin = getTestPlugin(pluginName);
-  while (plugin.enabledState != newEnabledState) {
-    // Run a nested event loop to wait for the preference change to
-    // propagate to the child. Yuck!
-    SpecialPowers.Services.tm.currentThread.processNextEvent(true);
-  }
+  // Run a nested event loop to wait for the preference change to
+  // propagate to the child. Yuck!
+  SpecialPowers.Services.tm.spinEventLoopUntil(() => {
+    return plugin.enabledState == newEnabledState;
+  });
   SimpleTest.registerCleanupFunction(function() {
     SpecialPowers.setTestPluginEnabledState(oldEnabledState, pluginName);
   });

dom/workers/test/serviceworkers/test_request_context.js

@@ -19,11 +19,9 @@ function setTestPluginEnabledState(newEnabledState, pluginName) {
     return;
   }
   var plugin = getTestPlugin(pluginName);
-  while (plugin.enabledState != newEnabledState) {
-    // Run a nested event loop to wait for the preference change to
-    // propagate to the child. Yuck!
-    SpecialPowers.Services.tm.currentThread.processNextEvent(true);
-  }
+  // Run a nested event loop to wait for the preference change to
+  // propagate to the child. Yuck!
+  SpecialPowers.Services.tm.spinEventLoopUntil(() => plugin.enabledState == newEnabledState);
   SimpleTest.registerCleanupFunction(function() {
     SpecialPowers.setTestPluginEnabledState(oldEnabledState, pluginName);
   });

mobile/android/components/FilePicker.js

@@ -179,9 +179,7 @@ FilePicker.prototype = {
     this._promptActive = true;
     this._sendMessage();
 
-    let thread = Services.tm.currentThread;
-    while (this._promptActive)
-      thread.processNextEvent(true);
+    Services.tm.spinEventLoopUntil(() => !this._promptActive);
     delete this._promptActive;
 
     if (this._domWin) {

mobile/android/components/NSSDialogService.js

@@ -71,9 +71,7 @@ NSSDialogs.prototype = {
     });
 
     // Spin this thread while we wait for a result
-    let thread = Services.tm.currentThread;
-    while (response === null)
-      thread.processNextEvent(true);
+    Services.tm.spinEventLoopUntil(() => response != null);
 
     return response;
   },

mobile/android/components/PromptService.js

@@ -200,9 +200,7 @@ InternalPrompt.prototype = {
     });
 
     // Spin this thread while we wait for a result
-    let thread = Services.tm.currentThread;
-    while (retval == null)
-      thread.processNextEvent(true);
+    Services.tm.spinEventLoopUntil(() => retval != null);
 
     if (this._domWin) {
       let winUtils = this._domWin.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);

mobile/android/components/TabSource.js

@@ -56,10 +56,7 @@ TabSource.prototype = {
     });
 
     // Spin this thread while we wait for a result.
-    let thread = Services.tm.currentThread;
-    while (result == null) {
-      thread.processNextEvent(true);
-    }
+    Services.tm.spinEventLoopUntil(() => result != null);
 
     if (result == -1) {
       return null;

mobile/android/components/geckoview/GeckoViewPrompt.js

@@ -460,10 +460,7 @@ PromptDelegate.prototype = {
       this.asyncShowPrompt(aMsg, res => result = res);
 
       // Spin this thread while we wait for a result
-      let thread = Services.tm.currentThread;
-      while (result === undefined) {
-        thread.processNextEvent(true);
-      }
+      Services.tm.spinEventLoopUntil(() => result !== undefined);
     } finally {
       this._changeModalState(/* aEntering */ false);
     }

mobile/android/tests/browser/robocop/robocop_head.js

@@ -838,9 +838,7 @@ JavaBridge.prototype = {
     // spin the event loop, but here we're in a test and our API
     // specifies a synchronous call, so we spin the loop to wait for
     // the call to finish.
-    while (this._repliesNeeded > initialReplies) {
-      thread.processNextEvent(true);
-    }
+    this._Services.tm.spinEventLoopUntil(() => this._repliesNeeded <= initialReplies);
   },
 
   /**

security/manager/tools/getHSTSPreloadList.js

@@ -387,10 +387,7 @@ function waitForAResponse(outputList) {
   // From <https://developer.mozilla.org/en/XPConnect/xpcshell/HOWTO>
   var threadManager = Cc["@mozilla.org/thread-manager;1"]
                       .getService(Ci.nsIThreadManager);
-  var mainThread = threadManager.currentThread;
-  while (outputList.length == 0) {
-    mainThread.processNextEvent(true);
-  }
+  threadManager.spinEventLoopUntil(() => outputList.length != 0);
 }
 
 function readCurrentList(filename) {

services/common/async.js

@@ -91,12 +91,10 @@ this.Async = {
    */
   waitForSyncCallback: function waitForSyncCallback(callback) {
     // Grab the current thread so we can make it give up priority.
-    let thread = Cc["@mozilla.org/thread-manager;1"].getService().currentThread;
+    let tm = Cc["@mozilla.org/thread-manager;1"].getService();
 
     // Keep waiting until our callback is triggered (unless the app is quitting).
-    while (Async.checkAppReady() && callback.state == CB_READY) {
-      thread.processNextEvent(true);
-    }
+    tm.spinEventLoopUntil(() => !Async.checkAppReady || callback.state != CB_READY);
 
     // Reset the state of the callback to prepare for another call.
     let state = callback.state;

services/sync/tps/extensions/mozmill/resource/modules/assertions.js

@@ -591,14 +591,15 @@ Assert.prototype = {
     var timeoutInterval = hwindow.setInterval(wait, interval);
     var thread = Services.tm.currentThread;
 
-    while (self.result !== true && !self.timeIsUp) {
-      thread.processNextEvent(true);
-
+    Services.tm.spinEventLoopUntil(() => {
       let type = typeof(self.result);
-      if (type !== 'boolean')
+      if (type !== 'boolean') {
         throw TypeError("waitFor() callback has to return a boolean" +
                         " instead of '" + type + "'");
-    }
+      }
+
+      return self.result === true || self.timeIsUp;
+    });
 
     hwindow.clearInterval(timeoutInterval);
 

services/sync/tps/extensions/mozmill/resource/stdlib/httpd.js

@@ -5341,9 +5341,9 @@ function server(port, basePath)
   srv.identity.setPrimary("http", "localhost", port);
   srv.start(port);
 
+  gThreadManager.spinEventLoopUntil(() => srv.isStopped());
+
   var thread = gThreadManager.currentThread;
-  while (!srv.isStopped())
-    thread.processNextEvent(true);
 
   // get rid of any pending requests
   while (thread.hasPendingEvents())

services/sync/tps/extensions/mozmill/resource/stdlib/utils.js

@@ -210,11 +210,7 @@ function sleep(milliseconds) {
   var timeup = false;
 
   hwindow.setTimeout(function () { timeup = true; }, milliseconds);
-  var thread = Services.tm.currentThread;
-
-  while (!timeup) {
-    thread.processNextEvent(true);
-  }
+  Services.tm.spinEventLoopUntil(() => timeup);
 
   broker.pass({'function':'utils.sleep()'});
 }

storage/test/unit/head_storage.js

@@ -73,10 +73,8 @@ function asyncCleanup() {
   print("*** Storage Tests: Trying to asyncClose!");
   getOpenedDatabase().asyncClose(function() { closed = true; });
 
-  let curThread = Components.classes["@mozilla.org/thread-manager;1"]
-                            .getService().currentThread;
-  while (!closed)
-    curThread.processNextEvent(true);
+  let tm = Cc["@mozilla.org/thread-manager;1"].getService();
+  tm.spinEventLoopUntil(() => closed);
 
   // we need to null out the database variable to get a new connection the next
   // time getOpenedDatabase is called

storage/test/unit/test_statement_executeAsync.js

@@ -135,10 +135,8 @@ function execAsync(aStmt, aOptions, aResults) {
   if ("cancel" in aOptions && aOptions.cancel)
     pending.cancel();
 
-  let curThread = Components.classes["@mozilla.org/thread-manager;1"]
-                            .getService().currentThread;
-  while (!completed && !_quit)
-    curThread.processNextEvent(true);
+  let tm = Cc["@mozilla.org/thread-manager;1"].getService(Ci.nsIThreadManager);
+  tm.spinEventLoopUntil(() => completed || _quit);
 
   return pending;
 }

testing/xpcshell/head.js

@@ -215,11 +215,10 @@ function _do_main() {
 
   _testLogger.info("running event loop");
 
-  var thr = Components.classes["@mozilla.org/thread-manager;1"]
-                      .getService().currentThread;
+  var tm = Components.classes["@mozilla.org/thread-manager;1"].getService();
+  var thr = tm.currentThread;
 
-  while (!_quit)
-    thr.processNextEvent(true);
+  tm.spinEventLoopUntil(() => _quit);
 
   while (thr.hasPendingEvents())
     thr.processNextEvent(true);
@@ -479,12 +478,14 @@ function _initDebugging(port) {
   listener.open();
 
   // spin an event loop until the debugger connects.
-  let thr = Components.classes["@mozilla.org/thread-manager;1"]
-              .getService().currentThread;
-  while (!initialized) {
+  let tm = Components.classes["@mozilla.org/thread-manager;1"].getService();
+  tm.spinEventLoopUntil(() => {
+    if (initialized) {
+      return true;
+    }
     do_print("Still waiting for debugger to connect...");
-    thr.processNextEvent(true);
-  }
+    return false;
+  });
   // NOTE: if you want to debug the harness itself, you can now add a 'debugger'
   // statement anywhere and it will stop - but we've already added a breakpoint
   // for the first line of the test scripts, so we just continue...
@@ -614,11 +615,8 @@ function _execute_test() {
     }
     _cleanupFunctions = [];
   }).catch(reportCleanupError).then(() => complete = true);
-  let thr = Components.classes["@mozilla.org/thread-manager;1"]
-                      .getService().currentThread;
-  while (!complete) {
-    thr.processNextEvent(true);
-  }
+  let tm = Components.classes["@mozilla.org/thread-manager;1"].getService();
+  tm.spinEventLoopUntil(() => complete);
 
   // Restore idle service to avoid leaks.
   _fakeIdleService.deactivate();

toolkit/components/places/PlacesUtils.jsm

@@ -3565,10 +3565,7 @@ PlacesEditBookmarkKeywordTransaction.prototype = {
                  .then(() => done = true);
     // TODO: Until we can move to PlacesTransactions.jsm, we must spin the
     // events loop :(
-    let thread = Services.tm.currentThread;
-    while (!done) {
-      thread.processNextEvent(true);
-    }
+    Services.tm.spinEventLoopUntil(() => done);
   },
 
   undoTransaction: function EBKTXN_undoTransaction() {
@@ -3590,10 +3587,9 @@ PlacesEditBookmarkKeywordTransaction.prototype = {
                  .then(() => done = true);
     // TODO: Until we can move to PlacesTransactions.jsm, we must spin the
     // events loop :(
-    let thread = Services.tm.currentThread;
-    while (!done) {
-      thread.processNextEvent(true);
-    }
+    Services.tm.spinEventLoopUntil(() => {
+      return done;
+    });
   }
 };
 

toolkit/components/places/tests/unit/test_async_in_batchmode.js

@@ -8,7 +8,7 @@ Cu.import("resource://gre/modules/PlacesUtils.jsm");
 // This function "waits" for a promise to resolve by spinning a nested event
 // loop.
 function waitForPromise(promise) {
-  let thread = Cc["@mozilla.org/thread-manager;1"].getService().currentThread;
+  let tm = Cc["@mozilla.org/thread-manager;1"].getService();
 
   let finalResult, finalException;
 
@@ -19,9 +19,8 @@ function waitForPromise(promise) {
   });
 
   // Keep waiting until our callback is triggered (unless the app is quitting).
-  while (!finalResult && !finalException) {
-    thread.processNextEvent(true);
-  }
+  tm.spinEventLoopUntil(() => finalResult || finalException);
+
   if (finalException) {
     throw finalException;
   }

toolkit/components/prompts/src/nsPrompter.js

@@ -415,9 +415,7 @@ function openTabPrompt(domWin, tabPrompt, args) {
         // there's other stuff in nsWindowWatcher::OpenWindowInternal
         // that we might need to do here as well.
 
-        let thread = Services.tm.currentThread;
-        while (args.promptActive)
-            thread.processNextEvent(true);
+	Services.tm.spinEventLoopUntil(() => !args.promptActive);
         delete args.promptActive;
 
         if (args.promptAborted)
@@ -489,10 +487,7 @@ function openRemotePrompt(domWin, args, tabPrompt) {
 
     messageManager.sendAsyncMessage("Prompt:Open", args, {});
 
-    let thread = Services.tm.currentThread;
-    while (!closed) {
-        thread.processNextEvent(true);
-    }
+    Services.tm.spinEventLoopUntil(() => closed);
 }
 
 function ModalPrompter(domWin) {

toolkit/components/satchel/FormHistory.jsm

@@ -605,10 +605,7 @@ function dbClose(aShutdown) {
   _dbConnection.asyncClose(() => closed = true);
 
   if (!aShutdown) {
-    let thread = Services.tm.currentThread;
-    while (!closed) {
-      thread.processNextEvent(true);
-    }
+    Services.tm.spinEventLoopUntil(() => closed);
   }
 }
 

toolkit/content/tests/browser/head.js

@@ -89,11 +89,11 @@ function setTestPluginEnabledState(newEnabledState, pluginName) {
     return;
   }
   var plugin = getTestPlugin(pluginName);
-  while (plugin.enabledState != newEnabledState) {
-    // Run a nested event loop to wait for the preference change to
-    // propagate to the child. Yuck!
-    SpecialPowers.Services.tm.currentThread.processNextEvent(true);
-  }
+  // Run a nested event loop to wait for the preference change to
+  // propagate to the child. Yuck!
+  SpecialPowers.Services.tm.spinEventLoopUntil(() => {
+    return plugin.enabledState == newEnabledState;
+  });
   SimpleTest.registerCleanupFunction(function() {
     SpecialPowers.setTestPluginEnabledState(oldEnabledState, pluginName);
   });

toolkit/crashreporter/test/unit/crasher_subprocess_tail.js

@@ -3,14 +3,13 @@
 // Let the event loop process a bit before crashing.
 if (shouldDelay) {
   let shouldCrashNow = false;
-  let thr = Components.classes["@mozilla.org/thread-manager;1"]
-                          .getService().currentThread;
+  let tm = Components.classes["@mozilla.org/thread-manager;1"]
+                     .getService();
+  let thr = tm.currentThread;
   thr.dispatch({ run: () => { shouldCrashNow = true; } },
                Components.interfaces.nsIThread.DISPATCH_NORMAL);
 
-  while (!shouldCrashNow) {
-    thr.processNextEvent(true);
-  }
+  tm.spinEventLoopUntil(() => shouldCrashNow);
 }
 
 // now actually crash

toolkit/crashreporter/test/unit/test_crash_terminator.js

@@ -24,9 +24,7 @@ function setup_crash() {
   terminator.observe(null, "profile-before-change", null);
 
   dump("Waiting (actively) for the crash\n");
-  while (true) {
-    Services.tm.currentThread.processNextEvent(true);
-  }
+  Services.tm.spinEventLoopUntil(() => false);
 }
 
 

toolkit/modules/tests/modules/PromiseTestUtils.jsm

@@ -114,9 +114,7 @@ this.PromiseTestUtils = {
 
     PromiseDebugging.addUncaughtRejectionObserver(observer);
     Promise.reject(this._ensureDOMPromiseRejectionsProcessedReason);
-    while (!observed) {
-      Services.tm.mainThread.processNextEvent(true);
-    }
+    Services.tm.spinEventLoopUntil(() => observed);
     PromiseDebugging.removeUncaughtRejectionObserver(observer);
   },
   _ensureDOMPromiseRejectionsProcessedReason: {},

toolkit/modules/tests/xpcshell/test_Promise.js

@@ -922,10 +922,7 @@ tests.push(
     let shouldExitNestedEventLoop = false;
 
     function event_loop() {
-      let thr = Services.tm.mainThread;
-      while (!shouldExitNestedEventLoop) {
-        thr.processNextEvent(true);
-      }
+      Services.tm.spinEventLoopUntil(() => shouldExitNestedEventLoop);
     }
 
     // I wish there was a way to cancel xpcshell do_timeout()s

toolkit/mozapps/extensions/internal/AddonTestUtils.jsm

@@ -401,8 +401,7 @@ var AddonTestUtils = {
       done = true;
     });
 
-    while (!done)
-      Services.tm.mainThread.processNextEvent(true);
+    Services.tm.spinEventLoopUntil(() => done);
 
     if (error !== undefined)
       throw error;

toolkit/mozapps/extensions/internal/XPIProvider.jsm

@@ -1012,10 +1012,7 @@ function syncLoadManifestFromFile(aFile, aInstallLocation) {
     result = val
   });
 
-  let thread = Services.tm.currentThread;
-
-  while (success === undefined)
-    thread.processNextEvent(true);
+  Services.tm.spinEventLoopUntil(() => success !== undefined);
 
   if (!success)
     throw result;

toolkit/mozapps/extensions/test/xpcshell/test_bug542391.js

@@ -60,12 +60,10 @@ var WindowWatcher = {
     // The dialog is meant to be opened modally and the install operation can be
     // asynchronous, so we must spin an event loop (like the modal window does)
     // until the install is complete
-    let thr = AM_Cc["@mozilla.org/thread-manager;1"].
-              getService(AM_Ci.nsIThreadManager).
-              mainThread;
+    let tm = AM_Cc["@mozilla.org/thread-manager;1"].
+             getService(AM_Ci.nsIThreadManager);
 
-    while (!installed || !updated)
-      thr.processNextEvent(false);
+    tm.spinEventLoopUntil(() => installed && updated);
   },
 
   QueryInterface(iid) {

xpcom/tests/gtest/TestThreadManager.cpp

@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIThreadManager.h"
+#include "nsCOMPtr.h"
+#include "nsXPCOM.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Atomics.h"
+#include "gtest/gtest.h"
+
+using mozilla::Atomic;
+using mozilla::Runnable;
+
+class WaitCondition final : public nsINestedEventLoopCondition
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  WaitCondition(Atomic<uint32_t>& aCounter, uint32_t aMaxCount)
+    : mCounter(aCounter)
+    , mMaxCount(aMaxCount)
+  {
+  }
+
+  NS_IMETHODIMP IsDone(bool* aDone) override
+  {
+    *aDone = (mCounter == mMaxCount);
+    return NS_OK;
+  }
+
+private:
+  ~WaitCondition() = default;
+
+  Atomic<uint32_t>& mCounter;
+  const uint32_t mMaxCount;
+};
+
+NS_IMPL_ISUPPORTS(WaitCondition, nsINestedEventLoopCondition)
+
+class SpinRunnable final : public Runnable
+{
+public:
+  explicit SpinRunnable(nsINestedEventLoopCondition* aCondition)
+    : mCondition(aCondition)
+    , mResult(NS_OK)
+  {
+  }
+
+  NS_IMETHODIMP Run()
+  {
+    nsCOMPtr<nsIThreadManager> threadMan =
+      do_GetService("@mozilla.org/thread-manager;1");
+    mResult = threadMan->SpinEventLoopUntil(mCondition);
+    return NS_OK;
+  }
+
+  nsresult SpinLoopResult()
+  {
+    return mResult;
+  }
+
+private:
+  ~SpinRunnable() = default;
+
+  nsCOMPtr<nsINestedEventLoopCondition> mCondition;
+  Atomic<nsresult> mResult;
+};
+
+class CountRunnable final : public Runnable
+{
+public:
+  explicit CountRunnable(Atomic<uint32_t>& aCounter)
+    : mCounter(aCounter)
+  {
+  }
+
+  NS_IMETHODIMP Run()
+  {
+    mCounter++;
+    return NS_OK;
+  }
+
+private:
+  Atomic<uint32_t>& mCounter;
+};
+
+TEST(ThreadManager, SpinEventLoopUntilSuccess)
+{
+  const uint32_t kRunnablesToDispatch = 100;
+  nsresult rv;
+  mozilla::Atomic<uint32_t> count(0);
+
+  nsCOMPtr<nsINestedEventLoopCondition> condition =
+    new WaitCondition(count, kRunnablesToDispatch);
+  RefPtr<SpinRunnable> spinner = new SpinRunnable(condition);
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_NewNamedThread("SpinEventLoop", getter_AddRefs(thread), spinner);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIRunnable> counter = new CountRunnable(count);
+  for (uint32_t i = 0; i < kRunnablesToDispatch; ++i) {
+    rv = thread->Dispatch(counter, NS_DISPATCH_NORMAL);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+  }
+
+  rv = thread->Shutdown();
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(NS_SUCCEEDED(spinner->SpinLoopResult()));
+}
+
+class ErrorCondition final : public nsINestedEventLoopCondition
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  ErrorCondition(Atomic<uint32_t>& aCounter, uint32_t aMaxCount)
+    : mCounter(aCounter)
+    , mMaxCount(aMaxCount)
+  {
+  }
+
+  NS_IMETHODIMP IsDone(bool* aDone) override
+  {
+    if (mCounter == mMaxCount) {
+      return NS_ERROR_ILLEGAL_VALUE;
+    }
+    return NS_OK;
+  }
+
+private:
+  ~ErrorCondition() = default;
+
+  Atomic<uint32_t>& mCounter;
+  const uint32_t mMaxCount;
+};
+
+NS_IMPL_ISUPPORTS(ErrorCondition, nsINestedEventLoopCondition)
+
+TEST(ThreadManager, SpinEventLoopUntilError)
+{
+  const uint32_t kRunnablesToDispatch = 100;
+  nsresult rv;
+  mozilla::Atomic<uint32_t> count(0);
+
+  nsCOMPtr<nsINestedEventLoopCondition> condition =
+    new ErrorCondition(count, kRunnablesToDispatch);
+  RefPtr<SpinRunnable> spinner = new SpinRunnable(condition);
+  nsCOMPtr<nsIThread> thread;
+  rv = NS_NewNamedThread("SpinEventLoop", getter_AddRefs(thread), spinner);
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  nsCOMPtr<nsIRunnable> counter = new CountRunnable(count);
+  for (uint32_t i = 0; i < kRunnablesToDispatch; ++i) {
+    rv = thread->Dispatch(counter, NS_DISPATCH_NORMAL);
+    ASSERT_TRUE(NS_SUCCEEDED(rv));
+  }
+
+  rv = thread->Shutdown();
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+  ASSERT_TRUE(NS_FAILED(spinner->SpinLoopResult()));
+}

xpcom/tests/gtest/moz.build

@@ -44,6 +44,7 @@ UNIFIED_SOURCES += [
     'TestTArray2.cpp',
     'TestTaskQueue.cpp',
     'TestTextFormatter.cpp',
+    'TestThreadManager.cpp',
     'TestThreadPool.cpp',
     'TestThreadPoolListener.cpp',
     'TestThreads.cpp',

xpcom/threads/nsIThreadManager.idl

@@ -11,6 +11,15 @@
 interface nsIRunnable;
 interface nsIThread;
 
+[scriptable, function, uuid(039a227d-0cb7-44a5-a8f9-dbb7071979f2)]
+interface nsINestedEventLoopCondition : nsISupports
+{
+  /**
+   * Returns true if the current nested event loop should stop spinning.
+   */
+  bool isDone();
+};
+
 /**
  * An interface for creating and locating nsIThread instances.
  */
@@ -85,6 +94,17 @@ interface nsIThreadManager : nsISupports
    */
   void dispatchToMainThread(in nsIRunnable event);
 
+  /**
+   * Enter a nested event loop on the current thread, waiting on, and
+   * processing events until condition.isDone() returns true.
+   *
+   * If condition.isDone() throws, this function will throw as well.
+   *
+   * C++ code should not use this function, instead preferring
+   * mozilla::SpinEventLoopUntil.
+   */
+  void spinEventLoopUntil(in nsINestedEventLoopCondition condition);
+
   /**
    * This queues a runnable to the main thread's idle queue.
    *

xpcom/threads/nsThreadManager.cpp

@@ -338,6 +338,32 @@ nsThreadManager::GetCurrentThread(nsIThread** aResult)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsThreadManager::SpinEventLoopUntil(nsINestedEventLoopCondition* aCondition)
+{
+  nsCOMPtr<nsINestedEventLoopCondition> condition(aCondition);
+  nsresult rv = NS_OK;
+
+  if (!mozilla::SpinEventLoopUntil([&]() -> bool {
+        bool isDone = false;
+        rv = condition->IsDone(&isDone);
+        // JS failure should be unusual, but we need to stop and propagate
+        // the error back to the caller.
+        if (NS_FAILED(rv)) {
+          return true;
+        }
+
+        return isDone;
+      })) {
+    // We stopped early for some reason, which is unexpected.
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // If we exited when the condition told us to, we need to return whether
+  // the condition encountered failure when executing.
+  return rv;
+}
+
 uint32_t
 nsThreadManager::GetHighestNumberOfThreads()
 {