Bug 1652613 - report slow script hang durations and only clear hang data after the observer notification, r=mconley

Differential Revision: https://phabricator.services.mozilla.com/D83989

dom/base/nsGlobalWindowInner.cpp

@@ -4720,7 +4720,8 @@ void nsGlobalWindowInner::FireOfflineStatusEventIfChanged() {
 
 nsGlobalWindowInner::SlowScriptResponse
 nsGlobalWindowInner::ShowSlowScriptDialog(JSContext* aCx,
-                                          const nsString& aAddonId) {
+                                          const nsString& aAddonId,
+                                          const double aDuration) {
   nsresult rv;
 
   if (Preferences::GetBool("dom.always_stop_slow_scripts")) {
@@ -4768,7 +4769,8 @@ nsGlobalWindowInner::ShowSlowScriptDialog(JSContext* aCx,
     nsIDocShell* docShell = GetDocShell();
     nsCOMPtr<nsIBrowserChild> child =
         docShell ? docShell->GetBrowserChild() : nullptr;
-    action = monitor->NotifySlowScript(child, filename.get(), aAddonId);
+    action =
+        monitor->NotifySlowScript(child, filename.get(), aAddonId, aDuration);
     if (action == ProcessHangMonitor::Terminate) {
       return KillSlowScript;
     }

dom/base/nsGlobalWindowInner.h

@@ -482,7 +482,8 @@ class nsGlobalWindowInner final : public mozilla::dom::EventTarget,
     KillScriptGlobal
   };
   SlowScriptResponse ShowSlowScriptDialog(JSContext* aCx,
-                                          const nsString& aAddonId);
+                                          const nsString& aAddonId,
+                                          const double aDuration);
 
   // Inner windows only.
   void AddGamepad(uint32_t aIndex, mozilla::dom::Gamepad* aGamepad);

dom/ipc/PProcessHangMonitor.ipdl

@@ -20,6 +20,7 @@ struct SlowScriptData
   TabId tabId;
   nsCString filename;
   nsString addonId;
+  double duration;
 };
 
 struct PluginHangData

dom/ipc/ProcessHangMonitor.cpp

@@ -89,9 +89,10 @@ class HangMonitorChild : public PProcessHangMonitorChild,
   typedef ProcessHangMonitor::SlowScriptAction SlowScriptAction;
   SlowScriptAction NotifySlowScript(nsIBrowserChild* aBrowserChild,
                                     const char* aFileName,
-                                    const nsString& aAddonId);
+                                    const nsString& aAddonId,
+                                    const double aDuration);
   void NotifySlowScriptAsync(TabId aTabId, const nsCString& aFileName,
-                             const nsString& aAddonId);
+                             const nsString& aAddonId, const double aDuration);
 
   bool IsDebuggerStartupComplete();
 
@@ -589,15 +590,17 @@ void HangMonitorChild::Bind(Endpoint<PProcessHangMonitorChild>&& aEndpoint) {
 
 void HangMonitorChild::NotifySlowScriptAsync(TabId aTabId,
                                              const nsCString& aFileName,
-                                             const nsString& aAddonId) {
+                                             const nsString& aAddonId,
+                                             const double aDuration) {
   if (mIPCOpen) {
-    Unused << SendHangEvidence(SlowScriptData(aTabId, aFileName, aAddonId));
+    Unused << SendHangEvidence(
+        SlowScriptData(aTabId, aFileName, aAddonId, aDuration));
   }
 }
 
 HangMonitorChild::SlowScriptAction HangMonitorChild::NotifySlowScript(
     nsIBrowserChild* aBrowserChild, const char* aFileName,
-    const nsString& aAddonId) {
+    const nsString& aAddonId, const double aDuration) {
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
 
   mSentReport = true;
@@ -629,9 +632,10 @@ HangMonitorChild::SlowScriptAction HangMonitorChild::NotifySlowScript(
   }
   nsAutoCString filename(aFileName);
 
-  Dispatch(NewNonOwningRunnableMethod<TabId, nsCString, nsString>(
+  Dispatch(NewNonOwningRunnableMethod<TabId, nsCString, nsString, double>(
       "HangMonitorChild::NotifySlowScriptAsync", this,
-      &HangMonitorChild::NotifySlowScriptAsync, id, filename, aAddonId));
+      &HangMonitorChild::NotifySlowScriptAsync, id, filename, aAddonId,
+      aDuration));
   return SlowScriptAction::Continue;
 }
 
@@ -851,11 +855,12 @@ void HangMonitorParent::SendHangNotification(const HangData& aHangData,
 void HangMonitorParent::ClearHangNotification() {
   // chrome process, main thread
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
-  mProcess->ClearHang();
 
   nsCOMPtr<nsIObserverService> observerService =
       mozilla::services::GetObserverService();
   observerService->NotifyObservers(mProcess, "clear-hang-report", nullptr);
+
+  mProcess->ClearHang();
 }
 
 // Take a minidump of the browser process if one wasn't already taken for the
@@ -1007,6 +1012,17 @@ HangMonitoredProcess::GetHangType(uint32_t* aHangType) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+HangMonitoredProcess::GetHangDuration(double* aHangDuration) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  if (mHangData.type() != HangData::TSlowScriptData) {
+    *aHangDuration = -1;
+  } else {
+    *aHangDuration = mHangData.get_SlowScriptData().duration();
+  }
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 HangMonitoredProcess::GetScriptBrowser(Element** aBrowser) {
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
@@ -1267,10 +1283,10 @@ ProcessHangMonitor::Observe(nsISupports* aSubject, const char* aTopic,
 
 ProcessHangMonitor::SlowScriptAction ProcessHangMonitor::NotifySlowScript(
     nsIBrowserChild* aBrowserChild, const char* aFileName,
-    const nsString& aAddonId) {
+    const nsString& aAddonId, const double aDuration) {
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
   return HangMonitorChild::Get()->NotifySlowScript(aBrowserChild, aFileName,
-                                                   aAddonId);
+                                                   aAddonId, aDuration);
 }
 
 bool ProcessHangMonitor::IsDebuggerStartupComplete() {

dom/ipc/ProcessHangMonitor.h

@@ -70,7 +70,8 @@ class ProcessHangMonitor final : public nsIObserver {
   };
   SlowScriptAction NotifySlowScript(nsIBrowserChild* aBrowserChild,
                                     const char* aFileName,
-                                    const nsString& aAddonId);
+                                    const nsString& aAddonId,
+                                    const double aDuration);
 
   void NotifyPluginHang(uint32_t aPluginId);
 

dom/ipc/nsIHangReport.idl

@@ -32,6 +32,8 @@ interface nsIHangReport : nsISupports
   // Only valid for SLOW_SCRIPT reports.
   readonly attribute Element scriptBrowser;
   readonly attribute ACString scriptFileName;
+  // Duration of the hang so far.
+  readonly attribute double hangDuration;
   readonly attribute AString addonId;
 
   // For PLUGIN_HANGs, this field contains information about the plugin.

js/xpconnect/src/XPCJSContext.cpp

@@ -701,8 +701,8 @@ bool XPCJSContext::InterruptCallback(JSContext* cx) {
   }
 
   // Show the prompt to the user, and kill if requested.
-  nsGlobalWindowInner::SlowScriptResponse response =
-      win->ShowSlowScriptDialog(cx, addonId);
+  nsGlobalWindowInner::SlowScriptResponse response = win->ShowSlowScriptDialog(
+      cx, addonId, self->mSlowScriptActualWait.ToMilliseconds());
   if (response == nsGlobalWindowInner::KillSlowScript) {
     if (Preferences::GetBool("dom.global_stop_script", true)) {
       xpc::Scriptability::Get(global).Block();