Bug 1661812 - Consider to use longer timeout for slow script warning if there isn't any important user input pending r=mccr8,geckoview-reviewers,snorp

The patch converts the relevant prefs to use StaticPrefList and let's content JS in child processes to run longer if there
aren't mousedown/ups or keyevents or such. mousemove or wheel aren't considered as important events.

Differential Revision: https://phabricator.services.mozilla.com/D88668

js/xpconnect/src/XPCJSContext.cpp

@@ -28,6 +28,7 @@
 #ifdef FUZZING
 #  include "mozilla/StaticPrefs_fuzzing.h"
 #endif
+#include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/StaticPrefs_browser.h"
 #include "mozilla/StaticPrefs_javascript.h"
 #include "mozilla/dom/ScriptSettings.h"
@@ -40,6 +41,7 @@
 #include "js/ContextOptions.h"
 #include "js/MemoryMetrics.h"
 #include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/WindowBinding.h"
@@ -378,18 +380,15 @@ class WatchdogManager {
     }
 
     if (mWatchdog) {
-      int32_t contentTime =
-          Preferences::GetInt(PREF_MAX_SCRIPT_RUN_TIME_CONTENT, 10);
+      int32_t contentTime = StaticPrefs::dom_max_script_run_time();
       if (contentTime <= 0) {
         contentTime = INT32_MAX;
       }
-      int32_t chromeTime =
-          Preferences::GetInt(PREF_MAX_SCRIPT_RUN_TIME_CHROME, 20);
+      int32_t chromeTime = StaticPrefs::dom_max_chrome_script_run_time();
       if (chromeTime <= 0) {
         chromeTime = INT32_MAX;
       }
-      int32_t extTime =
-          Preferences::GetInt(PREF_MAX_SCRIPT_RUN_TIME_EXT_CONTENT, 5);
+      int32_t extTime = StaticPrefs::dom_max_ext_content_script_run_time();
       if (extTime <= 0) {
         extTime = INT32_MAX;
       }
@@ -620,19 +619,20 @@ bool XPCJSContext::InterruptCallback(JSContext* cx) {
 
   nsString addonId;
   const char* prefName;
-
+  bool runningContentJS = false;
   auto principal = BasePrincipal::Cast(nsContentUtils::SubjectPrincipal(cx));
   bool chrome = principal->Is<SystemPrincipal>();
   if (chrome) {
     prefName = PREF_MAX_SCRIPT_RUN_TIME_CHROME;
-    limit = Preferences::GetInt(prefName, 20);
+    limit = StaticPrefs::dom_max_chrome_script_run_time();
   } else if (auto policy = principal->ContentScriptAddonPolicy()) {
     policy->GetId(addonId);
     prefName = PREF_MAX_SCRIPT_RUN_TIME_EXT_CONTENT;
-    limit = Preferences::GetInt(prefName, 5);
+    limit = StaticPrefs::dom_max_ext_content_script_run_time();
   } else {
     prefName = PREF_MAX_SCRIPT_RUN_TIME_CONTENT;
-    limit = Preferences::GetInt(prefName, 10);
+    limit = StaticPrefs::dom_max_script_run_time();
+    runningContentJS = true;
   }
 
   // If there's no limit, or we're within the limit, let it go.
@@ -651,6 +651,33 @@ bool XPCJSContext::InterruptCallback(JSContext* cx) {
     return true;
   }
 
+  int32_t limitWithoutImportantUserInput =
+      StaticPrefs::dom_max_script_run_time_without_important_user_input();
+  if (runningContentJS && XRE_IsContentProcess() && limit &&
+      limitWithoutImportantUserInput > limit &&
+      limitWithoutImportantUserInput >
+          self->mSlowScriptActualWait.ToSeconds()) {
+    // Call possibly slow PeekMessages after the other common early returns in
+    // this method.
+    ContentChild* contentChild = ContentChild::GetSingleton();
+    mozilla::ipc::MessageChannel* channel =
+        contentChild ? contentChild->GetIPCChannel() : nullptr;
+    if (channel) {
+      bool foundInputEvent = false;
+      channel->PeekMessages(
+          [&foundInputEvent](const IPC::Message& aMsg) -> bool {
+            if (nsContentUtils::IsMessageCriticalInputEvent(aMsg)) {
+              foundInputEvent = true;
+              return false;
+            }
+            return true;
+          });
+      if (!foundInputEvent) {
+        return true;
+      }
+    }
+  }
+
   //
   // This has gone on long enough! Time to take action. ;-)
   //

mobile/android/app/mobile.js

@@ -314,7 +314,6 @@ pref("privacy.item.syncAccount", true);
 
 pref("javascript.options.mem.high_water_mark", 32);
 
-pref("dom.max_chrome_script_run_time", 0); // disable slow script dialog for chrome
 pref("dom.max_script_run_time", 20);
 
 // Absolute path to the devtools unix domain socket file used

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/ContentDelegateTest.kt

@@ -360,6 +360,7 @@ class ContentDelegateTest : BaseSessionTest() {
     private fun setHangReportTestPrefs(timeout: Int = 20000) {
         sessionRule.setPrefsUntilTestEnd(mapOf(
                 "dom.max_script_run_time" to 1,
+                "dom.max_script_run_time_without_important_user_input" to 1,
                 "dom.max_chrome_script_run_time" to 1,
                 "dom.max_ext_content_script_run_time" to 1,
                 "dom.ipc.cpow.timeout" to 100,

modules/libpref/init/StaticPrefList.yaml

@@ -3373,6 +3373,32 @@
   value: @IS_ANDROID@
   mirror: always
 
+# The following four prefs control the maximum script run time before slow
+# script warning.
+- name: dom.max_script_run_time
+  type: int32_t
+  value: 10
+  mirror: always
+
+- name: dom.max_script_run_time_without_important_user_input
+  type: int32_t
+#ifdef NIGHTLY_BUILD
+  value: 20
+#else
+  value: 10
+#endif
+  mirror: always
+
+- name: dom.max_chrome_script_run_time
+  type: int32_t
+  value: 0
+  mirror: always
+
+- name: dom.max_ext_content_script_run_time
+  type: int32_t
+  value: 5
+  mirror: always
+
 #---------------------------------------------------------------------------
 # Prefs starting with "editor"
 #---------------------------------------------------------------------------

modules/libpref/init/all.js

@@ -2455,9 +2455,6 @@ pref("editor.resizing.preserve_ratio",       true);
 pref("editor.positioning.offset",            0);
 
 pref("dom.use_watchdog", true);
-pref("dom.max_chrome_script_run_time", 0);
-pref("dom.max_script_run_time", 10);
-pref("dom.max_ext_content_script_run_time", 5);
 
 // Stop all scripts in a compartment when the "stop script" dialog is used.
 pref("dom.global_stop_script", true);