Bug 1133521 - Enable BHR on Beta. r=vladan

toolkit/components/telemetry/Telemetry.cpp

@@ -2911,21 +2911,20 @@ TelemetryImpl::GetThreadHangStats(JSContext* cx, JS::MutableHandle<JS::Value> re
   }
   size_t threadIndex = 0;
 
-#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
-  /* First add active threads; we need to hold |iter| (and its lock)
-     throughout this method to avoid a race condition where a thread can
-     be recorded twice if the thread is destroyed while this method is
-     running */
-  BackgroundHangMonitor::ThreadHangStatsIterator iter;
-  for (Telemetry::ThreadHangStats* histogram = iter.GetNext();
-       histogram; histogram = iter.GetNext()) {
-    JS::RootedObject obj(cx,
-      CreateJSThreadHangStats(cx, *histogram));
-    if (!JS_DefineElement(cx, retObj, threadIndex++, obj, JSPROP_ENUMERATE)) {
-      return NS_ERROR_FAILURE;
+  if (!BackgroundHangMonitor::IsDisabled()) {
+    /* First add active threads; we need to hold |iter| (and its lock)
+       throughout this method to avoid a race condition where a thread can
+       be recorded twice if the thread is destroyed while this method is
+       running */
+    BackgroundHangMonitor::ThreadHangStatsIterator iter;
+    for (Telemetry::ThreadHangStats* histogram = iter.GetNext();
+         histogram; histogram = iter.GetNext()) {
+      JS::RootedObject obj(cx, CreateJSThreadHangStats(cx, *histogram));
+      if (!JS_DefineElement(cx, retObj, threadIndex++, obj, JSPROP_ENUMERATE)) {
+        return NS_ERROR_FAILURE;
+      }
     }
   }
-#endif
 
   // Add saved threads next
   MutexAutoLock autoLock(mThreadHangStatsMutex);

xpcom/threads/BackgroundHangMonitor.cpp

@@ -9,6 +9,7 @@
 #include "mozilla/LinkedList.h"
 #include "mozilla/Monitor.h"
 #include "mozilla/Move.h"
+#include "mozilla/Preferences.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/ThreadHangStats.h"
@@ -20,16 +21,23 @@
 #include "prinrval.h"
 #include "prthread.h"
 #include "ThreadStackHelper.h"
+#include "nsIObserverService.h"
+#include "nsIObserver.h"
+#include "mozilla/Services.h"
+#include "nsXULAppAPI.h"
 
 #include <algorithm>
 
+// Activate BHR only for one every BHR_BETA_MOD users.
+#define BHR_BETA_MOD 100;
+
 namespace mozilla {
 
 /**
  * BackgroundHangManager is the global object that
  * manages all instances of BackgroundHangThread.
  */
-class BackgroundHangManager
+class BackgroundHangManager : public nsIObserver
 {
 private:
   // Background hang monitor thread function
@@ -61,9 +69,11 @@ private:
   void RunMonitorThread();
 
 public:
-  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(BackgroundHangManager)
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
   static StaticRefPtr<BackgroundHangManager> sInstance;
   static bool sProhibited;
+  static bool sDisabled;
 
   // Lock for access to members of this class
   Monitor mLock;
@@ -90,9 +100,23 @@ public:
 
   BackgroundHangManager();
 private:
-  ~BackgroundHangManager();
+  virtual ~BackgroundHangManager();
 };
 
+NS_IMPL_ISUPPORTS(BackgroundHangManager, nsIObserver)
+
+NS_IMETHODIMP
+BackgroundHangManager::Observe(nsISupports* aSubject, const char* aTopic, const char16_t* aData) {
+  NS_ENSURE_TRUE(!strcmp(aTopic, "profile-after-change"), NS_ERROR_UNEXPECTED);
+  BackgroundHangMonitor::DisableOnBeta();
+
+  nsCOMPtr<nsIObserverService> observerService = mozilla::services::GetObserverService();
+  MOZ_ASSERT(observerService);
+  observerService->RemoveObserver(this, "profile-after-change");
+
+  return NS_OK;
+}
+
 /**
  * BackgroundHangThread is a per-thread object that is used
  * by all instances of BackgroundHangMonitor to monitor hangs.
@@ -162,6 +186,7 @@ public:
 
 StaticRefPtr<BackgroundHangManager> BackgroundHangManager::sInstance;
 bool BackgroundHangManager::sProhibited = false;
+bool BackgroundHangManager::sDisabled = false;
 
 ThreadLocal<BackgroundHangThread*> BackgroundHangThread::sTlsKey;
 
@@ -421,7 +446,7 @@ BackgroundHangThread::FindThread()
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   if (BackgroundHangManager::sInstance == nullptr) {
-    MOZ_ASSERT(BackgroundHangManager::sProhibited,
+    MOZ_ASSERT(BackgroundHangManager::sProhibited || BackgroundHangManager::sDisabled,
                "BackgroundHandleManager is not initialized");
     return nullptr;
   }
@@ -450,6 +475,38 @@ BackgroundHangThread::FindThread()
   return nullptr;
 }
 
+bool
+BackgroundHangMonitor::ShouldDisableOnBeta(const nsCString &clientID) {
+  MOZ_ASSERT(clientID.Length() == 36, "clientID is invalid");
+  const char *suffix = clientID.get() + clientID.Length() - 4;
+  return strtol(suffix, NULL, 16) % BHR_BETA_MOD;
+}
+
+bool
+BackgroundHangMonitor::IsDisabled() {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  return BackgroundHangManager::sDisabled;
+#else
+  return true;
+#endif
+}
+
+bool
+BackgroundHangMonitor::DisableOnBeta() {
+  nsAdoptingCString clientID = Preferences::GetCString("toolkit.telemetry.cachedClientID");
+  bool telemetryEnabled = Preferences::GetBool("toolkit.telemetry.enabled");
+
+  if (!telemetryEnabled || !clientID || BackgroundHangMonitor::ShouldDisableOnBeta(clientID)) {
+    if (XRE_IsParentProcess()) {
+      BackgroundHangMonitor::Shutdown();
+    } else {
+      BackgroundHangManager::sDisabled = true;
+    }
+    return true;
+  }
+
+  return false;
+}
 
 void
 BackgroundHangMonitor::Startup()
@@ -457,6 +514,23 @@ BackgroundHangMonitor::Startup()
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   MOZ_ASSERT(!BackgroundHangManager::sProhibited, "Prohibited");
   MOZ_ASSERT(!BackgroundHangManager::sInstance, "Already initialized");
+
+  if (!strcmp(NS_STRINGIFY(MOZ_UPDATE_CHANNEL), "beta")) {
+    if (XRE_IsParentProcess()) { // cached ClientID hasn't been read yet
+      ThreadStackHelper::Startup();
+      BackgroundHangThread::Startup();
+      BackgroundHangManager::sInstance = new BackgroundHangManager();
+
+      nsCOMPtr<nsIObserverService> observerService = mozilla::services::GetObserverService();
+      MOZ_ASSERT(observerService);
+
+      observerService->AddObserver(BackgroundHangManager::sInstance, "profile-after-change", false);
+      return;
+    } else if(DisableOnBeta()){
+      return;
+    }
+  }
+
   ThreadStackHelper::Startup();
   BackgroundHangThread::Startup();
   BackgroundHangManager::sInstance = new BackgroundHangManager();
@@ -467,6 +541,11 @@ void
 BackgroundHangMonitor::Shutdown()
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (BackgroundHangManager::sDisabled) {
+    MOZ_ASSERT(!BackgroundHangManager::sInstance, "Initialized");
+    return;
+  }
+
   MOZ_ASSERT(!BackgroundHangManager::sProhibited, "Prohibited");
   MOZ_ASSERT(BackgroundHangManager::sInstance, "Not initialized");
   /* Scope our lock inside Shutdown() because the sInstance object can
@@ -475,6 +554,7 @@ BackgroundHangMonitor::Shutdown()
   BackgroundHangManager::sInstance->Shutdown();
   BackgroundHangManager::sInstance = nullptr;
   ThreadStackHelper::Shutdown();
+  BackgroundHangManager::sDisabled = true;
 #endif
 }
 
@@ -484,7 +564,7 @@ BackgroundHangMonitor::BackgroundHangMonitor(const char* aName,
   : mThread(BackgroundHangThread::FindThread())
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
-  if (!BackgroundHangManager::sProhibited && !mThread) {
+  if (!BackgroundHangManager::sDisabled && !BackgroundHangManager::sProhibited && !mThread) {
     // If sProhibit is true, mThread would be null, and no monitoring.
     mThread = new BackgroundHangThread(aName, aTimeoutMs, aMaxTimeoutMs);
   }
@@ -495,6 +575,10 @@ BackgroundHangMonitor::BackgroundHangMonitor()
   : mThread(BackgroundHangThread::FindThread())
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  if (BackgroundHangManager::sDisabled) {
+    return;
+  }
+
   MOZ_ASSERT(!BackgroundHangManager::sProhibited || mThread,
              "This thread is not initialized for hang monitoring");
 #endif
@@ -509,7 +593,8 @@ BackgroundHangMonitor::NotifyActivity()
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   if (mThread == nullptr) {
-    MOZ_ASSERT(BackgroundHangManager::sProhibited,
+    MOZ_ASSERT(BackgroundHangManager::sProhibited ||
+               BackgroundHangManager::sDisabled,
                "This thread is not initialized for hang monitoring");
     return;
   }
@@ -525,7 +610,8 @@ BackgroundHangMonitor::NotifyWait()
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   if (mThread == nullptr) {
-    MOZ_ASSERT(BackgroundHangManager::sProhibited,
+    MOZ_ASSERT(BackgroundHangManager::sProhibited ||
+               BackgroundHangManager::sDisabled,
                "This thread is not initialized for hang monitoring");
     return;
   }
@@ -567,7 +653,9 @@ BackgroundHangMonitor::ThreadHangStatsIterator::ThreadHangStatsIterator()
             nullptr)
 {
 #ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
-  MOZ_ASSERT(BackgroundHangManager::sInstance || BackgroundHangManager::sProhibited,
+  MOZ_ASSERT(BackgroundHangManager::sInstance ||
+             BackgroundHangManager::sProhibited ||
+             BackgroundHangManager::sDisabled,
              "Inconsistent state");
 #endif
 }

xpcom/threads/BackgroundHangMonitor.h

@@ -10,6 +10,8 @@
 #include "mozilla/RefPtr.h"
 #include "mozilla/Monitor.h"
 
+#include "nsString.h"
+
 #include <stdint.h>
 
 namespace mozilla {
@@ -18,14 +20,8 @@ namespace Telemetry {
 class ThreadHangStats;
 };
 
-// Disabled for Beta/Release builds because of bug 965392.
-// Disabled for debug builds because of bug 979069.
-#if !defined(RELEASE_BUILD) && !defined(DEBUG)
-// Undefine to disable background hang monitor
-#define MOZ_ENABLE_BACKGROUND_HANG_MONITOR
-#endif
-
 class BackgroundHangThread;
+class BackgroundHangManager;
 
 /**
  * The background hang monitor is responsible for detecting and reporting
@@ -113,8 +109,13 @@ class BackgroundHangThread;
 class BackgroundHangMonitor
 {
 private:
+  friend BackgroundHangManager;
+
   RefPtr<BackgroundHangThread> mThread;
 
+  static bool ShouldDisableOnBeta(const nsCString &);
+  static bool DisableOnBeta();
+
 public:
   static const uint32_t kNoTimeout = 0;
 
@@ -168,6 +169,11 @@ public:
    */
   static void Shutdown();
 
+  /**
+   * Returns true if BHR is disabled.
+   */
+  static bool IsDisabled();
+
   /**
    * Start monitoring hangs for the current thread.
    *

xpcom/threads/moz.build

@@ -59,6 +59,11 @@ LOCAL_INCLUDES += [
     '/tools/profiler',
 ]
 
+# BHR disabled for Release builds because of bug 965392.
+# BHR disabled for debug builds because of bug 979069.
+if CONFIG['MOZ_UPDATE_CHANNEL'] not in ('release') and not CONFIG['MOZ_DEBUG']:
+    DEFINES['MOZ_ENABLE_BACKGROUND_HANG_MONITOR'] = 1
+
 FAIL_ON_WARNINGS = True
 
 FINAL_LIBRARY = 'xul'