Bug 1531917 - Add Telemetry for how pages use bfcache r=jesup,bdekoz,smaug

Differential Revision: https://phabricator.services.mozilla.com/D30211

--HG--
extra : moz-landing-system : lando

docshell/base/nsDocShell.cpp

@@ -7212,9 +7212,53 @@ bool nsDocShell::CanSavePresentation(uint32_t aLoadType,
 
   // If the document does not want its presentation cached, then don't.
   RefPtr<Document> doc = mScriptGlobal->GetExtantDoc();
-  return doc && doc->CanSavePresentation(aNewRequest);
+
+  uint16_t bfCacheCombo = 0;
+  bool canSavePresentation =
+      doc->CanSavePresentation(aNewRequest, bfCacheCombo);
+  ReportBFCacheComboTelemetry(bfCacheCombo);
+
+  return doc && canSavePresentation;
 }
 
+void nsDocShell::ReportBFCacheComboTelemetry(uint16_t aCombo) {
+  switch (aCombo) {
+    case BFCACHE_SUCCESS:
+      Telemetry::AccumulateCategorical(
+          Telemetry::LABELS_BFCACHE_COMBO::BFCache_Success);
+      break;
+    case UNLOAD:
+      Telemetry::AccumulateCategorical(Telemetry::LABELS_BFCACHE_COMBO::Unload);
+      break;
+    case UNLOAD_REQUEST:
+      Telemetry::AccumulateCategorical(
+          Telemetry::LABELS_BFCACHE_COMBO::Unload_Req);
+      break;
+    case REQUEST:
+      Telemetry::AccumulateCategorical(Telemetry::LABELS_BFCACHE_COMBO::Req);
+      break;
+    case UNLOAD_REQUEST_PEER:
+      Telemetry::AccumulateCategorical(
+          Telemetry::LABELS_BFCACHE_COMBO::Unload_Req_Peer);
+      break;
+    case UNLOAD_REQUEST_PEER_MSE:
+      Telemetry::AccumulateCategorical(
+          Telemetry::LABELS_BFCACHE_COMBO::Unload_Req_Peer_MSE);
+      break;
+    case UNLOAD_REQUEST_MSE:
+      Telemetry::AccumulateCategorical(
+          Telemetry::LABELS_BFCACHE_COMBO::Unload_Req_MSE);
+      break;
+    case SUSPENDED_UNLOAD_REQUEST_PEER:
+      Telemetry::AccumulateCategorical(
+          Telemetry::LABELS_BFCACHE_COMBO::SPD_Unload_Req_Peer);
+      break;
+    default:
+      Telemetry::AccumulateCategorical(Telemetry::LABELS_BFCACHE_COMBO::Other);
+      break;
+  }
+};
+
 void nsDocShell::ReattachEditorToWindow(nsISHEntry* aSHEntry) {
   MOZ_ASSERT(!mIsBeingDestroyed);
 

docshell/base/nsDocShell.h

@@ -751,6 +751,37 @@ class nsDocShell final : public nsDocLoader,
   bool CanSavePresentation(uint32_t aLoadType, nsIRequest* aNewRequest,
                            mozilla::dom::Document* aNewDocument);
 
+  // There are 11 possible reasons to make a request fails to use BFCache
+  // (see BFCacheStatus in dom/base/Document.h), and we'd like to record
+  // the common combinations for reasons which make requests fail to use
+  // BFCache. These combinations are generated based on some local browsings,
+  // we need to adjust them when necessary.
+  enum BFCacheStatusCombo : uint16_t {
+    BFCACHE_SUCCESS,
+    UNLOAD = mozilla::dom::BFCacheStatus::UNLOAD_LISTENER,
+    UNLOAD_REQUEST = mozilla::dom::BFCacheStatus::UNLOAD_LISTENER |
+                              mozilla::dom::BFCacheStatus::REQUEST,
+    REQUEST = mozilla::dom::BFCacheStatus::REQUEST,
+    UNLOAD_REQUEST_PEER = mozilla::dom::BFCacheStatus::UNLOAD_LISTENER |
+                          mozilla::dom::BFCacheStatus::REQUEST |
+                          mozilla::dom::BFCacheStatus::ACTIVE_PEER_CONNECTION,
+    UNLOAD_REQUEST_PEER_MSE =
+      mozilla::dom::BFCacheStatus::UNLOAD_LISTENER |
+      mozilla::dom::BFCacheStatus::REQUEST |
+      mozilla::dom::BFCacheStatus::ACTIVE_PEER_CONNECTION |
+      mozilla::dom::BFCacheStatus::CONTAINS_MSE_CONTENT,
+    UNLOAD_REQUEST_MSE = mozilla::dom::BFCacheStatus::UNLOAD_LISTENER |
+                         mozilla::dom::BFCacheStatus::REQUEST |
+                         mozilla::dom::BFCacheStatus::CONTAINS_MSE_CONTENT,
+    SUSPENDED_UNLOAD_REQUEST_PEER =
+      mozilla::dom::BFCacheStatus::SUSPENDED |
+      mozilla::dom::BFCacheStatus::UNLOAD_LISTENER |
+      mozilla::dom::BFCacheStatus::REQUEST |
+      mozilla::dom::BFCacheStatus::ACTIVE_PEER_CONNECTION,
+  };
+
+  void ReportBFCacheComboTelemetry(uint16_t aCombo);
+
   // Captures the state of the supporting elements of the presentation
   // (the "window" object, docshell tree, meta-refresh loads, and security
   // state) and stores them on |mOSHE|.

dom/base/Document.cpp

@@ -7634,9 +7634,13 @@ void Document::CollectDescendantDocuments(
   }
 }
 
-bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
+bool Document::CanSavePresentation(nsIRequest* aNewRequest,
+                                   uint16_t& aBFCacheCombo) {
+  bool ret = true;
+
   if (!IsBFCachingAllowed()) {
-    return false;
+    aBFCacheCombo |= BFCacheStatus::NOT_ALLOWED;
+    ret = false;
   }
 
   nsAutoCString uri;
@@ -7649,7 +7653,8 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
   if (EventHandlingSuppressed()) {
     MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
             ("Save of %s blocked on event handling suppression", uri.get()));
-    return false;
+    aBFCacheCombo |= BFCacheStatus::EVENT_HANDLING_SUPPRESSED;
+    ret = false;
   }
 
   // Do not allow suspended windows to be placed in the
@@ -7661,7 +7666,8 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
   if (win && win->IsSuspended() && !win->IsFrozen()) {
     MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
             ("Save of %s blocked on suspended Window", uri.get()));
-    return false;
+    aBFCacheCombo |= BFCacheStatus::SUSPENDED;
+    ret = false;
   }
 
   // Check our event listener manager for unload/beforeunload listeners.
@@ -7671,7 +7677,8 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
     if (manager && manager->HasUnloadListeners()) {
       MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
               ("Save of %s blocked due to unload handlers", uri.get()));
-      return false;
+      aBFCacheCombo |= BFCacheStatus::UNLOAD_LISTENER;
+      ret = false;
     }
   }
 
@@ -7715,8 +7722,8 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
                   ("Save of %s blocked because document has request %s",
                    uri.get(), requestName.get()));
         }
-
+        aBFCacheCombo |= BFCacheStatus::REQUEST;
-        return false;
+        ret = false;
       }
     }
   }
@@ -7726,7 +7733,8 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
       MediaManager::Get()->IsWindowStillActive(win->WindowID())) {
     MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
             ("Save of %s blocked due to GetUserMedia", uri.get()));
-    return false;
+    aBFCacheCombo |= BFCacheStatus::ACTIVE_GET_USER_MEDIA;
+    ret = false;
   }
 
 #ifdef MOZ_WEBRTC
@@ -7734,14 +7742,16 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
   if (win && win->HasActivePeerConnections()) {
     MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
             ("Save of %s blocked due to PeerConnection", uri.get()));
-    return false;
+    aBFCacheCombo |= BFCacheStatus::ACTIVE_PEER_CONNECTION;
+    ret = false;
   }
 #endif  // MOZ_WEBRTC
 
   // Don't save presentations for documents containing EME content, so that
   // CDMs reliably shutdown upon user navigation.
   if (ContainsEMEContent()) {
-    return false;
+    aBFCacheCombo |= BFCacheStatus::CONTAINS_EME_CONTENT;
+    ret = false;
   }
 
   // Don't save presentations for documents containing MSE content, to
@@ -7749,7 +7759,8 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
   if (ContainsMSEContent()) {
     MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
             ("Save of %s blocked due to MSE use", uri.get()));
-    return false;
+    aBFCacheCombo |= BFCacheStatus::CONTAINS_MSE_CONTENT;
+    ret = false;
   }
 
   if (mSubDocuments) {
@@ -7757,12 +7768,16 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
       auto entry = static_cast<SubDocMapEntry*>(iter.Get());
       Document* subdoc = entry->mSubDocument;
 
+      uint16_t subDocBFCacheCombo = 0;
       // The aIgnoreRequest we were passed is only for us, so don't pass it on.
-      bool canCache = subdoc ? subdoc->CanSavePresentation(nullptr) : false;
+      bool canCache =
+          subdoc ? subdoc->CanSavePresentation(nullptr, subDocBFCacheCombo)
+                 : false;
       if (!canCache) {
         MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
                 ("Save of %s blocked due to subdocument blocked", uri.get()));
-        return false;
+        aBFCacheCombo |= subDocBFCacheCombo;
+        ret = false;
       }
     }
   }
@@ -7773,17 +7788,19 @@ bool Document::CanSavePresentation(nsIRequest* aNewRequest) {
     if (globalWindow->HasActiveSpeechSynthesis()) {
       MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
               ("Save of %s blocked due to Speech use", uri.get()));
-      return false;
+      aBFCacheCombo |= BFCacheStatus::HAS_ACTIVE_SPEECH_SYNTHESIS;
+      ret = false;
     }
 #endif
     if (globalWindow->HasUsedVR()) {
       MOZ_LOG(gPageCacheLog, mozilla::LogLevel::Verbose,
               ("Save of %s blocked due to having used VR", uri.get()));
-      return false;
+      aBFCacheCombo |= BFCacheStatus::HAS_USED_VR;
+      ret = false;
     }
   }
 
-  return true;
+  return ret;
 }
 
 void Document::Destroy() {

dom/base/Document.h

@@ -221,6 +221,20 @@ class CallbackObjectHolder;
 
 enum class CallerType : uint32_t;
 
+enum BFCacheStatus {
+  NOT_ALLOWED = 1 << 0,                  // Status 0
+  EVENT_HANDLING_SUPPRESSED = 1 << 1,    // Status 1
+  SUSPENDED = 1 << 2,                    // Status 2
+  UNLOAD_LISTENER = 1 << 3,              // Status 3
+  REQUEST = 1 << 4,                      // Status 4
+  ACTIVE_GET_USER_MEDIA = 1 << 5,        // Status 5
+  ACTIVE_PEER_CONNECTION = 1 << 6,       // Status 6
+  CONTAINS_EME_CONTENT = 1 << 7,         // Status 7
+  CONTAINS_MSE_CONTENT = 1 << 8,         // Status 8
+  HAS_ACTIVE_SPEECH_SYNTHESIS = 1 << 9,  // Status 9
+  HAS_USED_VR = 1 << 10,                 // Status 10
+};
+
 }  // namespace dom
 }  // namespace mozilla
 
@@ -2252,8 +2266,12 @@ class Document : public nsINode,
    * replace this document in the docshell.  The new document's request
    * will be ignored when checking for active requests.  If there is no
    * request associated with the new document, this parameter may be null.
+   *
+   * |aBFCacheCombo| is used as a bitmask to indicate what the status
+   * combination is when we try to BFCache aNewRequest
    */
-  virtual bool CanSavePresentation(nsIRequest* aNewRequest);
+  virtual bool CanSavePresentation(nsIRequest* aNewRequest,
+                                   uint16_t& aBFCacheCombo);
 
   virtual nsresult Init();
 

dom/html/PluginDocument.cpp

@@ -42,7 +42,8 @@ class PluginDocument final : public MediaDocument, public nsIPluginDocument {
 
   void SetScriptGlobalObject(
       nsIScriptGlobalObject* aScriptGlobalObject) override;
-  bool CanSavePresentation(nsIRequest* aNewRequest) override;
+  bool CanSavePresentation(nsIRequest* aNewRequest,
+                           uint16_t& aBFCacheStatus) override;
 
   const nsCString& GetType() const { return mMimeType; }
   Element* GetPluginContent() { return mPluginContent; }
@@ -136,7 +137,8 @@ void PluginDocument::SetScriptGlobalObject(
   }
 }
 
-bool PluginDocument::CanSavePresentation(nsIRequest* aNewRequest) {
+bool PluginDocument::CanSavePresentation(nsIRequest* aNewRequest,
+                                         uint16_t& aBFCacheStatus) {
   // Full-page plugins cannot be cached, currently, because we don't have
   // the stream listener data to feed to the plugin instance.
   return false;

toolkit/components/telemetry/Histograms.json

@@ -14472,6 +14472,26 @@
     "labels": ["FullStandards", "AlmostStandards", "NavQuirks"],
     "description": "HTML document compat mode (quirks mode)"
   },
+  "BFCACHE_COMBO": {
+    "record_in_processes": ["main", "content"],
+    "alert_emails": ["sefeng@mozilla.com"],
+    "bug_numbers": [1531917],
+    "expires_in_version": "never",
+    "kind": "categorical",
+    "releaseChannelCollection": "opt-out",
+    "labels": [
+      "BFCache_Success",
+      "Unload",
+      "Unload_Req",
+      "Req",
+      "Unload_Req_Peer",
+      "Unload_Req_Peer_MSE",
+      "Unload_Req_MSE",
+      "SPD_Unload_Req_Peer",
+      "Other"
+    ],
+    "description": "The common combinations of BFCacheStatus when we determine whether the page can be BFCached or not; If it uses BFCache, we record BFCache_Success; If it's not and it falls under common failure reasons combinations, we record the corresponding combination; Otherwise, we record Other to indicate this is not a common failure"
+  },
   "HIDDEN_VIEWPORT_OVERFLOW_TYPE": {
     "record_in_processes": ["main", "content"],
     "alert_emails": ["mozilla-telemetry@upsuper.org", "botond@mozilla.com"],