Bug 1383977 - stylo: Measure Elements and ComputedValues. r=manishearth.

The patch provides FFI access to Gecko's SeenPtrs type from Rust, in order to record what has already been measured when measuring Arcs. (The SeenPtrs must be initialized on the Gecko side because the same table is reused for measuring all Elements within a window, because Elements can share ComputedValues.) I have confirmed with DMD that this is working correctly. The patch also introduces MallocSizeOfRepeats, which is like MallocSizeOf but takes a SizeOfState, which holds a SeenPtrs table. MozReview-Commit-ID: DHS8zvCsEdQ --HG-- extra : rebase_source : acf4d7909abf6ceb1719331ccf2e33137eb6dc91
trman · Jul 19, 2017 · cc91dee · cc91dee
1 parent 5340159
commit cc91dee
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Showing 5 changed files with 33 additions and 2 deletions.
diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
@@ -4138,13 +4138,20 @@ Element::SetCustomElementData(CustomElementData* aData)
   slots->mCustomElementData = aData;
 }
 
+MOZ_DEFINE_MALLOC_SIZE_OF(ServoElementMallocSizeOf)
+
 size_t
 Element::SizeOfExcludingThis(SizeOfState& aState) const
 {
   size_t n = FragmentOrElement::SizeOfExcludingThis(aState);
 
-  // XXX: measure mServoData.
-
+  // Measure mServoData. We use ServoElementMallocSizeOf rather than
+  // |aState.mMallocSizeOf| to distinguish in DMD's output the memory
+  // measured within Servo code.
+  if (mServoData.Get()) {
+    n += Servo_Element_SizeOfExcludingThis(ServoElementMallocSizeOf,
+                                           &aState.mSeenPtrs, this);
+  }
   return n;
 }
 
diff --git a/layout/style/ServoBindingList.h b/layout/style/ServoBindingList.h
@@ -20,6 +20,8 @@
 
 // Element data
 SERVO_BINDING_FUNC(Servo_Element_ClearData, void, RawGeckoElementBorrowed node)
+SERVO_BINDING_FUNC(Servo_Element_SizeOfExcludingThis, size_t, mozilla::MallocSizeOf,
+                   mozilla::SeenPtrs* seen_ptrs, RawGeckoElementBorrowed node)
 
 // Styleset and Stylesheet management
 SERVO_BINDING_FUNC(Servo_StyleSheet_FromUTF8Bytes, RawServoStyleSheetContentsStrong,

diff --git a/layout/style/ServoBindings.cpp b/layout/style/ServoBindings.cpp
@@ -56,6 +56,7 @@
 #include "mozilla/Mutex.h"
 #include "mozilla/ServoElementSnapshot.h"
 #include "mozilla/ServoRestyleManager.h"
+#include "mozilla/SizeOfState.h"
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/SystemGroup.h"
 #include "mozilla/ServoMediaList.h"
@@ -452,6 +453,18 @@ Gecko_GetElementSnapshot(const ServoElementSnapshotTable* aTable,
   return aTable->Get(const_cast<Element*>(aElement));
 }
 
+bool
+Gecko_HaveSeenPtr(SeenPtrs* aTable, const void* aPtr)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aTable);
+  // Empty Rust allocations are indicated by small values up to the alignment
+  // of the relevant type. We shouldn't see anything like that here.
+  MOZ_ASSERT(uintptr_t(aPtr) > 16);
+
+  return aTable->HaveSeenPtr(aPtr);
+}
+
 RawServoDeclarationBlockStrongBorrowedOrNull
 Gecko_GetStyleAttrDeclarationBlock(RawGeckoElementBorrowed aElement)
 {

diff --git a/layout/style/ServoBindings.h b/layout/style/ServoBindings.h
@@ -50,6 +50,7 @@ namespace mozilla {
   };
   enum class UpdateAnimationsTasks : uint8_t;
   struct LangGroupFontPrefs;
+  class SeenPtrs;
   class ServoStyleContext;
   class ServoStyleSheet;
   class ServoElementSnapshotTable;
@@ -397,6 +398,10 @@ Gecko_GetElementSnapshot(const mozilla::ServoElementSnapshotTable* table,
 
 void Gecko_DropElementSnapshot(ServoElementSnapshotOwned snapshot);
 
+// Have we seen this pointer before?
+bool
+Gecko_HaveSeenPtr(mozilla::SeenPtrs* table, const void* ptr);
+
 // `array` must be an nsTArray
 // If changing this signature, please update the
 // friend function declaration in nsTArray.h

diff --git a/layout/style/ServoBindings.toml b/layout/style/ServoBindings.toml
@@ -65,6 +65,7 @@ headers = [
     "mozilla/ServoBindings.h",
     "mozilla/ServoMediaList.h",
     "mozilla/ServoStyleContext.h",
+    "mozilla/SizeOfState.h",
     "nsCSSCounterStyleRule.h",
     "nsCSSFontFaceRule.h",
     "nsMediaFeatures.h",
@@ -123,6 +124,7 @@ whitelist-types = [
     "mozilla::ComputedTiming",
     "mozilla::ComputedTimingFunction",
     "mozilla::ComputedTimingFunction::BeforeFlag",
+    "mozilla::SeenPtrs",
     "mozilla::ServoElementSnapshot.*",
     "mozilla::ServoStyleContext",
     "mozilla::ServoStyleSheetInner",
@@ -297,6 +299,7 @@ opaque-types = [
     "nsAutoPtr_Proxy_member_function",
     "mozilla::detail::PointerType",
     "mozilla::Pair_Base",
+    "mozilla::SeenPtrs",
     "mozilla::SupportsWeakPtr",
     "SupportsWeakPtr",
     "mozilla::detail::WeakReference",
@@ -403,6 +406,7 @@ structs-types = [
     "IterationCompositeOperation",
     "Keyframe",
     "PropertyValuePair",
+    "SeenPtrs",
     "ServoBundledURI",
     "ServoElementSnapshot",
     "ServoElementSnapshotTable",