1 files changed, 214 insertions, 0 deletions
diff --git a/dom/base/nsJSEnvironment.h b/dom/base/nsJSEnvironment.h
new file mode 100644
index 0000000000..bb60b0e2b6
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+++ b/dom/base/nsJSEnvironment.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsJSEnvironment_h
+#define nsJSEnvironment_h
+
+#include "nsIScriptContext.h"
+#include "nsIScriptGlobalObject.h"
+#include "nsCOMPtr.h"
+#include "prtime.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsIArray.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/TimeStamp.h"
+#include "nsThreadUtils.h"
+#include "xpcpublic.h"
+
+class nsICycleCollectorListener;
+class nsIDocShell;
+
+namespace mozilla {
+
+template <class>
+class Maybe;
+struct CycleCollectorResults;
+
+static const uint32_t kMajorForgetSkippableCalls = 5;
+
+}  // namespace mozilla
+
+class nsJSContext : public nsIScriptContext {
+ public:
+  nsJSContext(bool aGCOnDestruction, nsIScriptGlobalObject* aGlobalObject);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(nsJSContext,
+                                                         nsIScriptContext)
+
+  virtual nsIScriptGlobalObject* GetGlobalObject() override;
+  inline nsIScriptGlobalObject* GetGlobalObjectRef() {
+    return mGlobalObjectRef;
+  }
+
+  virtual nsresult SetProperty(JS::Handle<JSObject*> aTarget,
+                               const char* aPropName,
+                               nsISupports* aVal) override;
+
+  virtual bool GetProcessingScriptTag() override;
+  virtual void SetProcessingScriptTag(bool aResult) override;
+
+  virtual nsresult InitClasses(JS::Handle<JSObject*> aGlobalObj) override;
+
+  virtual void SetWindowProxy(JS::Handle<JSObject*> aWindowProxy) override;
+  virtual JSObject* GetWindowProxy() override;
+
+  enum IsShrinking { ShrinkingGC, NonShrinkingGC };
+
+  enum IsIncremental { IncrementalGC, NonIncrementalGC };
+
+  // Setup all the statics etc - safe to call multiple times after Startup().
+  static void EnsureStatics();
+
+  static void SetLowMemoryState(bool aState);
+
+  static void GarbageCollectNow(JS::GCReason reason,
+                                IsIncremental aIncremental = NonIncrementalGC,
+                                IsShrinking aShrinking = NonShrinkingGC,
+                                int64_t aSliceMillis = 0);
+
+  static void CycleCollectNow(nsICycleCollectorListener* aListener = nullptr);
+
+  // Finish up any in-progress incremental GC.
+  static void PrepareForCycleCollectionSlice(mozilla::TimeStamp aDeadline);
+
+  // Run a cycle collector slice, using a heuristic to decide how long to run
+  // it.
+  static void RunCycleCollectorSlice(mozilla::TimeStamp aDeadline);
+
+  // Run a cycle collector slice, using the given work budget.
+  static void RunCycleCollectorWorkSlice(int64_t aWorkBudget);
+
+  static void BeginCycleCollectionCallback();
+  static void EndCycleCollectionCallback(
+      mozilla::CycleCollectorResults& aResults);
+
+  // Return the longest CC slice time since ClearMaxCCSliceTime() was last
+  // called.
+  static uint32_t GetMaxCCSliceTimeSinceClear();
+  static void ClearMaxCCSliceTime();
+
+  // If there is some pending CC or GC timer/runner, this will run it.
+  static void RunNextCollectorTimer(
+      JS::GCReason aReason,
+      mozilla::TimeStamp aDeadline = mozilla::TimeStamp());
+  // If user has been idle and aDocShell is for an iframe being loaded in an
+  // already loaded top level docshell, this will run a CC or GC
+  // timer/runner if there is such pending.
+  static void MaybeRunNextCollectorSlice(nsIDocShell* aDocShell,
+                                         JS::GCReason aReason);
+
+  // The GC should probably run soon, in the zone of object aObj (if given).
+  static void PokeGC(JS::GCReason aReason, JSObject* aObj, uint32_t aDelay = 0);
+  static void KillGCTimer();
+
+  static void PokeShrinkingGC();
+  static void KillShrinkingGCTimer();
+
+  static void MaybePokeCC();
+  static void EnsureCCRunner(mozilla::TimeDuration aDelay,
+                             mozilla::TimeDuration aBudget);
+  static void KillCCRunner();
+  static void KillFullGCTimer();
+  static void KillInterSliceGCRunner();
+
+  // Calling LikelyShortLivingObjectCreated() makes a GC more likely.
+  static void LikelyShortLivingObjectCreated();
+
+  static bool HasHadCleanupSinceLastGC();
+
+  nsIScriptGlobalObject* GetCachedGlobalObject() {
+    // Verify that we have a global so that this
+    // does always return a null when GetGlobalObject() is null.
+    JSObject* global = GetWindowProxy();
+    return global ? mGlobalObjectRef.get() : nullptr;
+  }
+
+ protected:
+  virtual ~nsJSContext();
+
+  // Helper to convert xpcom datatypes to jsvals.
+  nsresult ConvertSupportsTojsvals(JSContext* aCx, nsISupports* aArgs,
+                                   JS::Handle<JSObject*> aScope,
+                                   JS::MutableHandleVector<JS::Value> aArgsOut);
+
+  nsresult AddSupportsPrimitiveTojsvals(JSContext* aCx, nsISupports* aArg,
+                                        JS::Value* aArgv);
+
+ private:
+  void Destroy();
+
+  JS::Heap<JSObject*> mWindowProxy;
+
+  bool mGCOnDestruction;
+  bool mProcessingScriptTag;
+
+  // mGlobalObjectRef ensures that the outer window stays alive as long as the
+  // context does. It is eventually collected by the cycle collector.
+  nsCOMPtr<nsIScriptGlobalObject> mGlobalObjectRef;
+
+  static bool DOMOperationCallback(JSContext* cx);
+};
+
+namespace mozilla {
+namespace dom {
+
+class SerializedStackHolder;
+
+void StartupJSEnvironment();
+void ShutdownJSEnvironment();
+
+// Runnable that's used to do async error reporting
+class AsyncErrorReporter final : public mozilla::Runnable {
+ public:
+  explicit AsyncErrorReporter(xpc::ErrorReport* aReport);
+  // SerializeStack is suitable for main or worklet thread use.
+  // Stacks from worker threads are not supported.
+  // See https://bugzilla.mozilla.org/show_bug.cgi?id=1578968
+  void SerializeStack(JSContext* aCx, JS::Handle<JSObject*> aStack);
+
+  // Set the exception value associated with this error report.
+  // Should only be called from the main thread.
+  void SetException(JSContext* aCx, JS::Handle<JS::Value> aException);
+
+ protected:
+  NS_IMETHOD Run() override;
+
+  // This is only used on main thread!
+  JS::PersistentRootedValue mException;
+  bool mHasException = false;
+
+  RefPtr<xpc::ErrorReport> mReport;
+  // This may be used to marshal a stack from an arbitrary thread/runtime into
+  // the main thread/runtime where the console service runs.
+  UniquePtr<SerializedStackHolder> mStackHolder;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+// An interface for fast and native conversion to/from nsIArray. If an object
+// supports this interface, JS can reach directly in for the argv, and avoid
+// nsISupports conversion. If this interface is not supported, the object will
+// be queried for nsIArray, and everything converted via xpcom objects.
+#define NS_IJSARGARRAY_IID                           \
+  {                                                  \
+    0xb6acdac8, 0xf5c6, 0x432c, {                    \
+      0xa8, 0x6e, 0x33, 0xee, 0xb1, 0xb0, 0xcd, 0xdc \
+    }                                                \
+  }
+
+class nsIJSArgArray : public nsIArray {
+ public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IJSARGARRAY_IID)
+  // Bug 312003 describes why this must be "void **", but after calling argv
+  // may be cast to JS::Value* and the args found at:
+  //    ((JS::Value*)argv)[0], ..., ((JS::Value*)argv)[argc - 1]
+  virtual nsresult GetArgs(uint32_t* argc, void** argv) = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIJSArgArray, NS_IJSARGARRAY_IID)
+
+#endif /* nsJSEnvironment_h */