nsJSEnvironment.h - mozsearch

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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 };

  // 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,

                                IsShrinking aShrinking = NonShrinkingGC);

  static void RunIncrementalGCSlice(JS::GCReason aReason,

                                    IsShrinking aShrinking,

                                    js::SliceBudget& aBudget);

  static void CycleCollectNow(mozilla::CCReason aReason,

                              nsICycleCollectorListener* aListener = nullptr);

  // Finish up any in-progress incremental GC.

  static void PrepareForCycleCollectionSlice(mozilla::CCReason aReason,

                                             mozilla::TimeStamp aDeadline);

  // Run a cycle collector slice, using a heuristic to decide how long to run

  // it.

  static void RunCycleCollectorSlice(mozilla::CCReason aReason,

                                     mozilla::TimeStamp aDeadline);

  // Run a cycle collector slice, using the given work budget.

  static void RunCycleCollectorWorkSlice(int64_t aWorkBudget);

  static void BeginCycleCollectionCallback(mozilla::CCReason aReason);

  static void EndCycleCollectionCallback(

      const 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 run soon, in the zone of aObj if given. If aObj is

  // nullptr, collect all Zones.

  static void PokeGC(JS::GCReason aReason, JSObject* aObj,

                     mozilla::TimeDuration aDelay = 0);

  // If usage is nearing a threshold, request idle-only GC work. (This is called

  // when a collection would be relatively convenient.)

  static void MaybePokeGC();

  // Immediately perform a non-incremental shrinking GC and CC.

  static void DoLowMemoryGC();

  // Perform a non-incremental shrinking GC and CC according to

  // IdleScheduler.

  static void LowMemoryGC();

  static void MaybePokeCC();

  // 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::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::PersistentRooted<JS::Value> 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 mozilla::dom

// 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 */