gecko/dom/base/nsJSEnvironment.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsIScriptRuntime.h"
#include "nsIScriptGlobalObject.h"
#include "nsCOMPtr.h"
#include "jsapi.h"
#include "jsfriendapi.h"
#include "nsIObserver.h"
#include "nsIXPCScriptNotify.h"
#include "prtime.h"
#include "nsCycleCollectionParticipant.h"
#include "nsIXPConnect.h"
#include "nsIArray.h"
#include "mozilla/Attributes.h"

class nsICycleCollectorListener;
class nsIXPConnectJSObjectHolder;
class nsRootedJSValueArray;
class nsScriptNameSpaceManager;

namespace mozilla {
template <class> class Maybe;
}

// The amount of time we wait between a request to GC (due to leaving
// a page) and doing the actual GC.
#define NS_GC_DELAY                 4000 // ms

class nsJSContext : public nsIScriptContext,
                    public nsIXPCScriptNotify
{
public:
  nsJSContext(JSRuntime* aRuntime, bool aGCOnDestruction,
              nsIScriptGlobalObject* aGlobalObject);
  virtual ~nsJSContext();

  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(nsJSContext,
                                                         nsIScriptContext)

  virtual nsresult EvaluateString(const nsAString& aScript,
                                  JS::Handle<JSObject*> aScopeObject,
                                  JS::CompileOptions &aOptions,
                                  bool aCoerceToString,
                                  JS::Value* aRetValue) MOZ_OVERRIDE;

  virtual nsresult BindCompiledEventHandler(nsISupports *aTarget,
                                            JS::Handle<JSObject*> aScope,
                                            JS::Handle<JSObject*> aHandler,
                                            JS::MutableHandle<JSObject*> aBoundHandler) MOZ_OVERRIDE;

  virtual nsIScriptGlobalObject *GetGlobalObject() MOZ_OVERRIDE;
  inline nsIScriptGlobalObject *GetGlobalObjectRef() { return mGlobalObjectRef; }

  virtual JSContext* GetNativeContext() MOZ_OVERRIDE;
  virtual JSObject* GetNativeGlobal() MOZ_OVERRIDE;
  virtual nsresult InitContext() MOZ_OVERRIDE;
  virtual bool IsContextInitialized() MOZ_OVERRIDE;

  virtual bool GetScriptsEnabled() MOZ_OVERRIDE;
  virtual void SetScriptsEnabled(bool aEnabled, bool aFireTimeouts) MOZ_OVERRIDE;

  virtual nsresult SetProperty(JS::Handle<JSObject*> aTarget, const char* aPropName, nsISupports* aVal) MOZ_OVERRIDE;

  virtual bool GetProcessingScriptTag() MOZ_OVERRIDE;
  virtual void SetProcessingScriptTag(bool aResult) MOZ_OVERRIDE;

  virtual nsresult InitClasses(JS::Handle<JSObject*> aGlobalObj) MOZ_OVERRIDE;

  virtual void WillInitializeContext() MOZ_OVERRIDE;
  virtual void DidInitializeContext() MOZ_OVERRIDE;

  virtual nsresult Serialize(nsIObjectOutputStream* aStream,
                             JS::Handle<JSScript*> aScriptObject) MOZ_OVERRIDE;
  virtual nsresult Deserialize(nsIObjectInputStream* aStream,
                               JS::MutableHandle<JSScript*> aResult) MOZ_OVERRIDE;

  NS_DECL_NSIXPCSCRIPTNOTIFY

  static void LoadStart();
  static void LoadEnd();

  enum IsCompartment {
    CompartmentGC,
    NonCompartmentGC
  };

  enum IsShrinking {
    ShrinkingGC,
    NonShrinkingGC
  };

  enum IsIncremental {
    IncrementalGC,
    NonIncrementalGC
  };

  static void GarbageCollectNow(JS::gcreason::Reason reason,
                                IsIncremental aIncremental = NonIncrementalGC,
                                IsCompartment aCompartment = NonCompartmentGC,
                                IsShrinking aShrinking = NonShrinkingGC,
                                int64_t aSliceMillis = 0);
  static void ShrinkGCBuffersNow();
  // If aExtraForgetSkippableCalls is -1, forgetSkippable won't be
  // called even if the previous collection was GC.
  static void CycleCollectNow(nsICycleCollectorListener *aListener = nullptr,
                              int32_t aExtraForgetSkippableCalls = 0,
                              bool aManuallyTriggered = true);

  static void PokeGC(JS::gcreason::Reason aReason, int aDelay = 0);
  static void KillGCTimer();

  static void PokeShrinkGCBuffers();
  static void KillShrinkGCBuffersTimer();

  static void MaybePokeCC();
  static void KillCCTimer();
  static void KillFullGCTimer();
  static void KillInterSliceGCTimer();

  // Calling LikelyShortLivingObjectCreated() makes a GC more likely.
  static void LikelyShortLivingObjectCreated();

  virtual void GC(JS::gcreason::Reason aReason) MOZ_OVERRIDE;

  static uint32_t CleanupsSinceLastGC();

  nsIScriptGlobalObject* GetCachedGlobalObject()
  {
    // Verify that we have a global so that this
    // does always return a null when GetGlobalObject() is null.
    JSObject* global = GetNativeGlobal();
    return global ? mGlobalObjectRef.get() : nullptr;
  }
protected:
  nsresult InitializeExternalClasses();

  // Helper to convert xpcom datatypes to jsvals.
  nsresult ConvertSupportsTojsvals(nsISupports *aArgs,
                                   JS::Handle<JSObject*> aScope,
                                   uint32_t *aArgc,
                                   JS::Value **aArgv,
                                   mozilla::Maybe<nsRootedJSValueArray> &aPoolRelease);

  nsresult AddSupportsPrimitiveTojsvals(nsISupports *aArg, JS::Value *aArgv);

  // given an nsISupports object (presumably an event target or some other
  // DOM object), get (or create) the JSObject wrapping it.
  nsresult JSObjectFromInterface(nsISupports *aSup,
                                 JS::Handle<JSObject*> aScript,
                                 JSObject **aRet);

  // Report the pending exception on our mContext, if any.  This
  // function will set aside the frame chain on mContext before
  // reporting.
  void ReportPendingException();
private:
  void DestroyJSContext();

  nsrefcnt GetCCRefcnt();

  JSContext *mContext;

  bool mIsInitialized;
  bool mScriptsEnabled;
  bool mGCOnDestruction;
  bool mProcessingScriptTag;

  uint32_t mDefaultJSOptions;
  PRTime mOperationCallbackTime;

  PRTime mModalStateTime;
  uint32_t mModalStateDepth;

  nsJSContext *mNext;
  nsJSContext **mPrev;

  // 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 int JSOptionChangedCallback(const char *pref, void *data);

  static bool DOMOperationCallback(JSContext *cx);
};

class nsIJSRuntimeService;

class nsJSRuntime MOZ_FINAL : public nsIScriptRuntime
{
public:
  // let people who can see us use our runtime for convenience.
  static JSRuntime *sRuntime;

public:
  // nsISupports
  NS_DECL_ISUPPORTS

  virtual already_AddRefed<nsIScriptContext>
  CreateContext(bool aGCOnDestruction,
                nsIScriptGlobalObject* aGlobalObject) MOZ_OVERRIDE;

  static void Startup();
  static void Shutdown();
  // Setup all the statics etc - safe to call multiple times after Startup()
  static nsresult Init();
  // Get the NameSpaceManager, creating if necessary
  static nsScriptNameSpaceManager* GetNameSpaceManager();
};

// 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)

/* factory functions */
nsresult NS_CreateJSRuntime(nsIScriptRuntime **aRuntime);

/* prototypes */
void NS_ScriptErrorReporter(JSContext *cx, const char *message, JSErrorReport *report);

JSObject* NS_DOMReadStructuredClone(JSContext* cx,
                                    JSStructuredCloneReader* reader, uint32_t tag,
                                    uint32_t data, void* closure);

bool NS_DOMWriteStructuredClone(JSContext* cx,
                                JSStructuredCloneWriter* writer,
                                JS::Handle<JSObject*> obj, void *closure);

void NS_DOMStructuredCloneError(JSContext* cx, uint32_t errorid);

#endif /* nsJSEnvironment_h */