gecko/tools/profiler/IOInterposer.h

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/* 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 IOINTERPOSER_H_
#define IOINTERPOSER_H_
#include "mozilla/Attributes.h"
#include "mozilla/Mutex.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/XPCOM.h"
namespace mozilla {
/**
* Interface for I/O interposer observers. This is separate from
* IOInterposer itself because in the future we might use the I/O
* Interposer for shutdown write poisioning.
*/
class IOInterposeObserver
{
public:
enum Operation
{
OpNone = 0,
OpRead = (1 << 0),
OpWrite = (1 << 1),
OpFSync = (1 << 2),
OpWriteFSync = (OpWrite | OpFSync),
OpAll = (OpRead | OpWrite | OpFSync)
};
virtual void Observe(Operation aOp, double& aDuration,
const char* aModuleInfo) = 0;
};
/**
* Interface for I/O Interposer modules that actually generate the I/O
* Interposer events. Some concrete examples include NSPR, SQLite, ETW
*/
class IOInterposerModule
{
public:
virtual ~IOInterposerModule() {}
virtual void Enable(bool aEnable) = 0;
protected:
IOInterposerModule() {}
private:
IOInterposerModule(const IOInterposerModule&);
IOInterposerModule& operator=(const IOInterposerModule&);
};
/**
* This class is reponsible for managing the state of I/O interposer
* modules and ensuring that events are routed to the appropriate
* observers. All methods except for Enable should be called from the
* main thread.
*/
class IOInterposer MOZ_FINAL : public IOInterposeObserver
{
public:
~IOInterposer();
/**
* It is safe to call this method off of the main thread.
*
* @param aEnable true to enable all modules, false to disable all modules
*/
void Enable(bool aEnable);
void Register(IOInterposeObserver::Operation aOp,
IOInterposeObserver* aObserver);
void Deregister(IOInterposeObserver::Operation aOp,
IOInterposeObserver* aObserver);
void Observe(IOInterposeObserver::Operation aOp, double& aDuration,
const char* aModuleInfo);
static IOInterposer* GetInstance();
/**
* This function must be called from the main thread, and furthermore
* it must be called when no other threads are executing. Effectivly this
* restricts us to calling it only during shutdown.
*/
static void ClearInstance();
private:
IOInterposer();
bool Init();
IOInterposer(const IOInterposer&);
IOInterposer& operator=(const IOInterposer&);
// mMutex guards access to mModules, particularly to provide
// mutual exclusion during Enable()
mozilla::Mutex mMutex;
nsTArray<IOInterposerModule*> mModules;
nsTArray<IOInterposeObserver*> mReadObservers;
nsTArray<IOInterposeObserver*> mWriteObservers;
nsTArray<IOInterposeObserver*> mFSyncObservers;
};
} // namespace mozilla
#endif // IOINTERPOSER_H_