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107 lines
2.9 KiB
C++
107 lines
2.9 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef IOINTERPOSER_H_
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#define IOINTERPOSER_H_
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#include "mozilla/Attributes.h"
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#include "mozilla/Mutex.h"
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#include "mozilla/StaticPtr.h"
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#include "mozilla/XPCOM.h"
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namespace mozilla {
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/**
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* Interface for I/O interposer observers. This is separate from
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* IOInterposer itself because in the future we might use the I/O
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* Interposer for shutdown write poisioning.
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*/
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class IOInterposeObserver
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{
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public:
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enum Operation
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{
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OpNone = 0,
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OpRead = (1 << 0),
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OpWrite = (1 << 1),
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OpFSync = (1 << 2),
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OpWriteFSync = (OpWrite | OpFSync),
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OpAll = (OpRead | OpWrite | OpFSync)
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};
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virtual void Observe(Operation aOp, double& aDuration,
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const char* aModuleInfo) = 0;
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};
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/**
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* Interface for I/O Interposer modules that actually generate the I/O
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* Interposer events. Some concrete examples include NSPR, SQLite, ETW
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*/
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class IOInterposerModule
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{
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public:
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virtual ~IOInterposerModule() {}
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virtual void Enable(bool aEnable) = 0;
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protected:
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IOInterposerModule() {}
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private:
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IOInterposerModule(const IOInterposerModule&);
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IOInterposerModule& operator=(const IOInterposerModule&);
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};
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/**
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* This class is reponsible for managing the state of I/O interposer
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* modules and ensuring that events are routed to the appropriate
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* observers. All methods except for Enable should be called from the
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* main thread.
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*/
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class IOInterposer MOZ_FINAL : public IOInterposeObserver
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{
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public:
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~IOInterposer();
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/**
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* It is safe to call this method off of the main thread.
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*
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* @param aEnable true to enable all modules, false to disable all modules
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*/
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void Enable(bool aEnable);
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void Register(IOInterposeObserver::Operation aOp,
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IOInterposeObserver* aObserver);
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void Deregister(IOInterposeObserver::Operation aOp,
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IOInterposeObserver* aObserver);
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void Observe(IOInterposeObserver::Operation aOp, double& aDuration,
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const char* aModuleInfo);
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static IOInterposer* GetInstance();
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/**
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* This function must be called from the main thread, and furthermore
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* it must be called when no other threads are executing. Effectivly this
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* restricts us to calling it only during shutdown.
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*/
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static void ClearInstance();
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private:
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IOInterposer();
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bool Init();
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IOInterposer(const IOInterposer&);
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IOInterposer& operator=(const IOInterposer&);
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// mMutex guards access to mModules, particularly to provide
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// mutual exclusion during Enable()
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mozilla::Mutex mMutex;
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nsTArray<IOInterposerModule*> mModules;
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nsTArray<IOInterposeObserver*> mReadObservers;
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nsTArray<IOInterposeObserver*> mWriteObservers;
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nsTArray<IOInterposeObserver*> mFSyncObservers;
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};
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} // namespace mozilla
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#endif // IOINTERPOSER_H_
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