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| -rw-r--r-- | xpcom/threads/BlockingResourceBase.h | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/xpcom/threads/BlockingResourceBase.h b/xpcom/threads/BlockingResourceBase.h new file mode 100644 index 0000000000..8bb7a78f6f --- /dev/null +++ b/xpcom/threads/BlockingResourceBase.h @@ -0,0 +1,339 @@ +/* -*- 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 mozilla_BlockingResourceBase_h +#define mozilla_BlockingResourceBase_h + +#include "mozilla/MemoryReporting.h" +#include "mozilla/ThreadLocal.h" +#include "mozilla/Attributes.h" + +#include "nscore.h" +#include "nsDebug.h" + +#include "prtypes.h" + +#ifdef DEBUG + +// NB: Comment this out to enable callstack tracking. +# define MOZ_CALLSTACK_DISABLED + +# include "prinit.h" + +# ifndef MOZ_CALLSTACK_DISABLED +# include "mozilla/Maybe.h" +# include "nsTArray.h" +# endif + +#endif + +// +// This header is not meant to be included by client code. +// + +namespace mozilla { + +#ifdef DEBUG +template <class T> +class DeadlockDetector; +#endif + +/** + * BlockingResourceBase + * Base class of resources that might block clients trying to acquire them. + * Does debugging and deadlock detection in DEBUG builds. + **/ +class BlockingResourceBase { + public: + // Needs to be kept in sync with kResourceTypeNames. + enum BlockingResourceType { + eMutex, + eReentrantMonitor, + eCondVar, + eRecursiveMutex + }; + + /** + * kResourceTypeName + * Human-readable version of BlockingResourceType enum. + */ + static const char* const kResourceTypeName[]; + +#ifdef DEBUG + + static size_t SizeOfDeadlockDetector(MallocSizeOf aMallocSizeOf); + + /** + * Print + * Write a description of this blocking resource to |aOut|. If + * the resource appears to be currently acquired, the current + * acquisition context is printed and true is returned. + * Otherwise, we print the context from |aFirstSeen|, the + * first acquisition from which the code calling |Print()| + * became interested in us, and return false. + * + * *NOT* thread safe. Reads |mAcquisitionContext| without + * synchronization, but this will not cause correctness + * problems. + * + * FIXME bug 456272: hack alert: because we can't write call + * contexts into strings, all info is written to stderr, but + * only some info is written into |aOut| + */ + bool Print(nsACString& aOut) const; + + size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const { + // NB: |mName| is not reported as it's expected to be a static string. + // If we switch to a nsString it should be added to the tally. + // |mChainPrev| is not reported because its memory is not owned. + size_t n = aMallocSizeOf(this); + return n; + } + + // ``DDT'' = ``Deadlock Detector Type'' + typedef DeadlockDetector<BlockingResourceBase> DDT; + + protected: +# ifdef MOZ_CALLSTACK_DISABLED + typedef bool AcquisitionState; +# else + // Using maybe to use emplacement as the acquisition state flag; we may not + // always get a stack trace because of possible stack walk suppression or + // errors, hence can't use !IsEmpty() on the array itself as indication. + static size_t const kAcquisitionStateStackSize = 24; + typedef Maybe<AutoTArray<void*, kAcquisitionStateStackSize> > + AcquisitionState; +# endif + + /** + * BlockingResourceBase + * Initialize this blocking resource. Also hooks the resource into + * instrumentation code. + * + * Thread safe. + * + * @param aName A meaningful, unique name that can be used in + * error messages, et al. + * @param aType The specific type of |this|, if any. + **/ + BlockingResourceBase(const char* aName, BlockingResourceType aType); + + ~BlockingResourceBase(); + + /** + * CheckAcquire + * + * Thread safe. + **/ + void CheckAcquire(); + + /** + * Acquire + * + * *NOT* thread safe. Requires ownership of underlying resource. + **/ + void Acquire(); // NS_NEEDS_RESOURCE(this) + + /** + * Release + * Remove this resource from the current thread's acquisition chain. + * The resource does not have to be at the front of the chain, although + * it is confusing to release resources in a different order than they + * are acquired. This generates a warning. + * + * *NOT* thread safe. Requires ownership of underlying resource. + **/ + void Release(); // NS_NEEDS_RESOURCE(this) + + /** + * ResourceChainFront + * + * Thread safe. + * + * @return the front of the resource acquisition chain, i.e., the last + * resource acquired. + */ + static BlockingResourceBase* ResourceChainFront() { + return sResourceAcqnChainFront.get(); + } + + /** + * ResourceChainPrev + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + static BlockingResourceBase* ResourceChainPrev( + const BlockingResourceBase* aResource) { + return aResource->mChainPrev; + } // NS_NEEDS_RESOURCE(this) + + /** + * ResourceChainAppend + * Set |this| to the front of the resource acquisition chain, and link + * |this| to |aPrev|. + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + void ResourceChainAppend(BlockingResourceBase* aPrev) { + mChainPrev = aPrev; + sResourceAcqnChainFront.set(this); + } // NS_NEEDS_RESOURCE(this) + + /** + * ResourceChainRemove + * Remove |this| from the front of the resource acquisition chain. + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + void ResourceChainRemove() { + NS_ASSERTION(this == ResourceChainFront(), "not at chain front"); + sResourceAcqnChainFront.set(mChainPrev); + } // NS_NEEDS_RESOURCE(this) + + /** + * TakeAcquisitionState + * Return whether or not this resource was acquired and mark the resource + * as not acquired for subsequent uses. + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + AcquisitionState TakeAcquisitionState() { +# ifdef MOZ_CALLSTACK_DISABLED + bool acquired = mAcquired; + ClearAcquisitionState(); + return acquired; +# else + return mAcquired.take(); +# endif + } + + /** + * SetAcquisitionState + * Set whether or not this resource was acquired. + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + void SetAcquisitionState(AcquisitionState&& aAcquisitionState) { + mAcquired = std::move(aAcquisitionState); + } + + /** + * ClearAcquisitionState + * Indicate this resource is not acquired. + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + void ClearAcquisitionState() { +# ifdef MOZ_CALLSTACK_DISABLED + mAcquired = false; +# else + mAcquired.reset(); +# endif + } + + /** + * IsAcquired + * Indicates if this resource is acquired. + * + * *NOT* thread safe. Requires ownership of underlying resource. + */ + bool IsAcquired() const { return (bool)mAcquired; } + + /** + * mChainPrev + * A series of resource acquisitions creates a chain of orders. This + * chain is implemented as a linked list; |mChainPrev| points to the + * resource most recently Acquire()'d before this one. + **/ + BlockingResourceBase* mChainPrev; + + private: + /** + * mName + * A descriptive name for this resource. Used in error + * messages etc. + */ + const char* mName; + + /** + * mType + * The more specific type of this resource. Used to implement + * special semantics (e.g., reentrancy of monitors). + **/ + BlockingResourceType mType; + + /** + * mAcquired + * Indicates if this resource is currently acquired. + */ + AcquisitionState mAcquired; + +# ifndef MOZ_CALLSTACK_DISABLED + /** + * mFirstSeen + * Inidicates where this resource was first acquired. + */ + AcquisitionState mFirstSeen; +# endif + + /** + * sCallOnce + * Ensures static members are initialized only once, and in a + * thread-safe way. + */ + static PRCallOnceType sCallOnce; + + /** + * Thread-private pointer to the front of each thread's resource + * acquisition chain. + */ + static MOZ_THREAD_LOCAL(BlockingResourceBase*) sResourceAcqnChainFront; + + /** + * sDeadlockDetector + * Does as named. + */ + static DDT* sDeadlockDetector; + + /** + * InitStatics + * Inititialize static members of BlockingResourceBase that can't + * be statically initialized. + * + * *NOT* thread safe. + */ + static PRStatus InitStatics(); + + /** + * Shutdown + * Free static members. + * + * *NOT* thread safe. + */ + static void Shutdown(); + + static void StackWalkCallback(uint32_t aFrameNumber, void* aPc, void* aSp, + void* aClosure); + static void GetStackTrace(AcquisitionState& aState, + const void* aFirstFramePC); + +# ifdef MOZILLA_INTERNAL_API + // so it can call BlockingResourceBase::Shutdown() + friend void LogTerm(); +# endif // ifdef MOZILLA_INTERNAL_API + +#else // non-DEBUG implementation + + BlockingResourceBase(const char* aName, BlockingResourceType aType) {} + + ~BlockingResourceBase() {} + +#endif +}; + +} // namespace mozilla + +#endif // mozilla_BlockingResourceBase_h |