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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 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