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Diffstat (limited to 'third_party/glog/src/base/mutex.h')
| -rw-r--r-- | third_party/glog/src/base/mutex.h | 333 |
1 files changed, 0 insertions, 333 deletions
diff --git a/third_party/glog/src/base/mutex.h b/third_party/glog/src/base/mutex.h deleted file mode 100644 index ced2b9950e..0000000000 --- a/third_party/glog/src/base/mutex.h +++ /dev/null @@ -1,333 +0,0 @@ -// Copyright (c) 2007, Google Inc. -// All rights reserved. -// -// Redistribution and use in source and binary forms, with or without -// modification, are permitted provided that the following conditions are -// met: -// -// * Redistributions of source code must retain the above copyright -// notice, this list of conditions and the following disclaimer. -// * Redistributions in binary form must reproduce the above -// copyright notice, this list of conditions and the following disclaimer -// in the documentation and/or other materials provided with the -// distribution. -// * Neither the name of Google Inc. nor the names of its -// contributors may be used to endorse or promote products derived from -// this software without specific prior written permission. -// -// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR -// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT -// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, -// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT -// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE -// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -// -// --- -// Author: Craig Silverstein. -// -// A simple mutex wrapper, supporting locks and read-write locks. -// You should assume the locks are *not* re-entrant. -// -// To use: you should define the following macros in your configure.ac: -// ACX_PTHREAD -// AC_RWLOCK -// The latter is defined in ../autoconf. -// -// This class is meant to be internal-only and should be wrapped by an -// internal namespace. Before you use this module, please give the -// name of your internal namespace for this module. Or, if you want -// to expose it, you'll want to move it to the Google namespace. We -// cannot put this class in global namespace because there can be some -// problems when we have multiple versions of Mutex in each shared object. -// -// NOTE: by default, we have #ifdef'ed out the TryLock() method. -// This is for two reasons: -// 1) TryLock() under Windows is a bit annoying (it requires a -// #define to be defined very early). -// 2) TryLock() is broken for NO_THREADS mode, at least in NDEBUG -// mode. -// If you need TryLock(), and either these two caveats are not a -// problem for you, or you're willing to work around them, then -// feel free to #define GMUTEX_TRYLOCK, or to remove the #ifdefs -// in the code below. -// -// CYGWIN NOTE: Cygwin support for rwlock seems to be buggy: -// http://www.cygwin.com/ml/cygwin/2008-12/msg00017.html -// Because of that, we might as well use windows locks for -// cygwin. They seem to be more reliable than the cygwin pthreads layer. -// -// TRICKY IMPLEMENTATION NOTE: -// This class is designed to be safe to use during -// dynamic-initialization -- that is, by global constructors that are -// run before main() starts. The issue in this case is that -// dynamic-initialization happens in an unpredictable order, and it -// could be that someone else's dynamic initializer could call a -// function that tries to acquire this mutex -- but that all happens -// before this mutex's constructor has run. (This can happen even if -// the mutex and the function that uses the mutex are in the same .cc -// file.) Basically, because Mutex does non-trivial work in its -// constructor, it's not, in the naive implementation, safe to use -// before dynamic initialization has run on it. -// -// The solution used here is to pair the actual mutex primitive with a -// bool that is set to true when the mutex is dynamically initialized. -// (Before that it's false.) Then we modify all mutex routines to -// look at the bool, and not try to lock/unlock until the bool makes -// it to true (which happens after the Mutex constructor has run.) -// -// This works because before main() starts -- particularly, during -// dynamic initialization -- there are no threads, so a) it's ok that -// the mutex operations are a no-op, since we don't need locking then -// anyway; and b) we can be quite confident our bool won't change -// state between a call to Lock() and a call to Unlock() (that would -// require a global constructor in one translation unit to call Lock() -// and another global constructor in another translation unit to call -// Unlock() later, which is pretty perverse). -// -// That said, it's tricky, and can conceivably fail; it's safest to -// avoid trying to acquire a mutex in a global constructor, if you -// can. One way it can fail is that a really smart compiler might -// initialize the bool to true at static-initialization time (too -// early) rather than at dynamic-initialization time. To discourage -// that, we set is_safe_ to true in code (not the constructor -// colon-initializer) and set it to true via a function that always -// evaluates to true, but that the compiler can't know always -// evaluates to true. This should be good enough. - -#ifndef GOOGLE_MUTEX_H_ -#define GOOGLE_MUTEX_H_ - -#include "config.h" // to figure out pthreads support - -#if defined(NO_THREADS) - typedef int MutexType; // to keep a lock-count -#elif defined(_WIN32) || defined(__CYGWIN32__) || defined(__CYGWIN64__) -# ifndef WIN32_LEAN_AND_MEAN -# define WIN32_LEAN_AND_MEAN // We only need minimal includes -# endif -# ifdef GMUTEX_TRYLOCK - // We need Windows NT or later for TryEnterCriticalSection(). If you - // don't need that functionality, you can remove these _WIN32_WINNT - // lines, and change TryLock() to assert(0) or something. -# ifndef _WIN32_WINNT -# define _WIN32_WINNT 0x0400 -# endif -# endif -// To avoid macro definition of ERROR. -# ifndef NOGDI -# define NOGDI -# endif -// To avoid macro definition of min/max. -# ifndef NOMINMAX -# define NOMINMAX -# endif -# include <windows.h> - typedef CRITICAL_SECTION MutexType; -#elif defined(HAVE_PTHREAD) && defined(HAVE_RWLOCK) - // Needed for pthread_rwlock_*. If it causes problems, you could take it - // out, but then you'd have to unset HAVE_RWLOCK (at least on linux -- it - // *does* cause problems for FreeBSD, or MacOSX, but isn't needed - // for locking there.) -# ifdef __linux__ -# ifndef _XOPEN_SOURCE // Some other header might have already set it for us. -# define _XOPEN_SOURCE 500 // may be needed to get the rwlock calls -# endif -# endif -# include <pthread.h> - typedef pthread_rwlock_t MutexType; -#elif defined(HAVE_PTHREAD) -# include <pthread.h> - typedef pthread_mutex_t MutexType; -#else -# error Need to implement mutex.h for your architecture, or #define NO_THREADS -#endif - -// We need to include these header files after defining _XOPEN_SOURCE -// as they may define the _XOPEN_SOURCE macro. -#include <assert.h> -#include <stdlib.h> // for abort() - -#define MUTEX_NAMESPACE glog_internal_namespace_ - -namespace MUTEX_NAMESPACE { - -class Mutex { - public: - // Create a Mutex that is not held by anybody. This constructor is - // typically used for Mutexes allocated on the heap or the stack. - // See below for a recommendation for constructing global Mutex - // objects. - inline Mutex(); - - // Destructor - inline ~Mutex(); - - inline void Lock(); // Block if needed until free then acquire exclusively - inline void Unlock(); // Release a lock acquired via Lock() -#ifdef GMUTEX_TRYLOCK - inline bool TryLock(); // If free, Lock() and return true, else return false -#endif - // Note that on systems that don't support read-write locks, these may - // be implemented as synonyms to Lock() and Unlock(). So you can use - // these for efficiency, but don't use them anyplace where being able - // to do shared reads is necessary to avoid deadlock. - inline void ReaderLock(); // Block until free or shared then acquire a share - inline void ReaderUnlock(); // Release a read share of this Mutex - inline void WriterLock() { Lock(); } // Acquire an exclusive lock - inline void WriterUnlock() { Unlock(); } // Release a lock from WriterLock() - - // TODO(hamaji): Do nothing, implement correctly. - inline void AssertHeld() {} - - private: - MutexType mutex_; - // We want to make sure that the compiler sets is_safe_ to true only - // when we tell it to, and never makes assumptions is_safe_ is - // always true. volatile is the most reliable way to do that. - volatile bool is_safe_; - - inline void SetIsSafe() { is_safe_ = true; } - - // Catch the error of writing Mutex when intending MutexLock. - Mutex(Mutex* /*ignored*/) {} - // Disallow "evil" constructors - Mutex(const Mutex&); - void operator=(const Mutex&); -}; - -// Now the implementation of Mutex for various systems -#if defined(NO_THREADS) - -// When we don't have threads, we can be either reading or writing, -// but not both. We can have lots of readers at once (in no-threads -// mode, that's most likely to happen in recursive function calls), -// but only one writer. We represent this by having mutex_ be -1 when -// writing and a number > 0 when reading (and 0 when no lock is held). -// -// In debug mode, we assert these invariants, while in non-debug mode -// we do nothing, for efficiency. That's why everything is in an -// assert. - -Mutex::Mutex() : mutex_(0) { } -Mutex::~Mutex() { assert(mutex_ == 0); } -void Mutex::Lock() { assert(--mutex_ == -1); } -void Mutex::Unlock() { assert(mutex_++ == -1); } -#ifdef GMUTEX_TRYLOCK -bool Mutex::TryLock() { if (mutex_) return false; Lock(); return true; } -#endif -void Mutex::ReaderLock() { assert(++mutex_ > 0); } -void Mutex::ReaderUnlock() { assert(mutex_-- > 0); } - -#elif defined(_WIN32) || defined(__CYGWIN32__) || defined(__CYGWIN64__) - -Mutex::Mutex() { InitializeCriticalSection(&mutex_); SetIsSafe(); } -Mutex::~Mutex() { DeleteCriticalSection(&mutex_); } -void Mutex::Lock() { if (is_safe_) EnterCriticalSection(&mutex_); } -void Mutex::Unlock() { if (is_safe_) LeaveCriticalSection(&mutex_); } -#ifdef GMUTEX_TRYLOCK -bool Mutex::TryLock() { return is_safe_ ? - TryEnterCriticalSection(&mutex_) != 0 : true; } -#endif -void Mutex::ReaderLock() { Lock(); } // we don't have read-write locks -void Mutex::ReaderUnlock() { Unlock(); } - -#elif defined(HAVE_PTHREAD) && defined(HAVE_RWLOCK) - -#define SAFE_PTHREAD(fncall) do { /* run fncall if is_safe_ is true */ \ - if (is_safe_ && fncall(&mutex_) != 0) abort(); \ -} while (0) - -Mutex::Mutex() { - SetIsSafe(); - if (is_safe_ && pthread_rwlock_init(&mutex_, NULL) != 0) abort(); -} -Mutex::~Mutex() { SAFE_PTHREAD(pthread_rwlock_destroy); } -void Mutex::Lock() { SAFE_PTHREAD(pthread_rwlock_wrlock); } -void Mutex::Unlock() { SAFE_PTHREAD(pthread_rwlock_unlock); } -#ifdef GMUTEX_TRYLOCK -bool Mutex::TryLock() { return is_safe_ ? - pthread_rwlock_trywrlock(&mutex_) == 0 : - true; } -#endif -void Mutex::ReaderLock() { SAFE_PTHREAD(pthread_rwlock_rdlock); } -void Mutex::ReaderUnlock() { SAFE_PTHREAD(pthread_rwlock_unlock); } -#undef SAFE_PTHREAD - -#elif defined(HAVE_PTHREAD) - -#define SAFE_PTHREAD(fncall) do { /* run fncall if is_safe_ is true */ \ - if (is_safe_ && fncall(&mutex_) != 0) abort(); \ -} while (0) - -Mutex::Mutex() { - SetIsSafe(); - if (is_safe_ && pthread_mutex_init(&mutex_, NULL) != 0) abort(); -} -Mutex::~Mutex() { SAFE_PTHREAD(pthread_mutex_destroy); } -void Mutex::Lock() { SAFE_PTHREAD(pthread_mutex_lock); } -void Mutex::Unlock() { SAFE_PTHREAD(pthread_mutex_unlock); } -#ifdef GMUTEX_TRYLOCK -bool Mutex::TryLock() { return is_safe_ ? - pthread_mutex_trylock(&mutex_) == 0 : true; } -#endif -void Mutex::ReaderLock() { Lock(); } -void Mutex::ReaderUnlock() { Unlock(); } -#undef SAFE_PTHREAD - -#endif - -// -------------------------------------------------------------------------- -// Some helper classes - -// MutexLock(mu) acquires mu when constructed and releases it when destroyed. -class MutexLock { - public: - explicit MutexLock(Mutex *mu) : mu_(mu) { mu_->Lock(); } - ~MutexLock() { mu_->Unlock(); } - private: - Mutex * const mu_; - // Disallow "evil" constructors - MutexLock(const MutexLock&); - void operator=(const MutexLock&); -}; - -// ReaderMutexLock and WriterMutexLock do the same, for rwlocks -class ReaderMutexLock { - public: - explicit ReaderMutexLock(Mutex *mu) : mu_(mu) { mu_->ReaderLock(); } - ~ReaderMutexLock() { mu_->ReaderUnlock(); } - private: - Mutex * const mu_; - // Disallow "evil" constructors - ReaderMutexLock(const ReaderMutexLock&); - void operator=(const ReaderMutexLock&); -}; - -class WriterMutexLock { - public: - explicit WriterMutexLock(Mutex *mu) : mu_(mu) { mu_->WriterLock(); } - ~WriterMutexLock() { mu_->WriterUnlock(); } - private: - Mutex * const mu_; - // Disallow "evil" constructors - WriterMutexLock(const WriterMutexLock&); - void operator=(const WriterMutexLock&); -}; - -// Catch bug where variable name is omitted, e.g. MutexLock (&mu); -#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_decl_missing_var_name) -#define ReaderMutexLock(x) COMPILE_ASSERT(0, rmutex_lock_decl_missing_var_name) -#define WriterMutexLock(x) COMPILE_ASSERT(0, wmutex_lock_decl_missing_var_name) - -} // namespace MUTEX_NAMESPACE - -using namespace MUTEX_NAMESPACE; - -#undef MUTEX_NAMESPACE - -#endif /* #define GOOGLE_MUTEX_H__ */ |