mirror of
https://github.com/ilyakooo0/urbit.git
synced 2024-12-17 20:01:32 +03:00
27dd121d14
git-subtree-dir: outside/re2 git-subtree-mainline: f94738bfd171ae447133e0964843addbb497894f git-subtree-split: 539b44fc4c5a49c3453b80e3af85d297f4cab4bf
212 lines
7.3 KiB
C++
212 lines
7.3 KiB
C++
// Copyright 2007 The RE2 Authors. All Rights Reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
/*
|
|
* A simple mutex wrapper, supporting locks and read-write locks.
|
|
* You should assume the locks are *not* re-entrant.
|
|
*/
|
|
|
|
#ifndef RE2_UTIL_MUTEX_H_
|
|
#define RE2_UTIL_MUTEX_H_
|
|
|
|
#include <stdlib.h>
|
|
|
|
namespace re2 {
|
|
|
|
#define HAVE_PTHREAD 1
|
|
#define HAVE_RWLOCK 1
|
|
|
|
#if defined(NO_THREADS)
|
|
typedef int MutexType; // to keep a lock-count
|
|
#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__
|
|
# undef _XOPEN_SOURCE
|
|
# define _XOPEN_SOURCE 500 // may be needed to get the rwlock calls
|
|
# endif
|
|
# include <pthread.h>
|
|
typedef pthread_rwlock_t MutexType;
|
|
#elif defined(HAVE_PTHREAD)
|
|
# include <pthread.h>
|
|
typedef pthread_mutex_t MutexType;
|
|
#elif defined(WIN32)
|
|
# define WIN32_LEAN_AND_MEAN // We only need minimal includes
|
|
# 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
|
|
# include <windows.h>
|
|
typedef CRITICAL_SECTION MutexType;
|
|
#else
|
|
# error Need to implement mutex.h for your architecture, or #define NO_THREADS
|
|
#endif
|
|
|
|
class Mutex {
|
|
public:
|
|
// Create a Mutex that is not held by anybody.
|
|
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()
|
|
inline bool TryLock(); // If free, Lock() and return true, else return false
|
|
// 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()
|
|
inline void AssertHeld() { }
|
|
|
|
private:
|
|
MutexType mutex_;
|
|
|
|
// 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.
|
|
#include <assert.h>
|
|
|
|
Mutex::Mutex() : mutex_(0) { }
|
|
Mutex::~Mutex() { assert(mutex_ == 0); }
|
|
void Mutex::Lock() { assert(--mutex_ == -1); }
|
|
void Mutex::Unlock() { assert(mutex_++ == -1); }
|
|
bool Mutex::TryLock() { if (mutex_) return false; Lock(); return true; }
|
|
void Mutex::ReaderLock() { assert(++mutex_ > 0); }
|
|
void Mutex::ReaderUnlock() { assert(mutex_-- > 0); }
|
|
|
|
#elif defined(HAVE_PTHREAD) && defined(HAVE_RWLOCK)
|
|
|
|
#define SAFE_PTHREAD(fncall) do { if ((fncall) != 0) abort(); } while (0)
|
|
|
|
Mutex::Mutex() { SAFE_PTHREAD(pthread_rwlock_init(&mutex_, NULL)); }
|
|
Mutex::~Mutex() { SAFE_PTHREAD(pthread_rwlock_destroy(&mutex_)); }
|
|
void Mutex::Lock() { SAFE_PTHREAD(pthread_rwlock_wrlock(&mutex_)); }
|
|
void Mutex::Unlock() { SAFE_PTHREAD(pthread_rwlock_unlock(&mutex_)); }
|
|
bool Mutex::TryLock() { return pthread_rwlock_trywrlock(&mutex_) == 0; }
|
|
void Mutex::ReaderLock() { SAFE_PTHREAD(pthread_rwlock_rdlock(&mutex_)); }
|
|
void Mutex::ReaderUnlock() { SAFE_PTHREAD(pthread_rwlock_unlock(&mutex_)); }
|
|
|
|
#undef SAFE_PTHREAD
|
|
|
|
#elif defined(HAVE_PTHREAD)
|
|
|
|
#define SAFE_PTHREAD(fncall) do { if ((fncall) != 0) abort(); } while (0)
|
|
|
|
Mutex::Mutex() { SAFE_PTHREAD(pthread_mutex_init(&mutex_, NULL)); }
|
|
Mutex::~Mutex() { SAFE_PTHREAD(pthread_mutex_destroy(&mutex_)); }
|
|
void Mutex::Lock() { SAFE_PTHREAD(pthread_mutex_lock(&mutex_)); }
|
|
void Mutex::Unlock() { SAFE_PTHREAD(pthread_mutex_unlock(&mutex_)); }
|
|
bool Mutex::TryLock() { return pthread_mutex_trylock(&mutex_) == 0; }
|
|
void Mutex::ReaderLock() { Lock(); } // we don't have read-write locks
|
|
void Mutex::ReaderUnlock() { Unlock(); }
|
|
#undef SAFE_PTHREAD
|
|
|
|
#elif defined(WIN32)
|
|
|
|
Mutex::Mutex() { InitializeCriticalSection(&mutex_); }
|
|
Mutex::~Mutex() { DeleteCriticalSection(&mutex_); }
|
|
void Mutex::Lock() { EnterCriticalSection(&mutex_); }
|
|
void Mutex::Unlock() { LeaveCriticalSection(&mutex_); }
|
|
bool Mutex::TryLock() { return TryEnterCriticalSection(&mutex_) != 0; }
|
|
void Mutex::ReaderLock() { Lock(); } // we don't have read-write locks
|
|
void Mutex::ReaderUnlock() { Unlock(); }
|
|
|
|
#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)
|
|
|
|
// Provide safe way to declare and use global, linker-initialized mutex. Sigh.
|
|
#ifdef HAVE_PTHREAD
|
|
|
|
#define GLOBAL_MUTEX(name) \
|
|
static pthread_mutex_t (name) = PTHREAD_MUTEX_INITIALIZER
|
|
#define GLOBAL_MUTEX_LOCK(name) \
|
|
pthread_mutex_lock(&(name))
|
|
#define GLOBAL_MUTEX_UNLOCK(name) \
|
|
pthread_mutex_unlock(&(name))
|
|
|
|
#else
|
|
|
|
#define GLOBAL_MUTEX(name) \
|
|
static Mutex name
|
|
#define GLOBAL_MUTEX_LOCK(name) \
|
|
name.Lock()
|
|
#define GLOBAL_MUTEX_UNLOCK(name) \
|
|
name.Unlock()
|
|
|
|
#endif
|
|
|
|
} // namespace re2
|
|
|
|
#endif /* #define RE2_UTIL_MUTEX_H_ */
|