llvm-6502/lib/Support/Unix/RWMutex.inc
Mark Seaborn 79ac85be0b Fix RWMutex to be thread-safe when pthread_rwlock is not available
lib/Support/RWMutex.cpp contains an implementation of RWMutex that
uses pthread_rwlock, but when pthread_rwlock is not available (such as
under NaCl, when using newlib), it silently falls back to using the
no-op definition in lib/Support/Unix/RWMutex.inc, which is not
thread-safe.

Fix this case to be thread-safe by using a normal mutex.

Differential Revision: http://llvm-reviews.chandlerc.com/D2892

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202570 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-01 04:30:32 +00:00

52 lines
1.5 KiB
PHP

//= llvm/Support/Unix/RWMutex.inc - Unix Reader/Writer Mutual Exclusion Lock =//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Unix specific (non-pthread) RWMutex class.
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
//=== WARNING: Implementation here must contain only generic UNIX code that
//=== is guaranteed to work on *all* UNIX variants.
//===----------------------------------------------------------------------===//
#include "llvm/Support/Mutex.h"
namespace llvm {
using namespace sys;
// This naive implementation treats readers the same as writers. This
// will therefore deadlock if a thread tries to acquire a read lock
// multiple times.
RWMutexImpl::RWMutexImpl() : data_(new Mutex(false)) { }
RWMutexImpl::~RWMutexImpl() {
delete static_cast<Mutex *>(data_);
}
bool RWMutexImpl::reader_acquire() {
return static_cast<Mutex *>(data_)->acquire();
}
bool RWMutexImpl::reader_release() {
return static_cast<Mutex *>(data_)->release();
}
bool RWMutexImpl::writer_acquire() {
return static_cast<Mutex *>(data_)->acquire();
}
bool RWMutexImpl::writer_release() {
return static_cast<Mutex *>(data_)->release();
}
}