version 1.8.2.1, 2008/08/20 23:05:50
|
version 1.13, 2008/09/16 18:37:03
|
|
|
#include "Time.h" | #include "Time.h" |
#include "PegasusAssert.h" | #include "PegasusAssert.h" |
#include "Threads.h" | #include "Threads.h" |
|
#include "Exception.h" |
|
#include "System.h" |
| |
PEGASUS_NAMESPACE_BEGIN | PEGASUS_NAMESPACE_BEGIN |
| |
|
|
| |
#ifdef PEGASUS_USE_POSIX_RWLOCK | #ifdef PEGASUS_USE_POSIX_RWLOCK |
| |
ReadWriteSem::ReadWriteSem():_readers(0), _writers(0) |
ReadWriteSem::ReadWriteSem() |
{ | { |
pthread_rwlock_init(&_rwlock.rwlock, NULL); | pthread_rwlock_init(&_rwlock.rwlock, NULL); |
Threads::clear(_rwlock.owner); |
|
} | } |
| |
ReadWriteSem::~ReadWriteSem() | ReadWriteSem::~ReadWriteSem() |
|
|
} | } |
} | } |
| |
void ReadWriteSem::_wait(Boolean writeLock, ThreadType caller) |
void ReadWriteSem::waitRead() |
{ | { |
if (writeLock) |
int r = pthread_rwlock_rdlock(&_rwlock.rwlock); |
{ |
|
if (0 == pthread_rwlock_wrlock(&_rwlock.rwlock)) |
if (r != 0) |
{ |
|
_rwlock.owner = caller; |
|
_writers++; |
|
return; |
|
} |
|
} |
|
else |
|
{ | { |
if (0 == pthread_rwlock_rdlock(&_rwlock.rwlock)) |
if (r != -1) |
{ | { |
_readers++; |
// Special behavior for Single UNIX Specification, Version 3 |
return; |
errno = r; |
} |
|
} | } |
| |
throw WaitFailed(Threads::self()); |
throw Exception(MessageLoaderParms( |
|
"Common.InternalException.READ_LOCK_FAILED", |
|
"Failed to acquire read lock: $0", |
|
PEGASUS_SYSTEM_ERRORMSG_NLS)); |
|
} |
} | } |
| |
void ReadWriteSem::_unlock(Boolean writeLock, ThreadType caller) |
void ReadWriteSem::waitWrite() |
{ | { |
ThreadType owner; |
int r = pthread_rwlock_wrlock(&_rwlock.rwlock); |
| |
if (writeLock) |
if (r != 0) |
{ | { |
owner = _rwlock.owner; |
if (r != -1) |
Threads::clear(_rwlock.owner); |
|
} |
|
if (0 != pthread_rwlock_unlock(&_rwlock.rwlock)) |
|
{ | { |
_rwlock.owner = owner; |
// Special behavior for Single UNIX Specification, Version 3 |
throw(Permission(Threads::self())); |
errno = r; |
|
} |
|
|
|
throw Exception(MessageLoaderParms( |
|
"Common.InternalException.WRITE_LOCK_FAILED", |
|
"Failed to acquire write lock: $0", |
|
PEGASUS_SYSTEM_ERRORMSG_NLS)); |
} | } |
if (!writeLock && _readers.get() != 0) |
|
_readers--; |
|
else if (_writers.get() != 0) |
|
_writers--; |
|
} | } |
| |
int ReadWriteSem::read_count() const |
void ReadWriteSem::unlockRead() |
{ | { |
return _readers.get(); |
int rc = pthread_rwlock_unlock(&_rwlock.rwlock); |
|
// All documented error codes represent coding errors. |
|
PEGASUS_ASSERT(rc == 0); |
} | } |
| |
int ReadWriteSem::write_count() const |
void ReadWriteSem::unlockWrite() |
{ | { |
return _writers.get(); |
int rc = pthread_rwlock_unlock(&_rwlock.rwlock); |
|
// All documented error codes represent coding errors. |
|
PEGASUS_ASSERT(rc == 0); |
} | } |
| |
#endif /* PEGASUS_USE_POSIX_RWLOCK */ | #endif /* PEGASUS_USE_POSIX_RWLOCK */ |
|
|
// 2) I do not hold the write lock | // 2) I do not hold the write lock |
// 3) I am not using a reader slot | // 3) I am not using a reader slot |
| |
ReadWriteSem::ReadWriteSem():_readers(0), _writers(0), _rwlock() |
ReadWriteSem::ReadWriteSem() : _rwlock() |
{ | { |
} | } |
| |
|
|
{ | { |
_rwlock._internal_lock.lock(); | _rwlock._internal_lock.lock(); |
} | } |
catch (IPCException &) |
catch (...) |
{ | { |
PEGASUS_ASSERT(0); | PEGASUS_ASSERT(0); |
} | } |
while (_readers.get() > 0 || _writers.get() > 0) |
while (_rwlock._readers.get() > 0 || _rwlock._writers.get() > 0) |
{ | { |
Threads::yield(); | Threads::yield(); |
} | } |
_rwlock._internal_lock.unlock(); | _rwlock._internal_lock.unlock(); |
} | } |
| |
//--------------------------------------------------------------------- |
void ReadWriteSem::waitRead() |
void ReadWriteSem::_wait(Boolean writeLock, ThreadType caller) |
|
{ | { |
//----------------------------------------------------------------- |
// Lock the internal mutex to ensure only one waiter is processed at a time. |
// Lock this object to maintain integrity while we decide |
AutoMutex lock(_rwlock._internal_lock); |
// exactly what to do next. |
|
//----------------------------------------------------------------- |
|
_rwlock._internal_lock.lock(); |
|
| |
if (writeLock) |
// Wait for the existing writer (if any) to clear. |
|
while (_rwlock._writers.get() > 0) |
{ | { |
//----------------------------------------------------------------- |
|
// Write Lock Step 1: lock the object and allow all the readers to exit |
|
//----------------------------------------------------------------- |
|
while (_readers.get() > 0) |
|
Threads::yield(); | Threads::yield(); |
//----------------------------------------------------------------- |
|
// Write Lock Step 2: Obtain the Write Mutex |
|
// Although there are no readers, there may be a writer |
|
//----------------------------------------------------------------- |
|
try |
|
{ |
|
_rwlock._wlock.lock(); |
|
} |
|
catch (const IPCException&) |
|
{ |
|
_rwlock._internal_lock.unlock(); |
|
throw; |
|
} |
|
//----------------------------------------------------------------- |
|
// Write Lock Step 3: set the writer count to one, unlock the object |
|
// There are no readers and we are the only writer ! |
|
//----------------------------------------------------------------- |
|
_writers = 1; |
|
// set the owner |
|
_rwlock._owner = Threads::self(); |
|
// unlock the object |
|
_rwlock._internal_lock.unlock(); |
|
} | } |
else |
|
{ |
// Wait for a reader slot to open up. |
//----------------------------------------------------------------- |
|
// Read Lock Step 1: Wait for the existing writer (if any) to clear |
|
//----------------------------------------------------------------- |
|
while (_writers.get() > 0) |
|
Threads::yield(); |
|
//----------------------------------------------------------------- |
|
// Read Lock Step 2: wait for a reader slot to open up, then return |
|
// At this point there are no writers, but there may be too many |
|
// readers. |
|
//----------------------------------------------------------------- |
|
try |
|
{ |
|
_rwlock._rlock.wait(); | _rwlock._rlock.wait(); |
} |
|
catch (const IPCException&) |
// Increment the number of readers. |
{ |
_rwlock._readers++; |
_rwlock._internal_lock.unlock(); |
|
throw; |
|
} |
|
//----------------------------------------------------------------- |
|
// Read Lock Step 3: increment the number of readers, unlock the object, |
|
// return |
|
//----------------------------------------------------------------- |
|
_readers++; |
|
_rwlock._internal_lock.unlock(); |
|
} |
|
} | } |
| |
void ReadWriteSem::_unlock(Boolean writeLock, ThreadType caller) |
void ReadWriteSem::waitWrite() |
{ |
|
if (writeLock && _writers.get() != 0) |
|
{ | { |
_writers = 0; |
// Lock the internal mutex to ensure only one waiter is processed at a time. |
_rwlock._wlock.unlock(); |
AutoMutex lock(_rwlock._internal_lock); |
} |
|
else if (_readers.get() != 0) |
// Allow all the readers to exit. |
|
while (_rwlock._readers.get() > 0) |
{ | { |
_readers--; |
Threads::yield(); |
_rwlock._rlock.signal(); |
|
} | } |
|
|
|
// Obtain the write mutex. |
|
_rwlock._wlock.lock(); |
|
|
|
// Set the writer count to one. |
|
_rwlock._writers = 1; |
} | } |
| |
int ReadWriteSem::read_count() const |
void ReadWriteSem::unlockRead() |
{ | { |
return _readers.get(); |
PEGASUS_ASSERT(_rwlock._readers.get() > 0); |
|
_rwlock._readers--; |
|
_rwlock._rlock.signal(); |
} | } |
| |
int ReadWriteSem::write_count() const |
void ReadWriteSem::unlockWrite() |
{ | { |
return _writers.get(); |
PEGASUS_ASSERT(_rwlock._writers.get() == 1); |
|
_rwlock._writers = 0; |
|
_rwlock._wlock.unlock(); |
} | } |
| |
#endif /* !PEGASUS_USE_SEMAPHORE_RWLOCK */ | #endif /* !PEGASUS_USE_SEMAPHORE_RWLOCK */ |