diff options
Diffstat (limited to 'cppe/src/IceE/RWRecMutex.cpp')
| -rw-r--r-- | cppe/src/IceE/RWRecMutex.cpp | 127 |
1 files changed, 97 insertions, 30 deletions
diff --git a/cppe/src/IceE/RWRecMutex.cpp b/cppe/src/IceE/RWRecMutex.cpp index ed2caa767a4..52ef988db8e 100644 --- a/cppe/src/IceE/RWRecMutex.cpp +++ b/cppe/src/IceE/RWRecMutex.cpp @@ -11,11 +11,35 @@ #include <IceE/Exception.h> #include <IceE/Time.h> +IceUtil::DeadlockException::DeadlockException(const char* file, int line) : + Exception(file, line) +{ +} + +const char* IceUtil::DeadlockException::_name = "IceUtil::DeadlockException"; + +const ::std::string +IceUtil::DeadlockException::ice_name() const +{ + return _name; +} + +IceUtil::Exception* +IceUtil::DeadlockException::ice_clone() const +{ + return new DeadlockException(*this); +} + +void +IceUtil::DeadlockException::ice_throw() const +{ + throw *this; +} IceUtil::RWRecMutex::RWRecMutex() : _count(0), - _writerId(0), - _waitingWriters(0) + _waitingWriters(0), + _upgrading(false) { } @@ -95,7 +119,7 @@ IceUtil::RWRecMutex::writeLock() const // If the mutex is already write locked by this writer then // decrement _count, and return. // - if(_count < 0 && _writerId == ThreadControl().id()) + if(_count < 0 && _writerId == ThreadControl()) { --_count; return; @@ -107,7 +131,7 @@ IceUtil::RWRecMutex::writeLock() const // while(_count != 0) { - _waitingWriters++; + ++_waitingWriters; try { _writers.wait(lock); @@ -124,7 +148,7 @@ IceUtil::RWRecMutex::writeLock() const // Got the lock, indicate it's held by a writer. // _count = -1; - _writerId = ThreadControl().id(); + _writerId = ThreadControl(); } bool @@ -136,7 +160,7 @@ IceUtil::RWRecMutex::tryWriteLock() const // If the mutex is already write locked by this writer then // decrement _count, and return. // - if(_count < 0 && _writerId == ThreadControl().id()) + if(_count < 0 && _writerId == ThreadControl()) { --_count; return true; @@ -154,7 +178,7 @@ IceUtil::RWRecMutex::tryWriteLock() const // Got the lock, indicate it's held by a writer. // _count = -1; - _writerId = ThreadControl().id(); + _writerId = ThreadControl(); return true; } @@ -166,7 +190,7 @@ IceUtil::RWRecMutex::timedWriteLock(const Time& timeout) const // // If the mutex is already write locked by this writer then // decrement _count, and return. - if(_count < 0 && _writerId == ThreadControl().id()) + if(_count < 0 && _writerId == ThreadControl()) { --_count; return true; @@ -182,7 +206,7 @@ IceUtil::RWRecMutex::timedWriteLock(const Time& timeout) const Time remainder = end - Time::now(); if(remainder > Time()) { - _waitingWriters++; + ++_waitingWriters; try { bool result = _writers.timedWait(lock, remainder); @@ -208,7 +232,7 @@ IceUtil::RWRecMutex::timedWriteLock(const Time& timeout) const // Got the lock, indicate it's held by a writer. // _count = -1; - _writerId = ThreadControl().id(); + _writerId = ThreadControl(); return true; } @@ -258,7 +282,7 @@ IceUtil::RWRecMutex::unlock() const // ww = (_waitingWriters != 0 && _count == 0); wr = (_waitingWriters == 0); - } + } // Unlock mutex. // // Wake up a waiting writer if there is one. If not, wake up all @@ -266,14 +290,23 @@ IceUtil::RWRecMutex::unlock() const // if(ww) { - // - // Wake writer - // - _writers.signal(); + if(_upgrading) + { + // + // If there is an untimed upgrader, it runs. + // + _upgrader.signal(); + } + else + { + // + // Wake a normal writer. + // + _writers.signal(); + } } else if(wr) { - _writerId = 0; // // Wake readers // @@ -286,6 +319,11 @@ IceUtil::RWRecMutex::upgrade() const { Mutex::Lock lock(_mutex); + if(_upgrading) + { + throw DeadlockException(__FILE__, __LINE__); + } + // Reader owns at least one count // assert(_count > 0); @@ -294,27 +332,30 @@ IceUtil::RWRecMutex::upgrade() const // // Wait to acquire the write lock. // + _upgrading = true; while(_count != 0) { - _waitingWriters++; + ++_waitingWriters; try { - _writers.wait(lock); + _upgrader.wait(lock); } catch(...) { + _upgrading = false; --_waitingWriters; - _count++; + ++_count; throw; } - _waitingWriters--; + --_waitingWriters; } // // Got the lock, indicate it's held by a writer. // _count = -1; - _writerId = ThreadControl().id(); + _writerId = ThreadControl(); + _upgrading = false; } bool @@ -322,6 +363,15 @@ IceUtil::RWRecMutex::timedUpgrade(const Time& timeout) const { Mutex::Lock lock(_mutex); + // + // If another reader is already waiting for an upgrade, + // this upgrade cannot possibly succeed. + // + if(_upgrading) + { + return false; + } + // Reader owns at least one count // assert(_count > 0); @@ -330,35 +380,40 @@ IceUtil::RWRecMutex::timedUpgrade(const Time& timeout) const // // Wait to acquire the write lock. // + _upgrading = true; Time end = Time::now() + timeout; while(_count != 0) { Time remainder = end - Time::now(); if(remainder > Time()) { - _waitingWriters++; + ++_waitingWriters; try { - bool result = _writers.timedWait(lock, remainder); - _waitingWriters--; - if(result == false) + bool result = _upgrader.timedWait(lock, remainder); + --_waitingWriters; + if(!result) { - _count++; + _upgrading = false; + ++_count; return false; } } catch(...) { + _upgrading = false; --_waitingWriters; - _count++; + ++_count; throw; } } else { // - // If a timeout occurred then the lock wasn't acquired - _count++; + // The lock isn't acquired if a timeout occurred. + // + ++_count; + _upgrading = false; return false; } } @@ -367,6 +422,18 @@ IceUtil::RWRecMutex::timedUpgrade(const Time& timeout) const // Got the lock, indicate it's held by a writer. // _count = -1; - _writerId = ThreadControl().id(); + _writerId = ThreadControl(); + _upgrading = false; return true; } + +void +IceUtil::RWRecMutex::downgrade() const +{ + Mutex::Lock lock(_mutex); + + if(++_count == 0) + { + _count = 1; + } +} |