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// -*- C++ -*-
//==========================================================================
/**
* @file Thread_Mutex.h
*
* $Id$
*
* Moved from Synch.h.
*
* @author Douglas C. Schmidt <schmidt@cs.wustl.edu>
*/
//==========================================================================
#ifndef ACE_THREAD_MUTEX_H
#define ACE_THREAD_MUTEX_H
#include /**/ "ace/pre.h"
#include /**/ "ace/config-all.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#if !defined (ACE_HAS_THREADS)
# include "ace/Null_Mutex.h"
#else /* ACE_HAS_THREADS */
// ACE platform supports some form of threading.
#include /**/ "ace/ACE_export.h"
#include "ace/OS_NS_Thread.h"
ACE_BEGIN_VERSIONED_NAMESPACE_DECL
/**
* @class ACE_Thread_Mutex
*
* @brief ACE_Thread_Mutex wrapper (only valid for threads in the same
* process).
*
* This implementation is optimized for locking threads that are
* in the same process. It maps to <CRITICAL_SECTION>s on NT
* and <ACE_mutex_t> with <type> set to <USYNC_THREAD> on UNIX.
* ACE_Thread_Mutex is recursive on some platforms (like
* Win32). However, on most platforms (like Solaris) it is not
* recursive. To be totally safe and portable, developers
* should use ACE_Recursive_Thread_Mutex when they need a
* recursive mutex.
*/
class ACE_Export ACE_Thread_Mutex
{
friend class ACE_Condition_Thread_Mutex;
public:
/// Constructor.
ACE_Thread_Mutex (const ACE_TCHAR *name = 0,
ACE_mutexattr_t *attributes = 0);
/// Implicitly destroy the mutex.
~ACE_Thread_Mutex (void);
/**
* Explicitly destroy the mutex. Note that only one thread should
* call this method since it doesn't protect against race
* conditions.
*/
int remove (void);
/// Acquire lock ownership (wait on queue if necessary).
int acquire (void);
/**
* Block the thread until we acquire the mutex or until @a tv times
* out, in which case -1 is returned with <errno> == <ETIME>. Note
* that @a tv is assumed to be in "absolute" rather than "relative"
* time. The value of @a tv is updated upon return to show the
* actual (absolute) acquisition time.
*/
int acquire (ACE_Time_Value &tv);
/**
* If @a tv == 0 the call <acquire()> directly. Otherwise, Block the
* thread until we acquire the mutex or until @a tv times out, in
* which case -1 is returned with <errno> == <ETIME>. Note that
* <*tv> is assumed to be in "absolute" rather than "relative" time.
* The value of <*tv> is updated upon return to show the actual
* (absolute) acquisition time.
*/
int acquire (ACE_Time_Value *tv);
/**
* Conditionally acquire lock (i.e., don't wait on queue). Returns
* -1 on failure. If we "failed" because someone else already had
* the lock, <errno> is set to <EBUSY>.
*/
int tryacquire (void);
/// Release lock and unblock a thread at head of queue.
int release (void);
/**
* Acquire mutex ownership. This calls <acquire> and is only here
* to make the ACE_Thread_Mutex interface consistent with the
* other synchronization APIs.
*/
int acquire_read (void);
/**
* Acquire mutex ownership. This calls <acquire> and is only here
* to make the ACE_Thread_Mutex interface consistent with the
* other synchronization APIs.
*/
int acquire_write (void);
/**
* Conditionally acquire mutex (i.e., won't block). This calls
* <tryacquire> and is only here to make the ACE_Thread_Mutex
* interface consistent with the other synchronization APIs.
* Returns -1 on failure. If we "failed" because someone else
* already had the lock, <errno> is set to <EBUSY>.
*/
int tryacquire_read (void);
/**
* Conditionally acquire mutex (i.e., won't block). This calls
* <tryacquire> and is only here to make the ACE_Thread_Mutex
* interface consistent with the other synchronization APIs.
* Returns -1 on failure. If we "failed" because someone else
* already had the lock, <errno> is set to <EBUSY>.
*/
int tryacquire_write (void);
/**
* This is only here to make the ACE_Thread_Mutex
* interface consistent with the other synchronization APIs.
* Assumes the caller has already acquired the mutex using one of
* the above calls, and returns 0 (success) always.
*/
int tryacquire_write_upgrade (void);
/// Return the underlying mutex.
const ACE_thread_mutex_t &lock (void) const;
/// Dump the state of an object.
void dump (void) const;
/// Declare the dynamic allocation hooks.
ACE_ALLOC_HOOK_DECLARE;
// protected:
/// Mutex type that supports single-process locking efficiently.
ACE_thread_mutex_t lock_;
/// Keeps track of whether <remove> has been called yet to avoid
/// multiple <remove> calls, e.g., explicitly and implicitly in the
/// destructor. This flag isn't protected by a lock, so make sure
/// that you don't have multiple threads simultaneously calling
/// <remove> on the same object, which is a bad idea anyway...
bool removed_;
private:
// = Prevent assignment and initialization.
void operator= (const ACE_Thread_Mutex &);
ACE_Thread_Mutex (const ACE_Thread_Mutex &);
};
ACE_END_VERSIONED_NAMESPACE_DECL
#if defined (__ACE_INLINE__)
#include "ace/Thread_Mutex.inl"
#endif /* __ACE_INLINE__ */
#endif /* !ACE_HAS_THREADS */
#include /**/ "ace/post.h"
#endif /* ACE_THREAD_MUTEX_H */
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