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// -*- C++ -*-
//==========================================================================
/**
* @file Mutex.h
*
* @author Douglas C. Schmidt <d.schmidt@vanderbilt.edu>
*/
//==========================================================================
#ifndef ACE_MUTEX_H
#define ACE_MUTEX_H
#include /**/ "ace/pre.h"
#include /**/ "ace/ACE_export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "ace/OS_NS_Thread.h"
#include "ace/OS_NS_unistd.h"
#include "ace/os_include/os_fcntl.h"
#if !defined (ACE_DEFAULT_MUTEX_A)
# define ACE_DEFAULT_MUTEX_A "ACE_MUTEX"
#endif /* ACE_DEFAULT_MUTEX_A */
#if defined (ACE_HAS_WCHAR)
# define ACE_DEFAULT_MUTEX_W ACE_TEXT_WIDE (ACE_DEFAULT_MUTEX_A)
#endif /* ACE_HAS_WCHAR */
#define ACE_DEFAULT_MUTEX ACE_TEXT (ACE_DEFAULT_MUTEX_A)
ACE_BEGIN_VERSIONED_NAMESPACE_DECL
class ACE_Time_Value;
/**
* @class ACE_Mutex
*
* @brief @c ACE_Mutex wrapper (valid in same process or across
* processes (depending on @a TYPE flag)). In general,
* however, we recommend using @a ACE_Process_Mutex or @a
* ACE_Thread_Mutex rather than @a ACE_Mutex.
*/
class ACE_Export ACE_Mutex
{
public:
/// Initialize the mutex.
ACE_Mutex (int type = USYNC_THREAD,
const ACE_TCHAR *name = 0,
ACE_mutexattr_t *arg = 0,
mode_t mode = ACE_DEFAULT_FILE_PERMS);
/// Implicitly destroy the mutex.
~ACE_Mutex ();
/// Explicitly destroy the mutex.
/**
* @note Only one thread should call this method since it doesn't
* protect against race conditions.
*/
int remove ();
/// Acquire lock ownership (wait on queue if necessary).
int acquire ();
/// Block the thread until the mutex is acquired or @a tv times out,
/// in which case -1 is returned and @c errno == @c ETIME.
/**
* @note @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);
/// Block the thread until the mutex is acquired or @a *tv times
/// out, in which case -1 is returned and @c errno == @c ETIME.
/**
* If @a tv == 0 then call @c acquire() directly. Otherwise, block
* the thread until the mutex is acquired or @a tv times out, in
* which case -1 is returned and @c errno == @c ETIME.
*
* @note @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);
/// Conditionally acquire lock (i.e., don't wait on queue).
/**
* @return -1 on failure. If we "failed" because someone
* else already had the lock, @c errno is set to @c EBUSY.
*/
int tryacquire ();
/// Release lock and unblock a thread at head of queue.
int release ();
/// Acquire mutex ownership.
/**
* This calls @c acquire and is only here to make the @c ACE_Mutex
* interface consistent with the other synchronization APIs.
*/
int acquire_read ();
/// Acquire mutex ownership.
/**
* This calls @c acquire and is only here to make the @c ACE_Mutex
* interface consistent with the other synchronization APIs.
*/
int acquire_write ();
/// Conditionally acquire mutex (i.e., won't block).
/**
* This calls @c tryacquire and is only here to make the @c ACE_Mutex
* interface consistent with the other synchronization APIs.
*
* @return -1 on failure. If we "failed" because someone else
* already had the lock, @c errno is set to @c EBUSY.
*/
int tryacquire_read ();
/// Conditionally acquire mutex (i.e., won't block).
/**
* This calls @c tryacquire and is only here to make the @c ACE_Mutex
* interface consistent with the other synchronization APIs.
*
* @return -1 on failure. If we "failed" because someone else
* already had the lock, @c errno is set to @c EBUSY.
*/
int tryacquire_write ();
/**
* This is only here for consistency with the other synchronization
* APIs and usability with Lock adapters. Assumes the caller already has
* acquired the mutex and returns 0 in all cases.
*/
int tryacquire_write_upgrade ();
/// Return the underlying mutex.
const ACE_mutex_t &lock () const;
ACE_mutex_t &lock ();
/// If a file was created as the underlying storage for the mutex,
/// remove it from the filesystem (for process-shared mutexes).
static int unlink (const ACE_TCHAR *name);
/// Dump the state of an object.
void dump () const;
/// Declare the dynamic allocation hooks.
ACE_ALLOC_HOOK_DECLARE;
// = This should be protected but some C++ compilers complain...
public:
#if defined ACE_HAS_PTHREADS && defined ACE_LACKS_MUTEXATTR_PSHARED
# define ACE_MUTEX_USE_PROCESS_LOCK
# define ACE_MUTEX_PROCESS_LOCK_IS_SEMA
ACE_sema_t process_sema_;
typedef ACE_sema_t Process_Lock;
#elif defined ACE_HAS_PTHREADS || defined ACE_HAS_STHREADS
# define ACE_MUTEX_USE_PROCESS_LOCK
# define ACE_MUTEX_PROCESS_LOCK_IS_MUTEX
typedef ACE_mutex_t Process_Lock;
#endif
#ifdef ACE_MUTEX_USE_PROCESS_LOCK
/// This lock resides in shared memory.
Process_Lock *process_lock_;
/**
* Remember the name of the mutex if we created it so we can unlink
* it when we go away (only the actor that initialized the memory
* can destroy it).
*/
const ACE_TCHAR *lockname_;
#endif /* ACE_MUTEX_USE_PROCESS_LOCK */
/// Mutex type supported by the OS.
ACE_mutex_t lock_;
/// Keeps track of whether @c remove has been called yet to avoid
/// multiple @c 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
/// @c remove on the same object, which is a bad idea anyway.
bool removed_;
private:
ACE_Mutex &operator= (const ACE_Mutex &) = delete;
ACE_Mutex (const ACE_Mutex &) = delete;
};
ACE_END_VERSIONED_NAMESPACE_DECL
#if defined (__ACE_INLINE__)
#include "ace/Mutex.inl"
#endif /* __ACE_INLINE__ */
#include /**/ "ace/post.h"
#endif /* ACE_MUTEX_H */
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