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ACE_Process_Mutex Class Reference

A wrapper for mutexes that can be used across processes on the same host machine, as well as within a process, of course. More...

#include <Process_Mutex.h>

Collaboration diagram for ACE_Process_Mutex:

[legend]List of all members.

Public Methods
	ACE_Process_Mutex (const char *name=0, void *arg=0, mode_t mode=ACE_DEFAULT_FILE_PERMS)
	ACE_Process_Mutex (const wchar_t *name, void *arg=0, mode_t mode=ACE_DEFAULT_FILE_PERMS)
	~ACE_Process_Mutex (void)
int	remove (void)
int	acquire (void)
int	acquire (ACE_Time_Value &tv)
int	tryacquire (void)
int	release (void)
	Release lock and unblock a thread at head of queue.
int	acquire_read (void)
	Acquire lock ownership (wait on queue if necessary).
int	acquire_write (void)
	Acquire lock ownership (wait on queue if necessary).
int	tryacquire_read (void)
int	tryacquire_write (void)
int	tryacquire_write_upgrade (void)
const ACE_mutex_t &	lock (void) const
	Return the underlying mutex.
void	dump (void) const
	Dump the state of an object.
Public Attributes
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks.
Private Methods
const ACE_TCHAR *	unique_name (void)
	Create and return the unique name.
Private Attributes
ACE_TCHAR	name_ [ACE_UNIQUE_NAME_LEN]
ACE_Mutex	lock_

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Detailed Description

A wrapper for mutexes that can be used across processes on the same host machine, as well as within a process, of course.

Attention:

The mechanism upon which ACE_Process_Mutex is based can be configured at build time to be either ACE_SV_Semaphore_Complex (on platforms that support it) or ACE_Mutex. On platforms that require interprocess mutexes be allocated from shared memory (Pthreads and UI Threads are examples), ACE_SV_Semaphore_Complex provides a more reliable mechanism for implementing inter-process mutex than ACE_Mutex. However, at least on some platforms, ACE_SV_Semaphore_Complex is limited to a small number of objects by the underlying System V IPC kernel parameters. If you want to force use of ACE_Mutex as the underlying mechanism, set ACE_USES_MUTEX_FOR_PROCESS_MUTEX in your config.h file. Also, if you require the ability to do a timed acquire(), you must set ACE_USES_MUTEX_FOR_PROCESS_MUTEX, as timed acquire does not work with System V semaphores.

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Constructor & Destructor Documentation

ACE_Process_Mutex::ACE_Process_Mutex (  const char *    name = 0, void *    arg = 0, mode_t    mode = ACE_DEFAULT_FILE_PERMS )

Create a Process_Mutex, passing in the optional name. Parameters: name  optional, null-terminated string containing the name of the object. Multiple users of the same ACE_Process_Mutex must use the same name to access the same object. If not specified, a name is generated. arg  optional, attributes to be used to initialize the mutex. If using ACE_SV_Semaphore_Complex as the underlying mechanism, this argument is ignored. mode  optional, the protection mode for either the backing store file (for ACE_Mutex use) or the ACE_SV_Semaphore_Complex that's created.

ACE_Process_Mutex::ACE_Process_Mutex (  const wchar_t *    name, void *    arg = 0, mode_t    mode = ACE_DEFAULT_FILE_PERMS )

Create a Process_Mutex, passing in the optional name. (wchar_t version) Parameters: name  optional, null-terminated string containing the name of the object. Multiple users of the same ACE_Process_Mutex must use the same name to access the same object. If not specified, a name is generated. arg  optional, attributes to be used to initialize the mutex. If using ACE_SV_Semaphore_Complex as the underlying mechanism, this argument is ignored. mode  optional, the protection mode for either the backing store file (for ACE_Mutex use) or the ACE_SV_Semaphore_Complex that's created.

ACE_Process_Mutex::~ACE_Process_Mutex (  void    )

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Member Function Documentation

ACE_INLINE int ACE_Process_Mutex::acquire (  ACE_Time_Value &    tv )

Acquire lock ownership, but timeout if lock if hasn't been acquired by given time. Parameters: tv  the absolute time until which the caller is willing to wait to acquire the lock. Returns: 0 on success; -1 on failure.

ACE_INLINE int ACE_Process_Mutex::acquire (  void    )

Acquire lock ownership (wait on queue if necessary). Returns: 0 on success; -1 on failure.

ACE_INLINE int ACE_Process_Mutex::acquire_read (  void    )

Acquire lock ownership (wait on queue if necessary).

ACE_INLINE int ACE_Process_Mutex::acquire_write (  void    )

Acquire lock ownership (wait on queue if necessary).

void ACE_Process_Mutex::dump (  void    )  const

Dump the state of an object.

ACE_INLINE const ACE_mutex_t & ACE_Process_Mutex::lock (  void    )  const

Return the underlying mutex.

ACE_INLINE int ACE_Process_Mutex::release (  void    )

Release lock and unblock a thread at head of queue.

ACE_INLINE int ACE_Process_Mutex::remove (  void    )

Explicitly destroy the mutex. Note that only one thread should call this method since it doesn't protect against race conditions. Returns: 0 on success; -1 on failure.

ACE_INLINE int ACE_Process_Mutex::tryacquire (  void    )

Conditionally acquire lock (i.e., don't wait on queue). Returns: 0 on success; -1 on failure. If the lock could not be acquired because someone else already had the lock, errno is set to EBUSY.

ACE_INLINE int ACE_Process_Mutex::tryacquire_read (  void    )

Conditionally acquire a lock (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, <errno> is set to <EBUSY>.

ACE_INLINE int ACE_Process_Mutex::tryacquire_write (  void    )

Conditionally acquire a lock (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, <errno> is set to <EBUSY>.

ACE_INLINE int ACE_Process_Mutex::tryacquire_write_upgrade (  void    )

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.

const ACE_TCHAR * ACE_Process_Mutex::unique_name (  void    )  [private]

Create and return the unique name.

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Member Data Documentation

ACE_Process_Mutex::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

ACE_Mutex ACE_Process_Mutex::lock_ [private]

ACE_TCHAR ACE_Process_Mutex::name_[ACE_UNIQUE_NAME_LEN] [private]

If the user does not provide a name we generate a unique name in this buffer.

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The documentation for this class was generated from the following files:

• Process_Mutex.h
• Process_Mutex.cpp
• Process_Mutex.inl

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