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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_

## 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.

## 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 |  | ) |

## 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.

## 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.

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

- /export2/deucetmp/bala/release_try/ACE_wrappers/ace/Process_Mutex.h
- /export2/deucetmp/bala/release_try/ACE_wrappers/ace/Process_Mutex.cpp
- /export2/deucetmp/bala/release_try/ACE_wrappers/ace/Process_Mutex.inl