Process Locking Routines
[Apache Portability Runtime library]

Typedefs

typedef struct apr_proc_mutex_t apr_proc_mutex_t

Enumerations

enum  apr_lockmech_e {
  APR_LOCK_FCNTL, APR_LOCK_FLOCK, APR_LOCK_SYSVSEM, APR_LOCK_PROC_PTHREAD,
  APR_LOCK_POSIXSEM, APR_LOCK_DEFAULT
}

Functions

apr_status_t apr_proc_mutex_create (apr_proc_mutex_t **mutex, const char *fname, apr_lockmech_e mech, apr_pool_t *pool)
apr_status_t apr_proc_mutex_child_init (apr_proc_mutex_t **mutex, const char *fname, apr_pool_t *pool)
apr_status_t apr_proc_mutex_lock (apr_proc_mutex_t *mutex)
apr_status_t apr_proc_mutex_trylock (apr_proc_mutex_t *mutex)
apr_status_t apr_proc_mutex_unlock (apr_proc_mutex_t *mutex)
apr_status_t apr_proc_mutex_destroy (apr_proc_mutex_t *mutex)
apr_status_t apr_proc_mutex_cleanup (void *mutex)
const char * apr_proc_mutex_lockfile (apr_proc_mutex_t *mutex)
const char * apr_proc_mutex_name (apr_proc_mutex_t *mutex)
const char * apr_proc_mutex_defname (void)
apr_pool_tapr_proc_mutex_pool_get (const apr_proc_mutex_t *theproc_mutex)

Typedef Documentation

Opaque structure representing a process mutex.


Enumeration Type Documentation

Enumerated potential types for APR process locking methods

Warning:
Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
Enumerator:
APR_LOCK_FCNTL 

fcntl()

APR_LOCK_FLOCK 

flock()

APR_LOCK_SYSVSEM 

System V Semaphores

APR_LOCK_PROC_PTHREAD 

POSIX pthread process-based locking

APR_LOCK_POSIXSEM 

POSIX semaphore process-based locking

APR_LOCK_DEFAULT 

Use the default process lock


Function Documentation

apr_status_t apr_proc_mutex_child_init ( apr_proc_mutex_t **  mutex,
const char *  fname,
apr_pool_t pool 
)

Re-open a mutex in a child process.

Parameters:
mutex The newly re-opened mutex structure.
fname A file name to use if the mutex mechanism requires one. This argument should always be provided. The mutex code itself will determine if it should be used. This filename should be the same one that was passed to apr_proc_mutex_create().
pool The pool to operate on.
Remarks:
This function must be called to maintain portability, even if the underlying lock mechanism does not require it.
apr_status_t apr_proc_mutex_cleanup ( void *  mutex  ) 

Destroy the mutex and free the memory associated with the lock.

Parameters:
mutex the mutex to destroy.
Note:
This function is generally used to kill a cleanup on an already created mutex
apr_status_t apr_proc_mutex_create ( apr_proc_mutex_t **  mutex,
const char *  fname,
apr_lockmech_e  mech,
apr_pool_t pool 
)

Create and initialize a mutex that can be used to synchronize processes.

Parameters:
mutex the memory address where the newly created mutex will be stored.
fname A file name to use if the lock mechanism requires one. This argument should always be provided. The lock code itself will determine if it should be used.
mech The mechanism to use for the interprocess lock, if any; one of

            APR_LOCK_FCNTL
            APR_LOCK_FLOCK
            APR_LOCK_SYSVSEM
            APR_LOCK_POSIXSEM
            APR_LOCK_PROC_PTHREAD
            APR_LOCK_DEFAULT     pick the default mechanism for the platform
 
pool the pool from which to allocate the mutex.
See also:
apr_lockmech_e
Warning:
Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
const char* apr_proc_mutex_defname ( void   ) 

Display the name of the default mutex: APR_LOCK_DEFAULT

apr_status_t apr_proc_mutex_destroy ( apr_proc_mutex_t mutex  ) 

Destroy the mutex and free the memory associated with the lock.

Parameters:
mutex the mutex to destroy.
apr_status_t apr_proc_mutex_lock ( apr_proc_mutex_t mutex  ) 

Acquire the lock for the given mutex. If the mutex is already locked, the current thread will be put to sleep until the lock becomes available.

Parameters:
mutex the mutex on which to acquire the lock.
const char* apr_proc_mutex_lockfile ( apr_proc_mutex_t mutex  ) 

Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file

const char* apr_proc_mutex_name ( apr_proc_mutex_t mutex  ) 

Display the name of the mutex, as it relates to the actual method used. This matches the valid options for Apache's AcceptMutex directive

Parameters:
mutex the name of the mutex
apr_pool_t* apr_proc_mutex_pool_get ( const apr_proc_mutex_t theproc_mutex  ) 

Get the pool used by this proc_mutex.

Returns:
apr_pool_t the pool
apr_status_t apr_proc_mutex_trylock ( apr_proc_mutex_t mutex  ) 

Attempt to acquire the lock for the given mutex. If the mutex has already been acquired, the call returns immediately with APR_EBUSY. Note: it is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was APR_EBUSY, for portability reasons.

Parameters:
mutex the mutex on which to attempt the lock acquiring.
apr_status_t apr_proc_mutex_unlock ( apr_proc_mutex_t mutex  ) 

Release the lock for the given mutex.

Parameters:
mutex the mutex from which to release the lock.
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