ACE_Process_Semaphore(3)

NAME

ACE_Process_Semaphore - Wrapper for Dijkstra style general semaphores that work across processes.

SYNOPSIS

#include <ace/Synch.h>
class ACE_Process_Semaphore
{
  public:
    ACE_Process_Semaphore (
        u_int count = 1,
        LPCTSTR name = 0,
        void * = 0,
        int max = 0x7FFFFFFF
        );
    ~ACE_Process_Semaphore (void);
    int remove (void);
    int acquire (void);
    int tryacquire (void);
    int release (void);
    int acquire_read (void);
    int acquire_write (void);
    int tryacquire_read (void);
    int tryacquire_write (void);
    const ACE_sema_t &lock (void) const;
    void dump (void) const;
    ACE_ALLOC_HOOK_DECLARE;
  protected:
    ACE_Semaphore lock_;
    ACE_SV_Semaphore_Complex lock_;
};

DESCRIPTION

Wrappers for various synchronization routines.

PUBLIC MEMBERS

ACE_Process_Semaphore (
    u_int count = 1,
    LPCTSTR name = 0,
    void * = 0,
    int max = 0x7FFFFFFF
    );

Initialize the semaphore, with an initial value of count and a maximum value of max.

~ACE_Process_Semaphore (void);

This method is a no-op, i.e., it doesn't remove the semaphore. If you want to remove the semaphore, you must call the remove method explicitly.

int remove (void);

Explicitly destroy the semaphore. Note that only one thread should call this method since it doesn't protect against race conditions.

int acquire (void);

Block the thread until the semaphore count becomes greater than 0, then decrement it.

int tryacquire (void);

Conditionally decrement the semaphore if count is greater than 0 (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int release (void);

Increment the semaphore, potentially unblocking a waiting thread.

int acquire_read (void);

Acquire semaphore ownership. This calls acquire and is only here to make the ACE_Process_Semaphore interface consistent with the other synchronization APIs.

int acquire_write (void);

Acquire semaphore ownership. This calls acquire and is only here to make the ACE_Process_Semaphore interface consistent with the other synchronization APIs.

int tryacquire_read (void);

Conditionally acquire semaphore (i.e., won't block). This calls tryacquire and is only here to make the ACE_Process_Semaphore 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);

Conditionally acquire semaphore (i.e., won't block). This calls tryacquire and is only here to make the ACE_Process_Semaphore 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.

const ACE_sema_t &lock (void) const;

Return the underlying lock.

void dump (void) const;

Dump the state of an object.

ACE_ALLOC_HOOK_DECLARE;

Declare the dynamic allocation hooks.

PROTECTED MEMBERS

ACE_Semaphore lock_;

ACE_SV_Semaphore_Complex lock_;

We need this to get the right semantics...

AUTHOR

Doug Schmidt

LIBRARY

ace