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/* -*- C++ -*- */
//=============================================================================
/**
* @file SV_Semaphore_Simple.h
*
* $Id$
*
* @author Douglas C. Schmidt <schmidt@cs.wustl.edu>
*/
//=============================================================================
#ifndef ACE_SV_SEMAPHORE_SIMPLE_H
#define ACE_SV_SEMAPHORE_SIMPLE_H
#include "ace/pre.h"
#include "ace/ACE.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
/**
* @class ACE_SV_Semaphore_Simple
*
* @brief This is a simple semaphore package that assumes there are
* no race conditions for initialization (i.e., the order of
* process startup must be well defined).
*/
class ACE_Export ACE_SV_Semaphore_Simple
{
public:
enum
{
ACE_CREATE = IPC_CREAT,
ACE_EXCL = IPC_EXCL,
ACE_OPEN = 0
};
// = Initialization and termination methods.
ACE_SV_Semaphore_Simple (void);
ACE_SV_Semaphore_Simple (key_t key,
int flags = ACE_SV_Semaphore_Simple::ACE_CREATE,
int initial_value = 1,
u_short nsems = 1,
int perms = ACE_DEFAULT_FILE_PERMS);
ACE_SV_Semaphore_Simple (const char *name,
int flags = ACE_SV_Semaphore_Simple::ACE_CREATE,
int initial_value = 1,
u_short nsems = 1,
int perms = ACE_DEFAULT_FILE_PERMS);
~ACE_SV_Semaphore_Simple (void);
int open (const char *name,
int flags = ACE_SV_Semaphore_Simple::ACE_CREATE,
int initial_value = 1,
u_short nsems = 1,
int perms = ACE_DEFAULT_FILE_PERMS);
/// Open or create one or more SV_Semaphores. We return 0 if all is
/// OK, else -1.
int open (key_t key,
int flags = ACE_SV_Semaphore_Simple::ACE_CREATE,
int initial_value = 1,
u_short nsems = 1,
int perms = ACE_DEFAULT_FILE_PERMS);
/// Close a ACE_SV_Semaphore, marking it as invalid for subsequent
/// operations...
int close (void);
/**
* Remove all SV_Semaphores associated with a particular key. This
* call is intended to be called from a server, for example, when it
* is being shut down, as we do an IPC_RMID on the ACE_SV_Semaphore,
* regardless of whether other processes may be using it or not.
* Most other processes should use <close> below.
*/
int remove (void) const;
// = Semaphore acquire and release methods.
/**
* Wait until a ACE_SV_Semaphore's value is greater than 0, the
* decrement it by 1 and return. Dijkstra's P operation, Tannenbaums
* DOWN operation.
*/
int acquire (u_short n = 0, int flags = 0) const;
/// Acquire a semaphore for reading.
int acquire_read (u_short n = 0, int flags = 0) const;
/// Acquire a semaphore for writing
int acquire_write (u_short n = 0, int flags = 0) const;
/// Non-blocking version of <acquire>.
int tryacquire (u_short n = 0, int flags = 0) const;
/// Try to acquire the semaphore for reading.
int tryacquire_read (u_short n = 0, int flags = 0) const;
/// Try to acquire the semaphore for writing.
int tryacquire_write (u_short n = 0, int flags = 0) const;
/// Increment ACE_SV_Semaphore by one. Dijkstra's V operation,
/// Tannenbaums UP operation.
int release (u_short n = 0, int flags = 0) const;
// = Semaphore operation methods.
/// General ACE_SV_Semaphore operation. Increment or decrement by a
/// specific amount (positive or negative; amount can`t be zero).
int op (int val, u_short semnum = 0, int flags = SEM_UNDO) const;
/// General ACE_SV_Semaphore operation on an array of SV_Semaphores.
int op (sembuf op_vec[], u_short nsems) const;
// = Semaphore control methods.
int control (int cmd, semun arg, u_short n = 0) const;
int control (int cmd, int value = 0, u_short n = 0) const;
/// Get underlying internal id.
int get_id (void) const;
/// Dump the state of an object.
void dump (void) const;
/// Declare the dynamic allocation hooks.
ACE_ALLOC_HOOK_DECLARE;
protected:
/// Semaphore key.
key_t key_;
/// Internal ID to identify the semaphore group within this process.
int internal_id_;
/// Number of semaphores we're creating.
int sem_number_;
/**
* Convert name to key This function is used internally to create
* keys for the semaphores. A valid name contains letters and
* digits only and MUST start with a letter.
*
* The method for generating names is not very sophisticated, so
* caller should not pass strings which match each other for the first
* LUSED characters when he wants to get a different key.
*/
int init (key_t k = ACE_static_cast (key_t, ACE_INVALID_SEM_KEY),
int i = -1);
key_t name_2_key (const char *name);
};
#if !defined (ACE_LACKS_INLINE_FUNCTIONS)
#include "ace/SV_Semaphore_Simple.i"
#endif
#include "ace/post.h"
#endif /* _SV_SEMAPHORE_SIMPLE_H */
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