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/* -*- C++ -*- */
// $Id$
// ============================================================================
//
// = LIBRARY
// ace
//
// = FILENAME
// SV_Semaphore_Simple.h
//
// = AUTHOR
// Doug Schmidt
//
// ============================================================================
#if !defined (ACE_SV_SEMAPHORE_SIMPLE_H)
#define ACE_SV_SEMAPHORE_SIMPLE_H
#include "ace/ACE.h"
class ACE_Export ACE_SV_Semaphore_Simple
{
// = TITLE
// 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).
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);
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);
// Open or create one or more SV_Semaphores. We return 0 if all is
// OK, else -1.
int close (void);
// Close a ACE_SV_Semaphore, marking it as invalid for subsequent
// operations...
int remove (void) const;
// 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.
// = Semaphore acquire and release methods.
int acquire (u_short n = 0, int flags = 0) const;
// 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_read (u_short n = 0, int flags = 0) const;
// Acquire a semaphore for reading.
int acquire_write (u_short n = 0, int flags = 0) const;
// Acquire a semaphore for writing
int tryacquire (u_short n = 0, int flags = 0) const;
// Non-blocking version of <acquire>.
int tryacquire_read (u_short n = 0, int flags = 0) const;
// Try to acquire the semaphore for reading.
int tryacquire_write (u_short n = 0, int flags = 0) const;
// Try to acquire the semaphore for writing.
int release (u_short n = 0, int flags = 0) const;
// Increment ACE_SV_Semaphore by one. Dijkstra's V operation,
// Tannenbaums UP operation.
// = Semaphore operation methods.
int op (int val, u_short semnum = 0, int flags = SEM_UNDO) const;
// General ACE_SV_Semaphore operation. Increment or decrement by a
// specific amount (positive or negative; amount can`t be zero).
int op (sembuf op_vec[], u_short nsems) const;
// General ACE_SV_Semaphore operation on an array of SV_Semaphores.
// = 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;
int get_id (void) const;
// Get underlying internal id.
void dump (void) const;
// Dump the state of an object.
ACE_ALLOC_HOOK_DECLARE;
// Declare the dynamic allocation hooks.
protected:
key_t key_;
// Semaphore key.
int internal_id_;
// Internal ID to identify the semaphore group within this process.
int sem_number_;
// Number of semaphores we're creating.
int init (key_t k = ACE_INVALID_SEM_KEY, int i = -1);
key_t name_2_key (const char *name);
// 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.
};
#if !defined (ACE_LACKS_INLINE_FUNCTIONS)
#include "ace/SV_Semaphore_Simple.i"
#endif
#endif /* _SV_SEMAPHORE_SIMPLE_H */
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