Changes to attempt to silence bcc64x
[ACE_TAO.git] / ACE / ace / RW_Process_Mutex.h
blob193c88eb273b7c4a604ae5586b77cb6cffc8e41a
1 // -*- C++ -*-
2 //
3 //=============================================================================
4 /**
5 * @file RW_Process_Mutex.h
7 * @author Douglas C. Schmidt <d.schmidt@vanderbilt.edu>
8 */
9 //=============================================================================
11 #ifndef ACE_RW_PROCESS_MUTEX_H
12 #define ACE_RW_PROCESS_MUTEX_H
14 #include /**/ "ace/pre.h"
16 #include "ace/File_Lock.h"
18 #if !defined (ACE_LACKS_PRAGMA_ONCE)
19 # pragma once
20 #endif /* ACE_LACKS_PRAGMA_ONCE */
22 #include "ace/Default_Constants.h"
24 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
26 /**
27 * @class ACE_RW_Process_Mutex
29 * @brief Wrapper for readers/writer locks that exist across processes.
31 * @note This class uses an ACE_File_Lock as its implementation. Thus, it
32 * can only be reliably used between separate processes, rather than
33 * threads in the same process. This isn't a limitation of ACE, it's simply
34 * the file lock semantics on UNIX and Win32.
36 * @todo For systems with pthread_rwlockattr_setpshared one
37 * may consider using them to make the mutex faster.
39 class ACE_Export ACE_RW_Process_Mutex
41 public:
42 /// Create a cross-process readers/writer mutex, passing in the optional
43 /// @a name, @a flags and @a mode \sa ACE_File_Lock.
44 /// If not specified, a name is generated and flags and mode are set
45 /// to default platform values.
46 ACE_RW_Process_Mutex (const ACE_TCHAR *name = 0,
47 int flags = O_CREAT|O_RDWR,
48 mode_t mode = ACE_DEFAULT_RW_PROCESS_MUTEX_PERMS);
50 ~ACE_RW_Process_Mutex ();
52 /**
53 * Explicitly destroy the mutex. Note that only one thread should
54 * call this method since it doesn't protect against race
55 * conditions.
57 int remove ();
59 /// Same as acquire_write().
60 /// Acquire lock ownership; blocks until the lock is acquired or the
61 /// operation fails.
62 int acquire ();
64 /**
65 * Same as tryacquire_write().
66 * Try to acquire the lock, but do not block if the lock is not immediately
67 * acquired.
69 * @retval -1 on failure. If the lock is already held, @c errno is set
70 * to @c EBUSY.
72 int tryacquire ();
74 /// Release lock.
75 int release ();
77 /// Acquire read lock; blocks until the lock is acquired or the
78 /// operation fails.
79 int acquire_read ();
81 /// Acquire write lock; blocks until the lock is acquired or the
82 /// operation fails.
83 int acquire_write ();
85 /**
86 * Try to acquire the read lock, but do not block if the lock is not
87 * immediately acquired.
89 * @retval -1 on failure. If the lock is already held, @c errno is set
90 * to @c EBUSY.
92 int tryacquire_read ();
94 /**
95 * Try to acquire the write lock, but do not block if the lock is not
96 * immediately acquired.
98 * @retval -1 on failure. If the lock is already held, @c errno is set
99 * to @c EBUSY.
101 int tryacquire_write ();
103 /// Attempt to upgrade a read lock to a write lock. Returns 0 on
104 /// success, -1 on failure.
105 int tryacquire_write_upgrade ();
107 /// Return the underlying lock.
108 const ACE_File_Lock &lock () const;
110 /// Dump the state of an object.
111 void dump () const;
113 /// Declare the dynamic allocation hooks.
114 ACE_ALLOC_HOOK_DECLARE;
116 private:
117 /// If the user does not provide a name we generate a unique name in
118 /// this buffer.
119 ACE_TCHAR name_[ACE_UNIQUE_NAME_LEN];
121 /// Create and return the unique name.
122 const ACE_TCHAR *unique_name ();
124 /// We need this to get the readers/writer semantics...
125 ACE_File_Lock lock_;
128 ACE_END_VERSIONED_NAMESPACE_DECL
130 #if defined (__ACE_INLINE__)
131 #include "ace/RW_Process_Mutex.inl"
132 #endif /* __ACE_INLINE__ */
134 #include /**/ "ace/post.h"
135 #endif /* ACE_RW_PROCESS_MUTEX_H */