ChangeLogTag:Wed Sep 20 12:00:42 2000 Carlos O'Ryan <coryan@uci.edu>

1 files changed, 101 insertions, 0 deletions

diff --git a/ace/RW_Process_Mutex.h b/ace/RW_Process_Mutex.h
new file mode 100644
index 00000000000..51e1dbf6c75
--- /dev/null
+++ b/ace/RW_Process_Mutex.h
@@ -0,0 +1,101 @@
+/* -*- C++ -*- */
+// $Id$
+
+// ============================================================================
+//
+// = LIBRARY
+//    ace
+//
+// = FILENAME
+//    RW_Process_Mutex.h
+//
+// = AUTHOR
+//    Doug Schmidt
+//
+// ============================================================================
+
+#ifndef ACE_RW_PROCESS_MUTEX_H
+#define ACE_RW_PROCESS_MUTEX_H
+#include "ace/pre.h"
+
+#include "ace/File_Lock.h"
+
+#if !defined (ACE_LACKS_PRAGMA_ONCE)
+# pragma once
+#endif /* ACE_LACKS_PRAGMA_ONCE */
+
+class ACE_Export ACE_RW_Process_Mutex
+{
+  // = TITLE
+  //     Wrapper for readers/writer locks that exist across processes.
+  //
+  // = DESCRIPTION
+  //     Note that because this class uses the
+  //     <ACE_File_Lock> as its implementation it only can be reliably
+  //     used between separate processes, rather than threads in the
+  //     same process.  This isn't a limitation of ACE, it's simply
+  //     the file lock semantics on UNIX and Win32.
+public:
+  ACE_RW_Process_Mutex (const ACE_TCHAR *name = 0,
+                        int flags = O_CREAT|O_RDWR);
+  // Create a readers/writer <Process_Mutex>, passing in the optional
+  // <name>.
+
+  ~ACE_RW_Process_Mutex (void);
+
+  int remove (void);
+  // Explicitly destroy the mutex.  Note that only one thread should
+  // call this method since it doesn't protect against race
+  // conditions.
+
+  int acquire (void);
+  // Acquire lock ownership (wait on queue if necessary).
+
+  int tryacquire (void);
+  // Conditionally acquire lock (i.e., don't wait on queue).  Returns
+  // -1 on failure.  If we "failed" because someone else already had
+  // the lock, <errno> is set to <EBUSY>.
+
+  int release (void);
+  // Release lock and unblock a thread at head of queue.
+
+  int acquire_read (void);
+  // Acquire lock ownership (wait on queue if necessary).
+
+  int acquire_write (void);
+  // Acquire lock ownership (wait on queue if necessary).
+
+  int tryacquire_read (void);
+  // Conditionally acquire a lock (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 tryacquire_write (void);
+  // Conditionally acquire a lock (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 tryacquire_write_upgrade (void);
+  // Attempt to upgrade a read lock to a write lock. Returns 0 on
+  // success, -1 on failure.
+
+  const ACE_File_Lock &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.
+
+private:
+  ACE_File_Lock lock_;
+  // We need this to get the readers/writer semantics...
+};
+
+#if defined (__ACE_INLINE__)
+#include "ace/RW_Process_Mutex.inl"
+#endif /* __ACE_INLINE__ */
+
+#include "ace/post.h"
+#endif /* ACE_RW_PROCESS_MUTEX_H */