Copyright 1996-2003 John D. Polstra.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgment:
* This product includes software developed by John D. Polstra.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id: SyncQueue.mg.html,v 1.3 2010-04-29 17:17:58 wagner Exp $
GENERIC MODULE SyncQueue(Elem, Seq);
Where Seq is a generic instance Sequence(Elem).
IMPORT Thread;
REVEAL
Private = MUTEX BRANDED OBJECT END;
T = Public BRANDED OBJECT
seq: Seq.T;
cond: Thread.Condition;
qsize: CARDINAL := 0;
closed: BOOLEAN := FALSE;
OVERRIDES
init := Init;
put := Put;
close := Close;
get := Get;
EOF := TestEOF;
size := Size;
END;
PROCEDURE Close(self: T) =
VAR
doSignal: BOOLEAN;
BEGIN
LOCK self DO
doSignal := self.qsize = 0 AND NOT self.closed;
self.closed := TRUE;
END;
IF doSignal THEN Thread.Signal(self.cond) END;
END Close;
PROCEDURE Init(self: T; sizeHint: CARDINAL := 5): T =
BEGIN
self.seq := NEW(Seq.T).init(sizeHint);
self.cond := NEW(Thread.Condition);
RETURN self;
END Init;
PROCEDURE Get(self: T): Elem.T
RAISES {EndOfFile, Thread.Alerted} =
BEGIN
LOCK self DO
WHILE self.qsize = 0 AND NOT self.closed DO
Thread.AlertWait(self, self.cond);
END;
IF self.qsize = 0 THEN RAISE EndOfFile END;
DEC(self.qsize);
RETURN self.seq.remlo();
END;
END Get;
PROCEDURE Put(self: T; READONLY e: Elem.T) =
VAR
doSignal: BOOLEAN;
BEGIN
LOCK self DO
<* ASSERT NOT self.closed *>
doSignal := self.qsize = 0;
self.seq.addhi(e);
INC(self.qsize);
END;
IF doSignal THEN Thread.Signal(self.cond) END;
END Put;
PROCEDURE Size(self: T): CARDINAL =
VAR
size: CARDINAL;
BEGIN
LOCK self DO
size := self.qsize;
IF self.closed THEN INC(size) END;
END;
RETURN size;
END Size;
PROCEDURE TestEOF(self: T): BOOLEAN
RAISES {Thread.Alerted} =
BEGIN
LOCK self DO
WHILE self.qsize = 0 AND NOT self.closed DO
Thread.AlertWait(self, self.cond);
END;
RETURN self.qsize = 0;
END;
END TestEOF;
BEGIN
END SyncQueue.