[Scsh-checkins] scsh-0.6/scheme/big placeholder.scm queue.scm

[Mike Sperber <sperber@users.sourceforge.net>]

Update of /cvsroot/scsh/scsh-0.6/scheme/big
In directory usw-pr-cvs1:/tmp/cvs-serv5512/scheme/big

Modified Files:
        placeholder.scm queue.scm 
Log Message:
Replace Martin's implementation of selective blocking by the one in
Scheme 48 1.0.1.

Namely, instead of associating a list of queues with every thread, we
associate a single cell, holding the thread.  That cell is stored in
thread queues, and once a thread is made runnable again, the cell is
set to #f.  The thread-queue accessors ignore cells containing #f.

Implement an experimental OBTAIN-LOCK-MULTIPLE to test the whole
thing.