From bbae92ba08f8bc5d4d93d45b3e032686270dc99e Mon Sep 17 00:00:00 2001
From: rpj <rpj>
Date: Mon, 25 Apr 2005 00:49:04 +0000
Subject: ''

---
 pthread_cond_signal.c | 125 +-------------------------------------------------
 1 file changed, 1 insertion(+), 124 deletions(-)

(limited to 'pthread_cond_signal.c')

diff --git a/pthread_cond_signal.c b/pthread_cond_signal.c
index 220a5dd..2b4f6d4 100644
--- a/pthread_cond_signal.c
+++ b/pthread_cond_signal.c
@@ -36,130 +36,7 @@
  *
  * -------------------------------------------------------------
  * Algorithm:
- * The algorithm used in this implementation is that developed by
- * Alexander Terekhov in colaboration with Louis Thomas. The bulk
- * of the discussion is recorded in the file README.CV, which contains
- * several generations of both colaborators original algorithms. The final
- * algorithm used here is the one referred to as
- *
- *     Algorithm 8a / IMPL_SEM,UNBLOCK_STRATEGY == UNBLOCK_ALL
- * 
- * presented below in pseudo-code as it appeared:
- *
- *
- * given:
- * semBlockLock - bin.semaphore
- * semBlockQueue - semaphore
- * mtxExternal - mutex or CS
- * mtxUnblockLock - mutex or CS
- * nWaitersGone - int
- * nWaitersBlocked - int
- * nWaitersToUnblock - int
- * 
- * wait( timeout ) {
- * 
- *   [auto: register int result          ]     // error checking omitted
- *   [auto: register int nSignalsWasLeft ]
- *   [auto: register int nWaitersWasGone ]
- * 
- *   sem_wait( semBlockLock );
- *   nWaitersBlocked++;
- *   sem_post( semBlockLock );
- * 
- *   unlock( mtxExternal );
- *   bTimedOut = sem_wait( semBlockQueue,timeout );
- * 
- *   lock( mtxUnblockLock );
- *   if ( 0 != (nSignalsWasLeft = nWaitersToUnblock) ) {
- *     if ( bTimeout ) {                       // timeout (or canceled)
- *       if ( 0 != nWaitersBlocked ) {
- *         nWaitersBlocked--;
- *       }
- *       else {
- *         nWaitersGone++;                     // count spurious wakeups.
- *       }
- *     }
- *     if ( 0 == --nWaitersToUnblock ) {
- *       if ( 0 != nWaitersBlocked ) {
- *         sem_post( semBlockLock );           // open the gate.
- *         nSignalsWasLeft = 0;                // do not open the gate
- *                                             // below again.
- *       }
- *       else if ( 0 != (nWaitersWasGone = nWaitersGone) ) {
- *         nWaitersGone = 0;
- *       }
- *     }
- *   }
- *   else if ( INT_MAX/2 == ++nWaitersGone ) { // timeout/canceled or
- *                                             // spurious semaphore :-)
- *     sem_wait( semBlockLock );
- *     nWaitersBlocked -= nWaitersGone;     // something is going on here
- *                                          //  - test of timeouts? :-)
- *     sem_post( semBlockLock );
- *     nWaitersGone = 0;
- *   }
- *   unlock( mtxUnblockLock );
- * 
- *   if ( 1 == nSignalsWasLeft ) {
- *     if ( 0 != nWaitersWasGone ) {
- *       // sem_adjust( semBlockQueue,-nWaitersWasGone );
- *       while ( nWaitersWasGone-- ) {
- *         sem_wait( semBlockQueue );       // better now than spurious later
- *       }
- *     } sem_post( semBlockLock );          // open the gate
- *   }
- * 
- *   lock( mtxExternal );
- * 
- *   return ( bTimedOut ) ? ETIMEOUT : 0;
- * }
- * 
- * signal(bAll) {
- * 
- *   [auto: register int result         ]
- *   [auto: register int nSignalsToIssue]
- * 
- *   lock( mtxUnblockLock );
- * 
- *   if ( 0 != nWaitersToUnblock ) {        // the gate is closed!!!
- *     if ( 0 == nWaitersBlocked ) {        // NO-OP
- *       return unlock( mtxUnblockLock );
- *     }
- *     if (bAll) {
- *       nWaitersToUnblock += nSignalsToIssue=nWaitersBlocked;
- *       nWaitersBlocked = 0;
- *     }
- *     else {
- *       nSignalsToIssue = 1;
- *       nWaitersToUnblock++;
- *       nWaitersBlocked--;
- *     }
- *   }
- *   else if ( nWaitersBlocked > nWaitersGone ) { // HARMLESS RACE CONDITION!
- *     sem_wait( semBlockLock );                  // close the gate
- *     if ( 0 != nWaitersGone ) {
- *       nWaitersBlocked -= nWaitersGone;
- *       nWaitersGone = 0;
- *     }
- *     if (bAll) {
- *       nSignalsToIssue = nWaitersToUnblock = nWaitersBlocked;
- *       nWaitersBlocked = 0;
- *     }
- *     else {
- *       nSignalsToIssue = nWaitersToUnblock = 1;
- *       nWaitersBlocked--;
- *     }
- *   }
- *   else { // NO-OP
- *     return unlock( mtxUnblockLock );
- *   }
- * 
- *   unlock( mtxUnblockLock );
- *   sem_post( semBlockQueue,nSignalsToIssue );
- *   return result;
- * }
- * -------------------------------------------------------------
- *
+ * See the comments at the top of pthread_cond_wait.c.
  */
 
 #include "pthread.h"
-- 
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