X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FSelect.c;h=677fdd2c8198103a9e0c095efc532593c405b113;hb=c389ab20bbfd0ea98953d630502a43fe44050f2c;hp=a2c990ec60e7892a54e2fb825616aedee3829330;hpb=7457757f193b28b5fe8fee01edbed012c2fda897;p=ghc-hetmet.git diff --git a/ghc/rts/Select.c b/ghc/rts/Select.c index a2c990e..677fdd2 100644 --- a/ghc/rts/Select.c +++ b/ghc/rts/Select.c @@ -1,5 +1,5 @@ /* ----------------------------------------------------------------------------- - * $Id: Select.c,v 1.21 2002/07/17 09:21:51 simonmar Exp $ + * $Id: Select.c,v 1.29 2003/06/26 12:22:59 stolz Exp $ * * (c) The GHC Team 1995-2002 * @@ -7,6 +7,7 @@ * * ---------------------------------------------------------------------------*/ + /* we're outside the realms of POSIX here... */ /* #include "PosixSource.h" */ @@ -14,8 +15,10 @@ #include "Schedule.h" #include "RtsUtils.h" #include "RtsFlags.h" +#include "Timer.h" #include "Itimer.h" #include "Signals.h" +#include "Capability.h" # ifdef HAVE_SYS_TYPES_H # include @@ -25,16 +28,23 @@ # include # endif -# ifdef mingw32_TARGET_OS -# include -# endif - #include #include +#ifdef HAVE_UNISTD_H +#include +#endif + /* last timestamp */ nat timestamp = 0; +#ifdef RTS_SUPPORTS_THREADS +static rtsBool isWorkerBlockedInAwaitEvent = rtsFalse; +static rtsBool workerWakeupPending = rtsFalse; +static int workerWakeupPipe[2]; +static rtsBool workerWakeupInited = rtsFalse; +#endif + /* There's a clever trick here to avoid problems when the time wraps * around. Since our maximum delay is smaller than 31 bits of ticks * (it's actually 31 bits of microseconds), we can safely check @@ -84,13 +94,10 @@ awaitEvent(rtsBool wait) StgTSO *tso, *prev, *next; rtsBool ready; fd_set rfd,wfd; -#ifndef mingw32_TARGET_OS int numFound; int maxfd = -1; -#endif rtsBool select_succeeded = rtsTrue; rtsBool unblock_all = rtsFalse; - static rtsBool prev_unblocked_all = rtsFalse; struct timeval tv; lnat min, ticks; @@ -126,7 +133,6 @@ awaitEvent(rtsBool wait) min = 0x7ffffff; } -#ifndef mingw32_TARGET_OS /* * Collect all of the fd's that we're interested in */ @@ -158,6 +164,15 @@ awaitEvent(rtsBool wait) } } +#ifdef RTS_SUPPORTS_THREADS + if(!workerWakeupInited) { + pipe(workerWakeupPipe); + workerWakeupInited = rtsTrue; + } + FD_SET(workerWakeupPipe[0], &rfd); + maxfd = workerWakeupPipe[0] > maxfd ? workerWakeupPipe[0] : maxfd; +#endif + /* Release the scheduler lock while we do the poll. * this means that someone might muck with the blocked_queue * while we do this, but it shouldn't matter: @@ -170,6 +185,11 @@ awaitEvent(rtsBool wait) * * I believe none of these cases lead to trouble --SDM. */ + +#ifdef RTS_SUPPORTS_THREADS + isWorkerBlockedInAwaitEvent = rtsTrue; + workerWakeupPending = rtsFalse; +#endif RELEASE_LOCK(&sched_mutex); /* Check for any interesting events */ @@ -188,12 +208,16 @@ awaitEvent(rtsBool wait) should we see a bad file descriptor & give the threads a chance to clean up their act. - To avoid getting stuck in a loop, repeated EBADF failures - are 'handled' through barfing. + Note: assume here that threads becoming unblocked + will try to read/write the file descriptor before trying + to issue a threadWaitRead/threadWaitWrite again (==> an + IOError will result for the thread that's got the bad + file descriptor.) Hence, there's no danger of a bad + file descriptor being repeatedly select()'ed on, so + the RTS won't loop. */ - if ( errno == EBADF && !prev_unblocked_all) { + if ( errno == EBADF ) { unblock_all = rtsTrue; - prev_unblocked_all = rtsTrue; break; } else { fprintf(stderr,"%d\n", errno); @@ -202,20 +226,17 @@ awaitEvent(rtsBool wait) barf("select failed"); } } -#else /* on mingwin */ - while (1) { - Sleep(0); /* don't busy wait */ -#endif /* mingw32_TARGET_OS */ ACQUIRE_LOCK(&sched_mutex); +#ifdef RTS_SUPPORTS_THREADS + isWorkerBlockedInAwaitEvent = rtsFalse; +#endif - prev_unblocked_all = rtsFalse; - -#ifndef mingw32_TARGET_OS /* We got a signal; could be one of ours. If so, we need * to start up the signal handler straight away, otherwise * we could block for a long time before the signal is * serviced. */ +#if defined(RTS_USER_SIGNALS) if (signals_pending()) { RELEASE_LOCK(&sched_mutex); /* ToDo: kill */ startSignalHandlers(); @@ -241,6 +262,18 @@ awaitEvent(rtsBool wait) return; /* still hold the lock */ } +#ifdef RTS_SUPPORTS_THREADS + /* If another worker thread wants to take over, + * return to the scheduler + */ + if (needToYieldToReturningWorker()) { + return; /* still hold the lock */ + } +#endif + +#ifdef RTS_SUPPORTS_THREADS + isWorkerBlockedInAwaitEvent = rtsTrue; +#endif RELEASE_LOCK(&sched_mutex); } @@ -286,6 +319,36 @@ awaitEvent(rtsBool wait) blocked_queue_tl = prev; } } - + +#if defined(RTS_SUPPORTS_THREADS) + // if we were woken up by wakeBlockedWorkerThread, + // read the dummy byte from the pipe + if(select_succeeded && FD_ISSET(workerWakeupPipe[0], &rfd)) { + unsigned char dummy; + wait = rtsFalse; + read(workerWakeupPipe[0],&dummy,1); + } +#endif } while (wait && !interrupted && run_queue_hd == END_TSO_QUEUE); } + + +#ifdef RTS_SUPPORTS_THREADS +/* wakeBlockedWorkerThread + * + * If a worker thread is currently blocked within awaitEvent, + * wake it. + * Must be called with sched_mutex held. + */ +void +wakeBlockedWorkerThread() +{ + if(isWorkerBlockedInAwaitEvent && !workerWakeupPending) { + unsigned char dummy = 42; // Any value will do here + + // write something so that select() wakes up + write(workerWakeupPipe[1],&dummy,1); + workerWakeupPending = rtsTrue; + } +} +#endif