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authorrpj <rpj>2002-02-18 03:16:52 +0000
committerrpj <rpj>2002-02-18 03:16:52 +0000
commita416ab17ecf9f2cb0f1e3f7bd645a8d1ce690ca2 (patch)
tree72f776cd64e48824a5578ff7a523bc69097143b4 /pthread_timechange_handler_np.c
parente6f1797e9e9925ae7f9dda54806ef8f52ae3ed07 (diff)
Major reorganisation of source code; new routine and tests added.
Diffstat (limited to 'pthread_timechange_handler_np.c')
-rw-r--r--pthread_timechange_handler_np.c108
1 files changed, 108 insertions, 0 deletions
diff --git a/pthread_timechange_handler_np.c b/pthread_timechange_handler_np.c
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+/*
+ * pthread_timechange_handler_np.c
+ *
+ * Description:
+ * This translation unit implements miscellaneous thread functions.
+ *
+ * --------------------------------------------------------------------------
+ *
+ * Pthreads-win32 - POSIX Threads Library for Win32
+ * Copyright(C) 1998 John E. Bossom
+ * Copyright(C) 1999,2002 Pthreads-win32 contributors
+ *
+ * Contact Email: rpj@ise.canberra.edu.au
+ *
+ * The current list of contributors is contained
+ * in the file CONTRIBUTORS included with the source
+ * code distribution. The list can also be seen at the
+ * following World Wide Web location:
+ * http://sources.redhat.com/pthreads-win32/contributors.html
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library in the file COPYING.LIB;
+ * if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include "pthread.h"
+#include "implement.h"
+
+/*
+ * Notes on handling system time adjustments (especially negative ones).
+ * ---------------------------------------------------------------------
+ *
+ * This solution was suggested by Alexander Terekhov, but any errors
+ * in the implementation are mine - [Ross Johnson]
+ *
+ * 1) The problem: threads doing a timedwait on a CV may expect to timeout
+ * at a specific absolute time according to a system timer. If the
+ * system clock is adjusted backwards then those threads sleep longer than
+ * expected. Also, pthreads-win32 converts absolute times to intervals in
+ * order to make use of the underlying Win32, and so waiting threads may
+ * awake before their proper abstimes.
+ *
+ * 2) We aren't able to distinquish between threads on timed or untimed waits,
+ * so we wake them all at the time of the adjustment so that they can
+ * re-evaluate their conditions and re-compute their timeouts.
+ *
+ * 3) We rely on correctly written applications for this to work. Specifically,
+ * they must be able to deal properly with spurious wakeups. That is,
+ * they must re-test their condition upon wakeup and wait again if
+ * the condition is not satisfied.
+ */
+
+void *
+pthread_timechange_handler_np(void * arg)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * Broadcasts all CVs to force re-evaluation and
+ * new timeouts if required.
+ *
+ * PARAMETERS
+ * NONE
+ *
+ *
+ * DESCRIPTION
+ * Broadcasts all CVs to force re-evaluation and
+ * new timeouts if required.
+ *
+ * This routine may be passed directly to pthread_create()
+ * as a new thread in order to run asynchronously.
+ *
+ *
+ * RESULTS
+ * 0 successfully broadcast all CVs
+ * EAGAIN Not all CVs were broadcast
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result = 0;
+ pthread_cond_t cv;
+
+ EnterCriticalSection(&ptw32_cond_list_lock);
+
+ cv = ptw32_cond_list_head;
+
+ while (cv != NULL && 0 == result)
+ {
+ result = pthread_cond_broadcast(&cv);
+ cv = cv->next;
+ }
+
+ LeaveCriticalSection(&ptw32_cond_list_lock);
+
+ return (void *)(result != 0 ? EAGAIN : 0);
+}
+