Synchronization enhancements - inproc & msgqueue. Absolute waits...

5 files changed, 113 insertions, 126 deletions

diff --git a/src/platform/posix/posix_alloc.c b/src/platform/posix/posix_alloc.c
index eb5c889e..83fe305d 100644
--- a/src/platform/posix/posix_alloc.c
+++ b/src/platform/posix/posix_alloc.c
@@ -1,11 +1,11 @@
-/*
- * Copyright 2016 Garrett D'Amore <garrett@damore.org>
- *
- * This software is supplied under the terms of the MIT License, a
- * copy of which should be located in the distribution where this
- * file was obtained (LICENSE.txt).  A copy of the license may also be
- * found online at https://opensource.org/licenses/MIT.
- */
+//
+// Copyright 2016 Garrett D'Amore <garrett@damore.org>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
 
 #include "core/nng_impl.h"
 
@@ -13,9 +13,7 @@
 
 #include <stdlib.h>
 
-/*
- * POSIX memory allocation.  This is pretty much standard C.
- */
+// POSIX memory allocation.  This is pretty much standard C.
 void *
 nni_alloc(size_t size)
 {
diff --git a/src/platform/posix/posix_clock.c b/src/platform/posix/posix_clock.c
index 83f0b151..48a1e09b 100644
--- a/src/platform/posix/posix_clock.c
+++ b/src/platform/posix/posix_clock.c
@@ -1,15 +1,13 @@
-/*
- * Copyright 2016 Garrett D'Amore <garrett@damore.org>
- *
- * This software is supplied under the terms of the MIT License, a
- * copy of which should be located in the distribution where this
- * file was obtained (LICENSE.txt).  A copy of the license may also be
- * found online at https://opensource.org/licenses/MIT.
- */
-
-/*
- * POSIX clock stuff.
- */
+//
+// Copyright 2016 Garrett D'Amore <garrett@damore.org>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+// POSIX clock stuff.
 #include "core/nng_impl.h"
 
 #ifdef PLATFORM_POSIX_CLOCK
@@ -20,9 +18,7 @@
 
 #ifndef NNG_USE_GETTIMEOFDAY
 
-/*
- * Use POSIX realtime stuff.
- */
+// Use POSIX realtime stuff
 uint64_t
 nni_clock(void)
 {
@@ -56,18 +52,16 @@ nni_usleep(uint64_t usec)
 }
 
 
-#else   /* NNG_USE_GETTIMEOFDAY */
+#else   // NNG_USE_GETTIMEOFDAY
 
-/*
- * If you're here, its because you don't have a modern clock_gettime with
- * monotonic clocks, or the necessary pthread_condattr_settclock().  In
- * this case, you should be advised that *bad* things can happen if your
- * system clock changes time while programs using this library are running.
- * (Basically, timeouts can take longer or shorter, leading to either hangs
- * or apparent spurious errors.  Eventually it should all sort itself out,
- * but if you change the clock by a large amount you might wonder what the
- * heck is happening until it does.)
- */
+// If you're here, its because you don't have a modern clock_gettime with
+// monotonic clocks, or the necessary pthread_condattr_settclock().  In
+// this case, you should be advised that *bad* things can happen if your
+// system clock changes time while programs using this library are running.
+// (Basically, timeouts can take longer or shorter, leading to either hangs
+// or apparent spurious errors.  Eventually it should all sort itself out,
+// but if you change the clock by a large amount you might wonder what the
+// heck is happening until it does.)
 
 #include <pthread.h>
 #include <sys/time.h>
@@ -94,25 +88,21 @@ nni_clock(void)
 void
 nni_usleep(uint64_t usec)
 {
-	/*
-	 * So probably there is no nanosleep.  We could in theory use
-	 * pthread condition variables, but that means doing memory
-	 * allocation, or forcing the use of pthreads where the platform
-	 * might be preferring the use of another threading package.
-	 * Additionally, use of pthreads means that we cannot use
-	 * relative times in a clock_settime safe manner.
-	 * So we can use poll() instead, which is rather coarse, but
-	 * pretty much guaranteed to work.
-	 */
+	// So probably there is no nanosleep.  We could in theory use
+	// pthread condition variables, but that means doing memory
+	// allocation, or forcing the use of pthreads where the platform
+	// might be preferring the use of another threading package.
+	// Additionally, use of pthreads means that we cannot use
+	// relative times in a clock_settime safe manner.
+	// So we can use poll() instead, which is rather coarse, but
+	// pretty much guaranteed to work.
 	struct pollfd pfd;
 	uint64_t now;
 	uint64_t expire;
 
-	/*
-	 * Possibly we could pass NULL instead of pfd, but passing a valid
-	 * pointer ensures that if the system dereferences the pointer it
-	 * won't come back with EFAULT.
-	 */
+	// Possibly we could pass NULL instead of pfd, but passing a valid
+	// pointer ensures that if the system dereferences the pointer it
+	// won't come back with EFAULT.
 	pfd.fd = -1;
 	pfd.events = 0;
 
@@ -120,19 +110,17 @@ nni_usleep(uint64_t usec)
 	expire = now + usec;
 
 	while (now < expire) {
-		/*
-		 * In theory we could round up to a whole number of msec,
-		 * but under the covers poll already does some rounding up,
-		 * and the loop above guarantees that we will not bail out
-		 * early.  So this gives us a better chance to avoid adding
-		 * nearly an extra unneeded millisecond to the wait.
-		 */
+		// In theory we could round up to a whole number of msec,
+		// but under the covers poll already does some rounding up,
+		// and the loop above guarantees that we will not bail out
+		// early.  So this gives us a better chance to avoid adding
+		// nearly an extra unneeded millisecond to the wait.
 		(void) poll(&pfd, 0, (int) ((expire - now) / 1000));
 		now = nni_clock();
 	}
 }
 
 
-#endif  /* NNG_USE_GETTIMEOFDAY */
+#endif  // NNG_USE_GETTIMEOFDAY
 
-#endif  /* PLATFORM_POSIX_CLOCK */
+#endif  // PLATFORM_POSIX_CLOCK
diff --git a/src/platform/posix/posix_impl.h b/src/platform/posix/posix_impl.h
index a7b15edc..4f93b101 100644
--- a/src/platform/posix/posix_impl.h
+++ b/src/platform/posix/posix_impl.h
@@ -10,6 +10,13 @@
 #ifndef PLATFORM_POSIX_IMPL_H
 #define PLATFORM_POSIX_IMPL_H
 
+// Some dependency notes:
+//
+// PLATFORM_POSIX_THREAD and PLATFORM_POSIX_SYNCH depend on each other,
+// and they both depend on PLATFORM_POSIX_CLOCK.  Furthermore, note that
+// when using PLATFORM_POSIX_CLOCK, your condition variable timeouts need
+// to use the same base clock values.  Normally all three should be used
+// together.
 #ifdef  PLATFORM_POSIX
 #define PLATFORM_POSIX_ALLOC
 #define PLATFORM_POSIX_DEBUG
diff --git a/src/platform/posix/posix_synch.c b/src/platform/posix/posix_synch.c
index a3129f62..c0a2721c 100644
--- a/src/platform/posix/posix_synch.c
+++ b/src/platform/posix/posix_synch.c
@@ -1,23 +1,14 @@
-/*
- * Copyright 2016 Garrett D'Amore <garrett@damore.org>
- *
- * This software is supplied under the terms of the MIT License, a
- * copy of which should be located in the distribution where this
- * file was obtained (LICENSE.txt).  A copy of the license may also be
- * found online at https://opensource.org/licenses/MIT.
- */
-
-/*
- * This is more of a direct #include of a .c rather than .h file.
- * But having it be a .h makes compiler rules work out properly.  Do
- * not include this more than once into your program, or you will
- * get multiple symbols defined.
- */
-
-/*
- * POSIX synchronization (mutexes and condition variables).  This uses
- * pthreads.
- */
+//
+// Copyright 2016 Garrett D'Amore <garrett@damore.org>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+// POSIX synchronization (mutexes and condition variables).  This uses
+// pthreads.
 
 #include "core/nng_impl.h"
 
@@ -51,6 +42,7 @@ nni_mutex_fini(nni_mutex *mp)
 }
 
 
+// XXX: REMOVE THIS FUNCTION
 int
 nni_mutex_create(nni_mutex_t *mp)
 {
@@ -62,7 +54,7 @@ nni_mutex_create(nni_mutex_t *mp)
 		return (NNG_ENOMEM);
 	}
 
-	/* We ask for more error checking... */
+	// We ask for more error checking...
 	if (pthread_mutexattr_init(&attr) != 0) {
 		nni_free(m, sizeof (*m));
 		return (NNG_ENOMEM);
@@ -87,6 +79,7 @@ nni_mutex_create(nni_mutex_t *mp)
 }
 
 
+// XXX: REMOVE THIS FUNCTION
 void
 nni_mutex_destroy(nni_mutex_t m)
 {
@@ -98,7 +91,7 @@ nni_mutex_destroy(nni_mutex_t m)
 
 
 void
-nni_mutex_enter(nni_mutex_t m)
+nni_mutex_enter(nni_mutex *m)
 {
 	if (pthread_mutex_lock(&m->mx) != 0) {
 		nni_panic("pthread_mutex_lock failed");
@@ -107,7 +100,7 @@ nni_mutex_enter(nni_mutex_t m)
 
 
 void
-nni_mutex_exit(nni_mutex_t m)
+nni_mutex_exit(nni_mutex *m)
 {
 	if (pthread_mutex_unlock(&m->mx) != 0) {
 		nni_panic("pthread_mutex_unlock failed");
@@ -116,7 +109,7 @@ nni_mutex_exit(nni_mutex_t m)
 
 
 int
-nni_mutex_tryenter(nni_mutex_t m)
+nni_mutex_tryenter(nni_mutex *m)
 {
 	if (pthread_mutex_trylock(&m->mx) != 0) {
 		return (NNG_EBUSY);
@@ -125,51 +118,40 @@ nni_mutex_tryenter(nni_mutex_t m)
 }
 
 
-static int
-nni_cond_attr(pthread_condattr_t **attrpp)
+int
+nni_cond_init(nni_cond *c, nni_mutex *m)
 {
-#if defined(NNG_USE_GETTIMEOFDAY) || NNG_USE_CLOCKID == CLOCK_REALTIME
-	*attrpp = NULL;
+	if (pthread_cond_init(&c->cv, &nni_condattr) != 0) {
+		// In theory could be EAGAIN, but handle like ENOMEM
+		nni_free(c, sizeof (*c));
+		return (NNG_ENOMEM);
+	}
+	c->mx = &m->mx;
 	return (0);
+}
 
-#else
-	/* In order to make this fast, avoid reinitializing attrs. */
-	static pthread_condattr_t attr;
-	static pthread_mutex_t mx = PTHREAD_MUTEX_INITIALIZER;
-	static int init = 0;
-	int rv;
 
-	 // For efficiency's sake, we try to reuse the same attr for the
-	 // life of the library.  This avoids many reallocations.  Technically
-	 // this means that we will leak the attr on exit(), but this is
-	 // preferable to constantly allocating and reallocating it.
-	if (init) {
-		*attrpp = &attr;
-		return (0);
+void
+nni_cond_fini(nni_cond *c)
+{
+	if (pthread_cond_destroy(&c->cv) != 0) {
+		nni_panic("pthread_cond_destroy failed");
 	}
+}
 
-	(void) pthread_mutex_lock(&mx);
-	while (!init) {
-		if ((rv = pthread_condattr_init(&attr)) != 0) {
-			(void) pthread_mutex_unlock(&mx);
-			return (NNG_ENOMEM);
-		}
-		rv = pthread_condattr_setclock(&attr, NNG_USE_CLOCKID);
-		if (rv != 0) {
-			nni_panic("condattr_setclock: %s", strerror(rv));
-		}
-		init = 1;
-	}
-	(void) pthread_mutex_unlock(&mx);
-	*attrpp = &attr;
-	return (0);
 
-#endif
+// XXXX: REMOVE THIS FUNCTION
+static int
+nni_cond_attr(pthread_condattr_t **attrpp)
+{
+	*attrpp = NULL;
+	return (0);
 }
 
 
+// XXX: REMOVE THIS FUNCTION
 int
-nni_cond_create(nni_cond_t *cvp, nni_mutex_t mx)
+nni_cond_create(nni_cond **cvp, nni_mutex *mx)
 {
 	/*
 	 * By preference, we use a CLOCK_MONOTONIC version of condition
@@ -196,8 +178,9 @@ nni_cond_create(nni_cond_t *cvp, nni_mutex_t mx)
 }
 
 
+// XXX: REMOVE THIS FUNCTION
 void
-nni_cond_destroy(nni_cond_t c)
+nni_cond_destroy(nni_cond *c)
 {
 	if (pthread_cond_destroy(&c->cv) != 0) {
 		nni_panic("pthread_cond_destroy failed");
@@ -207,7 +190,7 @@ nni_cond_destroy(nni_cond_t c)
 
 
 void
-nni_cond_signal(nni_cond_t c)
+nni_cond_signal(nni_cond *c)
 {
 	if (pthread_cond_signal(&c->cv) != 0) {
 		nni_panic("pthread_cond_signal failed");
@@ -216,7 +199,7 @@ nni_cond_signal(nni_cond_t c)
 
 
 void
-nni_cond_broadcast(nni_cond_t c)
+nni_cond_broadcast(nni_cond *c)
 {
 	if (pthread_cond_broadcast(&c->cv) != 0) {
 		nni_panic("pthread_cond_broadcast failed");
@@ -225,7 +208,7 @@ nni_cond_broadcast(nni_cond_t c)
 
 
 void
-nni_cond_wait(nni_cond_t c)
+nni_cond_wait(nni_cond *c)
 {
 	if (pthread_cond_wait(&c->cv, c->mx) != 0) {
 		nni_panic("pthread_cond_wait failed");
@@ -234,7 +217,7 @@ nni_cond_wait(nni_cond_t c)
 
 
 int
-nni_cond_timedwait(nni_cond_t c, uint64_t usec)
+nni_cond_waituntil(nni_cond *c, uint64_t usec)
 {
 	struct timespec ts;
 	int rv;
@@ -255,4 +238,15 @@ nni_cond_timedwait(nni_cond_t c, uint64_t usec)
 }
 
 
+int
+nni_cond_timedwait(nni_cond *c, int usec)
+{
+	if (usec < 0) {
+		nni_cond_wait(c);
+		return (0);
+	}
+	return (nni_cond_waituntil(c, ((uint64_t) usec) + nni_clock()));
+}
+
+
 #endif
diff --git a/src/platform/posix/posix_thread.c b/src/platform/posix/posix_thread.c
index 1bbe6e28..79f69762 100644
--- a/src/platform/posix/posix_thread.c
+++ b/src/platform/posix/posix_thread.c
@@ -28,7 +28,7 @@ static int plat_init = 0;
 static int plat_fork = 0;
 
 static void *
-thrfunc(void *arg)
+nni_thrfunc(void *arg)
 {
 	nni_thread_t thr = arg;
 
@@ -49,7 +49,7 @@ nni_thread_create(nni_thread_t *tp, void (*fn)(void *), void *arg)
 	thr->func = fn;
 	thr->arg = arg;
 
-	if ((rv = pthread_create(&thr->tid, NULL, thrfunc, thr)) != 0) {
+	if ((rv = pthread_create(&thr->tid, NULL, nni_thrfunc, thr)) != 0) {
 		nni_free(thr, sizeof (*thr));
 		return (NNG_ENOMEM);
 	}