Added a condvar implementation that works with rwlock_t

src/libstrongswan/Makefile.am

@@ -60,10 +60,10 @@ processing/jobs/job.h processing/jobs/callback_job.h processing/processor.h \
 processing/scheduler.h selectors/traffic_selector.h \
 threading/thread.h threading/thread_value.h \
 threading/mutex.h threading/condvar.h threading/spinlock.h threading/semaphore.h \
-threading/rwlock.h threading/lock_profiler.h utils.h utils/host.h \
-utils/packet.h utils/identification.h utils/lexparser.h utils/linked_list.h \
-utils/blocking_queue.h utils/hashtable.h utils/enumerator.h utils/optionsfrom.h \
-utils/capabilities.h utils/backtrace.h utils/tun_device.h
+threading/rwlock.h threading/rwlock_condvar.h threading/lock_profiler.h \
+utils.h utils/host.h utils/packet.h utils/identification.h utils/lexparser.h \
+utils/linked_list.h utils/blocking_queue.h utils/hashtable.h utils/enumerator.h \
+utils/optionsfrom.h utils/capabilities.h utils/backtrace.h utils/tun_device.h
 endif
 
 library.lo :	$(top_builddir)/config.status

src/libstrongswan/threading/rwlock.c

@@ -21,11 +21,13 @@
 #include <debug.h>
 
 #include "rwlock.h"
+#include "rwlock_condvar.h"
 #include "condvar.h"
 #include "mutex.h"
 #include "lock_profiler.h"
 
 typedef struct private_rwlock_t private_rwlock_t;
+typedef struct private_rwlock_condvar_t private_rwlock_condvar_t;
 
 /**
  * private data of rwlock
@@ -84,6 +86,27 @@ struct private_rwlock_t {
 	lock_profile_t profile;
 };
 
+/**
+ * private data of condvar
+ */
+struct private_rwlock_condvar_t {
+
+	/**
+	 * public interface
+	 */
+	rwlock_condvar_t public;
+
+	/**
+	 * mutex used to implement rwlock condvar
+	 */
+	mutex_t *mutex;
+
+	/**
+	 * regular condvar to implement rwlock condvar
+	 */
+	condvar_t *condvar;
+};
+
 
 #ifdef HAVE_PTHREAD_RWLOCK_INIT
 
@@ -357,3 +380,106 @@ rwlock_t *rwlock_create(rwlock_type_t type)
 
 #endif /* HAVE_PTHREAD_RWLOCK_INIT */
 
+
+METHOD(rwlock_condvar_t, wait_, void,
+	private_rwlock_condvar_t *this, private_rwlock_t *lock)
+{
+	/* at this point we have the write lock locked, to make signals more
+	 * predictable we try to prevent other threads from signaling by acquiring
+	 * the mutex while we still hold the write lock (this assumes they will
+	 * hold the write lock themselves when signaling, which is not mandatory) */
+	this->mutex->lock(this->mutex);
+	/* unlock the rwlock and wait for a signal */
+	lock->public.unlock(&lock->public);
+	this->condvar->wait(this->condvar, this->mutex);
+	/* we release the mutex to allow other threads into the condvar (might even
+	 * be required so we can acquire the lock again below) */
+	this->mutex->unlock(this->mutex);
+	/* finally we reacquire the lock we held previously */
+	lock->public.write_lock(&lock->public);
+}
+
+METHOD(rwlock_condvar_t, timed_wait_abs, bool,
+	private_rwlock_condvar_t *this, private_rwlock_t *lock, timeval_t time)
+{
+	bool timed_out;
+
+	/* see wait() above for details on what is going on here */
+	this->mutex->lock(this->mutex);
+	lock->public.unlock(&lock->public);
+	timed_out = this->condvar->timed_wait_abs(this->condvar, this->mutex, time);
+	this->mutex->unlock(this->mutex);
+	if (!timed_out)
+	{
+		lock->public.write_lock(&lock->public);
+	}
+	return timed_out;
+}
+
+METHOD(rwlock_condvar_t, timed_wait, bool,
+	private_rwlock_condvar_t *this, private_rwlock_t *lock, u_int timeout)
+{
+	timeval_t tv;
+	u_int s, ms;
+
+	time_monotonic(&tv);
+
+	s = timeout / 1000;
+	ms = timeout % 1000;
+
+	tv.tv_sec += s;
+	tv.tv_usec += ms * 1000;
+
+	if (tv.tv_usec > 1000000 /* 1s */)
+	{
+		tv.tv_usec -= 1000000;
+		tv.tv_sec++;
+	}
+	return timed_wait_abs(this, lock, tv);
+}
+
+METHOD(rwlock_condvar_t, signal_, void,
+	private_rwlock_condvar_t *this)
+{
+	this->mutex->lock(this->mutex);
+	this->condvar->signal(this->condvar);
+	this->mutex->unlock(this->mutex);
+}
+
+METHOD(rwlock_condvar_t, broadcast, void,
+	private_rwlock_condvar_t *this)
+{
+	this->mutex->lock(this->mutex);
+	this->condvar->broadcast(this->condvar);
+	this->mutex->unlock(this->mutex);
+}
+
+METHOD(rwlock_condvar_t, condvar_destroy, void,
+	private_rwlock_condvar_t *this)
+{
+	this->condvar->destroy(this->condvar);
+	this->mutex->destroy(this->mutex);
+	free(this);
+}
+
+/*
+ * see header file
+ */
+rwlock_condvar_t *rwlock_condvar_create()
+{
+	private_rwlock_condvar_t *this;
+
+	INIT(this,
+		.public = {
+			.wait = (void*)_wait_,
+			.timed_wait = (void*)_timed_wait,
+			.timed_wait_abs = (void*)_timed_wait_abs,
+			.signal = _signal_,
+			.broadcast = _broadcast,
+			.destroy = _condvar_destroy,
+		},
+		.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
+		.condvar = condvar_create(CONDVAR_TYPE_DEFAULT),
+	);
+	return &this->public;
+}

src/libstrongswan/threading/rwlock_condvar.h

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2012 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup rwlock_condvar rwlock_condvar
+ * @{ @ingroup threading
+ */
+
+#ifndef RWLOCK_CONDVAR_H_
+#define RWLOCK_CONDVAR_H_
+
+typedef struct rwlock_condvar_t rwlock_condvar_t;
+
+#include "rwlock.h"
+
+/**
+ * A special condvar implementation that can be used in conjunction
+ * with rwlock_t (the write lock to be precise).
+ *
+ * @note The implementation does not verify that the current thread actually
+ * holds the write lock and not the read lock, so watch out.
+ */
+struct rwlock_condvar_t {
+
+	/**
+	 * Wait on a condvar until it gets signalized.
+	 *
+	 * @param lock			lock to release while waiting (write lock)
+	 */
+	void (*wait)(rwlock_condvar_t *this, rwlock_t *lock);
+
+	/**
+	 * Wait on a condvar until it gets signalized, or times out.
+	 *
+	 * @param lock			lock to release while waiting (write lock)
+	 * @param timeout		timeout im ms
+	 * @return				TRUE if timed out, FALSE otherwise
+	 */
+	bool (*timed_wait)(rwlock_condvar_t *this, rwlock_t *lock, u_int timeout);
+
+	/**
+	 * Wait on a condvar until it gets signalized, or times out.
+	 *
+	 * The passed timeval should be calculated based on the time_monotonic()
+	 * function.
+	 *
+	 * @param lock			lock to release while waiting (write lock)
+	 * @param tv			absolute time until timeout
+	 * @return				TRUE if timed out, FALSE otherwise
+	 */
+	bool (*timed_wait_abs)(rwlock_condvar_t *this, rwlock_t *lock,
+						   timeval_t tv);
+
+	/**
+	 * Wake up a single thread in a condvar.
+	 */
+	void (*signal)(rwlock_condvar_t *this);
+
+	/**
+	 * Wake up all threads in a condvar.
+	 */
+	void (*broadcast)(rwlock_condvar_t *this);
+
+	/**
+	 * Destroy a condvar and free its resources.
+	 */
+	void (*destroy)(rwlock_condvar_t *this);
+};
+
+/**
+ * Create a condvar instance.
+ *
+ * @return			condvar instance
+ */
+rwlock_condvar_t *rwlock_condvar_create();
+
+#endif /** RWLOCK_CONDVAR_H_ @} */
+