doc: Add ck_rwlock manual page.

doc/Makefile.in

@@ -141,6 +141,7 @@ OBJECTS=ck_brlock			\
 	ck_ring_enqueue_spsc_size	\
 	ck_ring_size			\
 	ck_ring_capacity		\
+	ck_rwlock			\
 	ck_sequence			\
 	ck_spinlock
 

doc/ck_rwlock

@@ -0,0 +1,128 @@
+.\"
+.\" Copyright 2013 Samy Al Bahra.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"
+.Dd July 26, 2013.
+.Dt ck_rwlock 3
+.Sh NAME
+.Nm ck_rwlock
+.Nd centralized write-biased reader-writer locks
+.Sh LIBRARY
+Concurrency Kit (libck, \-lck)
+.Sh SYNOPSIS
+.In ck_rwlock.h
+.Pp
+.Dv ck_rwlock_t lock = CK_RWLOCK_INITIALIZER;
+.Pp
+.Ft void
+.Fn ck_rwlock_init "ck_rwlock_t *lock"
+.Ft void
+.Fn ck_rwlock_write_lock "ck_rwlock_t *lock"
+.Ft void
+.Fn ck_rwlock_write_unlock "ck_rwlock_t *lock"
+.Ft bool
+.Fn ck_rwlock_write_trylock "ck_rwlock_t *lock"
+.Ft bool
+.Fn ck_rwlock_write_downgrade "ck_rwlock_t *lock"
+.Ft bool
+.Fn ck_rwlock_locked_writer "ck_rwlock_t *lock"
+.Ft void
+.Fn ck_rwlock_read_lock "ck_rwlock_t *lock"
+.Ft bool
+.Fn ck_rwlock_read_trylock "ck_rwlock_t *lock"
+.Ft void
+.Fn ck_rwlock_read_unlock "ck_rwlock_t *lock"
+.Ft bool
+.Fn ck_rwlock_locked_reader "ck_rwlock_t *lock"
+.Pp
+.Dv ck_rwlock_recursive_t lock = CK_RWLOCK_RECURSIVE_INITIALIZER;
+.Pp
+.Ft void
+.Fn ck_rwlock_recursive_write_lock "ck_rwlock_recursive_t *lock" "unsigned int tid"
+.Ft bool
+.Fn ck_rwlock_recursive_write_trylock "ck_rwlock_recursive_t *lock" "unsigned int tid"
+.Ft void
+.Fn ck_rwlock_recurisve_write_unlock "ck_rwlock_recursive_t *lock"
+.Ft void
+.Fn ck_rwlock_recursive_read_lock "ck_rwlock_recursive_t *lock"
+.Ft bool
+.Fn ck_rwlock_recursive_read_trylock "ck_rwlock_recursive_t *lock"
+.Ft void
+.Fn ck_rwlock_recursive_read_unlock "ck_rwlock_recursive_t *lock"
+.Sh DESCRIPTION
+This is a centralized write-biased reader-writer lock. It
+requires very little space overhead and has a low latency
+fast path. Write-side recursion requires usage of ck_rwlock_recursive.
+Read-side recursion is disallowed. The
+.Fn ck_rwlock_write_downgrade
+function degrades the caller's write-side acquisition to a read-side
+acquisition without forfeit of current critical section.
+.Sh EXAMPLE
+.Bd -literal -offset indent
+#include <ck_rwlock.h>
+
+static ck_rwlock_t lock = CK_RWLOCK_INITIALIZER;
+
+static void
+reader(void)
+{
+
+	for (;;) {
+		ck_rwlock_read_lock(&lock);
+		/* Read-side critical section. */
+		ck_rwlock_read_unlock(&lock);
+
+		if (ck_rwlock_read_trylock(&lock) == true) {
+			/* Read-side critical section. */
+			ck_rwlock_read_unlock(&lock);
+		}
+	}
+
+	return;
+}
+
+static void
+writer(void)
+{
+
+	for (;;) {
+		ck_rwlock_write_lock(&lock);
+		/* Write-side critical section. */
+		ck_rwlock_write_unlock(&lock);
+
+		if (ck_rwlock_write_trylock(&lock, 1) == true) {
+			/* Write-side critical section. */
+			ck_rwlock_write_unlock(&lock);
+		}
+	}
+
+	return;
+}
+.Ed
+.Sh SEE ALSO
+.Xr ck_brlock 3 ,
+.Xr ck_elide 3
+.Pp
+Additional information available at http://concurrencykit.org/