Adding upstream version 0.6.0.upstream/0.6.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 121 insertions, 0 deletions

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+.\"
+.\" 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_brlock 3
+.Sh NAME
+.Nm ck_brlock_init ,
+.Nm ck_brlock_write_lock ,
+.Nm ck_brlock_write_unlock ,
+.Nm ck_brlock_write_trylock ,
+.Nm ck_brlock_read_register ,
+.Nm ck_brlock_read_unregister ,
+.Nm ck_brlock_read_lock ,
+.Nm ck_brlock_read_trylock ,
+.Nm ck_brlock_read_unlock
+.Nd big-reader locks
+.Sh LIBRARY
+Concurrency Kit (libck, \-lck)
+.Sh SYNOPSIS
+.In ck_brlock.h
+.Pp
+.Dv ck_brlock_t brlock = CK_BRLOCK_INITIALIZER;
+.Pp
+.Dv ck_brlock_reader_t reader = CK_BRLOCK_READER_INITIALIZER;
+.Pp
+.Ft void
+.Fn ck_brlock_init "ck_brlock_t *br"
+.Ft void
+.Fn ck_brlock_write_lock "ck_brlock_t *br"
+.Ft void
+.Fn ck_brlock_write_unlock "ck_brlock_t *br"
+.Ft bool
+.Fn ck_brlock_write_trylock "ck_brlock_t *br" "unsigned int factor"
+.Ft void
+.Fn ck_brlock_read_register "ck_brlock_t *br" "ck_brlock_reader_t *reader"
+.Ft void
+.Fn ck_brlock_read_unregister "ck_brlock_t *br" "ck_brlock_reader_t *reader"
+.Ft void
+.Fn ck_brlock_read_lock "ck_brlock_t *br" "ck_brlock_reader_t *reader"
+.Ft bool
+.Fn ck_brlock_read_trylock "ck_brlock_t *br" "ck_brlock_reader_t *reader" \
+"unsigned int factor"
+.Ft void
+.Fn ck_brlock_read_unlock "ck_brlock_reader_t *reader"
+.Sh DESCRIPTION
+Big reader locks are distributed reader-writer locks with low latency constant time
+reader acquisition (with respect to number of concurrent readers). On the other
+hand, writer acquisitions are a relatively expensive O(n) operation. This is a write-biased
+lock.
+.Sh EXAMPLE
+.Bd -literal -offset indent
+static ck_brlock_t lock = CK_BRLOCK_INITIALIZER;
+static __thread ck_brlock_reader_t reader;
+
+static void
+reader(void)
+{
+
+	/* Add our thread as a lock participant. */
+	ck_brlock_read_register(&lock, &reader);
+
+	for (;;) {
+		ck_brlock_read_lock(&lock, &reader);
+		/* Read-side critical section. */
+		ck_brlock_read_unlock(&reader);
+
+		if (ck_brlock_read_trylock(&lock, &reader, 1) == true) {
+			/* Read-side critical section. */
+			ck_brlock_read_unlock(&reader);
+		}
+	}
+
+	return;
+}
+
+static void
+writer(void)
+{
+
+	for (;;) {
+		ck_brlock_write_lock(&lock);
+		/* Write-side critical section. */
+		ck_brlock_write_unlock(&lock);
+
+		if (ck_brlock_write_trylock(&lock, 1) == true) {
+			/* Write-side critical section. */
+			ck_brlock_write_unlock(&lock);
+		}
+	}
+
+	return;
+}
+.Ed
+.Sh SEE ALSO
+.Xr ck_bytelock 3 ,
+.Xr ck_rwlock 3
+.Pp
+Additional information available at http://concurrencykit.org/