* initial import from the cvs-tools module

1 files changed, 206 insertions, 0 deletions

diff --git a/usr.bin/cvs/cache.c b/usr.bin/cvs/cache.c
new file mode 100644
index 00000000000..cdd0922c21e
--- /dev/null
+++ b/usr.bin/cvs/cache.c
@@ -0,0 +1,206 @@
+/*	$OpenBSD: cache.c,v 1.1 2004/07/13 22:02:40 jfb Exp $	*/
+/*
+ * Copyright (c) 2004 Jean-Francois Brousseau <jfb@openbsd.org>
+ * 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. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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. 
+ */
+
+#include <sys/param.h>
+#include <sys/queue.h>
+#include <sys/time.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include "log.h"
+#include "rcs.h"
+#include "cache.h"
+
+#define RCS_CACHE_BUCKETS    256
+
+
+struct rcs_cachent {
+	u_int           rc_hits;
+	u_int8_t        rc_hash;
+	RCSFILE        *rc_rfp;
+	struct timeval  rc_atime;
+
+	TAILQ_ENTRY(rcs_cachent) rc_list;
+	TAILQ_ENTRY(rcs_cachent)  rc_lru;
+};
+
+
+static u_int8_t rcs_cache_hash (const char *);
+
+
+TAILQ_HEAD(rcs_cachebkt, rcs_cachent) rcs_cache[RCS_CACHE_BUCKETS];
+
+TAILQ_HEAD(rcs_lruhead, rcs_cachent) rcs_cache_lru;
+
+u_int rcs_cache_maxent;
+u_int rcs_cache_nbent;
+
+
+
+/*
+ * rcs_cache_init()
+ *
+ * Initialize the RCS file data cache.
+ * Returns 0 on success, -1 on failure.
+ */
+
+int
+rcs_cache_init(u_int maxent)
+{
+	u_int i;
+
+	for (i = 0; i < RCS_CACHE_BUCKETS; i++)
+		TAILQ_INIT(&rcs_cache[i]);
+
+	TAILQ_INIT(&rcs_cache_lru);
+
+	rcs_cache_maxent = maxent;
+	rcs_cache_nbent = 0;
+
+	return (0);
+}
+
+
+/*
+ * rcs_cache_destroy()
+ */
+
+void
+rcs_cache_destroy(void)
+{
+}
+
+
+/*
+ * rcs_cache_fetch()
+ *
+ */
+
+RCSFILE*
+rcs_cache_fetch(const char *path)
+{
+	u_int8_t hash;
+	struct rcs_cachent *rcp;
+	RCSFILE *rfp;
+
+	rfp = NULL;
+	hash = rcs_cache_hash(path);
+
+	TAILQ_FOREACH(rcp, &(rcs_cache[hash]), rc_list) {
+		if (strcmp(path, rcp->rc_rfp->rf_path) == 0) {
+			rfp = rcp->rc_rfp;
+			break;
+		}
+	}
+
+	if (rcp != NULL) {
+		(void)gettimeofday(&(rcp->rc_atime), NULL);
+		rcp->rc_hits++;
+
+		/* move this item back at the end of the LRU */
+		TAILQ_REMOVE(&rcs_cache_lru, rcp, rc_lru);
+		TAILQ_INSERT_TAIL(&rcs_cache_lru, rcp, rc_lru);
+
+		/* increment reference count for caller */
+		rfp->rf_ref++;
+	}
+
+	return (rfp);
+}
+
+
+/*
+ * rcs_cache_store()
+ *
+ * Store the RCSFILE <rfp> in the RCS file cache.  By storing the file, its
+ * reference count gets incremented for the cache reference, so the caller
+ * should still rcs_close() the file once they are done with it.
+ * Returns 0 on success, or -1 on failure.
+ */
+
+int
+rcs_cache_store(RCSFILE *rfp)
+{
+	struct rcs_cachent *rcp, *old_rcp;
+
+	/* don't store the same element twice */
+	if (rcs_cache_fetch(rfp->rf_path) != NULL)
+		return (0);
+
+	rcp = (struct rcs_cachent *)malloc(sizeof(*rcp));
+	if (rcp == NULL) {
+		cvs_log(LP_ERRNO, "failed to allocate RCS cache entry");
+		return (-1);
+	}
+
+	rcp->rc_hits = 0;
+
+	rcp->rc_rfp = rfp;
+	rfp->rf_ref++;
+
+	rcp->rc_hash = rcs_cache_hash(rfp->rf_path);
+
+	rcs_cache_nbent++;
+	if (rcs_cache_nbent == rcs_cache_maxent) {
+		/* ditch the oldest entry in the LRU */
+		old_rcp = TAILQ_FIRST(&rcs_cache_lru);
+		TAILQ_REMOVE(&rcs_cache_lru, old_rcp, rc_lru);
+		TAILQ_REMOVE(&(rcs_cache[old_rcp->rc_hash]), old_rcp, rc_list);
+
+		/* free our reference */
+		rcs_close(old_rcp->rc_rfp);
+		free(old_rcp);
+	}
+
+	TAILQ_INSERT_TAIL(&(rcs_cache[rcp->rc_hash]), rcp, rc_list);
+	TAILQ_INSERT_TAIL(&rcs_cache_lru, rcp, rc_lru);
+
+	return (0);
+}
+
+
+/*
+ * rcs_cache_hash()
+ *
+ * Hash the <path> string.
+ */
+
+static u_int8_t
+rcs_cache_hash(const char *path)
+{
+	const char *sp;
+	u_int8_t hash;
+
+	hash = 0;
+	for (sp = path; *sp != '\0'; sp++)
+		hash ^= (*sp << 3) ^ (*sp >> 2);
+
+	return (hash);
+}