libpmemlog examples

README

This is a gist containing libpmemlog examples, so they can be embedded in web pages.

addlog.c

/*
 * Copyright (c) 2014, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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 LOG OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * addlog -- given a log file, append a log entry
 *
 * Usage:
 *	fallocate -l 1G /path/to/pm-aware/file
 *	addlog /path/to/pm-aware/file "first line of entry" "second line"
 */

#include <stdio.h>
#include <fcntl.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libpmemlog.h>

#include "logentry.h"

int
main(int argc, char *argv[])
{
	PMEMlogpool *plp;
	struct logentry header;
	struct iovec *iovp;
	struct iovec *next_iovp;
	int iovcnt;

	if (argc < 3) {
		fprintf(stderr, "usage: %s filename lines...\n", argv[0]);
		exit(1);
	}

	const char *path = argv[1];

	/* create the log in the given file, or open it if already created */
	if ((plp = pmemlog_create(path, 0, 0)) == NULL &&
	    (plp = pmemlog_open(path)) == NULL) {
		perror(path);
		exit(1);
	}

	/* fill in the header */
	time(&header.timestamp);
	header.pid = getpid();

	/*
	 * Create an iov for pmemlog_appendv().  For each argument given,
	 * allocate two entries (one for the string, one for the newline
	 * appended to the string).  Allocate 1 additional entry for the
	 * header that gets prepended to the entry.
	 */
	iovcnt = (argc - 2) * 2 + 1;
	if ((iovp = malloc(sizeof (*iovp) * iovcnt)) == NULL) {
		perror("malloc");
		exit(1);
	}
	next_iovp = iovp;

	/* put the header into iov first */
	next_iovp->iov_base = &header;
	next_iovp->iov_len = sizeof (header);
	next_iovp++;

	/*
	 * Now put each arg in, following it with the string "\n".
	 * Calculate a total character count in header.len along the way.
	 */
	header.len = 0;
	for (int arg = 2; arg < argc; arg++) {
		/* add the string given */
		next_iovp->iov_base = argv[arg];
		next_iovp->iov_len = strlen(argv[arg]);
		header.len += next_iovp->iov_len;
		next_iovp++;

		/* add the newline */
		next_iovp->iov_base = "\n";
		next_iovp->iov_len = 1;
		header.len += 1;
		next_iovp++;
	}

	/* atomically add it all to the log */
	if (pmemlog_appendv(plp, iovp, iovcnt) < 0) {
		perror("pmemlog_appendv");
		exit(1);
	}

	pmemlog_close(plp);
}

logentry.h

/*
 * Copyright (c) 2014, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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 LOG OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * info prepended to each log entry...
 */
struct logentry {
	size_t len;		/* length of the rest of the log entry */
	time_t timestamp;
	pid_t pid;
};

manpage.c

/*
 * Copyright (c) 2014, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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 LOG OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * manpage.c -- simple example for the libpmemlog man page
 */

#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <libpmemlog.h>

/* size of the pmemlog pool -- 1 GB */
#define	POOL_SIZE ((off_t)(1 << 30))

/*
 * printit -- log processing callback for use with pmemlog_walk()
 */
int
printit(const void *buf, size_t len, void *arg)
{
	fwrite(buf, len, 1, stdout);
	return 0;
}

int
main(int argc, char *argv[])
{
	const char path[] = "/pmem-fs/myfile";
	PMEMlogpool *plp;
	size_t nbyte;
	char *str;

	/* create the pmemlog pool or open it if it already exists */
	plp = pmemlog_create(path, POOL_SIZE, 0666);

	if (plp == NULL)
	    plp = pmemlog_open(path);

	if (plp == NULL) {
		perror(path);
		exit(1);
	}

	/* how many bytes does the log hold? */
	nbyte = pmemlog_nbyte(plp);
	printf("log holds %zu bytes\n", nbyte);

	/* append to the log... */
	str = "This is the first string appended\n";
	if (pmemlog_append(plp, str, strlen(str)) < 0) {
		perror("pmemlog_append");
		exit(1);
	}
	str = "This is the second string appended\n";
	if (pmemlog_append(plp, str, strlen(str)) < 0) {
		perror("pmemlog_append");
		exit(1);
	}

	/* print the log contents */
	printf("log contains:\n");
	pmemlog_walk(plp, 0, printit, NULL);

	pmemlog_close(plp);
}

printlog.c

/*
 * Copyright (c) 2014, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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 LOG OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * printlog -- given a log file, print the entries
 *
 * Usage:
 *	printlog [-t] /path/to/pm-aware/file
 *
 * -t option means truncate the file after printing it.
 */

#include <stdio.h>
#include <fcntl.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libpmemlog.h>

#include "logentry.h"

/*
 * printlog -- callback function called when walking the log
 */
int
printlog(const void *buf, size_t len, void *arg)
{
	const void *endp = buf + len;	/* first byte after log contents */

	/* for each entry in the log... */
	while (buf < endp) {
		struct logentry *headerp = (struct logentry *)buf;
		buf += sizeof (struct logentry);

		/* print the header */
		printf("Entry from pid: %ld\n", (long)headerp->pid);
		printf("       Created: %s", ctime(&headerp->timestamp));
		printf("      Contents:\n");

		/* print the log data itself */
		fwrite(buf, headerp->len, 1, stdout);
		buf += headerp->len;
	}

	return 0;
}

int
main(int argc, char *argv[])
{
	int opt;
	int tflag = 0;
	PMEMlogpool *plp;

	while ((opt = getopt(argc, argv, "t")) != -1)
		switch (opt) {
		case 't':
			tflag = 1;
			break;

		default:
			fprintf(stderr, "usage: %s [-t] file\n", argv[0]);
			exit(1);
		}

	if (optind >= argc) {
		fprintf(stderr, "usage: %s [-t] file\n", argv[0]);
		exit(1);
	}

	const char *path = argv[optind];

	if ((plp = pmemlog_open(path)) == NULL) {
		perror(path);
		exit(1);
	}

	/* the rest of the work happens in printlog() above */
	pmemlog_walk(plp, 0, printlog, NULL);

	if (tflag)
		pmemlog_rewind(plp);

	pmemlog_close(plp);
}