From d2db585ce7e26851178104433fa9422482d8719e Mon Sep 17 00:00:00 2001
From: Venky Shankar <vshankar@redhat.com>
Date: Wed, 19 Feb 2014 20:47:46 +0530
Subject: features/changelog : historical journal consumption.

Facilitates Glusterfs with the ability to detect file-operations
happened in past by scanning the back-end(brick-level) glusterfs
journal (changelog).

Design:
  * List of changelogs produces in one perfectly running session are
    stored in htime file which also holds necessary information about
    the session start and end time.
  * Involves fixed sized seeks to identify N'th changelog in the list.
  * Requires O(log n), (where n is number of changelogs in the list),
    time to identify the end changelog for the given start-end time
    interval.

Currently the background processing of changelogs is sub optimal. BZ
1097041 tracks the development effort.

For complete design, refer the below link:
http://lists.nongnu.org/archive/html/gluster-devel/2014-02/msg00206.html

Change-Id: I27e49f75e492e843084d0ecaf9130224d08462a0
BUG: 1091961
Signed-off-by: Ajeet Jha <ajha@redhat.com>
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Signed-off-by: Ajeet Jha <ajha@redhat.com>
Reviewed-on: http://review.gluster.org/6930
Reviewed-by: Kotresh HR <khiremat@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
---
 .../changelog/lib/examples/c/get-history.c         | 109 +++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 xlators/features/changelog/lib/examples/c/get-history.c

(limited to 'xlators/features/changelog/lib/examples/c')

diff --git a/xlators/features/changelog/lib/examples/c/get-history.c b/xlators/features/changelog/lib/examples/c/get-history.c
new file mode 100644
index 00000000000..33eb8c32d4d
--- /dev/null
+++ b/xlators/features/changelog/lib/examples/c/get-history.c
@@ -0,0 +1,109 @@
+/*
+   Copyright (c) 2013 Red Hat, Inc. <http://www.redhat.com>
+   This file is part of GlusterFS.
+
+   This file is licensed to you under your choice of the GNU Lesser
+   General Public License, version 3 or any later version (LGPLv3 or
+   later), or the GNU General Public License, version 2 (GPLv2), in all
+   cases as published by the Free Software Foundation.
+*/
+
+/**
+ * get set of new changes every 10 seconds (just print the file names)
+ *
+ * Compile it using:
+ *  gcc -o gethistory `pkg-config --cflags libgfchangelog` get-history.c \
+ *  `pkg-config --libs libgfchangelog`
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/un.h>
+#include <limits.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <errno.h>
+
+#include "changelog.h"
+
+#define handle_error(fn)                                \
+        printf ("%s (reason: %s)\n", fn, strerror (errno))
+
+int
+main (int argc, char ** argv)
+{
+        int     i            = 0;
+        int     ret          = 0;
+        ssize_t nr_changes   = 0;
+        ssize_t changes      = 0;
+        char fbuf[PATH_MAX]  = {0,};
+        unsigned long end_ts = 0;
+
+        ret = gf_changelog_register ("/export1/v1/b1",
+                                     "/tmp/scratch_v1", "/tmp/scratch_v1/changes.log",
+                                     9, 5);
+        if (ret) {
+                handle_error ("register failed");
+                goto out;
+        }
+
+        int a, b;
+        printf ("give the two numbers start and end\t");
+        scanf ("%d%d", &a, &b);
+        ret = gf_history_changelog ("/export1/v1/b1/.glusterfs/changelogs",a, b, 3, &end_ts);
+        if (ret == -1) {
+                printf ("history failed");
+                goto out;
+        }
+
+        printf ("end time till when changelog available : %d , ret(%d) \t", end_ts, ret);
+        fflush(stdout);
+
+        while (1) {
+                nr_changes = gf_history_changelog_scan ();
+                printf ("scanned, nr_changes : %d\n",nr_changes);
+                if (nr_changes < 0) {
+                        handle_error ("scan(): ");
+                        break;
+                }
+
+                if (nr_changes == 0) {
+                        printf ("done scanning \n");
+                        goto out;
+                }
+
+                printf ("Got %ld changelog files\n", nr_changes);
+
+                while ( (changes =
+                         gf_history_changelog_next_change (fbuf, PATH_MAX)) > 0) {
+                        printf ("changelog file [%d]: %s\n", ++i, fbuf);
+
+                        /* process changelog */
+                        /* ... */
+                        /* ... */
+                        /* ... */
+                        /* done processing */
+
+                        ret = gf_history_changelog_done (fbuf);
+                        if (ret)
+                                handle_error ("gf_changelog_done");
+                }
+                /*
+                if (changes == -1)
+                        handle_error ("gf_changelog_next_change");
+                if (nr_changes ==1){
+                        printf("continue scanning\n");
+                }
+
+                if(nr_changes == 0){
+                        printf("done scanning \n");
+                        goto out;
+                }
+                */
+        }
+
+
+out:
+        return ret;
+}
-- 
cgit