geo-rep: checkpointing

- gluster vol geo-rep M S conf checkpoint <LABEL|now>

  sets a checkpoint with LABEL (the keyword "now" is special,
  it's rendered to the label "as of <timestamp of current time>")
  that's used to refer to the checkpoint in the sequel.

  (Technically, gsyncd makes a note of the xtime of master's root
  as of setting the checkpoint, called the "checkpoint target".)

- gluster vol geo-rep M S conf \!checkpoint

  deletes the checkpoint.

- gluster vol geo-rep M S stat

  if status is OK, and there is a checkpoint configured, the checkpoint
  info is appended to status (either "not yet reached", or
  "completed at <timestamp of completion>").

  (Technically, the worker runs a thread that monitors / serializes /
  verifies checkpoint status, and answers checkpoint status requests
  through a UNIX socket; monitoring boils down to querying the xtime
  of slave's root and comparing with the target.)

- gluster vol geo-rep M S conf log-file | xargs grep checkpoint

  displays the checkpoint history. Set, delete and completion events
  are logged properly.

Change-Id: I4398e0819f1504e6e496b4209e91a0e156e1a0f8
BUG: 826512
Signed-off-by: Csaba Henk <csaba@redhat.com>
Reviewed-on: http://review.gluster.com/3491
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>

1 files changed, 39 insertions, 17 deletions

diff --git a/xlators/features/marker/utils/syncdaemon/gsyncd.py b/xlators/features/marker/utils/syncdaemon/gsyncd.py
index 9ac32ce42..d68cea672 100644
--- a/xlators/features/marker/utils/syncdaemon/gsyncd.py
+++ b/xlators/features/marker/utils/syncdaemon/gsyncd.py
@@ -58,6 +58,25 @@ class GLogger(Logger):
         logging.getLogger().handlers = []
         logging.basicConfig(**lprm)
 
+    @classmethod
+    def _gsyncd_loginit(cls, **kw):
+        lkw = {}
+        if gconf.log_level:
+            lkw['level'] = gconf.log_level
+        if kw.get('log_file'):
+            if kw['log_file'] in ('-', '/dev/stderr'):
+                lkw['stream'] = sys.stderr
+            elif kw['log_file'] == '/dev/stdout':
+                lkw['stream'] = sys.stdout
+            else:
+                lkw['filename'] = kw['log_file']
+
+        cls.setup(label=kw.get('label'), **lkw)
+
+        lkw.update({'saved_label': kw.get('label')})
+        gconf.log_metadata = lkw
+        gconf.log_exit = True
+
 def startup(**kw):
     """set up logging, pidfile grabbing, daemonization"""
     if getattr(gconf, 'pid_file', None) and kw.get('go_daemon') != 'postconn':
@@ -88,22 +107,7 @@ def startup(**kw):
         select((x,), (), ())
         os.close(x)
 
-    lkw = {}
-    if gconf.log_level:
-        lkw['level'] = gconf.log_level
-    if kw.get('log_file'):
-        if kw['log_file'] in ('-', '/dev/stderr'):
-            lkw['stream'] = sys.stderr
-        elif kw['log_file'] == '/dev/stdout':
-            lkw['stream'] = sys.stdout
-        else:
-            lkw['filename'] = kw['log_file']
-
-    GLogger.setup(label=kw.get('label'), **lkw)
-
-    lkw.update({'saved_label': kw.get('label')})
-    gconf.log_metadata = lkw
-    gconf.log_exit = True
+    GLogger._gsyncd_loginit(**kw)
 
 def main():
     """main routine, signal/exception handling boilerplates"""
@@ -166,6 +170,8 @@ def main_i():
     op.add_option('--sync-jobs',           metavar='N',     type=int, default=3)
     op.add_option('--turns',               metavar='N',     type=int, default=0, help=SUPPRESS_HELP)
     op.add_option('--allow-network',       metavar='IPS',   default='')
+    op.add_option('--state-socket-unencoded', metavar='SOCKF', type=str, action='callback', callback=store_abs)
+    op.add_option('--checkpoint',          metavar='LABEL', default='')
 
     op.add_option('-c', '--config-file',   metavar='CONF',  type=str, action='callback', callback=store_local)
     # duh. need to specify dest or value will be mapped to None :S
@@ -278,6 +284,7 @@ def main_i():
         rconf['config_file'] = os.path.join(os.path.dirname(sys.argv[0]), "conf/gsyncd.conf")
     gcnf = GConffile(rconf['config_file'], canon_peers, defaults.__dict__, opts.__dict__, namedict)
 
+    checkpoint_change = False
     if confdata:
         opt_ok = norm(confdata.opt) in tunables + [None]
         if confdata.op == 'check':
@@ -293,7 +300,14 @@ def main_i():
             gcnf.set(confdata.opt, confdata.val, confdata.rx)
         elif confdata.op == 'del':
             gcnf.delete(confdata.opt, confdata.rx)
-        return
+        # when modifying checkpoint, it's important to make a log
+        # of that, so in that case we go on to set up logging even
+        # if its just config invocation
+        if confdata.opt == 'checkpoint' and confdata.op in ('set', 'del') and \
+           not confdata.rx:
+            checkpoint_change = True
+        if not checkpoint_change:
+            return
 
     gconf.__dict__.update(defaults.__dict__)
     gcnf.update_to(gconf.__dict__)
@@ -331,6 +345,14 @@ def main_i():
             raise GsyncdError('cannot recognize log level "%s"' % lvl0)
         gconf.log_level = lvl2
 
+    if checkpoint_change:
+        GLogger._gsyncd_loginit(log_file=gconf.log_file, label='conf')
+        if confdata.op == 'set':
+            logging.info('checkpoint %s set' % confdata.val)
+        elif confdata.op == 'del':
+            logging.info('checkpoint info was reset')
+        return
+
     go_daemon = rconf['go_daemon']
     be_monitor = rconf.get('monitor')