geo-rep: Consume Changelog History API

Every time when geo-rep restarts it first does FS crawl using
XCrawl and then switches to Changelog Mode. This is because changelog
only had live API, that is we can get changes only after registering.

Now this(http://review.gluster.org/#/c/6930/) patch introduces History
API for changelogs. If history is available then geo-rep will use it
instead of FS Crawl.

History API returns TS till what time history is available for
given start and end time. If TS < endtime then switch to FS Crawl.
(History => FS Crawl => Live Changelog)

If TS >= endtime, then switch directly to Changelog mode
(History => Live Changelog)

Change-Id: I4922f62b9f899c40643bd35720e0c81c36b2f255
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Reviewed-on: http://review.gluster.org/6938
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Humble Devassy Chirammal <humble.devassy@gmail.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>

1 files changed, 55 insertions, 7 deletions

diff --git a/geo-replication/syncdaemon/libgfchangelog.py b/geo-replication/syncdaemon/libgfchangelog.py
index ec563b36f29..0fa32a73499 100644
--- a/geo-replication/syncdaemon/libgfchangelog.py
+++ b/geo-replication/syncdaemon/libgfchangelog.py
@@ -13,6 +13,10 @@ from ctypes import CDLL, create_string_buffer, get_errno
 from ctypes.util import find_library
 
 
+class ChangelogException(OSError):
+    pass
+
+
 class Changes(object):
     libgfc = CDLL(find_library("gfchangelog"), use_errno=True)
 
@@ -21,9 +25,9 @@ class Changes(object):
         return get_errno()
 
     @classmethod
-    def raise_oserr(cls):
+    def raise_changelog_err(cls):
         errn = cls.geterrno()
-        raise OSError(errn, os.strerror(errn))
+        raise ChangelogException(errn, os.strerror(errn))
 
     @classmethod
     def _get_api(cls, call):
@@ -35,19 +39,19 @@ class Changes(object):
                                                     log_file,
                                                     log_level, retries)
         if ret == -1:
-            cls.raise_oserr()
+            cls.raise_changelog_err()
 
     @classmethod
     def cl_scan(cls):
         ret = cls._get_api('gf_changelog_scan')()
         if ret == -1:
-            cls.raise_oserr()
+            cls.raise_changelog_err()
 
     @classmethod
     def cl_startfresh(cls):
         ret = cls._get_api('gf_changelog_start_fresh')()
         if ret == -1:
-            cls.raise_oserr()
+            cls.raise_changelog_err()
 
     @classmethod
     def cl_getchanges(cls):
@@ -64,7 +68,7 @@ class Changes(object):
                 break
             changes.append(buf.raw[:ret - 1])
         if ret == -1:
-            cls.raise_oserr()
+            cls.raise_changelog_err()
         # cleanup tracker
         cls.cl_startfresh()
         return sorted(changes, key=clsort)
@@ -73,4 +77,48 @@ class Changes(object):
     def cl_done(cls, clfile):
         ret = cls._get_api('gf_changelog_done')(clfile)
         if ret == -1:
-            cls.raise_oserr()
+            cls.raise_changelog_err()
+
+    @classmethod
+    def cl_history_scan(cls):
+        ret = cls._get_api('gf_history_changelog_scan')()
+        if ret == -1:
+            cls.raise_changelog_err()
+
+        return ret
+
+    @classmethod
+    def cl_history_changelog(cls, changelog_path, start, end):
+        ret = cls._get_api('gf_history_changelog')(changelog_path, start, end)
+        if ret == -1:
+            cls.raise_changelog_err()
+
+        return ret
+
+    @classmethod
+    def cl_history_startfresh(cls):
+        ret = cls._get_api('gf_history_changelog_start_fresh')()
+        if ret == -1:
+            cls.raise_changelog_err()
+
+    @classmethod
+    def cl_history_getchanges(cls):
+        changes = []
+        buf = create_string_buffer('\0', 4096)
+        call = cls._get_api('gf_history_changelog_next_change')
+
+        while True:
+            ret = call(buf, 4096)
+            if ret in (0, -1):
+                break
+            changes.append(buf.raw[:ret - 1])
+        if ret == -1:
+            cls.raise_changelog_err()
+
+        return changes
+
+    @classmethod
+    def cl_history_done(cls, clfile):
+        ret = cls._get_api('gf_history_changelog_done')(clfile)
+        if ret == -1:
+            cls.raise_changelog_err()