refactor to support early exit when no media changes

- regular sync now receives a media USN as well
- server bumps media usn not only on sync but any other media change
- added local media.hasChanged()

anki/media.py

@@ -175,6 +175,9 @@ If the same name exists, compare checksums."""
     def clearLog(self):
         self.db.execute("delete from log")
 
+    def hasChanged(self):
+        return self.db.scalar("select 1 from log limit 1")
+
     # Tracking changes (private)
     ##########################################################################
 

anki/sync.py

@@ -47,8 +47,8 @@ class Syncer(object):
         "Returns 'noChanges', 'fullSync', or 'success'."
         # step 1: login & metadata
         self.status("login")
-        self.rmod, rscm, self.maxUsn, rts = self.server.meta()
+        self.rmod, rscm, self.maxUsn, rts, self.mediaUsn = self.server.meta()
-        self.lmod, lscm, self.minUsn, lts = self.meta()
+        self.lmod, lscm, self.minUsn, lts, dummy = self.meta()
         if abs(rts - lts) > 300:
             return "clockOff"
         if self.lmod == self.rmod:
@@ -90,7 +90,7 @@ class Syncer(object):
         return "success"
 
     def meta(self):
-        return (self.deck.mod, self.deck.scm, self.deck._usn, intTime())
+        return (self.deck.mod, self.deck.scm, self.deck._usn, intTime(), None)
 
     def changes(self):
         "Bundle up deletions and small objects, and apply if server."
@@ -535,21 +535,25 @@ class MediaSyncer(object):
         self.server = server
         self.added = None
 
-    def sync(self):
+    def sync(self, mediaUsn):
-        # step 1: send/recv deletions
+        # step 1: check if there have been any changes
+        self.deck.media.findChanges()
+        lusn = self.deck.media.usn()
+        if lusn == mediaUsn and not self.deck.media.hasChanged():
+            return "noChanges"
+        # step 2: send/recv deletions
         runHook("mediaSync", "remove")
-        usn = self.deck.media.usn()
         lrem = self.removed()
-        rrem = self.server.remove(fnames=lrem, minUsn=usn)
+        rrem = self.server.remove(fnames=lrem, minUsn=lusn)
         self.remove(rrem)
-        # step 2: stream files from server
+        # step 3: stream files from server
         runHook("mediaSync", "server")
         while 1:
             runHook("mediaSync", "stream")
             zip = self.server.files()
             if self.addFiles(zip=zip) != "continue":
                 break
-        # step 3: stream files to the server
+        # step 4: stream files to the server
         runHook("mediaSync", "client")
         while 1:
             runHook("mediaSync", "stream")
@@ -558,10 +562,12 @@ class MediaSyncer(object):
             if usn != "continue":
                 # when server has run out of files, it returns bumped usn
                 break
+        # step 5: finalize
         self.deck.media.setUsn(usn)
         self.deck.media.clearLog()
         # clear cursor so successive calls work
         self.added = None
+        return "success"
 
     def removed(self):
         return self.deck.media.removed()

tests/test_sync.py

@@ -19,6 +19,7 @@ deck1=None
 deck2=None
 client=None
 server=None
+server2=None
 
 def setup_basic():
     global deck1, deck2, client, server
@@ -271,7 +272,7 @@ def setup_remote():
 def test_meta():
     global TEST_REMOTE
     try:
-        (mod, scm, usn, ts) = server.meta()
+        (mod, scm, usn, ts, dummy) = server.meta()
     except Exception, e:
         if e.errno == 61:
             TEST_REMOTE = False
@@ -330,9 +331,10 @@ def test_remoteSync():
 # the current directory is the media folder.
 
 def setup_remoteMedia():
-    global client, server
+    global client, server, server2
     setup_basic()
     server = RemoteMediaServer(TEST_HKEY)
+    server2 = RemoteServer(TEST_USER, TEST_HKEY)
     client = MediaSyncer(deck1, server)
 
 @nose.with_setup(setup_remoteMedia)
@@ -340,26 +342,29 @@ def test_media():
     server.mediatest("reset")
     assert len(os.listdir(deck1.media.dir())) == 0
     assert server.mediatest("count") == 0
+    # initially, nothing to do
+    assert client.sync(server2.meta()[4]) == "noChanges"
     # add a file
+    time.sleep(1)
     os.chdir(deck1.media.dir())
     p = os.path.join(deck1.media.dir(), "foo.jpg")
     open(p, "wb").write("foo")
     assert len(os.listdir(deck1.media.dir())) == 1
     assert server.mediatest("count") == 0
-    client.sync()
+    assert client.sync(server2.meta()[4]) == "success"
     time.sleep(1)
     # should have been synced
     assert len(os.listdir(deck1.media.dir())) == 1
     assert server.mediatest("count") == 1
     # if we remove the file, should be removed
     os.unlink(p)
-    client.sync()
+    assert client.sync(server2.meta()[4]) == "success"
     assert len(os.listdir(deck1.media.dir())) == 0
     assert server.mediatest("count") == 0
     # we should be able to add it again
     time.sleep(1)
     open(p, "wb").write("foo")
-    client.sync()
+    assert client.sync(server2.meta()[4]) == "success"
     assert len(os.listdir(deck1.media.dir())) == 1
     assert server.mediatest("count") == 1
     # if we modify it, it should get sent too. also we set the zip size very
@@ -369,7 +374,7 @@ def test_media():
     open(p, "wb").write("bar")
     open(p+"2", "wb").write("baz")
     assert len(os.listdir(deck1.media.dir())) == 2
-    client.sync()
+    client.sync(server2.meta()[4])
     assert len(os.listdir(deck1.media.dir())) == 2
     assert server.mediatest("count") == 2
     # if we lose our media db, we should be able to bring it back in sync
@@ -379,12 +384,12 @@ def test_media():
     deck1.media.connect()
     changes = deck1.media.added().fetchall()
     assert len(changes) == 2
-    client.sync()
+    client.sync(server2.meta()[4])
     assert len(os.listdir(deck1.media.dir())) == 2
     assert server.mediatest("count") == 2
     # if we send an unchanged file, the server should cope
     time.sleep(1)
     deck1.media.db.execute("insert into log values ('foo.jpg', 0)")
-    client.sync()
+    client.sync(server2.meta()[4])
     assert len(os.listdir(deck1.media.dir())) == 2
     assert server.mediatest("count") == 2