[bug] ensure maximum concurrency on blobs transfer

The way in that concurrency limit was being enforced was such that
transfer attempts were being spawned in groups of 3, and all of them had
to finish before a new group could be spawned. This modification allows
for use of maximum concurrency level at all times.

2 files changed, 41 insertions, 21 deletions

diff --git a/src/leap/soledad/client/_db/blobs.py b/src/leap/soledad/client/_db/blobs.py
index afc92864..73f011c2 100644
--- a/src/leap/soledad/client/_db/blobs.py
+++ b/src/leap/soledad/client/_db/blobs.py
@@ -327,18 +327,27 @@ class BlobManager(object):
         d = self.local_list(namespace=namespace,
                             sync_status=SyncStatus.PENDING_UPLOAD)
         missing = yield d
-        logger.info("Amount of documents missing on server: %s" % len(missing))
-        while missing:
-            deferreds = []
-            for _ in range(min(self.concurrency_limit, len(missing))):
-                blob_id = missing.pop()
-                d = with_retry(self.__send_one, blob_id, namespace)
-                deferreds.append(d)
-            yield defer.gatherResults(deferreds)
+        total = len(missing)
+        logger.info("Will send %d blobs to server." % total)
+        deferreds = []
+        semaphore = defer.DeferredSemaphore(self.concurrency_limit)
+
+        def release(result):
+            semaphore.release()
+            return result
+
+        for i in xrange(total):
+            yield semaphore.acquire()
+            blob_id = missing.pop()
+            d = with_retry(self.__send_one, blob_id, namespace, i, total)
+            d.addCallbacks(release, release)
+            deferreds.append(d)
+        yield defer.gatherResults(deferreds)
 
     @defer.inlineCallbacks
-    def __send_one(self, blob_id, namespace):
-            logger.info("Upload local blob: %s" % blob_id)
+    def __send_one(self, blob_id, namespace, i, total):
+            logger.info("Sending blob to server (%d/%d): %s"
+                        % (i, total, blob_id))
             fd = yield self.local.get(blob_id, namespace=namespace)
             try:
                 yield self._encrypt_and_upload(blob_id, fd)
@@ -365,15 +374,23 @@ class BlobManager(object):
         d = self.local_list(namespace=namespace,
                             sync_status=SyncStatus.PENDING_DOWNLOAD)
         docs_we_want = yield d
-        logger.info("Fetching new docs from server: %s" % len(docs_we_want))
-        while docs_we_want:
-            deferreds = []
-            for _ in range(min(self.concurrency_limit, len(docs_we_want))):
-                blob_id = docs_we_want.pop()
-                logger.info("Fetching new doc: %s" % blob_id)
-                d = with_retry(self.get, blob_id, namespace)
-                deferreds.append(d)
-            yield defer.gatherResults(deferreds)
+        total = len(docs_we_want)
+        logger.info("Will fetch %d blobs from server." % total)
+        deferreds = []
+        semaphore = defer.DeferredSemaphore(self.concurrency_limit)
+
+        def release(result):
+            semaphore.release()
+            return result
+
+        for i in xrange(len(docs_we_want)):
+            yield semaphore.acquire()
+            blob_id = docs_we_want.pop()
+            logger.info("Fetching blob (%d/%d): %s" % (i, total, blob_id))
+            d = with_retry(self.get, blob_id, namespace)
+            d.addCallbacks(release, release)
+            deferreds.append(d)
+        yield defer.gatherResults(deferreds)
 
     @defer.inlineCallbacks
     def sync(self, namespace=''):
diff --git a/tests/blobs/test_blob_manager.py b/tests/blobs/test_blob_manager.py
index 81379c73..c6f84e29 100644
--- a/tests/blobs/test_blob_manager.py
+++ b/tests/blobs/test_blob_manager.py
@@ -19,6 +19,7 @@ Tests for BlobManager.
 """
 from twisted.trial import unittest
 from twisted.internet import defer
+from twisted.web.error import SchemeNotSupported
 from leap.soledad.client._db.blobs import BlobManager, BlobDoc, FIXED_REV
 from leap.soledad.client._db.blobs import BlobAlreadyExistsError
 from leap.soledad.client._db.blobs import SyncStatus
@@ -154,7 +155,8 @@ class BlobManagerTestCase(unittest.TestCase):
         self.manager._encrypt_and_upload = Mock(return_value=upload_failure)
         content, blob_id = "Blob content", uuid4().hex
         doc1 = BlobDoc(BytesIO(content), blob_id)
-        with pytest.raises(Exception):
+        with pytest.raises(SchemeNotSupported):
+            # should fail because manager URL is invalid
             yield self.manager.put(doc1, len(content))
         pending_upload = SyncStatus.PENDING_UPLOAD
         local_list = yield self.manager.local_list(sync_status=pending_upload)
@@ -166,7 +168,8 @@ class BlobManagerTestCase(unittest.TestCase):
         self.manager.remote_list = Mock(return_value=[])
         content, blob_id = "Blob content", uuid4().hex
         doc1 = BlobDoc(BytesIO(content), blob_id)
-        with pytest.raises(Exception):
+        with pytest.raises(SchemeNotSupported):
+            # should fail because manager URL is invalid
             yield self.manager.put(doc1, len(content))
         for _ in range(self.manager.max_retries + 1):
             with pytest.raises(defer.FirstError):