1 files changed, 74 insertions, 4 deletions
diff --git a/buildstream/_artifactcache/cascache.py b/buildstream/_artifactcache/cascache.py
index 936cb780b..3a3181bfb 100644
--- a/buildstream/_artifactcache/cascache.py
+++ b/buildstream/_artifactcache/cascache.py
@@ -1048,10 +1048,29 @@ class CASCache(ArtifactCache):
                 missing_blobs[d.hash] = d
 
         # Upload any blobs missing on the server
-        for blob_digest in missing_blobs.values():
-            with open(self.objpath(blob_digest), 'rb') as f:
-                assert os.fstat(f.fileno()).st_size == blob_digest.size_bytes
-                self._send_blob(remote, blob_digest, f, u_uid=u_uid)
+        self._send_blobs(remote, missing_blobs.values(), u_uid)
+
+    def _send_blobs(self, remote, digests, u_uid=uuid.uuid4()):
+        batch = _CASBatchUpdate(remote)
+
+        for digest in digests:
+            with open(self.objpath(digest), 'rb') as f:
+                assert os.fstat(f.fileno()).st_size == digest.size_bytes
+
+                if (digest.size_bytes >= remote.max_batch_total_size_bytes or
+                        not remote.batch_update_supported):
+                    # Too large for batch request, upload in independent request.
+                    self._send_blob(remote, digest, f, u_uid=u_uid)
+                else:
+                    if not batch.add(digest, f):
+                        # Not enough space left in batch request.
+                        # Complete pending batch first.
+                        batch.send()
+                        batch = _CASBatchUpdate(remote)
+                        batch.add(digest, f)
+
+        # Send final batch
+        batch.send()
 
 
 # Represents a single remote CAS cache.
@@ -1126,6 +1145,17 @@ class _CASRemote():
                 if e.code() != grpc.StatusCode.UNIMPLEMENTED:
                     raise
 
+            # Check whether the server supports BatchUpdateBlobs()
+            self.batch_update_supported = False
+            try:
+                request = remote_execution_pb2.BatchUpdateBlobsRequest()
+                response = self.cas.BatchUpdateBlobs(request)
+                self.batch_update_supported = True
+            except grpc.RpcError as e:
+                if (e.code() != grpc.StatusCode.UNIMPLEMENTED and
+                        e.code() != grpc.StatusCode.PERMISSION_DENIED):
+                    raise
+
             self._initialized = True
 
 
@@ -1173,6 +1203,46 @@ class _CASBatchRead():
             yield (response.digest, response.data)
 
 
+# Represents a batch of blobs queued for upload.
+#
+class _CASBatchUpdate():
+    def __init__(self, remote):
+        self._remote = remote
+        self._max_total_size_bytes = remote.max_batch_total_size_bytes
+        self._request = remote_execution_pb2.BatchUpdateBlobsRequest()
+        self._size = 0
+        self._sent = False
+
+    def add(self, digest, stream):
+        assert not self._sent
+
+        new_batch_size = self._size + digest.size_bytes
+        if new_batch_size > self._max_total_size_bytes:
+            # Not enough space left in current batch
+            return False
+
+        blob_request = self._request.requests.add()
+        blob_request.digest.hash = digest.hash
+        blob_request.digest.size_bytes = digest.size_bytes
+        blob_request.data = stream.read(digest.size_bytes)
+        self._size = new_batch_size
+        return True
+
+    def send(self):
+        assert not self._sent
+        self._sent = True
+
+        if len(self._request.requests) == 0:
+            return
+
+        batch_response = self._remote.cas.BatchUpdateBlobs(self._request)
+
+        for response in batch_response.responses:
+            if response.status.code != grpc.StatusCode.OK.value[0]:
+                raise ArtifactError("Failed to upload blob {}: {}".format(
+                    response.digest.hash, response.status.code))
+
+
 def _grouper(iterable, n):
     while True:
         try: