buildstream/_artifactcache/casserver.py

@@ -38,6 +38,10 @@ from .._context import Context
 from .cascache import CASCache
 
 
+# The default limit for gRPC messages is 4 MiB
+_MAX_BATCH_TOTAL_SIZE_BYTES = 4 * 1024 * 1024
+
+
 # Trying to push an artifact that is too large
 class ArtifactTooLargeException(Exception):
     pass
@@ -67,6 +71,9 @@ def create_server(repo, *, enable_push):
     remote_execution_pb2_grpc.add_ContentAddressableStorageServicer_to_server(
         _ContentAddressableStorageServicer(artifactcache), server)
 
+    remote_execution_pb2_grpc.add_CapabilitiesServicer_to_server(
+        _CapabilitiesServicer(), server)
+
     buildstream_pb2_grpc.add_ReferenceStorageServicer_to_server(
         _ReferenceStorageServicer(artifactcache, enable_push=enable_push), server)
 
@@ -229,6 +236,48 @@ class _ContentAddressableStorageServicer(remote_execution_pb2_grpc.ContentAddres
                 d.size_bytes = digest.size_bytes
         return response
 
+    def BatchReadBlobs(self, request, context):
+        response = remote_execution_pb2.BatchReadBlobsResponse()
+        batch_size = 0
+
+        for digest in request.digests:
+            batch_size += digest.size_bytes
+            if batch_size > _MAX_BATCH_TOTAL_SIZE_BYTES:
+                context.set_code(grpc.StatusCode.INVALID_ARGUMENT)
+                return response
+
+            blob_response = response.responses.add()
+            blob_response.digest.hash = digest.hash
+            blob_response.digest.size_bytes = digest.size_bytes
+            try:
+                with open(self.cas.objpath(digest), 'rb') as f:
+                    if os.fstat(f.fileno()).st_size != digest.size_bytes:
+                        blob_response.status.code = grpc.StatusCode.NOT_FOUND
+                        continue
+
+                    blob_response.data = f.read(digest.size_bytes)
+            except FileNotFoundError:
+                blob_response.status.code = grpc.StatusCode.NOT_FOUND
+
+        return response
+
+
+class _CapabilitiesServicer(remote_execution_pb2_grpc.CapabilitiesServicer):
+    def GetCapabilities(self, request, context):
+        response = remote_execution_pb2.ServerCapabilities()
+
+        cache_capabilities = response.cache_capabilities
+        cache_capabilities.digest_function.append(remote_execution_pb2.SHA256)
+        cache_capabilities.action_cache_update_capabilities.update_enabled = False
+        cache_capabilities.max_batch_total_size_bytes = _MAX_BATCH_TOTAL_SIZE_BYTES
+        cache_capabilities.symlink_absolute_path_strategy = remote_execution_pb2.CacheCapabilities.ALLOWED
+
+        response.deprecated_api_version.major = 2
+        response.low_api_version.major = 2
+        response.high_api_version.major = 2
+
+        return response
+
 
 class _ReferenceStorageServicer(buildstream_pb2_grpc.ReferenceStorageServicer):
     def __init__(self, cas, *, enable_push):