.pylintrc

@@ -460,6 +460,7 @@ known-third-party=boto3,
                   enchant,
                   google,
                   grpc,
+                  janus,
                   moto,
                   yaml
 
@@ -523,4 +524,4 @@ valid-metaclass-classmethod-first-arg=mcs
 
 # Exceptions that will emit a warning when being caught. Defaults to
 # "Exception"
-overgeneral-exceptions=Exception
+overgeneral-exceptions=Exception
\ No newline at end of file

buildgrid/_app/commands/cmd_server.py

@@ -20,7 +20,6 @@ Server command
 Create a BuildGrid server.
 """
 
-import asyncio
 import logging
 import sys
 
@@ -52,18 +51,14 @@ def start(context, config):
         click.echo("ERROR: Could not parse config: {}.\n".format(str(e)), err=True)
         sys.exit(-1)
 
-    loop = asyncio.get_event_loop()
     try:
         server.start()
-        loop.run_forever()
 
     except KeyboardInterrupt:
         pass
 
     finally:
-        context.logger.info("Stopping server")
         server.stop()
-        loop.close()
 
 
 def _create_server_from_config(config):

buildgrid/client/cas.py

@@ -171,7 +171,7 @@ class Downloader:
 
         return messages
 
-    def download_file(self, digest, file_path, queue=True):
+    def download_file(self, digest, file_path, is_executable=False, queue=True):
         """Retrieves a file from the remote CAS server.
 
         If queuing is allowed (`queue=True`), the download request **may** be
@@ -181,6 +181,7 @@ class Downloader:
         Args:
             digest (:obj:`Digest`): the file's digest to fetch.
             file_path (str): absolute or relative path to the local file to write.
+            is_executable (bool): whether the file is executable or not.
             queue (bool, optional): whether or not the download request may be
                 queued and submitted as part of a batch upload request. Defaults
                 to True.
@@ -193,9 +194,9 @@ class Downloader:
             file_path = os.path.abspath(file_path)
 
         if not queue or digest.size_bytes > FILE_SIZE_THRESHOLD:
-            self._fetch_file(digest, file_path)
+            self._fetch_file(digest, file_path, is_executable=is_executable)
         else:
-            self._queue_file(digest, file_path)
+            self._queue_file(digest, file_path, is_executable=is_executable)
 
     def download_directory(self, digest, directory_path):
         """Retrieves a :obj:`Directory` from the remote CAS server.
@@ -311,7 +312,7 @@ class Downloader:
 
         return read_blobs
 
-    def _fetch_file(self, digest, file_path):
+    def _fetch_file(self, digest, file_path, is_executable=False):
         """Fetches a file using ByteStream.Read()"""
         if self.instance_name:
             resource_name = '/'.join([self.instance_name, 'blobs',
@@ -332,7 +333,10 @@ class Downloader:
 
             assert byte_file.tell() == digest.size_bytes
 
-    def _queue_file(self, digest, file_path):
+        if is_executable:
+            os.chmod(file_path, 0o755)  # rwxr-xr-x / 755
+
+    def _queue_file(self, digest, file_path, is_executable=False):
         """Queues a file for later batch download"""
         if self.__file_request_size + digest.ByteSize() > MAX_REQUEST_SIZE:
             self.flush()
@@ -341,22 +345,25 @@ class Downloader:
         elif self.__file_request_count >= MAX_REQUEST_COUNT:
             self.flush()
 
-        self.__file_requests[digest.hash] = (digest, file_path)
+        self.__file_requests[digest.hash] = (digest, file_path, is_executable)
         self.__file_request_count += 1
         self.__file_request_size += digest.ByteSize()
         self.__file_response_size += digest.size_bytes
 
     def _fetch_file_batch(self, batch):
         """Sends queued data using ContentAddressableStorage.BatchReadBlobs()"""
-        batch_digests = [digest for digest, _ in batch.values()]
+        batch_digests = [digest for digest, _, _ in batch.values()]
         batch_blobs = self._fetch_blob_batch(batch_digests)
 
-        for (_, file_path), file_blob in zip(batch.values(), batch_blobs):
+        for (_, file_path, is_executable), file_blob in zip(batch.values(), batch_blobs):
             os.makedirs(os.path.dirname(file_path), exist_ok=True)
 
             with open(file_path, 'wb') as byte_file:
                 byte_file.write(file_blob)
 
+            if is_executable:
+                os.chmod(file_path, 0o755)  # rwxr-xr-x / 755
+
     def _fetch_directory(self, digest, directory_path):
         """Fetches a file using ByteStream.GetTree()"""
         # Better fail early if the local root path cannot be created:
@@ -414,7 +421,7 @@ class Downloader:
         for file_node in root_directory.files:
             file_path = os.path.join(root_path, file_node.name)
 
-            self._queue_file(file_node.digest, file_path)
+            self._queue_file(file_node.digest, file_path, is_executable=file_node.is_executable)
 
         for directory_node in root_directory.directories:
             directory_path = os.path.join(root_path, directory_node.name)

buildgrid/server/bots/instance.py

@@ -37,6 +37,10 @@ class BotsInterface:
         self._bot_sessions = {}
         self._scheduler = scheduler
 
+    @property
+    def scheduler(self):
+        return self._scheduler
+
     def register_instance_with_server(self, instance_name, server):
         server.add_bots_interface(self, instance_name)
 

buildgrid/server/bots/service.py

@@ -23,8 +23,9 @@ import logging
 
 import grpc
 
-from google.protobuf.empty_pb2 import Empty
+from google.protobuf import empty_pb2, timestamp_pb2
 
+from buildgrid._enums import BotStatus
 from buildgrid._exceptions import InvalidArgumentError, OutOfSyncError
 from buildgrid._protos.google.devtools.remoteworkers.v1test2 import bots_pb2
 from buildgrid._protos.google.devtools.remoteworkers.v1test2 import bots_pb2_grpc
@@ -32,24 +33,82 @@ from buildgrid._protos.google.devtools.remoteworkers.v1test2 import bots_pb2_grp
 
 class BotsService(bots_pb2_grpc.BotsServicer):
 
-    def __init__(self, server):
+    def __init__(self, server, monitor=True):
         self.__logger = logging.getLogger(__name__)
 
+        self.__bots_by_status = {}
+        self.__bots_by_instance = {}
+        self.__bots = {}
+
         self._instances = {}
+        self._is_monitored = True
 
         bots_pb2_grpc.add_BotsServicer_to_server(self, server)
 
-    def add_instance(self, name, instance):
-        self._instances[name] = instance
+        if self._is_monitored:
+            self.__bots_by_status[BotStatus.OK] = set()
+            self.__bots_by_status[BotStatus.UNHEALTHY] = set()
+            self.__bots_by_status[BotStatus.HOST_REBOOTING] = set()
+            self.__bots_by_status[BotStatus.BOT_TERMINATING] = set()
+
+    # --- Public API ---
+
+    def add_instance(self, instance_name, instance):
+        """Registers a new servicer instance.
+
+        Args:
+            instance_name (str): The new instance's name.
+            instance (BotsInterface): The new instance itself.
+        """
+        self._instances[instance_name] = instance
+
+        if self._is_monitored:
+            self.__bots_by_instance[instance_name] = 0
+
+    def get_scheduler(self, instance_name):
+        """Retrieves a reference to the scheduler for an instance.
+
+        Args:
+            instance_name (str): The name of the instance to query.
+
+        Returns:
+            Scheduler: A reference to the scheduler for `instance_name`.
+
+        Raises:
+            InvalidArgumentError: If no instance named `instance_name` exists.
+        """
+        instance = self._get_instance(instance_name)
+
+        return instance.scheduler
+
+    # --- Public API: Servicer ---
 
     def CreateBotSession(self, request, context):
+        """Handles CreateBotSessionRequest messages.
+
+        Args:
+            request (CreateBotSessionRequest): The incoming RPC request.
+            context (grpc.ServicerContext): Context for the RPC call.
+        """
         self.__logger.debug("CreateBotSession request from [%s]", context.peer())
 
+        instance_name = request.parent
+        bot_status = BotStatus(request.bot_session.status)
+        bot_id = request.bot_session.bot_id
+
         try:
-            parent = request.parent
-            instance = self._get_instance(request.parent)
-            return instance.create_bot_session(parent,
-                                               request.bot_session)
+            instance = self._get_instance(instance_name)
+            bot_session = instance.create_bot_session(instance_name,
+                                                      request.bot_session)
+            now = timestamp_pb2.Timestamp()
+            now.GetCurrentTime()
+
+            if self._is_monitored:
+                self.__bots[bot_id] = now
+                self.__bots_by_instance[instance_name] += 1
+                self.__bots_by_status[bot_status].add(bot_id)
+
+            return bot_session
 
         except InvalidArgumentError as e:
             self.__logger.error(e)
@@ -59,17 +118,36 @@ class BotsService(bots_pb2_grpc.BotsServicer):
         return bots_pb2.BotSession()
 
     def UpdateBotSession(self, request, context):
+        """Handles UpdateBotSessionRequest messages.
+
+        Args:
+            request (UpdateBotSessionRequest): The incoming RPC request.
+            context (grpc.ServicerContext): Context for the RPC call.
+        """
         self.__logger.debug("UpdateBotSession request from [%s]", context.peer())
 
+        names = request.name.split("/")
+        bot_status = BotStatus(request.bot_session.status)
+        bot_id = request.bot_session.bot_id
+
         try:
-            names = request.name.split("/")
-            # Operation name should be in format:
-            # {instance/name}/{uuid}
-            instance_name = ''.join(names[0:-1])
+            instance_name = '/'.join(names[:-1])
 
             instance = self._get_instance(instance_name)
-            return instance.update_bot_session(request.name,
-                                               request.bot_session)
+            bot_session = instance.update_bot_session(request.name,
+                                                      request.bot_session)
+
+            if self._is_monitored:
+                self.__bots[bot_id].GetCurrentTime()
+                if bot_id not in self.__bots_by_status[bot_status]:
+                    self.__bots_by_status[BotStatus.OK].discard(bot_id)
+                    self.__bots_by_status[BotStatus.UNHEALTHY].discard(bot_id)
+                    self.__bots_by_status[BotStatus.HOST_REBOOTING].discard(bot_id)
+                    self.__bots_by_status[BotStatus.BOT_TERMINATING].discard(bot_id)
+
+                    self.__bots_by_status[bot_status].add(bot_id)
+
+            return bot_session
 
         except InvalidArgumentError as e:
             self.__logger.error(e)
@@ -89,10 +167,40 @@ class BotsService(bots_pb2_grpc.BotsServicer):
         return bots_pb2.BotSession()
 
     def PostBotEventTemp(self, request, context):
+        """Handles PostBotEventTempRequest messages.
+
+        Args:
+            request (PostBotEventTempRequest): The incoming RPC request.
+            context (grpc.ServicerContext): Context for the RPC call.
+        """
         self.__logger.debug("PostBotEventTemp request from [%s]", context.peer())
 
         context.set_code(grpc.StatusCode.UNIMPLEMENTED)
-        return Empty()
+
+        return empty_pb2.Empty()
+
+    # --- Public API: Monitoring ---
+
+    @property
+    def is_monitored(self):
+        return self._is_monitored
+
+    def query_n_bots(self):
+        return len(self.__bots)
+
+    def query_n_bots_for_instance(self, instance_name):
+        try:
+            return self.__bots_by_instance[instance_name]
+        except KeyError:
+            return 0
+
+    def query_n_bots_for_status(self, bot_status):
+        try:
+            return len(self.__bots_by_status[bot_status])
+        except KeyError:
+            return 0
+
+    # --- Private API ---
 
     def _get_instance(self, name):
         try:

buildgrid/server/execution/instance.py

@@ -35,6 +35,10 @@ class ExecutionInstance:
         self._storage = storage
         self._scheduler = scheduler
 
+    @property
+    def scheduler(self):
+        return self._scheduler
+
     def register_instance_with_server(self, instance_name, server):
         server.add_execution_instance(self, instance_name)
 

buildgrid/server/execution/service.py

@@ -33,30 +33,79 @@ from buildgrid._protos.google.longrunning import operations_pb2
 
 class ExecutionService(remote_execution_pb2_grpc.ExecutionServicer):
 
-    def __init__(self, server):
+    def __init__(self, server, monitor=True):
         self.__logger = logging.getLogger(__name__)
 
+        self.__peers_by_instance = {}
+        self.__peers = {}
+
         self._instances = {}
+        self._is_monitored = True
+
         remote_execution_pb2_grpc.add_ExecutionServicer_to_server(self, server)
 
-    def add_instance(self, name, instance):
-        self._instances[name] = instance
+    # --- Public API ---
+
+    def add_instance(self, instance_name, instance):
+        """Registers a new servicer instance.
+
+        Args:
+            instance_name (str): The new instance's name.
+            instance (ExecutionInstance): The new instance itself.
+        """
+        self._instances[instance_name] = instance
+
+        if self._is_monitored:
+            self.__peers_by_instance[instance_name] = set()
+
+    def get_scheduler(self, instance_name):
+        """Retrieves a reference to the scheduler for an instance.
+
+        Args:
+            instance_name (str): The name of the instance to query.
+
+        Returns:
+            Scheduler: A reference to the scheduler for `instance_name`.
+
+        Raises:
+            InvalidArgumentError: If no instance named `instance_name` exists.
+        """
+        instance = self._get_instance(instance_name)
+
+        return instance.scheduler
+
+    # --- Public API: Servicer ---
 
     def Execute(self, request, context):
+        """Handles ExecuteRequest messages.
+
+        Args:
+            request (ExecuteRequest): The incoming RPC request.
+            context (grpc.ServicerContext): Context for the RPC call.
+        """
         self.__logger.debug("Execute request from [%s]", context.peer())
 
+        instance_name = request.instance_name
+        message_queue = queue.Queue()
+        peer = context.peer()
+
         try:
-            message_queue = queue.Queue()
-            instance = self._get_instance(request.instance_name)
+            instance = self._get_instance(instance_name)
             operation = instance.execute(request.action_digest,
                                          request.skip_cache_lookup,
                                          message_queue)
 
-            context.add_callback(partial(instance.unregister_message_client,
-                                         operation.name, message_queue))
+            context.add_callback(partial(self._rpc_termination_callback,
+                                         peer, instance_name, operation.name, message_queue))
 
-            instanced_op_name = "{}/{}".format(request.instance_name,
-                                               operation.name)
+            if self._is_monitored:
+                if peer not in self.__peers:
+                    self.__peers_by_instance[instance_name].add(peer)
+                    self.__peers[peer] = 1
+                else:
+                    self.__peers[peer] += 1
+
+            instanced_op_name = "{}/{}".format(instance_name, operation.name)
 
             self.__logger.info("Operation name: [%s]", instanced_op_name)
 
@@ -80,23 +129,37 @@ class ExecutionService(remote_execution_pb2_grpc.ExecutionServicer):
             yield operations_pb2.Operation()
 
     def WaitExecution(self, request, context):
+        """Handles WaitExecutionRequest messages.
+
+        Args:
+            request (WaitExecutionRequest): The incoming RPC request.
+            context (grpc.ServicerContext): Context for the RPC call.
+        """
         self.__logger.debug("WaitExecution request from [%s]", context.peer())
 
-        try:
-            names = request.name.split("/")
+        names = request.name.split('/')
+        instance_name = '/'.join(names[:-1])
+        operation_name = names[-1]
+        message_queue = queue.Queue()
+        peer = context.peer()
 
-            # Operation name should be in format:
-            # {instance/name}/{operation_id}
-            instance_name = ''.join(names[0:-1])
+        try:
+            if instance_name != request.instance_name:
+                raise InvalidArgumentError("Invalid operation [{}] for instance [{}]"
+                                            .format(request.name, instance_name))
 
-            message_queue = queue.Queue()
-            operation_name = names[-1]
             instance = self._get_instance(instance_name)
 
             instance.register_message_client(operation_name, message_queue)
+            context.add_callback(partial(self._rpc_termination_callback,
+                                         peer, instance_name, operation_name, message_queue))
 
-            context.add_callback(partial(instance.unregister_message_client,
-                                         operation_name, message_queue))
+            if self._is_monitored:
+                if peer not in self.__peers:
+                    self.__peers_by_instance[instance_name].add(peer)
+                    self.__peers[peer] = 1
+                else:
+                    self.__peers[peer] += 1
 
             for operation in instance.stream_operation_updates(message_queue,
                                                                operation_name):
@@ -111,6 +174,35 @@ class ExecutionService(remote_execution_pb2_grpc.ExecutionServicer):
             context.set_code(grpc.StatusCode.INVALID_ARGUMENT)
             yield operations_pb2.Operation()
 
+    # --- Public API: Monitoring ---
+
+    @property
+    def is_monitored(self):
+        return self._is_monitored
+
+    def query_n_clients(self):
+        return len(self.__peers)
+
+    def query_n_clients_for_instance(self, instance_name):
+        try:
+            return len(self.__peers_by_instance[instance_name])
+        except KeyError:
+            return 0
+
+    # --- Private API ---
+
+    def _rpc_termination_callback(self, peer, instance_name, job_name, message_queue):
+        instance = self._get_instance(instance_name)
+
+        instance.unregister_message_client(job_name, message_queue)
+
+        if self._is_monitored:
+            if self.__peers[peer] > 1:
+                self.__peers[peer] -= 1
+            else:
+                self.__peers_by_instance[instance_name].remove(peer)
+                del self.__peers[peer]
+
     def _get_instance(self, name):
         try:
             return self._instances[name]

buildgrid/server/instance.py

@@ -13,18 +13,21 @@
 # limitations under the License.
 
 
+import asyncio
 from concurrent import futures
 import logging
 import os
+import time
 
 import grpc
 
-from .cas.service import ByteStreamService, ContentAddressableStorageService
-from .actioncache.service import ActionCacheService
-from .execution.service import ExecutionService
-from .operations.service import OperationsService
-from .bots.service import BotsService
-from .referencestorage.service import ReferenceStorageService
+from buildgrid.server.cas.service import ByteStreamService, ContentAddressableStorageService
+from buildgrid.server.actioncache.service import ActionCacheService
+from buildgrid.server.execution.service import ExecutionService
+from buildgrid.server.operations.service import OperationsService
+from buildgrid.server.bots.service import BotsService
+from buildgrid.server.referencestorage.service import ReferenceStorageService
+from buildgrid.settings import MONITORING_PERIOD
 
 
 class BuildGridServer:
@@ -46,9 +49,11 @@ class BuildGridServer:
             # Use max_workers default from Python 3.5+
             max_workers = (os.cpu_count() or 1) * 5
 
-        server = grpc.server(futures.ThreadPoolExecutor(max_workers))
+        self.__grpc_executor = futures.ThreadPoolExecutor(max_workers)
+        self.__grpc_server = grpc.server(self.__grpc_executor)
 
-        self._server = server
+        self.__main_loop = asyncio.get_event_loop()
+        self.__monitoring_task = None
 
         self._execution_service = None
         self._bots_service = None
@@ -58,15 +63,32 @@ class BuildGridServer:
         self._cas_service = None
         self._bytestream_service = None
 
+        self._instances = set()
+
+    # --- Public API ---
+
     def start(self):
-        """Starts the server.
+        """Starts the BuildGrid server.
         """
-        self._server.start()
+        self.__grpc_server.start()
+
+        self.__monitoring_task = asyncio.ensure_future(
+            self._monitoring_worker(period=MONITORING_PERIOD), loop=self.__main_loop)
+        self.__main_loop.run_forever()
 
     def stop(self, grace=0):
-        """Stops the server.
+        """Stops the BuildGrid server.
+
+        Args:
+            grace (int, optional): A duration of time in seconds. Defaults to 0.
         """
-        self._server.stop(grace)
+        if self.__monitoring_task is not None:
+            self.__monitoring_task.cancel()
+
+        self.__grpc_server.stop(grace)
+
+        if grace > 0:
+            time.sleep(grace)
 
     def add_port(self, address, credentials):
         """Adds a port to the server.
@@ -80,11 +102,11 @@ class BuildGridServer:
         """
         if credentials is not None:
             self.__logger.info("Adding secure connection on: [%s]", address)
-            self._server.add_secure_port(address, credentials)
+            self.__grpc_server.add_secure_port(address, credentials)
 
         else:
             self.__logger.info("Adding insecure connection on [%s]", address)
-            self._server.add_insecure_port(address)
+            self.__grpc_server.add_insecure_port(address)
 
     def add_execution_instance(self, instance, instance_name):
         """Adds an :obj:`ExecutionInstance` to the service.
@@ -96,10 +118,11 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._execution_service is None:
-            self._execution_service = ExecutionService(self._server)
-
+            self._execution_service = ExecutionService(self.__grpc_server)
         self._execution_service.add_instance(instance_name, instance)
 
+        self._instances.add(instance_name)
+
     def add_bots_interface(self, instance, instance_name):
         """Adds a :obj:`BotsInterface` to the service.
 
@@ -110,10 +133,11 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._bots_service is None:
-            self._bots_service = BotsService(self._server)
-
+            self._bots_service = BotsService(self.__grpc_server)
         self._bots_service.add_instance(instance_name, instance)
 
+        self._instances.add(instance_name)
+
     def add_operations_instance(self, instance, instance_name):
         """Adds an :obj:`OperationsInstance` to the service.
 
@@ -124,8 +148,7 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._operations_service is None:
-            self._operations_service = OperationsService(self._server)
-
+            self._operations_service = OperationsService(self.__grpc_server)
         self._operations_service.add_instance(instance_name, instance)
 
     def add_reference_storage_instance(self, instance, instance_name):
@@ -138,8 +161,7 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._reference_storage_service is None:
-            self._reference_storage_service = ReferenceStorageService(self._server)
-
+            self._reference_storage_service = ReferenceStorageService(self.__grpc_server)
         self._reference_storage_service.add_instance(instance_name, instance)
 
     def add_action_cache_instance(self, instance, instance_name):
@@ -152,8 +174,7 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._action_cache_service is None:
-            self._action_cache_service = ActionCacheService(self._server)
-
+            self._action_cache_service = ActionCacheService(self.__grpc_server)
         self._action_cache_service.add_instance(instance_name, instance)
 
     def add_cas_instance(self, instance, instance_name):
@@ -166,8 +187,7 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._cas_service is None:
-            self._cas_service = ContentAddressableStorageService(self._server)
-
+            self._cas_service = ContentAddressableStorageService(self.__grpc_server)
         self._cas_service.add_instance(instance_name, instance)
 
     def add_bytestream_instance(self, instance, instance_name):
@@ -180,6 +200,33 @@ class BuildGridServer:
             instance_name (str): Instance name.
         """
         if self._bytestream_service is None:
-            self._bytestream_service = ByteStreamService(self._server)
-
+            self._bytestream_service = ByteStreamService(self.__grpc_server)
         self._bytestream_service.add_instance(instance_name, instance)
+
+    # --- Private API ---
+
+    async def _monitoring_worker(self, period=1):
+        while True:
+            try:
+                n_clients = self._execution_service.query_n_clients()
+                n_bots = self._bots_service.query_n_bots()
+
+                print('---')
+                print('Totals: n_clients={}, n_bots={}'.format(n_clients, n_bots))
+                print('Per instances:')
+                for instance_name in self._instances:
+                    n_clients = self._execution_service.query_n_clients_for_instance(instance_name)
+                    n_bots = self._bots_service.query_n_bots_for_instance(instance_name)
+                    am_queue_time = self._execution_service.get_scheduler(instance_name).query_am_queue_time()
+
+                    instance_name = instance_name or 'empty'
+
+                    print(' - {}: n_clients={}, n_bots={}, am_queue_time={}'
+                          .format(instance_name, n_clients, n_bots, am_queue_time))
+
+                await asyncio.sleep(period)
+
+            except asyncio.CancelledError:
+                break
+
+        self.__main_loop.stop()

buildgrid/server/job.py

@@ -13,10 +13,11 @@
 # limitations under the License.
 
 
+from datetime import datetime
 import logging
 import uuid
 
-from google.protobuf import timestamp_pb2
+from google.protobuf import duration_pb2, timestamp_pb2
 
 from buildgrid._enums import LeaseState, OperationStage
 from buildgrid._protos.build.bazel.remote.execution.v2 import remote_execution_pb2
@@ -37,6 +38,7 @@ class Job:
         self.__execute_response = None
         self.__operation_metadata = remote_execution_pb2.ExecuteOperationMetadata()
         self.__queued_timestamp = timestamp_pb2.Timestamp()
+        self.__queued_time_duration = duration_pb2.Duration()
         self.__worker_start_timestamp = timestamp_pb2.Timestamp()
         self.__worker_completed_timestamp = timestamp_pb2.Timestamp()
 
@@ -50,6 +52,8 @@ class Job:
         self._operation.done = False
         self._n_tries = 0
 
+    # --- Public API ---
+
     @property
     def name(self):
         return self._name
@@ -179,7 +183,7 @@ class Job:
                 result.Unpack(action_result)
 
             action_metadata = action_result.execution_metadata
-            action_metadata.queued_timestamp.CopyFrom(self.__worker_start_timestamp)
+            action_metadata.queued_timestamp.CopyFrom(self.__queued_timestamp)
             action_metadata.worker_start_timestamp.CopyFrom(self.__worker_start_timestamp)
             action_metadata.worker_completed_timestamp.CopyFrom(self.__worker_completed_timestamp)
 
@@ -204,6 +208,10 @@ class Job:
                 self.__queued_timestamp.GetCurrentTime()
             self._n_tries += 1
 
+        elif self.__operation_metadata.stage == OperationStage.EXECUTING.value:
+            queue_in, queue_out = self.__queued_timestamp.ToDatetime(), datetime.now()
+            self.__queued_time_duration.FromTimedelta(queue_out - queue_in)
+
         elif self.__operation_metadata.stage == OperationStage.COMPLETED.value:
             if self.__execute_response is not None:
                 self._operation.response.Pack(self.__execute_response)
@@ -213,3 +221,11 @@ class Job:
 
         for queue in self._operation_update_queues:
             queue.put(self._operation)
+
+    # --- Public API: Monitoring ---
+
+    def query_queue_time(self):
+        return self.__queued_time_duration.ToTimedelta()
+
+    def query_n_retries(self):
+        return self._n_tries - 1 if self._n_tries > 0 else 0

buildgrid/server/operations/instance.py

@@ -32,6 +32,10 @@ class OperationsInstance:
 
         self._scheduler = scheduler
 
+    @property
+    def scheduler(self):
+        return self._scheduler
+
     def register_instance_with_server(self, instance_name, server):
         server.add_operations_instance(self, instance_name)
 

buildgrid/server/operations/service.py

@@ -38,8 +38,34 @@ class OperationsService(operations_pb2_grpc.OperationsServicer):
 
         operations_pb2_grpc.add_OperationsServicer_to_server(self, server)
 
-    def add_instance(self, name, instance):
-        self._instances[name] = instance
+    # --- Public API ---
+
+    def add_instance(self, instance_name, instance):
+        """Registers a new servicer instance.
+
+        Args:
+            instance_name (str): The new instance's name.
+            instance (OperationsInstance): The new instance itself.
+        """
+        self._instances[instance_name] = instance
+
+    def get_scheduler(self, instance_name):
+        """Retrieves a reference to the scheduler for an instance.
+
+        Args:
+            instance_name (str): The name of the instance to query.
+
+        Returns:
+            Scheduler: A reference to the scheduler for `instance_name`.
+
+        Raises:
+            InvalidArgumentError: If no instance named `instance_name` exists.
+        """
+        instance = self._get_instance(instance_name)
+
+        return instance.scheduler
+
+    # --- Public API: Servicer ---
 
     def GetOperation(self, request, context):
         self.__logger.debug("GetOperation request from [%s]", context.peer())
@@ -132,6 +158,8 @@ class OperationsService(operations_pb2_grpc.OperationsServicer):
 
         return Empty()
 
+    # --- Private API ---
+
     def _parse_instance_name(self, name):
         """ If the instance name is not blank, 'name' will have the form
         {instance_name}/{operation_uuid}. Otherwise, it will just be

buildgrid/server/scheduler.py

@@ -22,22 +22,29 @@ Schedules jobs.
 from collections import deque
 import logging
 
+from buildgrid._enums import LeaseState, OperationStage
 from buildgrid._exceptions import NotFoundError
 
-from .job import OperationStage, LeaseState
-
 
 class Scheduler:
 
     MAX_N_TRIES = 5
 
-    def __init__(self, action_cache=None):
+    def __init__(self, action_cache=None, monitor=True):
         self.__logger = logging.getLogger(__name__)
 
+        self.__queue_times_by_priority = {}
+        self.__queue_time_average = 0, 0.0
+        self.__retries_by_error = {}
+        self.__retries_count = 0
+
         self._action_cache = action_cache
+        self._is_monitored = True
         self.jobs = {}
         self.queue = deque()
 
+    # --- Public API ---
+
     def register_client(self, job_name, queue):
         self.jobs[job_name].register_client(queue)
 
@@ -66,18 +73,22 @@ class Scheduler:
             operation_stage = OperationStage.QUEUED
             self.queue.append(job)
 
-        job.update_operation_stage(operation_stage)
+        self._update_job_operation_stage(job, operation_stage)
 
     def retry_job(self, job_name):
-        if job_name in self.jobs:
-            job = self.jobs[job_name]
-            if job.n_tries >= self.MAX_N_TRIES:
-                # TODO: Decide what to do with these jobs
-                job.update_operation_stage(OperationStage.COMPLETED)
-                # TODO: Mark these jobs as done
-            else:
-                job.update_operation_stage(OperationStage.QUEUED)
-                self.queue.appendleft(job)
+        job = self.jobs[job_name]
+
+        operation_stage = None
+        if job.n_tries >= self.MAX_N_TRIES:
+            # TODO: Decide what to do with these jobs
+            operation_stage = OperationStage.COMPLETED
+            # TODO: Mark these jobs as done
+
+        else:
+            operation_stage = OperationStage.QUEUED
+            self.queue.appendleft(job)
+
+        self._update_job_operation_stage(job, operation_stage)
 
     def list_jobs(self):
         return self.jobs.values()
@@ -112,13 +123,14 @@ class Scheduler:
         """
         job = self.jobs[job_name]
 
+        operation_stage = None
         if lease_state == LeaseState.PENDING:
             job.update_lease_state(LeaseState.PENDING)
-            job.update_operation_stage(OperationStage.QUEUED)
+            operation_stage = OperationStage.QUEUED
 
         elif lease_state == LeaseState.ACTIVE:
             job.update_lease_state(LeaseState.ACTIVE)
-            job.update_operation_stage(OperationStage.EXECUTING)
+            operation_stage = OperationStage.EXECUTING
 
         elif lease_state == LeaseState.COMPLETED:
             job.update_lease_state(LeaseState.COMPLETED,
@@ -127,7 +139,9 @@ class Scheduler:
             if self._action_cache is not None and not job.do_not_cache:
                 self._action_cache.update_action_result(job.action_digest, job.action_result)
 
-            job.update_operation_stage(OperationStage.COMPLETED)
+            operation_stage = OperationStage.COMPLETED
+
+        self._update_job_operation_stage(job, operation_stage)
 
     def get_job_lease(self, job_name):
         """Returns the lease associated to job, if any have been emitted yet."""
@@ -136,3 +150,59 @@ class Scheduler:
     def get_job_operation(self, job_name):
         """Returns the operation associated to job."""
         return self.jobs[job_name].operation
+
+    # --- Public API: Monitoring ---
+
+    @property
+    def is_monitored(self):
+        return self._is_monitored
+
+    def query_n_jobs(self):
+        return len(self.jobs)
+
+    def query_n_operations(self):
+        return len(self.jobs)
+
+    def query_n_operations_by_stage(self):
+        return len(self.jobs)
+
+    def query_n_leases(self):
+        return len(self.jobs)
+
+    def query_n_leases_by_state(self):
+        return len(self.jobs)
+
+    def query_n_retries(self):
+        return self.__retries_count
+
+    def query_n_retries_for_error(self, error_type):
+        try:
+            return self.__retries_by_error[error_type]
+        except KeyError:
+            return 0
+
+    def query_am_queue_time(self):
+        return self.__queue_time_average[1]
+
+    def query_am_queue_time_for_priority(self, priority_level):
+        try:
+            return self.__queue_times_by_priority[priority_level]
+        except KeyError:
+            return 0
+
+    # --- Private API ---
+
+    def _update_job_operation_stage(self, job, stage):
+        job.update_operation_stage(stage)
+
+        if self._is_monitored and stage == OperationStage.COMPLETED:
+            average_order, average_time = self.__queue_time_average
+            queue_time = job.query_queue_time().total_seconds()
+
+            average_order += 1
+            if average_order > 1:
+                average_time = average_time + (queue_time - average_time / average_order)
+            else:
+                average_time = queue_time
+
+            self.__queue_time_average = average_order, queue_time

buildgrid/settings.py

+# Copyright (C) 2018 Bloomberg LP
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  <http://www.apache.org/licenses/LICENSE-2.0>
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import hashlib
 
 
-# The hash function that CAS uses
+# Hash function used for computing digests:
 HASH = hashlib.sha256
+
+# Lenght in bytes of a hash string returned by HASH:
 HASH_LENGTH = HASH().digest_size * 2
+
+# Period, in seconds, for the monitoring cycle:
+MONITORING_PERIOD = 5.0

setup.py

@@ -112,13 +112,15 @@ setup(
     license="Apache License, Version 2.0",
     description="A remote execution service",
     packages=find_packages(),
+    python_requires='>= 3.5.3',  # janus requirement
     install_requires=[
-        'protobuf',
-        'grpcio',
-        'Click',
-        'PyYAML',
         'boto3 < 1.8.0',
         'botocore < 1.11.0',
+        'click',
+        'grpcio',
+        'janus',
+        'protobuf',
+        'pyyaml',
     ],
     entry_points={
         'console_scripts': [

tests/cas/data/hello/hello.sh

+#!/bin/bash
+
+echo "Hello, World!"