/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

package mesosproto;

import "mesos.proto";
import "github.com/gogo/protobuf/gogoproto/gogo.proto";


/**
 * Scheduler event API.
 *
 * An event is described using the standard protocol buffer "union"
 * trick, see:
 * https://developers.google.com/protocol-buffers/docs/techniques#union.
 */
message Event {
  // Possible event types, followed by message definitions if
  // applicable.
  enum Type {
    SUBSCRIBED = 1; // See 'Subscribed' below.
    OFFERS = 2;     // See 'Offers' below.
    RESCIND = 3;    // See 'Rescind' below.
    UPDATE = 4;     // See 'Update' below.
    MESSAGE = 5;    // See 'Message' below.
    FAILURE = 6;    // See 'Failure' below.
    ERROR = 7;      // See 'Error' below.
  }

  // First event received when the scheduler subscribes.
  message Subscribed {
    required FrameworkID framework_id = 1;
  }

  // Received whenever there are new resources that are offered to the
  // scheduler. Each offer corresponds to a set of resources on a
  // slave. Until the scheduler accepts or declines an offer the
  // resources are considered allocated to the scheduler.
  message Offers {
    repeated Offer offers = 1;
  }

  // Received when a particular offer is no longer valid (e.g., the
  // slave corresponding to the offer has been removed) and hence
  // needs to be rescinded. Any future calls ('Accept' / 'Decline') made
  // by the scheduler regarding this offer will be invalid.
  message Rescind {
    required OfferID offer_id = 1;
  }

  // Received whenever there is a status update that is generated by
  // the executor or slave or master. Status updates should be used by
  // executors to reliably communicate the status of the tasks that
  // they manage. It is crucial that a terminal update (see TaskState
  // in mesos.proto) is sent by the executor as soon as the task
  // terminates, in order for Mesos to release the resources allocated
  // to the task. It is also the responsibility of the scheduler to
  // explicitly acknowledge the receipt of a status update. See
  // 'Acknowledge' in the 'Call' section below for the semantics.
  message Update {
    required TaskStatus status = 1;
  }

  // Received when a custom message generated by the executor is
  // forwarded by the master. Note that this message is not
  // interpreted by Mesos and is only forwarded (without reliability
  // guarantees) to the scheduler. It is up to the executor to retry
  // if the message is dropped for any reason.
  message Message {
    required SlaveID slave_id = 1;
    required ExecutorID executor_id = 2;
    required bytes data = 3;
  }

  // Received when a slave is removed from the cluster (e.g., failed
  // health checks) or when an executor is terminated. Note that, this
  // event coincides with receipt of terminal UPDATE events for any
  // active tasks belonging to the slave or executor and receipt of
  // 'Rescind' events for any outstanding offers belonging to the
  // slave. Note that there is no guaranteed order between the
  // 'Failure', 'Update' and 'Rescind' events when a slave or executor
  // is removed.
  // TODO(vinod): Consider splitting the lost slave and terminated
  // executor into separate events and ensure it's reliably generated.
  message Failure {
    optional SlaveID slave_id = 1;

    // If this was just a failure of an executor on a slave then
    // 'executor_id' will be set and possibly 'status' (if we were
    // able to determine the exit status).
    optional ExecutorID executor_id = 2;
    optional int32 status = 3;
  }

  // Received when an invalid framework (e.g., unauthenticated,
  // unauthorized) attempts to subscribe with the master. Error can
  // also be received if scheduler sends invalid Calls (e.g., not
  // properly initialized).
  // TODO(vinod): Remove this once the old scheduler driver is no
  // longer supported. With HTTP API all errors will be signaled via
  // HTTP response codes.
  message Error {
    required string message = 1;
  }

  // Type of the event, indicates which optional field below should be
  // present if that type has a nested message definition.
  required Type type = 1;

  optional Subscribed subscribed = 2;
  optional Offers offers = 3;
  optional Rescind rescind = 4;
  optional Update update = 5;
  optional Message message = 6;
  optional Failure failure = 7;
  optional Error error = 8;
}


/**
 * Scheduler call API.
 *
 * Like Event, a Call is described using the standard protocol buffer
 * "union" trick (see above).
 */
message Call {
  // Possible call types, followed by message definitions if
  // applicable.
  enum Type {
    SUBSCRIBE = 1;   // See 'Subscribe' below.
    TEARDOWN = 2;    // Shuts down all tasks/executors and removes framework.
    ACCEPT = 3;      // See 'Accept' below.
    DECLINE = 4;     // See 'Decline' below.
    REVIVE = 5;      // Removes any previous filters set via ACCEPT or DECLINE.
    KILL = 6;        // See 'Kill' below.
    SHUTDOWN = 7;    // See 'Shutdown' below.
    ACKNOWLEDGE = 8; // See 'Acknowledge' below.
    RECONCILE = 9;   // See 'Reconcile' below.
    MESSAGE = 10;    // See 'Message' below.

    // TODO(benh): Consider adding an 'ACTIVATE' and 'DEACTIVATE' for
    // already subscribed frameworks as a way of stopping offers from
    // being generated and other events from being sent by the master.
    // Note that this functionality existed originally to support
    // SchedulerDriver::abort which was only necessary to handle
    // exceptions getting thrown from within Scheduler callbacks,
    // something that is not an issue with the Event/Call API.
  }

  // Subscribes the scheduler with the master to receive events. A
  // scheduler must send other calls only after it has received the
  // SUBCRIBED event.
  message Subscribe {
    // See the comments below on 'framework_id' on the semantics for
    // 'framework_info.id'.
    required FrameworkInfo framework_info = 1;

    // 'force' field is only relevant when 'framework_info.id' is set.
    // It tells the master what to do in case an instance of the
    // scheduler attempts to subscribe when another instance of it is
    // already connected (e.g., split brain due to network partition).
    // If 'force' is true, this scheduler instance is allowed and the
    // old connected scheduler instance is disconnected. If false,
    // this scheduler instance is disallowed subscription in favor of
    // the already connected scheduler instance.
    //
    // It is recommended to set this to true only when a newly elected
    // scheduler instance is attempting to subscribe but not when a
    // scheduler is retrying subscription (e.g., disconnection or
    // master failover; see sched/sched.cpp for an example).
    optional bool force = 2;
  }

  // Accepts an offer, performing the specified operations
  // in a sequential manner.
  //
  // E.g. Launch a task with a newly reserved persistent volume:
  //
  //   Accept {
  //     offer_ids: [ ... ]
  //     operations: [
  //       { type: RESERVE,
  //         reserve: { resources: [ disk(role):2 ] } }
  //       { type: CREATE,
  //         create: { volumes: [ disk(role):1+persistence ] } }
  //       { type: LAUNCH,
  //         launch: { task_infos ... disk(role):1;disk(role):1+persistence } }
  //     ]
  //   }
  //
  // Note that any of the offer’s resources not used in the 'Accept'
  // call (e.g., to launch a task) are considered unused and might be
  // reoffered to other frameworks. In other words, the same OfferID
  // cannot be used in more than one 'Accept' call.
  message Accept {
    repeated OfferID offer_ids = 1;
    repeated Offer.Operation operations = 2;
    optional Filters filters = 3;
  }

  // Declines an offer, signaling the master to potentially reoffer
  // the resources to a different framework. Note that this is same
  // as sending an Accept call with no operations. See comments on
  // top of 'Accept' for semantics.
  message Decline {
    repeated OfferID offer_ids = 1;
    optional Filters filters = 2;
  }

  // Kills a specific task. If the scheduler has a custom executor,
  // the kill is forwarded to the executor and it is up to the
  // executor to kill the task and send a TASK_KILLED (or TASK_FAILED)
  // update. Note that Mesos releases the resources for a task once it
  // receives a terminal update (See TaskState in mesos.proto) for it.
  // If the task is unknown to the master, a TASK_LOST update is
  // generated.
  message Kill {
    required TaskID task_id = 1;
    optional SlaveID slave_id = 2;
  }

  // Shuts down a custom executor. When the executor gets a shutdown
  // event, it is expected to kill all its tasks (and send TASK_KILLED
  // updates) and terminate. If the executor doesn’t terminate within
  // a certain timeout (configurable via
  // '--executor_shutdown_grace_period' slave flag), the slave will
  // forcefully destroy the container (executor and its tasks) and
  // transition its active tasks to TASK_LOST.
  message Shutdown {
    required ExecutorID executor_id = 1;
    required SlaveID slave_id = 2;
  }

  // Acknowledges the receipt of status update. Schedulers are
  // responsible for explicitly acknowledging the receipt of status
  // updates that have 'Update.status().uuid()' field set. Such status
  // updates are retried by the slave until they are acknowledged by
  // the scheduler.
  message Acknowledge {
    required SlaveID slave_id = 1;
    required TaskID task_id = 2;
    required bytes uuid = 3;
  }

  // Allows the scheduler to query the status for non-terminal tasks.
  // This causes the master to send back the latest task status for
  // each task in 'tasks', if possible. Tasks that are no longer known
  // will result in a TASK_LOST update. If 'statuses' is empty, then
  // the master will send the latest status for each task currently
  // known.
  message Reconcile {
   // TODO(vinod): Support arbitrary queries than just state of tasks.
    message Task {
      required TaskID task_id = 1;
      optional SlaveID slave_id = 2;
    }

    repeated Task tasks = 1;
  }

  // Sends arbitrary binary data to the executor. Note that Mesos
  // neither interprets this data nor makes any guarantees about the
  // delivery of this message to the executor.
  message Message {
    required SlaveID slave_id = 1;
    required ExecutorID executor_id = 2;
    required bytes data = 3;
  }

  // Identifies who generated this call. Master assigns a framework id
  // when a new scheduler subscribes for the first time. Once assigned,
  // the scheduler must set the 'framework_id' here and within its
  // FrameworkInfo (in any further 'Subscribe' calls). This allows the
  // master to identify a scheduler correctly across disconnections,
  // failovers, etc.
  optional FrameworkID framework_id = 1;

  // Type of the call, indicates which optional field below should be
  // present if that type has a nested message definition.
  required Type type = 2;

  optional Subscribe subscribe = 3;
  optional Accept accept = 4;
  optional Decline decline = 5;
  optional Kill kill = 6;
  optional Shutdown shutdown = 7;
  optional Acknowledge acknowledge = 8;
  optional Reconcile reconcile = 9;
  optional Message message = 10;
}
