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// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <string>
#include <mesos/mesos.hpp>
#include <process/future.hpp>
#include <stout/duration.hpp>
#include <stout/nothing.hpp>
#include <stout/option.hpp>
#include <stout/try.hpp>
namespace mesos {
namespace master {
namespace contender {
* An abstraction for contending to be a leading master.
* TODO(benh): Support contending with a v1::MasterInfo.
class MasterContender
* Creates a master contender. If `masterContenderModule` contains a valid
* module name (that is, a name that matches the name specified in a JSON
* file/string passed into the command-line invocations using the `--modules`
* flag). Additional parameters required to create an object of the contender
* type are expected to be specified in the JSON's `parameter` object. In
* command-line invocations, the value of `masterContenderModule` is expected
* to come from the `--master_contender` flag.
* If `masterContenderModule` is `None`, `zk` is checked and if it contains a
* valid `zk://` or `file://` path (passed in using the `--zk` flag), an
* instance of ZooKeeperMasterContender is returned.
* If both arguments are `None`, `StandaloneMasterDetector` is returned.
* Note that the returned contender still needs to be `initialize()`d.
static Try<MasterContender*> create(
const Option<std::string>& zk,
const Option<std::string>& masterContenderModule = None(),
const Option<Duration>& zkSessionTimeout = None());
* Note that the contender's membership, if obtained, is scheduled
* to be cancelled during destruction.
virtual ~MasterContender() = 0;
* Initializes the contender with the MasterInfo of the master it
* contends on behalf of.
virtual void initialize(const MasterInfo& masterInfo) = 0;
* Returns a Future<Nothing> once the contender has entered the
* contest (by obtaining a membership) and an error otherwise.
* A failed future is returned if this method is called before
* initialize().
* The inner Future returns Nothing when the contender is out of
* the contest (i.e. its membership is lost).
* This method can be used to contend again after candidacy is
* obtained (the outer future satisfied), otherwise the future for
* the pending election is returned.
* Recontending after candidacy is obtained causes the previous
* candidacy to be withdrawn.
virtual process::Future<process::Future<Nothing>> contend() = 0;
} // namespace contender {
} // namespace master {
} // namespace mesos {