169 lines
7.1 KiB
C++
169 lines
7.1 KiB
C++
/*
|
|
* FailureMonitor.h
|
|
*
|
|
* This source file is part of the FoundationDB open source project
|
|
*
|
|
* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifndef FLOW_FAILUREMONITOR_H
|
|
#define FLOW_FAILUREMONITOR_H
|
|
#pragma once
|
|
|
|
#include "flow/flow.h"
|
|
#include "fdbrpc/FlowTransport.h" // Endpoint
|
|
#include <unordered_map>
|
|
#include <unordered_set>
|
|
|
|
using std::vector;
|
|
|
|
/*
|
|
|
|
IFailureMonitor is used by load balancing, data distribution and other components
|
|
to report on which other machines are unresponsive or experiencing other failures.
|
|
This is vital both to reconfigure the system in response to failures and to prevent
|
|
actors from waiting forever for replies from remote machines that are no longer
|
|
available. When waiting for a reply, clients should generally stop waiting and
|
|
try an alternative server when a failure is reported, rather than relying on timeouts.
|
|
|
|
The information tracked for each machine is a FailureStatus, which
|
|
for the moment is just a boolean but might be richer in the future.
|
|
|
|
Get an IFailureMonitor by calling g_network->failureMonitor(); the simulator keeps
|
|
one for each simulated machine and ASIONetwork keeps one for each process.
|
|
|
|
The system attempts to ensure that failures are reported quickly, but may occasionally
|
|
report a working system as failed temporarily. Clients that intend to take very costly
|
|
actions as a result of a failure should probably wait a while to see if a machine becomes
|
|
unfailed first. If possible use onFailedFor() which in the future may react to 'permanent'
|
|
failures immediately.
|
|
|
|
In older FDB, information reported through this interface was actually actively supplied by
|
|
failureMonitorClient, which exchanges FailureMonitoringRequest/Reply pairs with the
|
|
failureDetectionServer actor on the ClusterController.
|
|
|
|
Now it is done locally by each process with help of of FlowTransport. Whenever a network
|
|
connection is establish/failed, the address is marked as available or failed accordingly. We
|
|
do however take an optimistic approach of assuming every newly discovered address
|
|
(when deserializing an endpoint) is healthy by default.
|
|
|
|
In the future it may be augmented with locally available information about failures (e.g.
|
|
TCP connection loss in ASIONetwork or unexpectedly long response times for application requests).
|
|
|
|
Communications failures are tracked at NetworkAddress granularity. When a request is made to
|
|
a missing endpoint on a non-failed machine, this information is reported back to the requesting
|
|
machine and tracked at the endpoint level.
|
|
|
|
*/
|
|
|
|
struct FailureStatus {
|
|
bool failed;
|
|
|
|
FailureStatus() : failed(true) {}
|
|
explicit FailureStatus(bool failed) : failed(failed) {}
|
|
bool isFailed() const { return failed; }
|
|
bool isAvailable() const { return !failed; }
|
|
|
|
bool operator==(FailureStatus const& r) const { return failed == r.failed; }
|
|
bool operator!=(FailureStatus const& r) const { return failed != r.failed; }
|
|
template <class Ar>
|
|
void serialize(Ar& ar) {
|
|
serializer(ar, failed);
|
|
}
|
|
};
|
|
|
|
class IFailureMonitor {
|
|
public:
|
|
// Returns the currently known status for the endpoint
|
|
virtual FailureStatus getState(Endpoint const& endpoint) const = 0;
|
|
|
|
// Returns the currently known status for the address
|
|
virtual FailureStatus getState(NetworkAddress const& address) const = 0;
|
|
|
|
// Only use this function when the endpoint is known to be failed
|
|
virtual void endpointNotFound(Endpoint const&) = 0;
|
|
|
|
// The next time the known status for the endpoint changes, returns the new status.
|
|
virtual Future<Void> onStateChanged(Endpoint const& endpoint) = 0;
|
|
|
|
// Returns when onFailed(endpoint) || transport().onDisconnect( endpoint.getPrimaryAddress() )
|
|
virtual Future<Void> onDisconnectOrFailure(Endpoint const& endpoint) = 0;
|
|
|
|
// Returns when transport().onDisconnect( address )
|
|
virtual Future<Void> onDisconnect(NetworkAddress const& address) = 0;
|
|
|
|
// Returns true if the endpoint is failed but the address of the endpoint is not failed.
|
|
virtual bool onlyEndpointFailed(Endpoint const& endpoint) const = 0;
|
|
|
|
// Returns true if the endpoint will never become available.
|
|
virtual bool permanentlyFailed(Endpoint const& endpoint) const = 0;
|
|
|
|
// Called by FlowTransport when a connection closes and a prior request or reply might be lost
|
|
virtual void notifyDisconnect(NetworkAddress const&) = 0;
|
|
|
|
// Called to update the failure status of network address directly when running client.
|
|
virtual void setStatus(NetworkAddress const& address, FailureStatus const& status) = 0;
|
|
|
|
// Returns when the known status of endpoint is next equal to status. Returns immediately
|
|
// if appropriate.
|
|
Future<Void> onStateEqual(Endpoint const& endpoint, FailureStatus status);
|
|
|
|
// Returns when the status of the given endpoint is next considered "failed"
|
|
Future<Void> onFailed(Endpoint const& endpoint) { return onStateEqual(endpoint, FailureStatus()); }
|
|
|
|
// Returns when the status of the given endpoint has continuously been "failed" for sustainedFailureDuration +
|
|
// (elapsedTime*sustainedFailureSlope)
|
|
Future<Void> onFailedFor(Endpoint const& endpoint,
|
|
double sustainedFailureDuration,
|
|
double sustainedFailureSlope = 0.0);
|
|
|
|
// Returns the failure monitor that the calling machine should use
|
|
static IFailureMonitor& failureMonitor() {
|
|
return *static_cast<IFailureMonitor*>((void*)g_network->global(INetwork::enFailureMonitor));
|
|
}
|
|
};
|
|
|
|
// SimpleFailureMonitor is the sole implementation of IFailureMonitor. It has no
|
|
// failure detection logic; it just implements the interface and reacts to setStatus() etc.
|
|
// Initially all addresses are considered failed, but all endpoints of a non-failed address are considered OK.
|
|
|
|
class SimpleFailureMonitor : public IFailureMonitor {
|
|
public:
|
|
SimpleFailureMonitor();
|
|
void setStatus(NetworkAddress const& address, FailureStatus const& status) override;
|
|
void endpointNotFound(Endpoint const&) override;
|
|
void notifyDisconnect(NetworkAddress const&) override;
|
|
|
|
Future<Void> onStateChanged(Endpoint const& endpoint) override;
|
|
FailureStatus getState(Endpoint const& endpoint) const override;
|
|
FailureStatus getState(NetworkAddress const& address) const override;
|
|
Future<Void> onDisconnectOrFailure(Endpoint const& endpoint) override;
|
|
Future<Void> onDisconnect(NetworkAddress const& address) override;
|
|
bool onlyEndpointFailed(Endpoint const& endpoint) const override;
|
|
bool permanentlyFailed(Endpoint const& endpoint) const override;
|
|
|
|
void reset();
|
|
|
|
private:
|
|
std::unordered_map<NetworkAddress, FailureStatus> addressStatus;
|
|
YieldedAsyncMap<Endpoint, bool> endpointKnownFailed;
|
|
YieldedAsyncMap<NetworkAddress, bool> disconnectTriggers;
|
|
std::unordered_set<Endpoint> failedEndpoints;
|
|
|
|
friend class OnStateChangedActorActor;
|
|
};
|
|
|
|
#endif
|