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arangodb/arangod/Cluster/HeartbeatThread.cpp

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////
#include "HeartbeatThread.h"
#include <velocypack/Iterator.h>
#include <velocypack/velocypack-aliases.h>
#include "ApplicationFeatures/ApplicationServer.h"
#include "Basics/ConditionLocker.h"
#include "Basics/MutexLocker.h"
#include "Basics/VelocyPackHelper.h"
#include "Basics/tri-strings.h"
#include "Cluster/ClusterComm.h"
#include "Cluster/ClusterInfo.h"
#include "Cluster/ClusterMethods.h"
#include "Cluster/DBServerAgencySync.h"
#include "Cluster/ServerState.h"
#include "Dispatcher/Dispatcher.h"
#include "Dispatcher/DispatcherFeature.h"
#include "Dispatcher/Job.h"
#include "GeneralServer/RestHandlerFactory.h"
#include "Logger/Logger.h"
#include "RestServer/RestServerFeature.h"
#include "V8/v8-globals.h"
#include "VocBase/AuthInfo.h"
#include "VocBase/server.h"
#include "VocBase/vocbase.h"
using namespace arangodb;
std::atomic<bool> HeartbeatThread::HasRunOnce(false);
////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a heartbeat thread
////////////////////////////////////////////////////////////////////////////////
HeartbeatThread::HeartbeatThread(TRI_server_t* server,
AgencyCallbackRegistry* agencyCallbackRegistry,
uint64_t interval,
uint64_t maxFailsBeforeWarning)
: Thread("Heartbeat"),
_server(server),
_agencyCallbackRegistry(agencyCallbackRegistry),
_statusLock(),
_agency(),
_condition(),
_myId(ServerState::instance()->getId()),
_interval(interval),
_maxFailsBeforeWarning(maxFailsBeforeWarning),
_numFails(0),
_lastSuccessfulVersion(0),
_isDispatchingChange(false),
_currentPlanVersion(0),
_ready(false),
_currentVersions(0, 0),
_desiredVersions(0, 0),
_wasNotified(false) {}
////////////////////////////////////////////////////////////////////////////////
/// @brief destroys a heartbeat thread
////////////////////////////////////////////////////////////////////////////////
HeartbeatThread::~HeartbeatThread() { shutdown(); }
////////////////////////////////////////////////////////////////////////////////
/// @brief heartbeat main loop
/// the heartbeat thread constantly reports the current server status to the
/// agency. it does so by sending the current state string to the key
/// "Sync/ServerStates/" + my-id.
/// after transferring the current state to the agency, the heartbeat thread
/// will wait for changes on the "Sync/Commands/" + my-id key. If no changes
/// occur,
/// then the request it aborted and the heartbeat thread will go on with
/// reporting its state to the agency again. If it notices a change when
/// watching the command key, it will wake up and apply the change locally.
////////////////////////////////////////////////////////////////////////////////
void HeartbeatThread::run() {
if (ServerState::instance()->isCoordinator()) {
runCoordinator();
} else {
runDBServer();
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief heartbeat main loop, dbserver version
////////////////////////////////////////////////////////////////////////////////
void HeartbeatThread::runDBServer() {
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "starting heartbeat thread (DBServer version)";
// mop: the heartbeat thread itself is now ready
setReady();
// mop: however we need to wait for the rest server here to come up
// otherwise we would already create collections and the coordinator would
// think
// ohhh the dbserver is online...pump some documents into it
// which fails when it is still in maintenance mode
while (arangodb::rest::RestHandlerFactory::isMaintenance()) {
usleep(100000);
}
// convert timeout to seconds
double const interval = (double)_interval / 1000.0 / 1000.0;
std::function<bool(VPackSlice const& result)> updatePlan =
[&](VPackSlice const& result) {
if (!result.isNumber()) {
LOG_TOPIC(ERR, Logger::HEARTBEAT) << "Plan Version is not a number! "
<< result.toJson();
return false;
}
uint64_t version = result.getNumber<uint64_t>();
bool doSync = false;
{
MUTEX_LOCKER(mutexLocker, _statusLock);
if (version > _desiredVersions.plan) {
_desiredVersions.plan = version;
LOG_TOPIC(DEBUG, Logger::HEARTBEAT) << "Desired Current Version is now "
<< _desiredVersions.plan;
doSync = true;
}
}
if (doSync) {
syncDBServerStatusQuo();
}
return true;
};
auto planAgencyCallback = std::make_shared<AgencyCallback>(
_agency, "Plan/Version", updatePlan, true);
bool registered = false;
while (!registered) {
registered = _agencyCallbackRegistry->registerCallback(planAgencyCallback);
if (!registered) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "Couldn't register plan change in agency!";
sleep(1);
}
}
// we check Current/Version every few heartbeats:
int const currentCountStart = 1; // set to 1 by Max to speed up discovery
int currentCount = currentCountStart;
while (!isStopping()) {
LOG_TOPIC(DEBUG, Logger::HEARTBEAT) << "sending heartbeat to agency";
double const start = TRI_microtime();
// send our state to the agency.
// we don't care if this fails
sendState();
if (isStopping()) {
break;
}
if (--currentCount == 0) {
currentCount = currentCountStart;
// send an initial GET request to Sync/Commands/my-id
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "Looking at Sync/Commands/" + _myId;
AgencyCommResult result = _agency.getValues("Sync/Commands/" + _myId);
if (result.successful()) {
handleStateChange(result);
}
if (isStopping()) {
break;
}
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "Refetching Current/Version...";
AgencyCommResult res = _agency.getValues("Current/Version");
if (!res.successful()) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "Could not read Current/Version from agency.";
} else {
VPackSlice s = res.slice()[0].get(
std::vector<std::string>({_agency.prefix(), std::string("Current"),
std::string("Version")}));
if (!s.isInteger()) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "Current/Version in agency is not an integer.";
} else {
uint64_t currentVersion = 0;
try {
currentVersion = s.getUInt();
} catch (...) {
}
if (currentVersion == 0) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "Current/Version in agency is 0.";
} else {
{
MUTEX_LOCKER(mutexLocker, _statusLock);
if (currentVersion > _desiredVersions.current) {
_desiredVersions.current = currentVersion;
LOG_TOPIC(DEBUG, Logger::HEARTBEAT)
<< "Found greater Current/Version in agency.";
}
}
syncDBServerStatusQuo();
}
}
}
}
if (isStopping()) {
break;
}
double remain = interval - (TRI_microtime() - start);
// mop: execute at least once
do {
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "Entering update loop";
bool wasNotified;
{
CONDITION_LOCKER(locker, _condition);
wasNotified = _wasNotified;
if (!wasNotified) {
if (remain > 0.0) {
locker.wait(static_cast<uint64_t>(remain * 1000000.0));
wasNotified = _wasNotified;
}
}
_wasNotified = false;
}
if (!wasNotified) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "Lock reached timeout";
planAgencyCallback->refetchAndUpdate(true);
} else {
// mop: a plan change returned successfully...
// recheck and redispatch in case our desired versions increased
// in the meantime
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "wasNotified==true";
syncDBServerStatusQuo();
}
remain = interval - (TRI_microtime() - start);
} while (remain > 0);
}
_agencyCallbackRegistry->unregisterCallback(planAgencyCallback);
int count = 0;
while (++count < 3000) {
bool isInPlanChange;
{
MUTEX_LOCKER(mutexLocker, _statusLock);
isInPlanChange = _isDispatchingChange;
}
if (!isInPlanChange) {
break;
}
usleep(1000);
}
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "stopped heartbeat thread (DBServer version)";
}
////////////////////////////////////////////////////////////////////////////////
/// @brief heartbeat main loop, coordinator version
////////////////////////////////////////////////////////////////////////////////
void HeartbeatThread::runCoordinator() {
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "starting heartbeat thread (coordinator version)";
uint64_t oldUserVersion = 0;
// convert timeout to seconds
double const interval = (double)_interval / 1000.0 / 1000.0;
// last value of plan which we have noticed:
uint64_t lastPlanVersionNoticed = 0;
// last value of current which we have noticed:
uint64_t lastCurrentVersionNoticed = 0;
setReady();
while (!isStopping()) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "sending heartbeat to agency";
double const start = TRI_microtime();
// send our state to the agency.
// we don't care if this fails
sendState();
if (isStopping()) {
break;
}
AgencyReadTransaction trx(std::vector<std::string>(
{_agency.prefixPath() + "Plan/Version",
_agency.prefixPath() + "Current/Version",
_agency.prefixPath() + "Sync/Commands/" + _myId,
_agency.prefixPath() + "Sync/UserVersion"}));
AgencyCommResult result = _agency.sendTransactionWithFailover(trx);
if (!result.successful()) {
LOG_TOPIC(WARN, Logger::HEARTBEAT)
<< "Heartbeat: Could not read from agency!";
} else {
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "Looking at Sync/Commands/" + _myId;
handleStateChange(result);
VPackSlice versionSlice = result.slice()[0].get(
std::vector<std::string>({_agency.prefix(), "Plan", "Version"}));
if (versionSlice.isInteger()) {
// there is a plan version
uint64_t planVersion = 0;
try {
planVersion = versionSlice.getUInt();
} catch (...) {
}
if (planVersion > lastPlanVersionNoticed) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "Found planVersion " << planVersion << " which is newer than "
<< lastPlanVersionNoticed;
if (handlePlanChangeCoordinator(planVersion)) {
lastPlanVersionNoticed = planVersion;
} else {
LOG_TOPIC(WARN, Logger::HEARTBEAT)
<< "handlePlanChangeCoordinator was unsuccessful";
}
}
}
VPackSlice slice = result.slice()[0].get(
std::vector<std::string>({_agency.prefix(), "Sync", "UserVersion"}));
if (slice.isInteger()) {
// there is a UserVersion
uint64_t userVersion = 0;
try {
userVersion = slice.getUInt();
} catch (...) {
}
if (userVersion > 0 && userVersion != oldUserVersion) {
oldUserVersion = userVersion;
RestServerFeature::AUTH_INFO.outdate();
}
}
versionSlice = result.slice()[0].get(
std::vector<std::string>({_agency.prefix(), "Current", "Version"}));
if (versionSlice.isInteger()) {
uint64_t currentVersion = 0;
try {
currentVersion = versionSlice.getUInt();
} catch (...) {
}
if (currentVersion > lastCurrentVersionNoticed) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT)
<< "Found currentVersion " << currentVersion
<< " which is newer than " << lastCurrentVersionNoticed;
lastCurrentVersionNoticed = currentVersion;
ClusterInfo::instance()->invalidateCurrent();
}
}
}
double remain = interval - (TRI_microtime() - start);
// sleep for a while if appropriate, on some systems usleep does not
// like arguments greater than 1000000
while (remain > 0.0) {
if (remain >= 0.5) {
usleep(500000);
remain -= 0.5;
} else {
usleep((unsigned long)(remain * 1000.0 * 1000.0));
remain = 0.0;
}
}
}
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "stopped heartbeat thread";
}
////////////////////////////////////////////////////////////////////////////////
/// @brief initializes the heartbeat
////////////////////////////////////////////////////////////////////////////////
bool HeartbeatThread::init() {
// send the server state a first time and use this as an indicator about
// the agency's health
if (!sendState()) {
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief finished plan change
////////////////////////////////////////////////////////////////////////////////
void HeartbeatThread::removeDispatchedJob(DBServerAgencySyncResult result) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "Dispatched job returned!";
bool doSleep = false;
{
MUTEX_LOCKER(mutexLocker, _statusLock);
if (result.success) {
LOG_TOPIC(DEBUG, Logger::HEARTBEAT)
<< "Sync request successful. Now have Plan " << result.planVersion
<< ", Current " << result.currentVersion;
_currentVersions = AgencyVersions(result);
} else {
LOG_TOPIC(DEBUG, Logger::HEARTBEAT) << "Sync request failed!";
// mop: we will retry immediately so wait at least a LITTLE bit
doSleep = true;
}
_isDispatchingChange = false;
}
if (doSleep) {
// Sleep a little longer, since this might be due to some synchronisation
// of shards going on in the background
usleep(500000);
usleep(500000);
}
CONDITION_LOCKER(guard, _condition);
_wasNotified = true;
_condition.signal();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief handles a plan version change, coordinator case
/// this is triggered if the heartbeat thread finds a new plan version number
////////////////////////////////////////////////////////////////////////////////
static std::string const prefixPlanChangeCoordinator = "Plan/Databases";
bool HeartbeatThread::handlePlanChangeCoordinator(uint64_t currentPlanVersion) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "found a plan update";
AgencyCommResult result = _agency.getValues(prefixPlanChangeCoordinator);
if (result.successful()) {
std::vector<TRI_voc_tick_t> ids;
velocypack::Slice databases = result.slice()[0].get(
std::vector<std::string>({AgencyComm::prefix(), "Plan", "Databases"}));
if (!databases.isObject()) {
return false;
}
// loop over all database names we got and create a local database
// instance if not yet present:
for (auto const& options : VPackObjectIterator(databases)) {
if (!options.value.isObject()) {
continue;
}
auto nameSlice = options.value.get("name");
if (nameSlice.isNone()) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "Missing name in agency database plan";
continue;
}
std::string const name = options.value.get("name").copyString();
TRI_voc_tick_t id = 0;
if (options.value.hasKey("id")) {
VPackSlice const v = options.value.get("id");
if (v.isString()) {
try {
id = std::stoul(v.copyString());
} catch (std::exception const& e) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "Failed to convert id string to number";
LOG_TOPIC(ERR, Logger::HEARTBEAT) << e.what();
}
}
}
if (id > 0) {
ids.push_back(id);
}
TRI_vocbase_t* vocbase =
TRI_UseCoordinatorDatabaseServer(_server, name.c_str());
if (vocbase == nullptr) {
// database does not yet exist, create it now
if (id == 0) {
// verify that we have an id
id = ClusterInfo::instance()->uniqid();
}
TRI_vocbase_defaults_t defaults;
TRI_GetDatabaseDefaultsServer(_server, &defaults);
// create a local database object...
TRI_CreateCoordinatorDatabaseServer(_server, id, name.c_str(),
&defaults, &vocbase);
HasRunOnce = true;
} else {
TRI_ReleaseVocBase(vocbase);
}
}
// get the list of databases that we know about locally
std::vector<TRI_voc_tick_t> localIds =
TRI_GetIdsCoordinatorDatabaseServer(_server);
for (auto id : localIds) {
auto r = std::find(ids.begin(), ids.end(), id);
if (r == ids.end()) {
// local database not found in the plan...
TRI_DropByIdCoordinatorDatabaseServer(_server, id, false);
}
}
} else {
return false;
}
// invalidate our local cache
ClusterInfo::instance()->flush();
// turn on error logging now
if (!ClusterComm::instance()->enableConnectionErrorLogging(true)) {
LOG_TOPIC(DEBUG, Logger::HEARTBEAT)
<< "created coordinator databases for the first time";
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief handles a plan version change, DBServer case
/// this is triggered if the heartbeat thread finds a new plan version number,
/// and every few heartbeats if the Current/Version has changed.
////////////////////////////////////////////////////////////////////////////////
bool HeartbeatThread::syncDBServerStatusQuo() {
bool shouldUpdate = false;
bool becauseOfPlan = false;
bool becauseOfCurrent = false;
{
MUTEX_LOCKER(mutexLocker, _statusLock);
// mop: only dispatch one at a time
if (_isDispatchingChange) {
return false;
}
if (_desiredVersions.plan > _currentVersions.plan) {
LOG_TOPIC(DEBUG, Logger::HEARTBEAT)
<< "Plan version " << _currentVersions.plan
<< " is lower than desired version " << _desiredVersions.plan;
_isDispatchingChange = true;
becauseOfPlan = true;
}
if (_desiredVersions.current > _currentVersions.current) {
LOG_TOPIC(DEBUG, Logger::HEARTBEAT)
<< "Current version " << _currentVersions.current
<< " is lower than desired version " << _desiredVersions.current;
_isDispatchingChange = true;
becauseOfCurrent = true;
}
shouldUpdate = _isDispatchingChange;
}
if (shouldUpdate) {
// First invalidate the caches in ClusterInfo:
auto ci = ClusterInfo::instance();
if (becauseOfPlan) {
ci->invalidatePlan();
}
if (becauseOfCurrent) {
ci->invalidateCurrent();
}
// only warn if the application server is still there and dispatching
// should succeed
bool warn = false;
application_features::ApplicationServer* server =
application_features::ApplicationServer::server;
if (server != nullptr) {
auto state = server->state();
warn = (state != application_features::ServerState::IN_STOP &&
state != application_features::ServerState::IN_UNPREPARE &&
state != application_features::ServerState::STOPPED &&
state != application_features::ServerState::ABORT);
}
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "dispatching sync";
// schedule a job for the change
std::unique_ptr<arangodb::rest::Job> job(new DBServerAgencySync(this));
auto dispatcher = DispatcherFeature::DISPATCHER;
if (dispatcher == nullptr) {
if (warn) {
LOG_TOPIC(ERR, Logger::HEARTBEAT)
<< "could not schedule dbserver sync - dispatcher gone.";
}
return false;
}
int res = dispatcher->addJob(job, false);
if (res == TRI_ERROR_NO_ERROR) {
LOG_TOPIC(TRACE, Logger::HEARTBEAT) << "scheduled dbserver sync";
return true;
}
MUTEX_LOCKER(mutexLocker, _statusLock);
_isDispatchingChange = false;
if (warn && res != TRI_ERROR_SHUTTING_DOWN) {
LOG_TOPIC(ERR, Logger::HEARTBEAT) << "could not schedule dbserver sync";
}
}
return false;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief handles a state change
/// this is triggered if the watch command reports a change
/// when this is called, it will update the index value of the last command
/// (we'll pass the updated index value to the next watches so we don't get
/// notified about this particular change again).
////////////////////////////////////////////////////////////////////////////////
bool HeartbeatThread::handleStateChange(AgencyCommResult& result) {
VPackSlice const slice = result.slice()[0].get(std::vector<std::string>(
{AgencyComm::prefix(), "Sync", "Commands", _myId}));
if (slice.isString()) {
std::string command = slice.copyString();
ServerState::StateEnum newState = ServerState::stringToState(command);
if (newState != ServerState::STATE_UNDEFINED) {
// state change.
ServerState::instance()->setState(newState);
return true;
}
}
return false;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief sends the current server's state to the agency
////////////////////////////////////////////////////////////////////////////////
bool HeartbeatThread::sendState() {
const AgencyCommResult result = _agency.sendServerState(0.0);
// 8.0 * static_cast<double>(_interval) / 1000.0 / 1000.0);
if (result.successful()) {
_numFails = 0;
return true;
}
if (++_numFails % _maxFailsBeforeWarning == 0) {
std::string const endpoints = AgencyComm::getEndpointsString();
LOG_TOPIC(WARN, Logger::HEARTBEAT)
<< "heartbeat could not be sent to agency endpoints (" << endpoints
<< "): http code: " << result.httpCode() << ", body: " << result.body();
_numFails = 0;
}
return false;
}
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