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arangodb/arangod/Agency/AddFollower.cpp

284 lines
8.6 KiB
C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2016 ArangoDB 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 Andreas Streichardt
////////////////////////////////////////////////////////////////////////////////
#include "AddFollower.h"
#include "Agency/Agent.h"
#include "Agency/Job.h"
using namespace arangodb::consensus;
AddFollower::AddFollower(Node const& snapshot, Agent* agent,
std::string const& jobId, std::string const& creator,
std::string const& prefix, std::string const& database,
std::string const& collection,
std::string const& shard,
std::string const& newFollower)
: Job(snapshot, agent, jobId, creator, prefix),
_database(database),
_collection(collection),
_shard(shard),
_newFollower(newFollower) {
try {
JOB_STATUS js = status();
if (js == TODO) {
start();
} else if (js == NOTFOUND) {
if (create()) {
start();
}
}
} catch (std::exception const& e) {
LOG_TOPIC(WARN, Logger::AGENCY) << e.what() << __FILE__ << __LINE__;
finish("Shards/" + _shard, false, e.what());
}
}
AddFollower::~AddFollower() {}
bool AddFollower::create() {
LOG_TOPIC(INFO, Logger::AGENCY) << "Todo: AddFollower " << _newFollower
<< " to shard " + _shard;
std::string path, now(timepointToString(std::chrono::system_clock::now()));
// DBservers
#ifdef ARANGODB_ENABLE_MAINTAINER_MODE
std::string curPath =
curColPrefix + _database + "/" + _collection + "/" + _shard + "/servers";
Slice current = _snapshot(curPath).slice();
TRI_ASSERT(current.isArray());
TRI_ASSERT(current[0].isString());
#endif
std::string planPath =
planColPrefix + _database + "/" + _collection + "/shards";
auto const& myClones = clones(_snapshot, _database, _collection);
if (!myClones.empty()) {
size_t sub = 0;
auto myshards = _snapshot(planPath).children();
auto mpos = std::distance(myshards.begin(), myshards.find(_shard));
// Deal with my clones
for (auto const& collection : myClones) {
auto othershards = _snapshot(
planColPrefix + _database + "/" + collection + "/shards").children();
auto opos = othershards.begin();
std::advance(opos, mpos);
auto const& shard = opos->first;
AddFollower(_snapshot, _agent, _jobId + "-" + std::to_string(sub++),
_jobId, _agencyPrefix, _database, collection, shard,
_newFollower);
}
}
_jb = std::make_shared<Builder>();
_jb->openArray();
_jb->openObject();
path = _agencyPrefix + toDoPrefix + _jobId;
_jb->add(path, VPackValue(VPackValueType::Object));
_jb->add("creator", VPackValue(_creator));
_jb->add("type", VPackValue("addFollower"));
_jb->add("database", VPackValue(_database));
_jb->add("collection", VPackValue(_collection));
_jb->add("shard", VPackValue(_shard));
_jb->add("newFollower", VPackValue(_newFollower));
_jb->add("jobId", VPackValue(_jobId));
_jb->add("timeCreated", VPackValue(now));
_jb->close();
_jb->close();
_jb->close();
write_ret_t res = transact(_agent, *_jb);
if (res.accepted && res.indices.size() == 1 && res.indices[0]) {
return true;
}
LOG_TOPIC(INFO, Logger::AGENCY) << "Failed to insert job " + _jobId;
return false;
}
bool AddFollower::start() {
// DBservers
std::string planPath =
planColPrefix + _database + "/" + _collection + "/shards/" + _shard;
std::string curPath =
curColPrefix + _database + "/" + _collection + "/" + _shard + "/servers";
Slice current = _snapshot(curPath).slice();
Slice planned = _snapshot(planPath).slice();
TRI_ASSERT(current.isArray());
TRI_ASSERT(planned.isArray());
for (auto const& srv : VPackArrayIterator(current)) {
TRI_ASSERT(srv.isString());
if (srv.copyString() == _newFollower) {
finish("Shards/" + _shard, false,
"newFollower must not be already holding the shard.");
return false;
}
}
for (auto const& srv : VPackArrayIterator(planned)) {
TRI_ASSERT(srv.isString());
if (srv.copyString() == _newFollower) {
finish("Shards/" + _shard, false,
"newFollower must not be planned for shard already.");
return false;
}
}
// Copy todo to pending
Builder todo, pending;
// Get todo entry
todo.openArray();
if (_jb == nullptr) {
try {
_snapshot(toDoPrefix + _jobId).toBuilder(todo);
} catch (std::exception const&) {
LOG_TOPIC(INFO, Logger::AGENCY) << "Failed to get key " + toDoPrefix +
_jobId + " from agency snapshot";
return false;
}
} else {
todo.add(_jb->slice()[0].valueAt(0));
}
todo.close();
// Enter pending, remove todo, block toserver
pending.openArray();
// --- Add pending
pending.openObject();
pending.add(_agencyPrefix + pendingPrefix + _jobId,
VPackValue(VPackValueType::Object));
pending.add("timeStarted",
VPackValue(timepointToString(std::chrono::system_clock::now())));
for (auto const& obj : VPackObjectIterator(todo.slice()[0])) {
pending.add(obj.key.copyString(), obj.value);
}
pending.close();
// --- Delete todo
pending.add(_agencyPrefix + toDoPrefix + _jobId,
VPackValue(VPackValueType::Object));
pending.add("op", VPackValue("delete"));
pending.close();
// --- Block shard
pending.add(_agencyPrefix + blockedShardsPrefix + _shard,
VPackValue(VPackValueType::Object));
pending.add("jobId", VPackValue(_jobId));
pending.close();
// --- Plan changes
pending.add(_agencyPrefix + planPath, VPackValue(VPackValueType::Array));
for (auto const& srv : VPackArrayIterator(planned)) {
pending.add(srv);
}
pending.add(VPackValue(_newFollower));
pending.close();
// --- Increment Plan/Version
pending.add(_agencyPrefix + planVersion, VPackValue(VPackValueType::Object));
pending.add("op", VPackValue("increment"));
pending.close();
pending.close();
// Preconditions
// --- Check that Current servers are as we expect
pending.openObject();
pending.add(_agencyPrefix + curPath, VPackValue(VPackValueType::Object));
pending.add("old", current);
pending.close();
// --- Check if shard is not blocked
pending.add(_agencyPrefix + blockedShardsPrefix + _shard,
VPackValue(VPackValueType::Object));
pending.add("oldEmpty", VPackValue(true));
pending.close();
pending.close();
pending.close();
// Transact to agency
write_ret_t res = transact(_agent, pending);
if (res.accepted && res.indices.size() == 1 && res.indices[0]) {
LOG_TOPIC(INFO, Logger::AGENCY)
<< "Pending: Addfollower " + _newFollower + " to shard " + _shard;
return true;
}
LOG_TOPIC(INFO, Logger::AGENCY) << "Start precondition failed for " + _jobId;
return false;
}
JOB_STATUS AddFollower::status() {
auto status = exists();
if (status != NOTFOUND) { // Get job details from agency
try {
_database = _snapshot(pos[status] + _jobId + "/database").getString();
_collection = _snapshot(pos[status] + _jobId + "/collection").getString();
_newFollower =
_snapshot(pos[status] + _jobId + "/newFollower").getString();
_shard = _snapshot(pos[status] + _jobId + "/shard").getString();
} catch (std::exception const& e) {
std::stringstream err;
err << "Failed to find job " << _jobId << " in agency: " << e.what();
LOG_TOPIC(ERR, Logger::AGENCY) << err.str();
finish("Shards/" + _shard, false, err.str());
return FAILED;
}
}
if (status == PENDING) {
std::string curPath = curColPrefix + _database + "/" + _collection + "/" +
_shard + "/servers";
Slice current = _snapshot(curPath).slice();
for (auto const& srv : VPackArrayIterator(current)) {
if (srv.copyString() == _newFollower) {
if (finish("Shards/" + _shard)) {
return FINISHED;
}
}
}
}
return status;
}