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arangodb/js/server/modules/@arangodb/cluster.js

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JavaScript

/*global ArangoServerState, ArangoClusterInfo */
'use strict';
////////////////////////////////////////////////////////////////////////////////
/// @brief JavaScript cluster functionality
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2012 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 triAGENS GmbH, Cologne, Germany
///
/// @author Jan Steemann
/// @author Copyright 2012, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////
var console = require("console");
var arangodb = require("@arangodb");
var ArangoCollection = arangodb.ArangoCollection;
var ArangoError = arangodb.ArangoError;
var request = require("@arangodb/request").request;
var endpointToURL = function (endpoint) {
if (endpoint.substr(0,6) === "ssl://") {
return "https://" + endpoint.substr(6);
}
var pos = endpoint.indexOf("://");
if (pos === -1) {
return "http://" + endpoint;
}
return "http" + endpoint.substr(pos);
};
////////////////////////////////////////////////////////////////////////////////
/// @brief create a unique identifier
////////////////////////////////////////////////////////////////////////////////
function getUUID () {
var rand = require("internal").rand;
var sha1 = require("internal").sha1;
return sha1("blabla"+rand());
}
////////////////////////////////////////////////////////////////////////////////
/// @brief create and post an AQL query that will fetch a READ lock on a
/// collection and will time out after a number of seconds
////////////////////////////////////////////////////////////////////////////////
function startReadingQuery (endpoint, collName, timeout) {
var uuid = getUUID();
var query = {"query": `LET t=SLEEP(${timeout})
FOR x IN ${collName}
LIMIT 1
RETURN "${uuid}" + t`};
var url = endpointToURL(endpoint);
var r = request({ url: url + "/_api/cursor", body: JSON.stringify(query),
method: "POST", headers: {"x-arango-async": true} });
if (r.status !== 202) {
console.error("startReadingQuery: Could not start read transaction for shard", collName, r);
return false;
}
var count = 0;
while (true) {
count += 1;
if (count > 500) {
console.error("startReadingQuery: Read transaction did not begin. Giving up");
return false;
}
require("internal").wait(0.2);
r = request({ url: url + "/_api/query/current", method: "GET" });
if (r.status !== 200) {
console.error("startReadingQuery: Bad response from /_api/query/current",
r);
continue;
}
try {
r = JSON.parse(r.body);
}
catch (err) {
console.error("startReadingQuery: Bad response body from",
"/_api/query/current", r, JSON.stringify(err));
continue;
}
for (var i = 0; i < r.length; i++) {
if (r[i].query.indexOf(uuid) !== -1) {
// Bingo, found it:
if (r[i].state === "executing") {
console.info("startReadingQuery: OK");
return r[i].id;
}
console.info("startReadingQuery: query found but not yet executing");
break;
}
}
console.error("startReadingQuery: Did not find query.");
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief cancel such a query, return whether or not the query was found
////////////////////////////////////////////////////////////////////////////////
function cancelReadingQuery (endpoint, queryid) {
var url = endpointToURL(endpoint) + "/_api/query/" + queryid;
var r = request({url, method: "DELETE" });
if (r.status !== 200) {
console.error("CancelReadingQuery: error", r);
return false;
}
console.info("CancelReadingQuery: success");
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief cancel barrier from sync
////////////////////////////////////////////////////////////////////////////////
function cancelBarrier (endpoint, barrierId) {
var url = endpointToURL(endpoint) + "/_api/replication/barrier/" + barrierId;
var r = request({url, method: "DELETE" });
if (r.status !== 200 && r.status !== 204) {
console.error("CancelBarrier: error", r);
return false;
}
console.info("cancelBarrier: success");
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief tell leader that we are in sync
////////////////////////////////////////////////////////////////////////////////
function addShardFollower(endpoint, shard) {
console.info("addShardFollower: tell the leader to put us into the follower list...");
var url = endpointToURL(endpoint) + "/_api/replication/addFollower";
var body = {followerId: ArangoServerState.id(), shard };
var r = request({url, body: JSON.stringify(body), method: "PUT"});
if (r.status !== 200) {
console.error("addShardFollower: could not add us to the leader's follower list.", r);
return false;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief get values from Plan or Current by a prefix
////////////////////////////////////////////////////////////////////////////////
function getByPrefix (values, prefix) {
var result = { };
var a;
var n = prefix.length;
for (a in values) {
if (values.hasOwnProperty(a)) {
if (a.substr(0, n) === prefix) {
result[a.substr(n)] = values[a];
}
}
}
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief get values from Plan or Current by a prefix
////////////////////////////////////////////////////////////////////////////////
function getByPrefix3d (values, prefix) {
var result = { };
var a;
var n = prefix.length;
for (a in values) {
if (values.hasOwnProperty(a)) {
if (a.substr(0, n) === prefix) {
var key = a.substr(n);
var parts = key.split('/');
if (parts.length >= 2) {
if (! result.hasOwnProperty(parts[0])) {
result[parts[0]] = { };
}
result[parts[0]][parts[1]] = values[a];
}
}
}
}
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief get values from Plan or Current by a prefix
////////////////////////////////////////////////////////////////////////////////
function getByPrefix4d (values, prefix) {
var result = { };
var a;
var n = prefix.length;
for (a in values) {
if (values.hasOwnProperty(a)) {
if (a.substr(0, n) === prefix) {
var key = a.substr(n);
var parts = key.split('/');
if (parts.length >= 3) {
if (! result.hasOwnProperty(parts[0])) {
result[parts[0]] = { };
}
if (! result[parts[0]].hasOwnProperty(parts[1])) {
result[parts[0]][parts[1]] = { };
}
result[parts[0]][parts[1]][parts[2]] = values[a];
}
}
}
}
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief lookup for 4-dimensional nested dictionary data
////////////////////////////////////////////////////////////////////////////////
function lookup4d (data, a, b, c) {
if (! data.hasOwnProperty(a)) {
return undefined;
}
if (! data[a].hasOwnProperty(b)) {
return undefined;
}
if (! data[a][b].hasOwnProperty(c)) {
return undefined;
}
return data[a][b][c];
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return a shardId => server map
////////////////////////////////////////////////////////////////////////////////
function getShardMap (plannedCollections) {
var shardMap = { };
var database;
for (database in plannedCollections) {
if (plannedCollections.hasOwnProperty(database)) {
var collections = plannedCollections[database];
var collection;
for (collection in collections) {
if (collections.hasOwnProperty(collection)) {
var shards = collections[collection].shards;
var shard;
for (shard in shards) {
if (shards.hasOwnProperty(shard)) {
shardMap[shard] = shards[shard];
}
}
}
}
}
}
return shardMap;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return the indexes of a collection as a map
////////////////////////////////////////////////////////////////////////////////
function getIndexMap (shard) {
var indexes = { }, i;
var idx = arangodb.db._collection(shard).getIndexes();
for (i = 0; i < idx.length; ++i) {
// fetch id without collection name
var id = idx[i].id.replace(/^[a-zA-Z0-9_\-]*?\/([0-9]+)$/, '$1');
idx[i].id = id;
indexes[id] = idx[i];
}
return indexes;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return a hash with the local databases
////////////////////////////////////////////////////////////////////////////////
function getLocalDatabases () {
var result = { };
var db = require("internal").db;
db._listDatabases().forEach(function (database) {
result[database] = { name: database };
});
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return a hash with the local collections
////////////////////////////////////////////////////////////////////////////////
function getLocalCollections () {
var result = { };
var db = require("internal").db;
db._collections().forEach(function (collection) {
var name = collection.name();
if (name.substr(0, 1) !== '_') {
var data = {
id: collection._id,
name: name,
type: collection.type(),
status: collection.status(),
planId: collection.planId()
};
// merge properties
var properties = collection.properties();
var p;
for (p in properties) {
if (properties.hasOwnProperty(p)) {
data[p] = properties[p];
}
}
result[name] = data;
}
});
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief create databases if they exist in the plan but not locally
////////////////////////////////////////////////////////////////////////////////
function createLocalDatabases (plannedDatabases, currentDatabases, writeLocked) {
var ourselves = global.ArangoServerState.id();
var createDatabaseAgency = function (payload) {
global.ArangoAgency.set("Current/Databases/" + payload.name + "/" + ourselves,
payload);
};
var db = require("internal").db;
db._useDatabase("_system");
var localDatabases = getLocalDatabases();
var name;
// check which databases need to be created locally
for (name in plannedDatabases) {
if (plannedDatabases.hasOwnProperty(name)) {
var payload = plannedDatabases[name];
payload.error = false;
payload.errorNum = 0;
payload.errorMessage = "no error";
if (! localDatabases.hasOwnProperty(name)) {
// must create database
// TODO: handle options and user information
console.info("creating local database '%s'", payload.name);
try {
db._createDatabase(payload.name);
payload.error = false;
payload.errorNum = 0;
payload.errorMessage = "no error";
}
catch (err) {
payload.error = true;
payload.errorNum = err.errorNum;
payload.errorMessage = err.errorMessage;
}
writeLocked({ part: "Current" },
createDatabaseAgency,
[ payload ]);
} else if (typeof currentDatabases[name] !== 'object' || !currentDatabases[name].hasOwnProperty(ourselves)) {
// mop: ok during cluster startup we have this buggy situation where a dbserver
// has a database but has not yet announced it to the agency :S
writeLocked({ part: "Current" },
createDatabaseAgency,
[ payload ]);
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief drop databases if they do exist locally but not in the plan
////////////////////////////////////////////////////////////////////////////////
function dropLocalDatabases (plannedDatabases, writeLocked) {
var ourselves = global.ArangoServerState.id();
var dropDatabaseAgency = function (payload) {
try {
global.ArangoAgency.remove("Current/Databases/" + payload.name + "/" + ourselves);
}
catch (err) {
// ignore errors
}
};
var db = require("internal").db;
db._useDatabase("_system");
var localDatabases = getLocalDatabases();
var name;
// check which databases need to be deleted locally
for (name in localDatabases) {
if (localDatabases.hasOwnProperty(name)) {
if (! plannedDatabases.hasOwnProperty(name) && name.substr(0, 1) !== '_') {
// must drop database
console.info("dropping local database '%s'", name);
// Do we have to stop a replication applier first?
if (ArangoServerState.role() === "SECONDARY") {
try {
db._useDatabase(name);
var rep = require("@arangodb/replication");
var state = rep.applier.state();
if (state.state.running === true) {
console.info("stopping replication applier first");
rep.applier.stop();
}
db._useDatabase("_system");
}
catch (err) {
db._useDatabase("_system");
}
}
db._dropDatabase(name);
writeLocked({ part: "Current" },
dropDatabaseAgency,
[ { name: name } ]);
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief clean up what's in Current/Databases for ourselves
////////////////////////////////////////////////////////////////////////////////
function cleanupCurrentDatabases (writeLocked) {
var ourselves = global.ArangoServerState.id();
var dropDatabaseAgency = function (payload) {
try {
global.ArangoAgency.remove("Current/Databases/" + payload.name + "/" + ourselves);
}
catch (err) {
// ignore errors
}
};
var db = require("internal").db;
db._useDatabase("_system");
var all = global.ArangoAgency.get("Current/Databases", true);
var currentDatabases = getByPrefix3d(all, "Current/Databases/");
var localDatabases = getLocalDatabases();
var name;
for (name in currentDatabases) {
if (currentDatabases.hasOwnProperty(name) && name.substr(0, 1) !== '_') {
if (! localDatabases.hasOwnProperty(name)) {
// we found a database we don't have locally
if (currentDatabases[name].hasOwnProperty(ourselves)) {
// we are entered for a database that we don't have locally
console.info("cleaning up entry for unknown database '%s'", name);
writeLocked({ part: "Current" },
dropDatabaseAgency,
[ { name: name } ]);
}
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief handle database changes
////////////////////////////////////////////////////////////////////////////////
function handleDatabaseChanges (plan, current, writeLocked) {
var plannedDatabases = getByPrefix(plan, "Plan/Databases/");
var currentDatabases = getByPrefix(plan, "Current/Databases/");
createLocalDatabases(plannedDatabases, currentDatabases, writeLocked);
dropLocalDatabases(plannedDatabases, writeLocked);
cleanupCurrentDatabases(writeLocked);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief create collections if they exist in the plan but not locally
////////////////////////////////////////////////////////////////////////////////
function createLocalCollections (plannedCollections, planVersion, takeOverResponsibility, writeLocked) {
var ourselves = global.ArangoServerState.id();
var createCollectionAgency = function (database, shard, collInfo, error) {
var payload = { error: error.error,
errorNum: error.errorNum,
errorMessage: error.errorMessage,
indexes: collInfo.indexes,
servers: [ ourselves ],
planVersion: planVersion };
global.ArangoAgency.set("Current/Collections/" + database + "/" +
collInfo.planId + "/" + shard,
payload);
};
var takeOver = createCollectionAgency;
var db = require("internal").db;
db._useDatabase("_system");
var migrate = writeLocked => {
var localDatabases = getLocalDatabases();
var database;
var i;
// iterate over all matching databases
for (database in plannedCollections) {
if (plannedCollections.hasOwnProperty(database)) {
if (localDatabases.hasOwnProperty(database)) {
// save old database name
var previousDatabase = db._name();
// switch into other database
db._useDatabase(database);
try {
// iterate over collections of database
var localCollections = getLocalCollections();
var collections = plannedCollections[database];
// diff the collections
Object.keys(collections).forEach(function(collection) {
var collInfo = collections[collection];
var shards = collInfo.shards;
var shard;
collInfo.planId = collInfo.id;
var save = [collInfo.id, collInfo.name];
delete collInfo.id; // must not actually set it here
delete collInfo.name; // name is now shard
for (shard in shards) {
if (shards.hasOwnProperty(shard)) {
var didWrite = false;
if (shards[shard][0] === ourselves) {
// found a shard we are responsible for
var error = { error: false, errorNum: 0,
errorMessage: "no error" };
if (! localCollections.hasOwnProperty(shard)) {
// must create this shard
console.info("creating local shard '%s/%s' for central '%s/%s'",
database,
shard,
database,
collInfo.planId);
try {
if (collInfo.type === ArangoCollection.TYPE_EDGE) {
db._createEdgeCollection(shard, collInfo);
}
else {
db._create(shard, collInfo);
}
}
catch (err2) {
error = { error: true, errorNum: err2.errorNum,
errorMessage: err2.errorMessage };
console.error("creating local shard '%s/%s' for central '%s/%s' failed: %s",
database,
shard,
database,
collInfo.planId,
JSON.stringify(err2));
}
writeLocked({ part: "Current" },
createCollectionAgency,
[ database, shard, collInfo, error ]);
didWrite = true;
}
else {
if (localCollections[shard].status !== collInfo.status) {
console.info("detected status change for local shard '%s/%s'",
database,
shard);
if (collInfo.status === ArangoCollection.STATUS_UNLOADED) {
console.info("unloading local shard '%s/%s'",
database,
shard);
db._collection(shard).unload();
}
else if (collInfo.status === ArangoCollection.STATUS_LOADED) {
console.info("loading local shard '%s/%s'",
database,
shard);
db._collection(shard).load();
}
writeLocked({ part: "Current" },
createCollectionAgency,
[ database, shard, collInfo, error ]);
didWrite = true;
}
// collection exists, now compare collection properties
var properties = { };
var cmp = [ "journalSize", "waitForSync", "doCompact",
"indexBuckets" ];
for (i = 0; i < cmp.length; ++i) {
var p = cmp[i];
if (localCollections[shard][p] !== collInfo[p]) {
// property change
properties[p] = collInfo[p];
}
}
if (Object.keys(properties).length > 0) {
console.info("updating properties for local shard '%s/%s'",
database,
shard);
try {
db._collection(shard).properties(properties);
}
catch (err3) {
error = { error: true, errorNum: err3.errorNum,
errorMessage: err3.errorMessage };
}
writeLocked({ part: "Current" },
createCollectionAgency,
[ database, shard, collInfo, error ]);
didWrite = true;
}
}
if (error.error) {
if (takeOverResponsibility && !didWrite) {
writeLocked({ part: "Current" },
takeOver,
[ database, shard, collInfo, error ]);
}
continue; // No point to look for properties and
// indices, if the creation has not worked
}
var indexes = getIndexMap(shard);
var idx;
var index;
if (collInfo.hasOwnProperty("indexes")) {
for (i = 0; i < collInfo.indexes.length; ++i) {
index = collInfo.indexes[i];
var changed = false;
if (index.type !== "primary" && index.type !== "edge" &&
! indexes.hasOwnProperty(index.id)) {
console.info("creating index '%s/%s': %s",
database,
shard,
JSON.stringify(index));
try {
arangodb.db._collection(shard).ensureIndex(index);
index.error = false;
index.errorNum = 0;
index.errorMessage = "";
}
catch (err5) {
index.error = true;
index.errorNum = err5.errorNum;
index.errorMessage = err5.errorMessage;
}
changed = true;
}
if (changed) {
writeLocked({ part: "Current" },
createCollectionAgency,
[ database, shard, collInfo, error ]);
didWrite = true;
}
}
var changed2 = false;
for (idx in indexes) {
if (indexes.hasOwnProperty(idx)) {
// found an index in the index map, check if it must be deleted
if (indexes[idx].type !== "primary" && indexes[idx].type !== "edge") {
var found = false;
for (i = 0; i < collInfo.indexes.length; ++i) {
if (collInfo.indexes[i].id === idx) {
found = true;
break;
}
}
if (! found) {
// found an index to delete locally
changed2 = true;
index = indexes[idx];
console.info("dropping index '%s/%s': %s",
database,
shard,
JSON.stringify(index));
arangodb.db._collection(shard).dropIndex(index);
delete indexes[idx];
collInfo.indexes.splice(i, i);
}
}
}
}
if (changed2) {
writeLocked({ part: "Current" },
createCollectionAgency,
[ database, shard, collInfo, error ]);
didWrite = true;
}
}
if (takeOverResponsibility && !didWrite) {
writeLocked({ part: "Current" },
takeOver,
[ database, shard, collInfo, error ]);
}
}
}
}
collInfo.id = save[0];
collInfo.name = save[1];
});
}
catch (err) {
// always return to previous database
db._useDatabase(previousDatabase);
throw err;
}
}
}
}
};
if (takeOverResponsibility) {
// mop: if this is a complete takeover we need a global lock because
// otherwise the coordinator might fetch results which are only partly
// migrated
var fakeLock = (lockInfo, cb, args) => {
if (!lockInfo || lockInfo.part !== 'Current') {
throw new Error("Invalid lockInfo " + JSON.stringify(lockInfo));
}
return cb(...args);
};
writeLocked({ part: "Current" }, migrate, [fakeLock]);
} else {
migrate(writeLocked);
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief drop collections if they exist locally but not in the plan
////////////////////////////////////////////////////////////////////////////////
function dropLocalCollections (plannedCollections, writeLocked) {
var ourselves = global.ArangoServerState.id();
var dropCollectionAgency = function (database, shardID, id) {
try {
global.ArangoAgency.remove("Current/Collections/" + database + "/" + id + "/" + shardID);
}
catch (err) {
// ignore errors
}
};
var db = require("internal").db;
db._useDatabase("_system");
var shardMap = getShardMap(plannedCollections);
var localDatabases = getLocalDatabases();
var database;
// iterate over all databases
for (database in localDatabases) {
if (localDatabases.hasOwnProperty(database)) {
var removeAll = ! plannedCollections.hasOwnProperty(database);
// save old database name
var previousDatabase = db._name();
// switch into other database
db._useDatabase(database);
try {
// iterate over collections of database
var collections = getLocalCollections();
var collection;
for (collection in collections) {
if (collections.hasOwnProperty(collection)) {
// found a local collection
// check if it is in the plan and we are responsible for it
var remove = removeAll ||
(! shardMap.hasOwnProperty(collection)) ||
(shardMap[collection].indexOf(ourselves) === -1);
if (remove) {
console.info("dropping local shard '%s/%s' of '%s/%s",
database,
collection,
database,
collections[collection].planId);
db._drop(collection);
writeLocked({ part: "Current" },
dropCollectionAgency,
[ database, collection, collections[collection].planId ]);
}
}
}
}
catch (err) {
db._useDatabase(previousDatabase);
throw err;
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief clean up what's in Current/Collections for ourselves
////////////////////////////////////////////////////////////////////////////////
function cleanupCurrentCollections (plannedCollections, writeLocked) {
var ourselves = global.ArangoServerState.id();
var dropCollectionAgency = function (database, collection, shardID) {
try {
global.ArangoAgency.remove("Current/Collections/" + database + "/" + collection + "/" + shardID);
}
catch (err) {
// ignore errors
}
};
var db = require("internal").db;
db._useDatabase("_system");
var all = global.ArangoAgency.get("Current/Collections", true);
var currentCollections = getByPrefix4d(all, "Current/Collections/");
var shardMap = getShardMap(plannedCollections);
var database;
for (database in currentCollections) {
if (currentCollections.hasOwnProperty(database)) {
var collections = currentCollections[database];
var collection;
for (collection in collections) {
if (collections.hasOwnProperty(collection)) {
var shards = collections[collection];
var shard;
for (shard in shards) {
if (shards.hasOwnProperty(shard)) {
if (shards[shard].servers[0] === ourselves &&
(! shardMap.hasOwnProperty(shard) ||
shardMap[shard].indexOf(ourselves) !== 0)) {
// found an entry in current of a shard that we used to be
// leader for but that we are no longer leader for
console.info("cleaning up entry for shard '%s' of '%s/%s",
shard,
database,
collection);
writeLocked({ part: "Current" },
dropCollectionAgency,
[ database, collection, shard ]);
}
}
}
}
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief synchronize collections for which we are followers (synchronously
/// replicated shards)
////////////////////////////////////////////////////////////////////////////////
function synchronizeLocalFollowerCollections (plannedCollections) {
var ourselves = global.ArangoServerState.id();
var db = require("internal").db;
db._useDatabase("_system");
var localDatabases = getLocalDatabases();
var database;
// Get current information about collections from agency:
var all = global.ArangoAgency.get("Current/Collections", true);
var currentCollections = getByPrefix4d(all, "Current/Collections/");
var rep = require("@arangodb/replication");
// iterate over all matching databases
for (database in plannedCollections) {
if (plannedCollections.hasOwnProperty(database)) {
if (localDatabases.hasOwnProperty(database)) {
// save old database name
var previousDatabase = db._name();
// switch into other database
db._useDatabase(database);
try {
// iterate over collections of database
var collections = plannedCollections[database];
var collection;
// diff the collections
for (collection in collections) {
if (collections.hasOwnProperty(collection)) {
var collInfo = collections[collection];
var shards = collInfo.shards; // this is the Plan
var shard;
collInfo.planId = collInfo.id;
for (shard in shards) {
if (shards.hasOwnProperty(shard)) {
var pos = shards[shard].indexOf(ourselves);
if (pos > 0) { // found and not in position 0
// found a shard we have to replicate synchronously
// now see whether we are in sync by looking at the
// current entry in the agency:
var inCurrent = lookup4d(currentCollections, database,
collection, shard);
var count = 0;
while (inCurrent === undefined ||
! inCurrent.hasOwnProperty("servers") ||
typeof inCurrent.servers !== "object" ||
typeof inCurrent.servers[0] !== "string" ||
inCurrent.servers[0] === "") {
count++;
if (count > 10) {
throw new Error("timeout waiting for leader for shard "
+ shard);
}
console.info("Waiting for 0.5 second for leader to create shard...");
require("internal").wait(0.5);
all = global.ArangoAgency.get("Current/Collections",
true);
currentCollections = getByPrefix4d(all,
"Current/Collections/");
inCurrent = lookup4d(currentCollections, database,
collection, shard);
}
if (inCurrent.servers.indexOf(ourselves) === -1) {
// we not in there - must synchronize this shard from
// the leader
console.info("trying to synchronize local shard '%s/%s' for central '%s/%s'",
database,
shard,
database,
collInfo.planId);
try {
var ep = ArangoClusterInfo.getServerEndpoint(
inCurrent.servers[0]);
// First once without a read transaction:
var sy = rep.syncCollection(shard,
{ endpoint: ep, incremental: true,
keepBarrier: true });
// Now start a read transaction to stop writes:
var queryid;
try {
queryid = startReadingQuery(ep, shard, 300);
}
finally {
cancelBarrier(ep, sy.barrierId);
}
var ok = false;
try {
var sy2 = rep.syncCollectionFinalize(
shard, sy.collections[0].id, sy.lastLogTick,
{ endpoint: ep });
if (sy2.error) {
console.error("Could not synchronize shard", shard,
sy2);
}
ok = addShardFollower(ep, shard);
}
finally {
if (!cancelReadingQuery(ep, queryid)) {
console.error("Read transaction has timed out for shard", shard);
ok = false;
}
}
if (ok) {
console.info("Synchronization worked for shard", shard);
} else {
throw "Did not work."; // just to log below in catch
}
}
catch (err2) {
console.error("synchronization of local shard '%s/%s' for central '%s/%s' failed: %s",
database,
shard,
database,
collInfo.planId,
JSON.stringify(err2));
}
}
}
}
}
}
}
}
catch (err) {
// always return to previous database
db._useDatabase(previousDatabase);
throw err;
}
}
}
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief handle collection changes
////////////////////////////////////////////////////////////////////////////////
function handleCollectionChanges (plan, takeOverResponsibility, writeLocked) {
var plannedCollections = getByPrefix3d(plan, "Plan/Collections/");
var ok = true;
try {
createLocalCollections(plannedCollections, plan["Plan/Version"], takeOverResponsibility, writeLocked);
dropLocalCollections(plannedCollections, writeLocked);
cleanupCurrentCollections(plannedCollections, writeLocked);
synchronizeLocalFollowerCollections(plannedCollections);
}
catch (err) {
console.error("Caught error in handleCollectionChanges: " +
JSON.stringify(err), JSON.stringify(err.stack));
ok = false;
}
return ok;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief make sure that replication is set up for all databases
////////////////////////////////////////////////////////////////////////////////
function setupReplication () {
console.debug("Setting up replication...");
var db = require("internal").db;
var rep = require("@arangodb/replication");
var dbs = db._listDatabases();
var i;
var ok = true;
for (i = 0; i < dbs.length; i++) {
var database = dbs[i];
try {
console.debug("Checking replication of database "+database);
db._useDatabase(database);
var state = rep.applier.state();
if (state.state.running === false) {
var endpoint = ArangoClusterInfo.getServerEndpoint(
ArangoServerState.idOfPrimary());
var config = { "endpoint": endpoint, "includeSystem": false,
"incremental": false, "autoStart": true,
"requireFromPresent": true};
console.info("Starting synchronization...");
var res = rep.sync(config);
console.info("Last log tick: "+res.lastLogTick+
", starting replication...");
rep.applier.properties(config);
var res2 = rep.applier.start(res.lastLogTick);
console.info("Result of replication start: "+res2);
}
}
catch (err) {
console.error("Could not set up replication for database ", database, JSON.stringify(err));
ok = false;
}
}
db._useDatabase("_system");
return ok;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief role change from secondary to primary
////////////////////////////////////////////////////////////////////////////////
function secondaryToPrimary () {
console.info("Switching role from secondary to primary...");
var db = require("internal").db;
var rep = require("@arangodb/replication");
var dbs = db._listDatabases();
var i;
try {
for (i = 0; i < dbs.length; i++) {
var database = dbs[i];
console.info("Stopping asynchronous replication for db " +
database + "...");
db._useDatabase(database);
var state = rep.applier.state();
if (state.state.running === true) {
try {
rep.applier.stop();
}
catch (err) {
console.info("Exception caught whilst stopping replication!");
}
}
rep.applier.forget();
}
}
finally {
db._useDatabase("_system");
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief role change from primary to secondary
////////////////////////////////////////////////////////////////////////////////
function primaryToSecondary () {
console.info("Switching role from primary to secondary...");
}
////////////////////////////////////////////////////////////////////////////////
/// @brief change handling trampoline function
////////////////////////////////////////////////////////////////////////////////
function handleChanges (plan, current, writeLocked) {
var changed = false;
var role = ArangoServerState.role();
if (role === "PRIMARY" || role === "SECONDARY") {
// Need to check role change for automatic failover:
var myId = ArangoServerState.id();
if (role === "PRIMARY") {
if (! plan.hasOwnProperty("Plan/DBServers/"+myId)) {
// Ooops! We do not seem to be a primary any more!
changed = ArangoServerState.redetermineRole();
}
}
else { // role === "SECONDARY"
if (plan.hasOwnProperty("Plan/DBServers/"+myId)) {
changed = ArangoServerState.redetermineRole();
if (!changed) {
// mop: oops...changing role has failed. retry next time.
return false;
}
}
else {
var found = null;
var p;
for (p in plan) {
if (plan.hasOwnProperty(p) && plan[p] === myId) {
found = p;
break;
}
}
if (found !== ArangoServerState.idOfPrimary()) {
// Note this includes the case that we are not found at all!
changed = ArangoServerState.redetermineRole();
}
}
}
}
var oldRole = role;
if (changed) {
role = ArangoServerState.role();
console.log("Our role has changed to " + role);
if (oldRole === "SECONDARY" && role === "PRIMARY") {
secondaryToPrimary();
}
else if (oldRole === "PRIMARY" && role === "SECONDARY") {
primaryToSecondary();
}
}
handleDatabaseChanges(plan, current, writeLocked);
var success;
if (role === "PRIMARY" || role === "COORDINATOR") {
// Note: This is only ever called for DBservers (primary and secondary),
// we keep the coordinator case here just in case...
success = handleCollectionChanges(plan, changed, writeLocked);
}
else {
success = setupReplication();
}
return success;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief throw an ArangoError
////////////////////////////////////////////////////////////////////////////////
var raiseError = function (code, msg) {
var err = new ArangoError();
err.errorNum = code;
err.errorMessage = msg;
throw err;
};
////////////////////////////////////////////////////////////////////////////////
/// @brief retrieve a list of shards for a collection
////////////////////////////////////////////////////////////////////////////////
var shardList = function (dbName, collectionName) {
var ci = global.ArangoClusterInfo.getCollectionInfo(dbName, collectionName);
if (ci === undefined || typeof ci !== 'object') {
throw "unable to determine shard list for '" + dbName + "/" + collectionName + "'";
}
var shards = [ ], shard;
for (shard in ci.shards) {
if (ci.shards.hasOwnProperty(shard)) {
shards.push(shard);
}
}
if (shards.length === 0) {
raiseError(arangodb.errors.ERROR_ARANGO_COLLECTION_NOT_FOUND.code,
arangodb.errors.ERROR_ARANGO_COLLECTION_NOT_FOUND.message);
}
return shards;
};
////////////////////////////////////////////////////////////////////////////////
/// @brief wait for a distributed response
////////////////////////////////////////////////////////////////////////////////
var waitForDistributedResponse = function (data, shards) {
var received = [ ];
while (received.length < shards.length) {
var result = global.ArangoClusterComm.wait(data);
var status = result.status;
if (status === "ERROR") {
raiseError(arangodb.errors.ERROR_INTERNAL.code,
"received an error from a DB server: " + JSON.stringify(result));
}
else if (status === "TIMEOUT") {
raiseError(arangodb.errors.ERROR_CLUSTER_TIMEOUT.code,
arangodb.errors.ERROR_CLUSTER_TIMEOUT.message);
}
else if (status === "DROPPED") {
raiseError(arangodb.errors.ERROR_INTERNAL.code,
"the operation was dropped");
}
else if (status === "RECEIVED") {
received.push(result);
if (result.headers && result.headers.hasOwnProperty('x-arango-response-code')) {
var code = parseInt(result.headers['x-arango-response-code'].substr(0, 3), 10);
if (code >= 400) {
var body;
try {
body = JSON.parse(result.body);
}
catch (err) {
raiseError(arangodb.errors.ERROR_INTERNAL.code,
"error parsing JSON received from a DB server: " + err.message);
}
raiseError(body.errorNum,
body.errorMessage);
}
}
}
else {
// something else... wait without GC
require("internal").wait(0.1, false);
}
}
return received;
};
////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not clustering is enabled
////////////////////////////////////////////////////////////////////////////////
var isCluster = function () {
var role = global.ArangoServerState.role();
return (role !== undefined && role !== "SINGLE");
};
////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not we are a coordinator
////////////////////////////////////////////////////////////////////////////////
var isCoordinator = function () {
return global.ArangoServerState.isCoordinator();
};
////////////////////////////////////////////////////////////////////////////////
/// @brief role
////////////////////////////////////////////////////////////////////////////////
var role = function () {
var role = global.ArangoServerState.role();
if (role !== "SINGLE") {
return role;
}
return undefined;
};
////////////////////////////////////////////////////////////////////////////////
/// @brief status
////////////////////////////////////////////////////////////////////////////////
var status = function () {
if (! isCluster() || ! global.ArangoServerState.initialized()) {
return undefined;
}
return global.ArangoServerState.status();
};
////////////////////////////////////////////////////////////////////////////////
/// @brief isCoordinatorRequest
////////////////////////////////////////////////////////////////////////////////
var isCoordinatorRequest = function (req) {
if (! req || ! req.hasOwnProperty("headers")) {
return false;
}
return req.headers.hasOwnProperty("x-arango-coordinator");
};
////////////////////////////////////////////////////////////////////////////////
/// @brief handlePlanChange
////////////////////////////////////////////////////////////////////////////////
var handlePlanChange = function () {
if (! isCluster() || isCoordinator() || ! global.ArangoServerState.initialized()) {
return;
}
let versions = {
plan: 0,
current: 0
};
////////////////////////////////////////////////////////////////////////////////
/// @brief execute an action under a write-lock
////////////////////////////////////////////////////////////////////////////////
function writeLocked (lockInfo, cb, args) {
var timeout = lockInfo.timeout;
if (timeout === undefined) {
timeout = 60;
}
var ttl = lockInfo.ttl;
if (ttl === undefined) {
ttl = 120;
}
if (require("internal").coverage || require("internal").valgrind) {
ttl *= 10;
timeout *= 10;
}
global.ArangoAgency.lockWrite(lockInfo.part, ttl, timeout);
try {
cb.apply(null, args);
global.ArangoAgency.increaseVersion(lockInfo.part + "/Version");
let version = global.ArangoAgency.get(lockInfo.part + "/Version");
versions[lockInfo.part.toLowerCase()] = version[lockInfo.part + "/Version"];
global.ArangoAgency.unlockWrite(lockInfo.part, timeout);
}
catch (err) {
global.ArangoAgency.unlockWrite(lockInfo.part, timeout);
throw err;
}
}
try {
var plan = global.ArangoAgency.get("Plan", true);
var current = global.ArangoAgency.get("Current", true);
versions.plan = plan['Plan/Version'];
versions.current = current['Current/Version'];
handleChanges(plan, current, writeLocked);
console.info("plan change handling successful");
}
catch (err) {
console.error("error details: %s", JSON.stringify(err));
console.error("error stack: %s", err.stack);
console.error("plan change handling failed");
}
return versions;
};
////////////////////////////////////////////////////////////////////////////////
/// @brief coordinatorId
////////////////////////////////////////////////////////////////////////////////
var coordinatorId = function () {
if (! isCoordinator()) {
console.error("not a coordinator");
}
return global.ArangoServerState.id();
};
////////////////////////////////////////////////////////////////////////////////
/// @brief bootstrap db servers
////////////////////////////////////////////////////////////////////////////////
var bootstrapDbServers = function (isRelaunch) {
global.ArangoClusterInfo.reloadDBServers();
var dbServers = global.ArangoClusterInfo.getDBServers();
var ops = [];
var i;
var options = {
coordTransactionID: global.ArangoClusterInfo.uniqid(),
timeout: 90
};
for (i = 0; i < dbServers.length; ++i) {
var server = dbServers[i];
var op = global.ArangoClusterComm.asyncRequest(
"POST",
"server:" + server,
"_system",
"/_admin/cluster/bootstrapDbServer",
'{"isRelaunch": ' + (isRelaunch ? "true" : "false") + '}',
{},
options);
ops.push(op);
}
var result = true;
for (i = 0; i < ops.length; ++i) {
var r = global.ArangoClusterComm.wait(ops[i]);
if (r.status === "RECEIVED") {
console.info("bootstraped DB server %s", dbServers[i]);
}
else if (r.status === "TIMEOUT") {
console.error("cannot bootstrap DB server %s: operation timed out", dbServers[i]);
result = false;
}
else {
console.error("cannot bootstrap DB server %s: %s", dbServers[i], JSON.stringify(r));
result = false;
}
}
return result;
};
exports.bootstrapDbServers = bootstrapDbServers;
exports.coordinatorId = coordinatorId;
exports.handlePlanChange = handlePlanChange;
exports.isCluster = isCluster;
exports.isCoordinator = isCoordinator;
exports.isCoordinatorRequest = isCoordinatorRequest;
exports.role = role;
exports.shardList = shardList;
exports.status = status;
exports.wait = waitForDistributedResponse;
exports.endpointToURL = endpointToURL;