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// exemplify and test the difference in meaning of w: "majority" between 2.6 and 2.8
load("jstests/replsets/rslib.js");
(function() {
"use strict";
var newVersion = "latest";
var oldVersion = "2.6";
// this first 7-node configuration will consist of 4 arbiters, 2 voting, non-arbiter nodes,
// and 1 non-voting, non-arbiter node
var name = "write_concern_many_arbiters";
var nodes = {n0: {binVersion: newVersion},
n1: {binVersion: newVersion},
n2: {binVersion: oldVersion},
n3: {binVersion: oldVersion},
n4: {binVersion: oldVersion},
n5: {binVersion: newVersion},
n6: {binVersion: newVersion}};
var replTest = new ReplSetTest({name: name, nodes: nodes});
nodes = replTest.startSet();
var config = {_id: name,
version: 1,
members: [{_id:0, host: nodes[0].host, priority: 3, votes: 1},
{_id:1, host: nodes[1].host, priority: 0, votes: 0},
{_id:2, host: nodes[2].host, priority: 0, votes: 1},
{_id:3, host: nodes[3].host, votes: 1, arbiterOnly: true},
{_id:4, host: nodes[4].host, votes: 1, arbiterOnly: true},
{_id:5, host: nodes[5].host, votes: 1, arbiterOnly: true},
{_id:6, host: nodes[6].host, votes: 1, arbiterOnly: true},
],
};
replTest.initiate(config);
var writeConcern = {writeConcern: {w: "majority", wtimeout: 9*1000}};
var primary = replTest.getPrimary();
primary.forceWriteMode("commands");
assert.eq(primary.host, nodes[0].host, "2.8 node failed to become primary");
// w: majority on node 0 (2.8) will need both voting, non-arbiter nodes in this configuration
// take down one voting, non-arbiter node. fails because we are missing a voter
replTest.stop(2);
assert.writeError(primary.getDB(name).foo.insert({x: 1}, writeConcern));
// bring it back
replTest.restart(2);
assert.writeOK(primary.getDB(name).foo.insert({x: 2}, writeConcern));
// take down one non-voting, non-arbiter node. passes because the non-voter does not matter
replTest.stop(1);
assert.writeOK(primary.getDB(name).foo.insert({x: 3}, writeConcern));
replTest.restart(1);
// reconfig such that a 2.6 node (node 2) will be primary
config.version++;
config.members[0].priority = 0;
config.members[2].priority = 3;
reconfig(replTest, config, true);
primary = replTest.getPrimary();
assert.eq(primary.host, nodes[2].host, "2.6 node failed to become primary");
primary.forceWriteMode("commands");
// w: majority on 2.6 will need all non-arbiter nodes in this configuration
// take down one voting, non-arbiter node. fails because all nodes are needed
replTest.stop(0);
assert.writeError(primary.getDB(name).foo.insert({x: 4}, writeConcern));
// bring it back
replTest.restart(0);
assert.writeOK(primary.getDB(name).foo.insert({x: 5}, writeConcern));
// take down one non-voting, non-arbiter node. fails because all nodes are needed
replTest.stop(1);
assert.writeError(primary.getDB(name).foo.insert({x: 6}, writeConcern));
replTest.stopSet();
// this second 7-node configuration will consist of 1 arbiter, 4 voting, non-arbiter nodes, and
// 2 non-voting, non-arbiter nodes
name = "write_concern_few_arbiters";
nodes = {n0: {binVersion: newVersion},
n1: {binVersion: newVersion},
n2: {binVersion: oldVersion},
n3: {binVersion: oldVersion},
n4: {binVersion: oldVersion},
n5: {binVersion: newVersion},
n6: {binVersion: newVersion}};
replTest = new ReplSetTest({name: name, nodes: nodes});
nodes = replTest.startSet();
config = {_id: name,
version: 1,
members: [{_id:0, host: nodes[0].host, priority: 3, votes: 1},
{_id:1, host: nodes[1].host, priority: 0, votes: 1},
{_id:2, host: nodes[2].host, priority: 0, votes: 1},
{_id:3, host: nodes[3].host, priority: 0, votes: 1},
{_id:4, host: nodes[4].host, priority: 0, votes: 0},
{_id:5, host: nodes[5].host, priority: 0, votes: 0},
{_id:6, host: nodes[6].host, votes: 1, arbiterOnly: true},
],
};
replTest.initiate(config);
var primary = replTest.getPrimary();
primary.forceWriteMode("commands");
assert.eq(primary.host, nodes[0].host, "2.8 node failed to become primary");
// w: majority on node 0 (2.8) will need 3 voting, non-arbiter nodes in this configuration
// take down both non-voting nodes. passes because non-voting nodes do not matter
replTest.stop(5);
replTest.stop(4);
assert.writeOK(primary.getDB(name).foo.insert({x: 7}, writeConcern));
// take down one voting node. passes because we still have sufficient voting nodes
replTest.stop(3);
assert.writeOK(primary.getDB(name).foo.insert({x: 8}, writeConcern));
// take down another voting node. fails because we have insufficient voting nodes
replTest.stop(2);
assert.writeError(primary.getDB(name).foo.insert({x: 9}, writeConcern));
// bring back both non-voting nodes. fails because non-voters still do not matter
replTest.restart(5);
replTest.restart(4);
assert.writeError(primary.getDB(name).foo.insert({x: 10}, writeConcern));
// bring back a voting node. passes because we have sufficient voting nodes
replTest.restart(3);
assert.writeOK(primary.getDB(name).foo.insert({x: 11}, writeConcern));
replTest.restart(2);
// reconfig such that a 2.6 node (node 2) will be primary
config.version++;
config.members[0].priority = 0;
config.members[2].priority = 3;
reconfig(replTest, config, true);
primary = replTest.getPrimary();
assert.eq(primary.host, nodes[2].host, "2.6 node failed to become primary");
primary.forceWriteMode("commands");
// w: majority on 2.6 will need 4 non-arbiter nodes in this configuration
// take down both non-voting nodes. passes because there are still sufficient nodes
replTest.stop(5);
replTest.stop(4);
assert.writeOK(primary.getDB(name).foo.insert({x: 12}, writeConcern));
// take down one voting node. fails because there are insufficient nodes
replTest.stop(3);
assert.writeError(primary.getDB(name).foo.insert({x: 13}, writeConcern));
// bring up both non-voting nodes and take down a voting one
// passes because only number of nodes matters in 2.6, not voting like in 2.8
replTest.restart(5);
replTest.restart(4);
replTest.stop(1);
assert.writeOK(primary.getDB(name).foo.insert({x: 15}, writeConcern));
replTest.stopSet();
}());
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