// ensure removing a chained node does not break reporting of replication progress (SERVER-15849)

(function() {
"use strict";
load("jstests/replsets/rslib.js");

var numNodes = 5;
var host = getHostName();
var name = "chaining_removal";

var replTest = new ReplSetTest({name: name, nodes: numNodes});
var nodes = replTest.startSet();
var port = replTest.ports;
replTest.initiate({
    _id: name,
    members: [
        {_id: 0, host: nodes[0].host, priority: 3},
        {_id: 1, host: nodes[1].host, priority: 0},
        {_id: 2, host: nodes[2].host, priority: 0},
        {_id: 3, host: nodes[3].host, priority: 0},
        {_id: 4, host: nodes[4].host, priority: 0},
    ],
});
replTest.awaitNodesAgreeOnPrimary(replTest.kDefaultTimeoutMS, nodes, 0);
var primary = replTest.getPrimary();
replTest.awaitReplication();

// When setting up chaining on slow machines, we do not want slow writes or delayed heartbeats
// to cause our nodes to invalidate the sync source provided in the 'replSetSyncFrom' command.
// To achieve this, we disable the server parameter 'maxSyncSourceLagSecs' (see
// repl_settings_init.cpp and TopologyCoordinatorImpl::Options) in
// TopologyCoordinatorImpl::shouldChangeSyncSource().
assert.commandWorked(nodes[1].getDB('admin').runCommand(
    {configureFailPoint: 'disableMaxSyncSourceLagSecs', mode: 'alwaysOn'}));
assert.commandWorked(nodes[4].getDB('admin').runCommand(
    {configureFailPoint: 'disableMaxSyncSourceLagSecs', mode: 'alwaysOn'}));

// Force node 1 to sync directly from node 0.
syncFrom(nodes[1], nodes[0], replTest);
// Force node 4 to sync through node 1.
syncFrom(nodes[4], nodes[1], replTest);

// write that should reach all nodes
var timeout = ReplSetTest.kDefaultTimeoutMS;
var options = {writeConcern: {w: numNodes, wtimeout: timeout}};
assert.commandWorked(primary.getDB(name).foo.insert({x: 1}, options));

// Re-enable 'maxSyncSourceLagSecs' checking on sync source.
assert.commandWorked(nodes[1].getDB('admin').runCommand(
    {configureFailPoint: 'disableMaxSyncSourceLagSecs', mode: 'off'}));
assert.commandWorked(nodes[4].getDB('admin').runCommand(
    {configureFailPoint: 'disableMaxSyncSourceLagSecs', mode: 'off'}));

var config = primary.getDB("local").system.replset.findOne();
config.members.pop();
config.version++;
// remove node 4
replTest.stop(4);
try {
    primary.adminCommand({replSetReconfig: config});
} catch (e) {
    print("error: " + e);
}

// ensure writing to all four nodes still works
primary = replTest.getPrimary();
const liveSlaves = [nodes[1], nodes[2], nodes[3]];
replTest.awaitReplication(null, null, liveSlaves);
options.writeConcern.w = 4;
assert.commandWorked(primary.getDB(name).foo.insert({x: 2}, options));

replTest.stopSet();
}());