// Test that setting maxSyncSourceLagSecs causes the set to change sync target
//
// This test requires the fsync command to ensure members experience a delay.
// @tags: [requires_fsync]
(function() {
"use strict";
load("jstests/replsets/rslib.js");

var name = "maxSyncSourceLagSecs";
var replTest = new ReplSetTest({
    name: name,
    nodes: [
        {rsConfig: {priority: 3}},
        {rsConfig: {priority: 0}},
        {rsConfig: {priority: 0}, setParameter: 'maxSyncSourceLagSecs=3'},
    ],
    oplogSize: 5,
});
var nodes = replTest.nodeList();
replTest.startSet();
replTest.initiate();
replTest.awaitNodesAgreeOnPrimary();

var master = replTest.getPrimary();
var slaves = replTest._slaves;
syncFrom(slaves[0], master, replTest);
syncFrom(slaves[1], master, replTest);
master.getDB("foo").bar.save({a: 1});
replTest.awaitReplication();

jsTestLog("Setting sync target of slave 2 to slave 1");
syncFrom(slaves[1], slaves[0], replTest);
printjson(replTest.status());

// need to put at least maxSyncSourceLagSecs b/w first op and subsequent ops
// so that the shouldChangeSyncSource logic goes into effect
sleep(4000);

jsTestLog("Lock slave 1 and add some docs. Force sync target for slave 2 to change to primary");
assert.commandWorked(slaves[0].getDB("admin").runCommand({fsync: 1, lock: 1}));

assert.soon(function() {
    master.getDB("foo").bar.insert({a: 2});
    var res = slaves[1].getDB("admin").runCommand({"replSetGetStatus": 1});
    return res.syncingTo === master.name;
}, "sync target not changed back to primary", 100 * 1000, 2 * 1000);
printjson(replTest.status());

assert.soon(function() {
    return (slaves[1].getDB("foo").bar.count({a: 1}) > 0 &&
            slaves[1].getDB("foo").bar.count({a: 2}) > 0);
}, "slave should have caught up after syncing to primary.");

assert.commandWorked(slaves[0].getDB("admin").fsyncUnlock());
replTest.stopSet();
}());