// Test for SERVER-8070: Flush buffer before changing sync targets to prevent unnecessary rollbacks
// This test writes 50 ops to one secondary's data (member2) and 25 ops to the other secondary's
// data (member3), then puts 50 more ops in member3's buffer and makes sure that member3 doesn't try
// to sync from member2.

// helper to ensure two nodes are at the same place in the oplog
var waitForSameOplogPosition = function(db1, db2, errmsg) {
    assert.soon(function() {
        var last1 = db1.getSisterDB("local").oplog.rs.find().sort({$natural: -1}).limit(1).next();
        var last2 = db2.getSisterDB("local").oplog.rs.find().sort({$natural: -1}).limit(1).next();
        jsTest.log("primary: " + tojson(last1) + " secondary: " + tojson(last2));

        return ((last1.ts.t === last2.ts.t) && (last1.ts.i === last2.ts.i));
    }, errmsg);
};

// start set
var replSet = new ReplSetTest({name: 'testSet', nodes: 3});
replSet.startSet();
replSet.initiate({
    _id: 'testSet',
    members: [
        {_id: 0, host: getHostName() + ":" + replSet.ports[0]},
        {_id: 1, host: getHostName() + ":" + replSet.ports[1], priority: 0},
        {_id: 2, host: getHostName() + ":" + replSet.ports[2], priority: 0}
    ],
    settings: {chainingAllowed: false}
});

// set up common points of access
var master = replSet.getPrimary();
var primary = master.getDB("foo");
replSet.nodes[1].setSlaveOk();
replSet.nodes[2].setSlaveOk();
var member2 = replSet.nodes[1].getDB("admin");
var member3 = replSet.nodes[2].getDB("admin");

// Do an initial write
master.getDB("foo").bar.insert({x: 1});
replSet.awaitReplication();

jsTest.log("Make sure 2 & 3 are syncing from the primary");
member2.adminCommand({replSetSyncFrom: getHostName() + ":" + replSet.ports[0]});
member3.adminCommand({replSetSyncFrom: getHostName() + ":" + replSet.ports[0]});

jsTest.log("Stop 2's replication");
member2.runCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'alwaysOn'});

jsTest.log("Do a few writes");
for (var i = 0; i < 25; i++) {
    primary.bar.insert({x: i});
}

jsTest.log("Make sure 3 is at write #25");
waitForSameOplogPosition(primary, member3, "node 3 failed to catch up to the primary");
// This means 3's buffer is empty

jsTest.log("Stop 3's replication");
member3.runCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'alwaysOn'});
// logLevel 3 will allow us to see each op the secondary pulls from the primary so that we can
// determine whether or not all ops are actually being pulled
member3.runCommand({setParameter: 1, logLevel: 3});

jsTest.log("Start 2's replication");
member2.runCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'off'});

jsTest.log("Do some writes");
for (var i = 25; i < 50; i++) {
    primary.bar.insert({x: i});
}

jsTest.log("Make sure 2 is at write #50");
waitForSameOplogPosition(primary, member2, "node 2 failed to catch up to the primary");
// This means 2's buffer is empty

jsTest.log("Stop 2's replication");
member2.runCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'alwaysOn'});

jsTest.log("Do some writes - 2 & 3 should have up to write #75 in their buffers, but unapplied");
for (var i = 50; i < 75; i++) {
    primary.bar.insert({x: i});
}
var primaryCollectionSize = primary.bar.find().itcount();
jsTest.log("primary collection size: " + primaryCollectionSize);
var last = primary.getSisterDB("local").oplog.rs.find().sort({$natural: -1}).limit(1).next();

jsTest.log("waiting a bit for the secondaries to get the write");
sleep(10000);

jsTest.log("Shut down the primary");
replSet.stop(0);

// make sure 3 doesn't try to sync from 2
// the sleep 30sec is a hold over from the unsafe assert.throws(assert.soon())
// which would check for 30 seconds that node 3 didn't try to sync from 2
sleep(30 * 1000);
jsTest.log("3 should not attempt to sync from 2, as it cannot clear its buffer");
var syncingTo = member3.adminCommand({replSetGetStatus: 1}).syncingTo;
assert(syncingTo !== getHostName() + ":" + replSet.ports[1], "node 3 is syncing from node 2 :(");

jsTest.log("Pause 3's bgsync thread");
var pauseRsBgSyncProducerResult3 =
    member3.runCommand({configureFailPoint: 'pauseRsBgSyncProducer', mode: 'alwaysOn'});
assert.eq(1, pauseRsBgSyncProducerResult3.ok, "member 3 pauseRsBgSyncProducer command failed");

// count documents in member 3
assert.eq(26,
          member3.getSisterDB("foo").bar.find().itcount(),
          "collection size incorrect on node 3 before applying ops 25-75");

jsTest.log("Allow 3 to apply ops 25-75");
assert.commandWorked(member3.runCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'off'}),
                     "member 3 rsSyncApplyStop admin command failed");

assert.soon(function() {
    var last3 = member3.getSisterDB("local").oplog.rs.find().sort({$natural: -1}).limit(1).next();
    jsTest.log("primary: " + tojson(last, '', true) + " secondary: " + tojson(last3, '', true));
    jsTest.log("member 3 collection size: " + member3.getSisterDB("foo").bar.find().itcount());
    jsTest.log("curop: ");
    printjson(member3.getSisterDB("foo").currentOp(true));
    return ((last.ts.t === last3.ts.t) && (last.ts.i === last3.ts.i));
}, "Replication member 3 did not apply ops 25-75");

jsTest.log("Start 3's bgsync thread");
member3.runCommand({configureFailPoint: 'pauseRsBgSyncProducer', mode: 'off'});

jsTest.log("Node 3 shouldn't hit rollback");
var end = (new Date()).getTime() + 10000;
while ((new Date()).getTime() < end) {
    assert('ROLLBACK' !== member3.runCommand({replSetGetStatus: 1}).members[2].stateStr);
    sleep(30);
}

// Need to re-enable writes before clean shutdown.
assert.commandWorked(member2.runCommand({configureFailPoint: 'rsSyncApplyStop', mode: 'off'}));

replSet.stopSet();