/**
 * When two concurrent identical upsert operations are performed, for which a unique index exists on
 * the query values, it is possible that they will both attempt to perform an insert with one of
 * the two failing on the unique index constraint. This test confirms that the failed insert will be
 * retried, resulting in an update.
 *
 * In order for one of the two conflicting upserts to make progress we require a storage engine
 * which supports document level locking.
 *  @tags: [requires_replication, requires_document_locking]
 */

(function() {
    "use strict";

    const rst = new ReplSetTest({nodes: 1});
    rst.startSet();
    rst.initiate();

    const testDB = rst.getPrimary().getDB("test");
    const adminDB = testDB.getSiblingDB("admin");
    const collName = "upsert_duplicate_key_retry";
    const testColl = testDB.getCollection(collName);

    testDB.runCommand({drop: collName});

    // Queries current operations until 'count' matching operations are found.
    function awaitMatchingCurrentOpCount(message, count) {
        assert.soon(() => {
            const currentOp =
                adminDB.aggregate([{$currentOp: {}}, {$match: {msg: message}}]).toArray();
            return (currentOp.length === count);
        });
    }

    function performUpsert() {
        // This function is called from startParallelShell(), so closed-over variables will not be
        // available. We must re-obtain the value of 'testColl' in the function body.
        const testColl = db.getMongo().getDB("test").getCollection("upsert_duplicate_key_retry");
        assert.commandWorked(testColl.update({x: 3}, {$inc: {y: 1}}, {upsert: true}));
    }

    assert.commandWorked(testColl.createIndex({x: 1}, {unique: true}));

    // Will hang upsert operations just prior to performing an insert.
    assert.commandWorked(testDB.adminCommand(
        {configureFailPoint: "hangBeforeUpsertPerformsInsert", mode: "alwaysOn"}));

    const awaitUpdate1 = startParallelShell(performUpsert, rst.ports[0]);
    const awaitUpdate2 = startParallelShell(performUpsert, rst.ports[0]);

    awaitMatchingCurrentOpCount("hangBeforeUpsertPerformsInsert", 2);

    assert.commandWorked(
        testDB.adminCommand({configureFailPoint: "hangBeforeUpsertPerformsInsert", mode: "off"}));

    awaitUpdate1();
    awaitUpdate2();

    const cursor = testColl.find({}, {_id: 0});
    assert.eq(cursor.next(), {x: 3, y: 2});
    assert(!cursor.hasNext(), cursor.toArray());

    // Confirm that oplog entries exist for both insert and update operation.
    const oplogColl = testDB.getSiblingDB("local").getCollection("oplog.rs");
    assert.eq(1, oplogColl.find({"op": "i", "ns": "test.upsert_duplicate_key_retry"}).itcount());
    assert.eq(1, oplogColl.find({"op": "u", "ns": "test.upsert_duplicate_key_retry"}).itcount());

    //
    // Confirm DuplicateKey error for cases that should not be retried.
    //
    assert.commandWorked(testDB.runCommand({drop: collName}));
    assert.commandWorked(testColl.createIndex({x: 1}, {unique: true}));

    // DuplicateKey error on replacement-style upsert, where the unique index key value to be
    // written does not match the value of the query predicate.
    assert.commandWorked(testColl.createIndex({x: 1}, {unique: true}));
    assert.commandWorked(testColl.insert({_id: 1, 'a': 12345}));
    assert.commandFailedWithCode(testColl.update({x: 3}, {}, {upsert: true}),
                                 ErrorCodes.DuplicateKey);

    // DuplicateKey error on update-style upsert, where the unique index key value to be written
    // does not match the value of the query predicate.
    assert.commandWorked(testColl.remove({}));
    assert.commandWorked(testColl.insert({x: 3}));
    assert.commandWorked(testColl.insert({x: 4}));
    assert.commandFailedWithCode(testColl.update({x: 3}, {$inc: {x: 1}}, {upsert: true}),
                                 ErrorCodes.DuplicateKey);

    rst.stopSet();
})();