/**
 * Tests that the $currentOp aggregation stage behaves as expected. Specifically:
 * - It must be the first stage in the pipeline.
 * - It can only be run on admin, and the "aggregate" field must be 1.
 * - Only active connections are shown unless {idleConnections: true} is specified.
 * - Specifying {localOps: true} shows the local ops on mongoS rather than shard ops.
 * - A user without the inprog privilege can see their own ops, but no-one else's.
 * - A user with the inprog privilege can see all ops.
 * - Non-local readConcerns are rejected.
 * - Collation rules are respected.
 *
 * Also verifies that the aggregation-backed currentOp command obeys the same rules, where
 * applicable.
 *
 * This test requires replica set configuration and user credentials to persist across a restart.
 * @tags: [requires_persistence, uses_transactions, uses_prepare_transaction]
 */

// Restarts cause issues with authentication for awaiting replication.
TestData.skipAwaitingReplicationOnShardsBeforeCheckingUUIDs = true;

(function() {
    "use strict";

    load("jstests/libs/fixture_helpers.js");  // For FixtureHelpers.
    load("jstests/libs/namespace_utils.js");  // For getCollectionNameFromFullNamespace.

    // Replica set nodes started with --shardsvr do not enable key generation until they are added
    // to a sharded cluster and reject commands with gossiped clusterTime from users without the
    // advanceClusterTime privilege. This causes ShardingTest setup to fail because the shell
    // briefly authenticates as __system and recieves clusterTime metadata then will fail trying to
    // gossip that time later in setup.
    //
    // TODO SERVER-32672: remove this flag.
    TestData.skipGossipingClusterTime = true;

    const key = "jstests/libs/key1";

    // Parameters used to establish the sharded cluster.
    const stParams = {
        name: jsTestName(),
        keyFile: key,
        shards: 3,
        rs: {nodes: 1, setParameter: {internalQueryExecYieldIterations: 1}}
    };

    // Create a new sharded cluster for testing. We set the internalQueryExecYieldIterations
    // parameter so that plan execution yields on every iteration. For some tests, we will
    // temporarily set yields to hang the mongod so we can capture particular operations in the
    // currentOp output.
    const st = new ShardingTest(stParams);

    // Assign various elements of the cluster. We will use shard rs0 to test replica-set level
    // $currentOp behaviour.
    let shardConn = st.rs0.getPrimary();
    let mongosConn = st.s;
    let shardRS = st.rs0;

    let clusterTestDB = mongosConn.getDB(jsTestName());
    let clusterAdminDB = mongosConn.getDB("admin");
    shardConn.waitForClusterTime(60);
    let shardTestDB = shardConn.getDB(jsTestName());
    let shardAdminDB = shardConn.getDB("admin");

    function createUsers(conn) {
        let adminDB = conn.getDB("admin");

        // Create an admin user, one user with the inprog privilege, and one without.
        assert.commandWorked(
            adminDB.runCommand({createUser: "admin", pwd: "pwd", roles: ["root"]}));
        assert(adminDB.auth("admin", "pwd"));

        assert.commandWorked(adminDB.runCommand({
            createRole: "role_inprog",
            roles: [],
            privileges: [{resource: {cluster: true}, actions: ["inprog"]}]
        }));

        assert.commandWorked(adminDB.runCommand({
            createUser: "user_inprog",
            pwd: "pwd",
            roles: ["readWriteAnyDatabase", "role_inprog"]
        }));

        assert.commandWorked(adminDB.runCommand(
            {createUser: "user_no_inprog", pwd: "pwd", roles: ["readWriteAnyDatabase"]}));
    }

    // Create necessary users at both cluster and shard-local level.
    createUsers(shardConn);
    createUsers(mongosConn);

    // Create a test database and some dummy data on rs0.
    assert(clusterAdminDB.auth("admin", "pwd"));

    for (let i = 0; i < 5; i++) {
        assert.writeOK(clusterTestDB.test.insert({_id: i, a: i}));
    }

    st.ensurePrimaryShard(clusterTestDB.getName(), shardRS.name);

    // Restarts a replset with a different set of parameters. Explicitly set the keyFile to null,
    // since if ReplSetTest#stopSet sees a keyFile property, it attempts to auth before dbhash
    // checks.
    function restartReplSet(replSet, newOpts) {
        const numNodes = replSet.nodeList().length;
        for (let n = 0; n < numNodes; n++) {
            replSet.restart(n, newOpts);
        }
        replSet.keyFile = newOpts.keyFile;
        return replSet.getPrimary();
    }
    // Restarts a cluster with a different set of parameters.
    function restartCluster(st, newOpts) {
        restartReplSet(st.configRS, newOpts);
        for (let i = 0; i < stParams.shards; i++) {
            restartReplSet(st[`rs${i}`], newOpts);
        }
        st.restartMongos(0, Object.assign(newOpts, {restart: true}));
        st.keyFile = newOpts.keyFile;
        // Re-link the cluster components.
        shardConn = st.rs0.getPrimary();
        mongosConn = st.s;
        shardRS = st.rs0;
        clusterTestDB = mongosConn.getDB(jsTestName());
        clusterAdminDB = mongosConn.getDB("admin");
        shardTestDB = shardConn.getDB(jsTestName());
        shardAdminDB = shardConn.getDB("admin");
    }

    function runCommandOnAllPrimaries({dbName, cmdObj, username, password}) {
        for (let i = 0; i < stParams.shards; i++) {
            const rsAdminDB = st[`rs${i}`].getPrimary().getDB("admin");
            rsAdminDB.auth(username, password);
            assert.commandWorked(rsAdminDB.getSiblingDB(dbName).runCommand(cmdObj));
        }
    }

    // Functions to support running an operation in a parallel shell for testing allUsers behaviour.
    function runInParallelShell({conn, testfunc, username, password}) {
        TestData.aggCurOpTest = testfunc;
        TestData.aggCurOpUser = username;
        TestData.aggCurOpPwd = password;

        runCommandOnAllPrimaries({
            dbName: "admin",
            username: username,
            password: password,
            cmdObj: {configureFailPoint: "setYieldAllLocksHang", mode: "alwaysOn"}
        });

        testfunc = function() {
            db.getSiblingDB("admin").auth(TestData.aggCurOpUser, TestData.aggCurOpPwd);
            TestData.aggCurOpTest();
            db.getSiblingDB("admin").logout();
        };

        return startParallelShell(testfunc, conn.port);
    }

    function assertCurrentOpHasSingleMatchingEntry({conn, currentOpAggFilter, curOpSpec}) {
        curOpSpec = (curOpSpec || {allUsers: true});

        const connAdminDB = conn.getDB("admin");

        let curOpResult;

        assert.soon(
            function() {
                curOpResult =
                    connAdminDB.aggregate([{$currentOp: curOpSpec}, {$match: currentOpAggFilter}])
                        .toArray();

                return curOpResult.length === 1;
            },
            function() {
                return "Failed to find operation " + tojson(currentOpAggFilter) +
                    " in $currentOp output: " + tojson(curOpResult);
            });

        return curOpResult[0];
    }

    function waitForParallelShell({conn, username, password, awaitShell}) {
        runCommandOnAllPrimaries({
            dbName: "admin",
            username: username,
            password: password,
            cmdObj: {configureFailPoint: "setYieldAllLocksHang", mode: "off"}
        });

        awaitShell();
    }

    // Generic function for running getMore on a $currentOp aggregation cursor and returning the
    // command response.
    function getMoreTest({conn, curOpSpec, getMoreBatchSize}) {
        // Ensure that there are some other connections present so that the result set is larger
        // than 1 $currentOp entry.
        const otherConns = [new Mongo(conn.host), new Mongo(conn.host)];
        curOpSpec = Object.assign({idleConnections: true}, (curOpSpec || {}));

        // Log the other connections in as user_no_inprog so that they will show up for user_inprog
        // with {allUsers: true} and user_no_inprog with {allUsers: false}.
        for (let otherConn of otherConns) {
            assert(otherConn.getDB("admin").auth("user_no_inprog", "pwd"));
        }

        const connAdminDB = conn.getDB("admin");

        const aggCmdRes = assert.commandWorked(connAdminDB.runCommand(
            {aggregate: 1, pipeline: [{$currentOp: curOpSpec}], cursor: {batchSize: 0}}));
        assert.neq(aggCmdRes.cursor.id, 0);

        return connAdminDB.runCommand({
            getMore: aggCmdRes.cursor.id,
            collection: getCollectionNameFromFullNamespace(aggCmdRes.cursor.ns),
            batchSize: (getMoreBatchSize || 100)
        });
    }

    //
    // Common tests.
    //

    // Runs a suite of tests for behaviour common to both the replica set and cluster levels.
    function runCommonTests(conn, curOpSpec) {
        const testDB = conn.getDB(jsTestName());
        const adminDB = conn.getDB("admin");
        curOpSpec = (curOpSpec || {});

        function addToSpec(spec) {
            return Object.assign({}, curOpSpec, spec);
        }

        const isLocalMongosCurOp = (conn == mongosConn && curOpSpec.localOps);
        const isRemoteShardCurOp = (conn == mongosConn && !curOpSpec.localOps);

        // Test that an unauthenticated connection cannot run $currentOp even with {allUsers:
        // false}.
        assert(adminDB.logout());

        assert.commandFailedWithCode(
            adminDB.runCommand(
                {aggregate: 1, pipeline: [{$currentOp: addToSpec({allUsers: false})}], cursor: {}}),
            ErrorCodes.Unauthorized);

        // Test that an unauthenticated connection cannot run the currentOp command even with
        // {$ownOps: true}.
        assert.commandFailedWithCode(adminDB.currentOp({$ownOps: true}), ErrorCodes.Unauthorized);

        //
        // Authenticate as user_no_inprog.
        //
        assert(adminDB.logout());
        assert(adminDB.auth("user_no_inprog", "pwd"));

        // Test that $currentOp fails with {allUsers: true} for a user without the "inprog"
        // privilege.
        assert.commandFailedWithCode(
            adminDB.runCommand(
                {aggregate: 1, pipeline: [{$currentOp: addToSpec({allUsers: true})}], cursor: {}}),
            ErrorCodes.Unauthorized);

        // Test that the currentOp command fails with {ownOps: false} for a user without the
        // "inprog" privilege.
        assert.commandFailedWithCode(adminDB.currentOp({$ownOps: false}), ErrorCodes.Unauthorized);

        // Test that {aggregate: 1} fails when the first stage in the pipeline is not $currentOp.
        assert.commandFailedWithCode(
            adminDB.runCommand({aggregate: 1, pipeline: [{$match: {}}], cursor: {}}),
            ErrorCodes.InvalidNamespace);

        //
        // Authenticate as user_inprog.
        //
        assert(adminDB.logout());
        assert(adminDB.auth("user_inprog", "pwd"));

        // Test that $currentOp fails when it is not the first stage in the pipeline. We use two
        // $currentOp stages since any other stage in the initial position will trip the {aggregate:
        // 1} namespace check.
        assert.commandFailedWithCode(
            adminDB.runCommand(
                {aggregate: 1, pipeline: [{$currentOp: {}}, {$currentOp: curOpSpec}], cursor: {}}),
            40602);

        // Test that $currentOp fails when run on admin without {aggregate: 1}.
        assert.commandFailedWithCode(
            adminDB.runCommand(
                {aggregate: "collname", pipeline: [{$currentOp: curOpSpec}], cursor: {}}),
            ErrorCodes.InvalidNamespace);

        // Test that $currentOp fails when run as {aggregate: 1} on a database other than admin.
        assert.commandFailedWithCode(
            testDB.runCommand({aggregate: 1, pipeline: [{$currentOp: curOpSpec}], cursor: {}}),
            ErrorCodes.InvalidNamespace);

        // Test that the currentOp command fails when run directly on a database other than admin.
        assert.commandFailedWithCode(testDB.runCommand({currentOp: 1}), ErrorCodes.Unauthorized);

        // Test that the currentOp command helper succeeds when run on a database other than admin.
        // This is because the currentOp shell helper redirects the command to the admin database.
        assert.commandWorked(testDB.currentOp());

        // Test that $currentOp and the currentOp command accept all numeric types.
        const ones = [1, 1.0, NumberInt(1), NumberLong(1), NumberDecimal(1)];

        for (let one of ones) {
            assert.commandWorked(adminDB.runCommand(
                {aggregate: one, pipeline: [{$currentOp: curOpSpec}], cursor: {}}));

            assert.commandWorked(adminDB.runCommand({currentOp: one, $ownOps: true}));
        }

        // Test that $currentOp with {allUsers: true} succeeds for a user with the "inprog"
        // privilege.
        assert.commandWorked(adminDB.runCommand(
            {aggregate: 1, pipeline: [{$currentOp: addToSpec({allUsers: true})}], cursor: {}}));

        // Test that the currentOp command with {$ownOps: false} succeeds for a user with the
        // "inprog" privilege.
        assert.commandWorked(adminDB.currentOp({$ownOps: false}));

        // Test that $currentOp succeeds if local readConcern is specified.
        assert.commandWorked(adminDB.runCommand({
            aggregate: 1,
            pipeline: [{$currentOp: curOpSpec}],
            readConcern: {level: "local"},
            cursor: {}
        }));

        // Test that $currentOp fails if a non-local readConcern is specified for any data-bearing
        // target.
        const linearizableAggCmd = {
            aggregate: 1,
            pipeline: [{$currentOp: curOpSpec}],
            readConcern: {level: "linearizable"},
            cursor: {}
        };
        assert.commandFailedWithCode(adminDB.runCommand(linearizableAggCmd),
                                     ErrorCodes.InvalidOptions);

        // Test that {idleConnections: false} returns only active connections.
        const idleConn = new Mongo(conn.host);

        assert.eq(adminDB
                      .aggregate([
                          {$currentOp: addToSpec({allUsers: true, idleConnections: false})},
                          {$match: {active: false}}
                      ])
                      .itcount(),
                  0);

        // Test that the currentOp command with {$all: false} returns only active connections.
        assert.eq(adminDB.currentOp({$ownOps: false, $all: false, active: false}).inprog.length, 0);

        // Test that {idleConnections: true} returns inactive connections.
        assert.gte(adminDB
                       .aggregate([
                           {$currentOp: addToSpec({allUsers: true, idleConnections: true})},
                           {$match: {active: false}}
                       ])
                       .itcount(),
                   1);

        // Test that the currentOp command with {$all: true} returns inactive connections.
        assert.gte(adminDB.currentOp({$ownOps: false, $all: true, active: false}).inprog.length, 1);

        // Test that collation rules apply to matches on $currentOp output.
        const matchField =
            (isRemoteShardCurOp ? "cursor.originatingCommand.comment" : "command.comment");
        const numExpectedMatches = (isRemoteShardCurOp ? stParams.shards : 1);

        assert.eq(
            adminDB
                .aggregate(
                    [{$currentOp: curOpSpec}, {$match: {[matchField]: "AGG_currént_op_COLLATION"}}],
                    {
                      collation: {locale: "en_US", strength: 1},  // Case and diacritic insensitive.
                      comment: "agg_current_op_collation"
                    })
                .itcount(),
            numExpectedMatches);

        // Test that $currentOp output can be processed by $facet subpipelines.
        assert.eq(adminDB
                      .aggregate(
                          [
                            {$currentOp: curOpSpec},
                            {
                              $facet: {
                                  testFacet: [
                                      {$match: {[matchField]: "agg_current_op_facets"}},
                                      {$count: "count"}
                                  ]
                              }
                            },
                            {$unwind: "$testFacet"},
                            {$replaceRoot: {newRoot: "$testFacet"}}
                          ],
                          {comment: "agg_current_op_facets"})
                      .next()
                      .count,
                  numExpectedMatches);

        // Test that $currentOp is explainable.
        const explainPlan = assert.commandWorked(adminDB.runCommand({
            aggregate: 1,
            pipeline: [
                {$currentOp: addToSpec({idleConnections: true, allUsers: false})},
                {$match: {desc: "test"}}
            ],
            explain: true
        }));

        let expectedStages =
            [{$currentOp: {idleConnections: true}}, {$match: {desc: {$eq: "test"}}}];

        if (isRemoteShardCurOp) {
            assert.docEq(explainPlan.splitPipeline.shardsPart, expectedStages);
            for (let i = 0; i < stParams.shards; i++) {
                let shardName = st["rs" + i].name;
                assert.docEq(explainPlan.shards[shardName].stages, expectedStages);
            }
        } else if (isLocalMongosCurOp) {
            expectedStages[0].$currentOp.localOps = true;
            assert.docEq(explainPlan.mongos.stages, expectedStages);
        } else {
            assert.docEq(explainPlan.stages, expectedStages);
        }

        // Test that a user with the inprog privilege can run getMore on a $currentOp aggregation
        // cursor which they created with {allUsers: true}.
        let getMoreCmdRes = assert.commandWorked(
            getMoreTest({conn: conn, curOpSpec: {allUsers: true}, getMoreBatchSize: 1}));

        // Test that a user without the inprog privilege cannot run getMore on a $currentOp
        // aggregation cursor created by a user with {allUsers: true}.
        assert(adminDB.logout());
        assert(adminDB.auth("user_no_inprog", "pwd"));

        assert.neq(getMoreCmdRes.cursor.id, 0);
        assert.commandFailedWithCode(adminDB.runCommand({
            getMore: getMoreCmdRes.cursor.id,
            collection: getCollectionNameFromFullNamespace(getMoreCmdRes.cursor.ns),
            batchSize: 100
        }),
                                     ErrorCodes.Unauthorized);
    }

    // Run the common tests on a shard, through mongoS, and on mongoS with 'localOps' enabled.
    runCommonTests(shardConn);
    runCommonTests(mongosConn);
    runCommonTests(mongosConn, {localOps: true});

    //
    // mongoS specific tests.
    //

    // Test that a user without the inprog privilege cannot run non-local $currentOp via mongoS even
    // if allUsers is false.
    assert(clusterAdminDB.logout());
    assert(clusterAdminDB.auth("user_no_inprog", "pwd"));

    assert.commandFailedWithCode(
        clusterAdminDB.runCommand(
            {aggregate: 1, pipeline: [{$currentOp: {allUsers: false}}], cursor: {}}),
        ErrorCodes.Unauthorized);

    // Test that a user without the inprog privilege cannot run non-local currentOp command via
    // mongoS even if $ownOps is true.
    assert.commandFailedWithCode(clusterAdminDB.currentOp({$ownOps: true}),
                                 ErrorCodes.Unauthorized);

    // Test that a non-local $currentOp pipeline via mongoS returns results from all shards, and
    // includes both the shard and host names.
    assert(clusterAdminDB.logout());
    assert(clusterAdminDB.auth("user_inprog", "pwd"));

    assert.eq(clusterAdminDB
                  .aggregate([
                      {$currentOp: {allUsers: true, idleConnections: true}},
                      {$group: {_id: {shard: "$shard", host: "$host"}}},
                      {$sort: {_id: 1}}
                  ])
                  .toArray(),
              [
                {_id: {shard: "aggregation_currentop-rs0", host: st.rs0.getPrimary().host}},
                {_id: {shard: "aggregation_currentop-rs1", host: st.rs1.getPrimary().host}},
                {_id: {shard: "aggregation_currentop-rs2", host: st.rs2.getPrimary().host}}
              ]);

    // Test that a $currentOp pipeline with {localOps:true} returns operations from the mongoS
    // itself rather than the shards.
    assert.eq(clusterAdminDB
                  .aggregate(
                      [
                        {$currentOp: {localOps: true}},
                        {
                          $match: {
                              $expr: {$eq: ["$host", "$clientMetadata.mongos.host"]},
                              "command.comment": "mongos_currentop_localOps"
                          }
                        }
                      ],
                      {comment: "mongos_currentop_localOps"})
                  .itcount(),
              1);

    //
    // localOps tests.
    //

    // Runs a suite of tests for behaviour common to both replica sets and mongoS with
    // {localOps:true}.
    function runLocalOpsTests(conn) {
        // The 'localOps' parameter is not supported by the currentOp command, so we limit its
        // testing to the replica set in certain cases.
        const connAdminDB = conn.getDB("admin");
        const isMongos = FixtureHelpers.isMongos(connAdminDB);

        // Test that a user with the inprog privilege can see another user's ops with
        // {allUsers:true}.
        assert(connAdminDB.logout());
        assert(connAdminDB.auth("user_inprog", "pwd"));

        let awaitShell = runInParallelShell({
            testfunc: function() {
                assert.eq(db.getSiblingDB(jsTestName())
                              .test.find({})
                              .comment("agg_current_op_allusers_test")
                              .itcount(),
                          5);
            },
            conn: conn,
            username: "admin",
            password: "pwd"
        });

        assertCurrentOpHasSingleMatchingEntry({
            conn: conn,
            currentOpAggFilter: {"command.comment": "agg_current_op_allusers_test"},
            curOpSpec: {allUsers: true, localOps: true}
        });

        // Test that the currentOp command can see another user's operations with {$ownOps: false}.
        // Only test on a replica set since 'localOps' isn't supported by the currentOp command.
        if (!isMongos) {
            assert.eq(
                connAdminDB
                    .currentOp({$ownOps: false, "command.comment": "agg_current_op_allusers_test"})
                    .inprog.length,
                1);
        }

        // Test that $currentOp succeeds with {allUsers: false} for a user without the "inprog"
        // privilege.
        assert(connAdminDB.logout());
        assert(connAdminDB.auth("user_no_inprog", "pwd"));

        assert.commandWorked(connAdminDB.runCommand({
            aggregate: 1,
            pipeline: [{$currentOp: {allUsers: false, localOps: true}}],
            cursor: {}
        }));

        // Test that the currentOp command succeeds with {$ownOps: true} for a user without the
        // "inprog" privilege. Because currentOp does not support the 'localOps' parameter, we only
        // perform this test in the replica set case.
        if (!isMongos) {
            assert.commandWorked(connAdminDB.currentOp({$ownOps: true}));
        }

        // Test that a user without the inprog privilege cannot see another user's operations.
        assert.eq(connAdminDB
                      .aggregate([
                          {$currentOp: {allUsers: false, localOps: true}},
                          {$match: {"command.comment": "agg_current_op_allusers_test"}}
                      ])
                      .itcount(),
                  0);

        // Test that a user without the inprog privilege cannot see another user's operations via
        // the currentOp command. Limit this test to the replica set case due to the absence of a
        // 'localOps' parameter for the currentOp command.
        if (!isMongos) {
            assert.eq(
                connAdminDB
                    .currentOp({$ownOps: true, "command.comment": "agg_current_op_allusers_test"})
                    .inprog.length,
                0);
        }

        // Release the failpoint and wait for the parallel shell to complete.
        waitForParallelShell(
            {conn: conn, username: "admin", password: "pwd", awaitShell: awaitShell});

        // Test that a user without the inprog privilege can run getMore on a $currentOp cursor
        // which they created with {allUsers: false}.
        assert.commandWorked(
            getMoreTest({conn: conn, curOpSpec: {allUsers: false, localOps: true}}));
    }

    // Run the localOps tests for both replset and mongoS.
    runLocalOpsTests(mongosConn);
    runLocalOpsTests(shardConn);

    //
    // Stashed transactions tests.
    //

    // Test that $currentOp will display stashed transaction locks if 'idleSessions' is true, and
    // will only permit a user to view other users' sessions if the caller possesses the 'inprog'
    // privilege and 'allUsers' is true.
    const userNames = ["user_inprog", "admin", "user_no_inprog"];
    let sessionDBs = [];
    let sessions = [];

    // Returns a set of predicates that filter $currentOp for all stashed transactions.
    function sessionFilter() {
        return {
            type: "idleSession",
            active: false,
            opid: {$exists: false},
            desc: "inactive transaction",
            "lsid.id": {$in: sessions.map((session) => session.getSessionId().id)},
            "transaction.parameters.txnNumber": {$gte: 0, $lt: sessions.length},
        };
    }

    for (let i in userNames) {
        shardAdminDB.logout();
        assert(shardAdminDB.auth(userNames[i], "pwd"));

        // Create a session for this user.
        const session = shardAdminDB.getMongo().startSession();

        // For each session, start but do not complete a transaction.
        const sessionDB = session.getDatabase(shardTestDB.getName());
        assert.commandWorked(sessionDB.runCommand({
            insert: "test",
            documents: [{_id: `txn-insert-${userNames[i]}-${i}`}],
            readConcern: {level: "snapshot"},
            txnNumber: NumberLong(i),
            startTransaction: true,
            autocommit: false
        }));
        sessionDBs.push(sessionDB);
        sessions.push(session);

        // Use $currentOp to confirm that the incomplete transactions have stashed their locks while
        // inactive, and that each user can only view their own sessions with 'allUsers:false'.
        assert.eq(shardAdminDB
                      .aggregate([
                          {$currentOp: {allUsers: false, idleSessions: true}},
                          {$match: sessionFilter()}
                      ])
                      .itcount(),
                  1);
    }

    // Log in as 'user_no_inprog' to verify that the user cannot view other users' sessions via
    // 'allUsers:true'.
    shardAdminDB.logout();
    assert(shardAdminDB.auth("user_no_inprog", "pwd"));

    assert.commandFailedWithCode(shardAdminDB.runCommand({
        aggregate: 1,
        cursor: {},
        pipeline: [{$currentOp: {allUsers: true, idleSessions: true}}, {$match: sessionFilter()}]
    }),
                                 ErrorCodes.Unauthorized);

    // Log in as 'user_inprog' to confirm that a user with the 'inprog' privilege can see all three
    // stashed transactions with 'allUsers:true'.
    shardAdminDB.logout();
    assert(shardAdminDB.auth("user_inprog", "pwd"));

    assert.eq(
        shardAdminDB
            .aggregate(
                [{$currentOp: {allUsers: true, idleSessions: true}}, {$match: sessionFilter()}])
            .itcount(),
        3);

    // Confirm that the 'idleSessions' parameter defaults to true.
    assert.eq(shardAdminDB.aggregate([{$currentOp: {allUsers: true}}, {$match: sessionFilter()}])
                  .itcount(),
              3);

    // Confirm that idleSessions:false omits the stashed locks from the report.
    assert.eq(
        shardAdminDB
            .aggregate(
                [{$currentOp: {allUsers: true, idleSessions: false}}, {$match: sessionFilter()}])
            .itcount(),
        0);

    // Allow all transactions to complete and close the associated sessions.
    for (let i in userNames) {
        assert(shardAdminDB.auth(userNames[i], "pwd"));
        assert.commandWorked(sessionDBs[i].adminCommand({
            commitTransaction: 1,
            txnNumber: NumberLong(i),
            autocommit: false,
            writeConcern: {w: 'majority'}
        }));
        sessions[i].endSession();
    }

    //
    // No-auth tests.
    //

    // Restart the cluster with auth disabled.
    restartCluster(st, {keyFile: null});

    // Test that $currentOp will display all stashed transaction locks by default if auth is
    // disabled, even with 'allUsers:false'.
    const session = shardAdminDB.getMongo().startSession();

    // Run an operation prior to starting the transaction and save its operation time.
    const sessionDB = session.getDatabase(shardTestDB.getName());
    const res = assert.commandWorked(sessionDB.runCommand({insert: "test", documents: [{x: 1}]}));
    const operationTime = res.operationTime;

    // Set and save the transaction's lifetime. We will use this later to assert that our
    // transaction's expiry time is equal to its start time + lifetime.
    const transactionLifeTime = 10;
    assert.commandWorked(sessionDB.adminCommand(
        {setParameter: 1, transactionLifetimeLimitSeconds: transactionLifeTime}));

    // Start but do not complete a transaction.
    assert.commandWorked(sessionDB.runCommand({
        insert: "test",
        documents: [{_id: `txn-insert-no-auth`}],
        readConcern: {level: "snapshot"},
        txnNumber: NumberLong(0),
        startTransaction: true,
        autocommit: false
    }));
    sessionDBs = [sessionDB];
    sessions = [session];

    const timeAfterTransactionStarts = new ISODate();

    // Use $currentOp to confirm that the incomplete transaction has stashed its locks.
    assert.eq(shardAdminDB.aggregate([{$currentOp: {allUsers: false}}, {$match: sessionFilter()}])
                  .itcount(),
              1);

    // Confirm that idleSessions:false omits the stashed locks from the report.
    assert.eq(
        shardAdminDB
            .aggregate(
                [{$currentOp: {allUsers: false, idleSessions: false}}, {$match: sessionFilter()}])
            .itcount(),
        0);

    // Prepare the transaction and ensure the prepareTimestamp is valid.
    const prepareRes = assert.commandWorked(sessionDB.adminCommand({
        prepareTransaction: 1,
        txnNumber: NumberLong(0),
        autocommit: false,
        writeConcern: {w: "majority"}
    }));
    assert(prepareRes.prepareTimestamp,
           "prepareTransaction did not return a 'prepareTimestamp': " + tojson(prepareRes));
    assert(prepareRes.prepareTimestamp instanceof Timestamp,
           'prepareTimestamp was not a Timestamp: ' + tojson(prepareRes));
    assert.neq(prepareRes.prepareTimestamp,
               Timestamp(0, 0),
               "prepareTimestamp cannot be null: " + tojson(prepareRes));

    const timeBeforeCurrentOp = new ISODate();

    // Check that the currentOp's transaction subdocument's fields align with our expectations.
    let currentOp =
        shardAdminDB.aggregate([{$currentOp: {allUsers: false}}, {$match: sessionFilter()}])
            .toArray();
    let transactionDocument = currentOp[0].transaction;
    assert.eq(transactionDocument.parameters.autocommit, false);
    assert.eq(transactionDocument.parameters.readConcern, {level: "snapshot"});
    assert.gte(transactionDocument.readTimestamp, operationTime);
    // We round timeOpenMicros up to the nearest multiple of 1000 to avoid occasional assertion
    // failures caused by timeOpenMicros having microsecond precision while
    // timeBeforeCurrentOp/timeAfterTransactionStarts only have millisecond precision.
    assert.gte(Math.ceil(transactionDocument.timeOpenMicros / 1000) * 1000,
               (timeBeforeCurrentOp - timeAfterTransactionStarts) * 1000);
    assert.gte(transactionDocument.timeActiveMicros, 0);
    assert.gte(transactionDocument.timeInactiveMicros, 0);
    assert.gte(transactionDocument.timePreparedMicros, 0);
    // Not worried about its specific value, validate that in general we return some non-zero &
    // valid time greater than epoch time.
    assert.gt(ISODate(transactionDocument.startWallClockTime), ISODate("1970-01-01T00:00:00.000Z"));
    assert.eq(
        ISODate(transactionDocument.expiryTime).getTime(),
        ISODate(transactionDocument.startWallClockTime).getTime() + transactionLifeTime * 1000);

    // Allow the transactions to complete and close the session. We must commit prepared
    // transactions at a timestamp greater than the prepare timestamp.
    const commitTimestamp =
        Timestamp(prepareRes.prepareTimestamp.getTime(), prepareRes.prepareTimestamp.getInc() + 1);
    assert.commandWorked(sessionDB.adminCommand({
        commitTransaction: 1,
        txnNumber: NumberLong(0),
        autocommit: false,
        writeConcern: {w: 'majority'},
        commitTimestamp: commitTimestamp
    }));
    session.endSession();

    // Run a set of tests of behaviour common to replset and mongoS when auth is disabled.
    function runNoAuthTests(conn, curOpSpec) {
        // Test that the allUsers parameter is ignored when authentication is disabled.
        // Ensure that there is at least one other connection present.
        const connAdminDB = conn.getDB("admin");
        const otherConn = new Mongo(conn.host);
        curOpSpec = Object.assign({localOps: false}, (curOpSpec || {}));

        // Verify that $currentOp displays all operations when auth is disabled regardless of the
        // allUsers parameter, by confirming that we can see non-client system operations when
        // {allUsers: false} is specified.
        assert.gte(
            connAdminDB
                .aggregate([
                    {
                      $currentOp:
                          {allUsers: false, idleConnections: true, localOps: curOpSpec.localOps}
                    },
                    {$match: {connectionId: {$exists: false}}}
                ])
                .itcount(),
            1);

        // Verify that the currentOp command displays all operations when auth is disabled
        // regardless of
        // the $ownOps parameter, by confirming that we can see non-client system operations when
        // {$ownOps: true} is specified.
        assert.gte(
            connAdminDB.currentOp({$ownOps: true, $all: true, connectionId: {$exists: false}})
                .inprog.length,
            1);

        // Test that a user can run getMore on a $currentOp cursor when authentication is disabled.
        assert.commandWorked(
            getMoreTest({conn: conn, curOpSpec: {allUsers: true, localOps: curOpSpec.localOps}}));
    }

    runNoAuthTests(shardConn);
    runNoAuthTests(mongosConn);
    runNoAuthTests(mongosConn, {localOps: true});

    //
    // Replset specific tests.
    //

    // Take the replica set out of the cluster.
    shardConn = restartReplSet(st.rs0, {shardsvr: null});
    shardTestDB = shardConn.getDB(jsTestName());
    shardAdminDB = shardConn.getDB("admin");

    // Test that the host field is present and the shard field is absent when run on mongoD.
    assert.eq(shardAdminDB
                  .aggregate([
                      {$currentOp: {allUsers: true, idleConnections: true}},
                      {$group: {_id: {shard: "$shard", host: "$host"}}}
                  ])
                  .toArray(),
              [
                {_id: {host: shardConn.host}},
              ]);

    // Test that attempting to 'spoof' a sharded request on non-shardsvr mongoD fails.
    assert.commandFailedWithCode(
        shardAdminDB.runCommand(
            {aggregate: 1, pipeline: [{$currentOp: {}}], fromMongos: true, cursor: {}}),
        40465);

    // Test that an operation which is at the BSON user size limit does not throw an error when the
    // currentOp metadata is added to the output document.
    const bsonUserSizeLimit = assert.commandWorked(shardAdminDB.isMaster()).maxBsonObjectSize;

    let aggPipeline = [
        {$currentOp: {}},
        {
          $match: {
              $or: [
                  {
                    "command.comment": "agg_current_op_bson_limit_test",
                    "command.$truncated": {$exists: false}
                  },
                  {padding: ""}
              ]
          }
        }
    ];

    aggPipeline[1].$match.$or[1].padding =
        "a".repeat(bsonUserSizeLimit - Object.bsonsize(aggPipeline));

    assert.eq(Object.bsonsize(aggPipeline), bsonUserSizeLimit);

    assert.eq(
        shardAdminDB.aggregate(aggPipeline, {comment: "agg_current_op_bson_limit_test"}).itcount(),
        1);

    // Test that $currentOp can run while the mongoD is write-locked.
    let awaitShell = startParallelShell(function() {
        assert.commandFailedWithCode(db.adminCommand({sleep: 1, lock: "w", secs: 300}),
                                     ErrorCodes.Interrupted);
    }, shardConn.port);

    const op = assertCurrentOpHasSingleMatchingEntry(
        {conn: shardConn, currentOpAggFilter: {"command.sleep": 1, active: true}});

    assert.commandWorked(shardAdminDB.killOp(op.opid));

    awaitShell();

    // Add the shard back into the replset so that it can be validated by st.stop().
    shardConn = restartReplSet(st.rs0, {shardsvr: ""});
    st.stop();
})();