/**
 * Tests that the server status metrics correctly reflect the number of waiting hello/isMaster
 * requests before and after a state change.
 */
(function() {
"use strict";
load("jstests/libs/parallel_shell_helpers.js");
load("jstests/libs/fail_point_util.js");

function runAwaitableCmd(cmd, topologyVersionField) {
    const res = assert.commandWorked(db.runCommand({
        [cmd]: 1,
        topologyVersion: topologyVersionField,
        maxAwaitTimeMS: 99999999,
    }));
    assert.eq(topologyVersionField.counter + 1, res.topologyVersion.counter);
}

function runTest(cmd) {
    // Test hello/isMaster paramaters on a single node replica set.
    const replTest = new ReplSetTest({name: "awaitable_cmd_metrics", nodes: 1});
    replTest.startSet();
    replTest.initiate();

    const dbName = "awaitable_cmd_metrics";
    const node = replTest.getPrimary();
    const db = node.getDB(dbName);

    const res = assert.commandWorked(db.runCommand({[cmd]: 1}));
    assert(res.hasOwnProperty("topologyVersion"), res);
    const topologyVersionField = res.topologyVersion;
    assert(topologyVersionField.hasOwnProperty("processId"), topologyVersionField);
    assert(topologyVersionField.hasOwnProperty("counter"), topologyVersionField);

    // A failpoint signalling that the server has received the hello/isMaster request and is waiting
    // for a topology change.
    let failPoint = configureFailPoint(node, "waitForHelloResponse");
    // Send an awaitable hello/isMaster request. This will block until maxAwaitTimeMS has elapsed or
    // a topology change happens.
    let firstCmdBeforeStepDown =
        startParallelShell(funWithArgs(runAwaitableCmd, cmd, topologyVersionField), node.port);
    failPoint.wait();
    // awaitingTopologyChanges should increment once.
    let numAwaitingTopologyChange = db.serverStatus().connections.awaitingTopologyChanges;
    assert.eq(1, numAwaitingTopologyChange);

    // Reconfigure failpoint to refresh the number of times entered.
    failPoint = configureFailPoint(node, "waitForHelloResponse");
    let secondCmdBeforeStepdown =
        startParallelShell(funWithArgs(runAwaitableCmd, cmd, topologyVersionField), node.port);
    failPoint.wait();
    numAwaitingTopologyChange = db.serverStatus().connections.awaitingTopologyChanges;
    assert.eq(2, numAwaitingTopologyChange);

    // Call stepdown to increment the server TopologyVersion and respond to the waiting
    // hello/isMaster requests.
    assert.commandWorked(db.adminCommand({replSetStepDown: 60, force: true}));
    firstCmdBeforeStepDown();
    secondCmdBeforeStepdown();
    // All hello/isMaster requests should have been responded to.
    numAwaitingTopologyChange = db.serverStatus().connections.awaitingTopologyChanges;
    assert.eq(0, numAwaitingTopologyChange);
    replTest.stopSet();
}

runTest("hello");
runTest("isMaster");
runTest("ismaster");
})();