apminsight/lib/instrument/modules/memcached.js

monitor nodejs applications

// supported upto v2.2.2

var wrapper = require("./../wrapper");
var logger = require("./../../util/logger");
var utils = require("./../../util/utils");

var componentName = "MEMCACHED";

var moduleInfo = {
    functions: [
        {
            functionName: "prototype.command",
            component: componentName,
            wrapper: wrapCommand
        }
    ]
};

function wrapCommand(actual) {
    return function (getCommandInfo) {
        try {
            var curTracker;
            var parentTracker = apmInsightAgentInstance.getCurTracker();
            if (getCommandInfo && utils.isFunction(getCommandInfo)) {
                var commandInfo = getCommandInfo();
                if (isCommandInfoValid(commandInfo)) {
                    var trackerName =
                        componentName +
                        " - " +
                        commandInfo.type +
                        " - " +
                        commandInfo.key;
                    var trackerInfo = {
                        trackerName: trackerName,
                        component: componentName,
                        parent: parentTracker
                    };
                    curTracker =
                        apmInsightAgentInstance.createTracker(trackerInfo);
                    commandInfo.callback = wrapper.wrapCallBack(
                        commandInfo.callback,
                        curTracker,
                        apmInsightAgentInstance.getCurTxn()
                    );
                    arguments[0] = function () {
                        return commandInfo;
                    };
                    extractMachineInfo(curTracker, this, commandInfo);
                }
            }
            var result = actual.apply(this, arguments);
            return result;
        } catch (e) {
            logger.error("memcache command handler", e);
            apmInsightAgentInstance.handleErrorTracker(curTracker, e);
            throw e;
        } finally {
            apmInsightAgentInstance.setCurTracker(parentTracker);
        }
    };
}

function extractMachineInfo(curTracker, invoker, commandInfo) {
    if (curTracker && invoker) {
        var machineInfo;
        if (invoker.servers && typeof invoker.servers === "string") {
            machineInfo = invoker.servers.split(":");
        } else if (
            invoker.HashRing &&
            invoker.HashRing.get &&
            invoker.HashRing.get(commandInfo.key)
        ) {
            machineInfo = invoker.HashRing.get(commandInfo.key).split(":");
        }
        if (machineInfo && machineInfo.length === 2) {
            var info = {};
            info.host = machineInfo[0];
            info.port = machineInfo[1];
            curTracker.updateInfo(info);
        }
    }
}

function isCommandInfoValid(commandInfo) {
    return (
        commandInfo &&
        commandInfo.type &&
        commandInfo.key &&
        utils.isFunction(commandInfo.callback)
    );
}

module.exports = moduleInfo;