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chore: address comments
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@kjin
kjin committed May 14, 2018
1 parent 5143691 commit db058d7
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Showing 2 changed files with 80 additions and 75 deletions.
77 changes: 66 additions & 11 deletions src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -19,16 +19,74 @@ const filesLoadedBeforeTrace = Object.keys(require.cache);
// This file's top-level imports must not transitively depend on modules that
// do I/O, or continuation-local-storage will not work.
import * as semver from 'semver';
import {Config} from './config';
import {Config, defaultConfig} from './config';
import * as extend from 'extend';
import * as path from 'path';
import * as PluginTypes from './plugin-types';
import {tracing, Tracing} from './tracing';
import {Singleton} from './util';
import {tracing, Tracing, NormalizedConfig} from './tracing';
import {Singleton, FORCE_NEW, Forceable} from './util';
import {Constants} from './constants';

export {Config, PluginTypes};

let tracingSingleton: typeof tracing;

/**
* Normalizes the user-provided configuration object by adding default values
* and overriding with env variables when they are provided.
* @param projectConfig The user-provided configuration object. It will not
* be modified.
* @return A normalized configuration object.
*/
function initConfig(projectConfig: Forceable<Config>):
Forceable<NormalizedConfig> {
// `|| undefined` prevents environmental variables that are empty strings
// from overriding values provided in the config object passed to start().
const envConfig = {
logLevel: Number(process.env.GCLOUD_TRACE_LOGLEVEL) || undefined,
projectId: process.env.GCLOUD_PROJECT || undefined,
serviceContext: {
service:
process.env.GAE_SERVICE || process.env.GAE_MODULE_NAME || undefined,
version: process.env.GAE_VERSION || process.env.GAE_MODULE_VERSION ||
undefined,
minorVersion: process.env.GAE_MINOR_VERSION || undefined
}
};

let envSetConfig: Config = {};
if (!!process.env.GCLOUD_TRACE_CONFIG) {
envSetConfig =
require(path.resolve(process.env.GCLOUD_TRACE_CONFIG!)) as Config;
}
// Configuration order of precedence:
// 1. Environment Variables
// 2. Project Config
// 3. Environment Variable Set Configuration File (from GCLOUD_TRACE_CONFIG)
// 4. Default Config (as specified in './config')
const config = extend(
true, {[FORCE_NEW]: projectConfig[FORCE_NEW]}, defaultConfig,
envSetConfig, projectConfig, envConfig, {plugins: {}});
// The empty plugins object guarantees that plugins is a plain object,
// even if it's explicitly specified in the config to be a non-object.

// Enforce the upper limit for the label value size.
if (config.maximumLabelValueSize >
Constants.TRACE_SERVICE_LABEL_VALUE_LIMIT) {
config.maximumLabelValueSize = Constants.TRACE_SERVICE_LABEL_VALUE_LIMIT;
}

// If the CLS mechanism is set to auto-determined, decide now what it should
// be.
const ahAvailable = semver.satisfies(process.version, '>=8') &&
process.env.GCLOUD_TRACE_NEW_CONTEXT;
if (config.clsMechanism === 'auto') {
config.clsMechanism = ahAvailable ? 'async-hooks' : 'async-listener';
}

return config;
}

/**
* Start the Stackdriver Trace Agent with the given configuration (if provided).
* This function should only be called once, and before any other modules are
Expand All @@ -43,26 +101,23 @@ let tracingSingleton: typeof tracing;
* trace.start();
*/
export function start(config?: Config): PluginTypes.TraceAgent {
const normalizedConfig = initConfig(config || {});
// Determine the preferred context propagation mechanism, as
// continuation-local-storage should be loaded before any modules that do I/O.
const ahAvailable = semver.satisfies(process.version, '>=8') &&
process.env.GCLOUD_TRACE_NEW_CONTEXT;
const agentEnabled = !config || config.enabled !== false;
const alAutoPreferred =
!ahAvailable && (!config || config.clsMechanism === 'auto');
const alUserPreferred = config && (config.clsMechanism === 'async-listener');
if (agentEnabled && (alAutoPreferred || alUserPreferred)) {
if (normalizedConfig.enabled &&
normalizedConfig.clsMechanism === 'async-listener') {
// This is the earliest we can load continuation-local-storage.
require('continuation-local-storage');
}

if (!tracingSingleton) {
tracingSingleton = require('./tracing').tracing;
}

try {
let tracing: Tracing;
try {
tracing = tracingSingleton.create(config || {}, {});
tracing = tracingSingleton.create(normalizedConfig, {});
} catch (e) {
// An error could be thrown if create() is called multiple times.
// It's not a helpful error message for the end user, so make it more
Expand Down
78 changes: 14 additions & 64 deletions src/tracing.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,6 @@
*/

import * as common from '@google-cloud/common';
import * as extend from 'extend';
import * as path from 'path';
import * as semver from 'semver';

Expand All @@ -28,14 +27,15 @@ import {pluginLoader, PluginLoaderConfig} from './trace-plugin-loader';
import {traceWriter, TraceWriterConfig} from './trace-writer';
import {Component, FORCE_NEW, Forceable, packageNameFromPath, Singleton} from './util';

interface TopLevelConfig {
export interface TopLevelConfig {
enabled: boolean;
logLevel: number;
clsMechanism: CLSMechanism;
}

// PluginLoaderConfig extends TraceAgentConfig
type NormalizedConfig = TraceWriterConfig&PluginLoaderConfig&TopLevelConfig;
export type NormalizedConfig =
(TraceWriterConfig&PluginLoaderConfig&TopLevelConfig)|{enabled: false};

/**
* A class that represents automatic tracing.
Expand All @@ -50,66 +50,22 @@ export class Tracing implements Component {
* Constructs a new Tracing instance.
* @param config The configuration for this instance.
*/
constructor(config: Config) {
this.config = Tracing.initConfig(config);
constructor(config: NormalizedConfig) {
this.config = config;
let logLevel = config.enabled ? config.logLevel : 0;
// Clamp the logger level.
if (logLevel < 0) {
logLevel = 0;
} else if (logLevel >= common.logger.LEVELS.length) {
logLevel = common.logger.LEVELS.length - 1;
}
this.logger = common.logger({
level: common.logger.LEVELS[this.config.logLevel],
level: common.logger.LEVELS[logLevel],
tag: '@google-cloud/trace-agent'
});
}

/**
* Normalizes the user-provided configuration object by adding default values
* and overriding with env variables when they are provided.
* @param projectConfig The user-provided configuration object. It will not
* be modified.
* @return A normalized configuration object.
*/
private static initConfig(projectConfig: Forceable<Config>):
Forceable<NormalizedConfig> {
// `|| undefined` prevents environmental variables that are empty strings
// from overriding values provided in the config object passed to start().
const envConfig = {
logLevel: Number(process.env.GCLOUD_TRACE_LOGLEVEL) || undefined,
projectId: process.env.GCLOUD_PROJECT || undefined,
serviceContext: {
service:
process.env.GAE_SERVICE || process.env.GAE_MODULE_NAME || undefined,
version: process.env.GAE_VERSION || process.env.GAE_MODULE_VERSION ||
undefined,
minorVersion: process.env.GAE_MINOR_VERSION || undefined
}
};

let envSetConfig: Config = {};
if (!!process.env.GCLOUD_TRACE_CONFIG) {
envSetConfig =
require(path.resolve(process.env.GCLOUD_TRACE_CONFIG!)) as Config;
}
// Configuration order of precedence:
// 1. Environment Variables
// 2. Project Config
// 3. Environment Variable Set Configuration File (from GCLOUD_TRACE_CONFIG)
// 4. Default Config (as specified in './config')
const config = extend(
true, {[FORCE_NEW]: projectConfig[FORCE_NEW]}, defaultConfig,
envSetConfig, projectConfig, envConfig, {plugins: {}});
// The empty plugins object guarantees that plugins is a plain object,
// even if it's explicitly specified in the config to be a non-object.

// Enforce the upper limit for the label value size.
if (config.maximumLabelValueSize >
Constants.TRACE_SERVICE_LABEL_VALUE_LIMIT) {
config.maximumLabelValueSize = Constants.TRACE_SERVICE_LABEL_VALUE_LIMIT;
}
// Clamp the logger level.
if (config.logLevel < 0) {
config.logLevel = 0;
} else if (config.logLevel >= common.logger.LEVELS.length) {
config.logLevel = common.logger.LEVELS.length - 1;
}
return config;
}

/**
* Logs an error message detailing the list of modules that were loaded before
Expand Down Expand Up @@ -152,14 +108,8 @@ export class Tracing implements Component {

try {
// Initialize context propagation mechanism.
const m = this.config.clsMechanism;
const ahAvailable = semver.satisfies(process.version, '>=8') &&
process.env.GCLOUD_TRACE_NEW_CONTEXT;
const clsConfig: Forceable<TraceCLSConfig> = {
mechanism: m === 'auto' ?
(ahAvailable ? TraceCLSMechanism.ASYNC_HOOKS :
TraceCLSMechanism.ASYNC_LISTENER) :
m as TraceCLSMechanism,
mechanism: this.config.clsMechanism as TraceCLSMechanism,
[FORCE_NEW]: this.config[FORCE_NEW]
};
cls.create(clsConfig, this.logger).enable();
Expand Down

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