feat: add options to set the cls mechanism to async-hooks or async-listener by kjin · Pull Request #741 · googleapis/cloud-trace-nodejs

kjin · 2018-05-07T23:05:03Z

This PR makes async_hooks-based Tracing the default option for tracing using Node 8+. To go back to using async-listener (via continuation-local-storage), new config.clsMechanism options are accepted: async-listener (and async-hooks).

This PR provides two new possible values for config.clsMechanism: async-listener and async-hooks.

Because context tracking is now specified as a config option rather than strictly as an environmental variable, a fair bit of refactoring is needed to support conditionally loading continuation-local-storage as late as possible. The constraints to satisfy are as following:

continuation-local-storage needs to be loaded as early as possible, and definitely before any modules that do I/O.
continuation-local-storage must be loaded after start() is called, so we know whether to load it (via the config option passed to start).

To accomplish this, most of the logic in index.ts has been moved to a new file, tracing.ts, where it is now encapsulated in a class Tracing. Barring the feat: change, there should be no behavioral changes; however there are some caveats that hopefully are captured in the added comments.

There is also a small change to prevent PluginLoader#deactivate from throwing when being called on an already deactivated plugin loader. This is only required to prevent large-scale changes to tests, as the case when it might be called when the plugin loader is de-activated is from test code that sets the [FORCE_NEW] flag in configuration objects.

codecov · 2018-05-07T23:21:23Z

Codecov Report

❗ No coverage uploaded for pull request base (master@000643f). Click here to learn what that means.
The diff coverage is 87.95%.

@@            Coverage Diff            @@
##             master     #741   +/-   ##
=========================================
  Coverage          ?   91.15%           
=========================================
  Files             ?       31           
  Lines             ?     1595           
  Branches          ?      312           
=========================================
  Hits              ?     1454           
  Misses            ?       60           
  Partials          ?       81

Impacted Files	Coverage Δ
src/trace-plugin-loader.ts	`92.51% <ø> (ø)`
src/config.ts	`100% <ø> (ø)`
src/util.ts	`95.77% <100%> (ø)`
src/tracing.ts	`87.03% <87.03%> (ø)`
src/index.ts	`89.58% <88.46%> (ø)`

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+  const agentEnabled = !config || config.enabled !== false;
+  const alAutoPreferred =
+      !ahAvailable && (!config || config.clsMechanism === 'auto');
+  const alUserPreferred = config && (config.clsMechanism === 'async-listener');


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@@ -1,5 +1,5 @@
 /**
- * Copyright 2015 Google Inc. All Rights Reserved.
+ * Copyright 2018 Google LLC


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-        'Disabling trace agent.');
-    stop();
-    return traceAgent;
+    throw e;


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+    // This code path maintains the current contract that calling get() before
+    // start() yields a disabled custom span API. It assumes that the use case
+    // for doing so (instead of returning null) is when get() is called in
+    // a file where it is unknown whether start() has been called.


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+   * Constructs a new Tracing instance.
+   * @param config The configuration for this instance.
+   */
+  constructor(config: NormalizedConfig, traceAgent: TraceAgent) {


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+   */
+  enable(): void {
+    if (this.traceAgent.isActive()) {
+      // For unit tests only.


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+
+      this.traceAgent.enable(this.config, this.logger);
+
+      pluginLoader.create(this.config, this.logger).activate();


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+      this.traceAgent.enable(this.config, this.logger);
+
+      pluginLoader.create(this.config, this.logger).activate();
+    } catch (e) {


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+  constructor(
+      config: NormalizedConfig, private readonly traceAgent: TraceAgent) {
+    this.config = config;
+    this.traceAgent = traceAgent;


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+      const clsConfig: Forceable<TraceCLSConfig> = {
+        mechanism: this.config.clsMechanism as TraceCLSMechanism,
+        [FORCE_NEW]: this.config[FORCE_NEW]
+      };


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+          this.disable();
+        }
+      });
+    } catch (e) {


src

googlebot added the cla: yes This human has signed the Contributor License Agreement. label May 7, 2018

ofrobots reviewed May 8, 2018

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kjin force-pushed the ah-default branch 4 times, most recently from 82bc9f7 to 1990e4a Compare May 12, 2018 00:43

kjin changed the title ~~feat: making async_hooks tracing the default on Node 8+~~ feat: add options to set the cls mechanism to async-hooks or async-listener May 12, 2018

kjin force-pushed the ah-default branch from 1990e4a to 65e4cf1 Compare May 14, 2018 19:14

kjin requested review from DominicKramer, jinwoo and ofrobots May 14, 2018 20:03

ofrobots suggested changes May 14, 2018

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kjin force-pushed the ah-default branch 3 times, most recently from 1fbcd68 to 409693a Compare May 14, 2018 22:50

ofrobots reviewed May 16, 2018

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kjin mentioned this pull request May 16, 2018

refactor: address cls TODOs #753

Merged

ofrobots reviewed May 16, 2018

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kjin added 6 commits May 17, 2018 11:26

refactor: create Tracing class and delay loading c-l-s

801b758

src

refactor: stop throwing in PluginLoader#deactivate

cc5d267

chore: address comments

0d047a4

chore: address comments, pt 2

6f6aa40

refactor: address comments, pt 3

3b159ea

refactor: address comments, pt 4

6f00010

kjin force-pushed the ah-default branch from f606ce1 to 6f00010 Compare May 17, 2018 18:27

ofrobots approved these changes May 17, 2018

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kjin merged commit f34aac5 into googleapis:master May 17, 2018

release-please Bot mentioned this pull request Jun 30, 2022

chore(main): release 7.0.0 #1452

Merged


		this.traceAgent.enable(this.config, this.logger);

		pluginLoader.create(this.config, this.logger).activate();

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kjin commented May 7, 2018 •

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