feat(scope-manager): implements AsyncHooks Scope Manager (open-telemetry#103)

* feat(scope-manager): Add AsyncHooks implementations of ScopeManager

* fix(ah-scope): remove shimmer, handle methods that remove listeners

* test(ah-scope): add tests for binding scope on event emitter

* feat(ah-scope): handle bind with promise + tests

* chore(ah-scope): update automatic tracer dependency to new name

* chore(ah-scope): remove support for event emitter and promises for now

* chore(ah-scope): address pr comments

Author: vmarchaud

packages/opentelemetry-node-tracer/package.json

@@ -50,7 +50,7 @@
   },
   "dependencies": {
     "@opentelemetry/core": "^0.0.1",
-    "@opentelemetry/context-async-hooks": "^0.0.1",
+    "@opentelemetry/scope-async-hooks": "^0.0.1",
     "@opentelemetry/scope-base": "^0.0.1",
     "@opentelemetry/types": "^0.0.1"
   }

packages/opentelemetry-context-async-hooks/.npmignore packages/opentelemetry-scope-async-hooks/.npmignore

@@ -1,13 +1,14 @@
 {
-  "name": "@opentelemetry/context-async-hooks",
+  "name": "@opentelemetry/scope-async-hooks",
   "version": "0.0.1",
-  "description": "OpenTelemetry AsyncHooks-based Context Manager",
+  "description": "OpenTelemetry AsyncHooks-based Scope Manager",
   "main": "build/src/index.js",
   "types": "build/src/index.d.ts",
   "repository": "open-telemetry/opentelemetry-js",
   "scripts": {
     "test": "c8 ts-mocha -p tsconfig.json test/**/*.ts",
     "tdd": "yarn test -- --watch-extensions ts --watch",
+    "codecov": "c8 report --reporter=json && codecov -f coverage/*.json -p ../../",
     "clean": "rimraf build/*",
     "check": "gts check",
     "compile": "tsc -p .",
@@ -40,6 +41,7 @@
   "devDependencies": {
     "@types/mocha": "^5.2.5",
     "@types/node": "^12.0.10",
+    "@types/shimmer": "^1.0.1",
     "c8": "^5.0.1",
     "codecov": "^3.1.0",
     "gts": "^1.0.0",
@@ -48,5 +50,7 @@
     "ts-node": "^8.0.0",
     "typescript": "^3.4.5"
   },
-  "dependencies": {}
+  "dependencies": {
+    "@opentelemetry/scope-base": "^0.0.1"
+  }
 }

packages/opentelemetry-context-async-hooks/LICENSE packages/opentelemetry-scope-async-hooks/LICENSE

@@ -0,0 +1,114 @@
+/**
+ * Copyright 2019, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ScopeManager } from '@opentelemetry/scope-base';
+import * as asyncHooks from 'async_hooks';
+
+export class AsyncHooksScopeManager implements ScopeManager {
+  private _asyncHook: asyncHooks.AsyncHook;
+  private _scopes: { [uid: number]: unknown } = Object.create(null);
+
+  constructor() {
+    this._asyncHook = asyncHooks.createHook({
+      init: this._init.bind(this),
+      destroy: this._destroy.bind(this),
+      promiseResolve: this._destroy.bind(this),
+    });
+  }
+
+  active(): unknown {
+    return this._scopes[asyncHooks.executionAsyncId()] || null;
+  }
+
+  with<T extends (...args: unknown[]) => ReturnType<T>>(
+    scope: unknown,
+    fn: T
+  ): ReturnType<T> {
+    const uid = asyncHooks.executionAsyncId();
+    const oldScope = this._scopes[uid];
+    this._scopes[uid] = scope;
+    try {
+      return fn();
+    } catch (err) {
+      throw err;
+    } finally {
+      if (oldScope === undefined) {
+        this._destroy(uid);
+      } else {
+        this._scopes[uid] = oldScope;
+      }
+    }
+  }
+
+  bind<T>(target: T, scope?: unknown): T {
+    // if no specific scope to propagate is given, we use the current one
+    if (scope === undefined) {
+      scope = this.active();
+    }
+    if (typeof target === 'function') {
+      return this._bindFunction(target, scope);
+    }
+    return target;
+  }
+
+  enable(): this {
+    this._asyncHook.enable();
+    return this;
+  }
+
+  disable(): this {
+    this._asyncHook.disable();
+    this._scopes = {};
+    return this;
+  }
+
+  private _bindFunction<T extends Function>(target: T, scope?: unknown): T {
+    const manager = this;
+    const contextWrapper = function(this: {}) {
+      return manager.with(scope, () => target.apply(this, arguments));
+    };
+    Object.defineProperty(contextWrapper, 'length', {
+      enumerable: false,
+      configurable: true,
+      writable: false,
+      value: target.length,
+    });
+    /**
+     * It isnt possible to tell Typescript that contextWrapper is the same as T
+     * so we forced to cast as any here.
+     */
+    // tslint:disable-next-line:no-any
+    return contextWrapper as any;
+  }
+
+  /**
+   * Init hook will be called when userland create a async scope, setting the
+   * scope as the current one if it exist.
+   * @param uid id of the async scope
+   */
+  private _init(uid: number) {
+    this._scopes[uid] = this._scopes[asyncHooks.executionAsyncId()];
+  }
+
+  /**
+   * Destroy hook will be called when a given scope is no longer used so we can
+   * remove its attached scope.
+   * @param uid uid of the async scope
+   */
+  private _destroy(uid: number) {
+    delete this._scopes[uid];
+  }
+}

packages/opentelemetry-context-async-hooks/README.md packages/opentelemetry-scope-async-hooks/README.md

@@ -13,3 +13,5 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+export * from './AsyncHooksScopeManager';

packages/opentelemetry-context-async-hooks/package.json packages/opentelemetry-scope-async-hooks/package.json

@@ -0,0 +1,132 @@
+/**
+ * Copyright 2019, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as assert from 'assert';
+import { AsyncHooksScopeManager } from '../../src';
+
+describe('AsyncHooksScopeManager', () => {
+  let scopeManager: AsyncHooksScopeManager;
+
+  afterEach(() => {
+    scopeManager.disable();
+    scopeManager.enable();
+  });
+
+  describe('.enable()', () => {
+    it('should work', () => {
+      assert.doesNotThrow(() => {
+        scopeManager = new AsyncHooksScopeManager();
+        assert(scopeManager.enable() === scopeManager, 'should return this');
+      });
+    });
+  });
+
+  describe('.disable()', () => {
+    it('should work', () => {
+      assert.doesNotThrow(() => {
+        assert(scopeManager.disable() === scopeManager, 'should return this');
+      });
+      scopeManager.enable();
+    });
+  });
+
+  describe('.with()', () => {
+    it('should run the callback (null as target)', done => {
+      scopeManager.with(null, done);
+    });
+
+    it('should run the callback (object as target)', done => {
+      const test = { a: 1 };
+      scopeManager.with(test, () => {
+        assert.strictEqual(scopeManager.active(), test, 'should have scope');
+        return done();
+      });
+    });
+
+    it('should run the callback (when disabled)', done => {
+      scopeManager.disable();
+      scopeManager.with(null, () => {
+        scopeManager.enable();
+        return done();
+      });
+    });
+  });
+
+  describe('.bind(function)', () => {
+    it('should return the same target (when enabled)', () => {
+      const test = { a: 1 };
+      assert.deepStrictEqual(scopeManager.bind(test), test);
+    });
+
+    it('should return the same target (when disabled)', () => {
+      scopeManager.disable();
+      const test = { a: 1 };
+      assert.deepStrictEqual(scopeManager.bind(test), test);
+      scopeManager.enable();
+    });
+
+    it('should return current scope (when enabled)', done => {
+      const scope = { a: 1 };
+      const fn = scopeManager.bind(() => {
+        assert.strictEqual(scopeManager.active(), scope, 'should have scope');
+        return done();
+      }, scope);
+      fn();
+    });
+
+    /**
+     * Even if asynchooks is disabled, the scope propagation will
+     * still works but it might be lost after any async op.
+     */
+    it('should return current scope (when disabled)', done => {
+      scopeManager.disable();
+      const scope = { a: 1 };
+      const fn = scopeManager.bind(() => {
+        assert.strictEqual(scopeManager.active(), scope, 'should have scope');
+        return done();
+      }, scope);
+      fn();
+    });
+
+    it('should fail to return current scope (when disabled + async op)', done => {
+      scopeManager.disable();
+      const scope = { a: 1 };
+      const fn = scopeManager.bind(() => {
+        setTimeout(() => {
+          assert.strictEqual(
+            scopeManager.active(),
+            null,
+            'should have no scope'
+          );
+          return done();
+        }, 100);
+      }, scope);
+      fn();
+    });
+
+    it('should return current scope (when re-enabled + async op)', done => {
+      scopeManager.enable();
+      const scope = { a: 1 };
+      const fn = scopeManager.bind(() => {
+        setTimeout(() => {
+          assert.strictEqual(scopeManager.active(), scope, 'should have scope');
+          return done();
+        }, 100);
+      }, scope);
+      fn();
+    });
+  });
+});