chore: adding component logger (#62)

Author: obecny

src/api/diag.ts

@@ -14,8 +14,14 @@
  * limitations under the License.
  */
 
+import { DiagComponentLogger } from '../diag/ComponentLogger';
 import { createLogLevelDiagLogger } from '../diag/internal/logLevelLogger';
-import { DiagLogFunction, DiagLogger, DiagLogLevel } from '../diag/types';
+import {
+  ComponentLoggerOptions,
+  DiagLogFunction,
+  DiagLogger,
+  DiagLogLevel,
+} from '../diag/types';
 import {
   getGlobal,
   registerGlobal,
@@ -90,6 +96,10 @@ export class DiagAPI implements DiagLogger {
       unregisterGlobal(API_NAME);
     };
 
+    self.createComponentLogger = (options: ComponentLoggerOptions) => {
+      return new DiagComponentLogger(options);
+    };
+
     self.verbose = _logProxy('verbose');
     self.debug = _logProxy('debug');
     self.info = _logProxy('info');
@@ -106,6 +116,12 @@ export class DiagAPI implements DiagLogger {
    * @returns true if the logger was successfully registered, else false
    */
   public setLogger!: (logger: DiagLogger, logLevel?: DiagLogLevel) => boolean;
+  /**
+   *
+   */
+  public createComponentLogger!: (
+    options: ComponentLoggerOptions
+  ) => DiagLogger;
 
   // DiagLogger implementation
   public verbose!: DiagLogFunction;

src/diag/ComponentLogger.ts

@@ -0,0 +1,70 @@
+/*
+ * Copyright The 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
+ *
+ *      https://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 { getGlobal } from '../internal/global-utils';
+import { ComponentLoggerOptions, DiagLogger } from './types';
+
+/**
+ * Component Logger which is meant to be used as part of any component which
+ * will add automatically additional namespace in front of the log message.
+ * It will then forward all message to global diag logger
+ * @example
+ * const cLogger = diag.createComponentLogger({ namespace: '@opentelemetry/instrumentation-http' });
+ * cLogger.debug('test');
+ * // @opentelemetry/instrumentation-http test
+ */
+export class DiagComponentLogger implements DiagLogger {
+  private _namespace: string;
+
+  constructor(props: ComponentLoggerOptions) {
+    this._namespace = props.namespace || 'DiagComponentLogger';
+  }
+
+  public debug(...args: any[]): void {
+    return logProxy('debug', this._namespace, args);
+  }
+
+  public error(...args: any[]): void {
+    return logProxy('error', this._namespace, args);
+  }
+
+  public info(...args: any[]): void {
+    return logProxy('info', this._namespace, args);
+  }
+
+  public warn(...args: any[]): void {
+    return logProxy('warn', this._namespace, args);
+  }
+
+  public verbose(...args: any[]): void {
+    return logProxy('verbose', this._namespace, args);
+  }
+}
+
+function logProxy(
+  funcName: keyof DiagLogger,
+  namespace: string,
+  args: any
+): void {
+  const logger = getGlobal('diag');
+  // shortcut if logger not set
+  if (!logger) {
+    return;
+  }
+
+  args.unshift(namespace);
+  return logger[funcName].apply(logger, args);
+}

src/diag/types.ts

@@ -89,3 +89,10 @@ export enum DiagLogLevel {
   /** Used to set the logging level to include all logging */
   ALL = 9999,
 }
+
+/**
+ * Defines options for ComponentLogger
+ */
+export interface ComponentLoggerOptions {
+  namespace: string;
+}

test/diag/ComponentLogger.test.ts

@@ -0,0 +1,63 @@
+/*
+ * Copyright The 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
+ *
+ *      https://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 * as sinon from 'sinon';
+import { diag, DiagLogger, DiagLogLevel } from '../../src';
+
+class SpyLogger implements DiagLogger {
+  debug() {}
+
+  error() {}
+
+  info() {}
+
+  warn() {}
+
+  verbose() {}
+}
+
+const loggerFunctions = ['verbose', 'debug', 'info', 'warn', 'error'];
+
+describe('ComponentLogger', () => {
+  let logger: DiagLogger;
+
+  const sandbox = sinon.createSandbox();
+
+  beforeEach(() => {
+    logger = new SpyLogger();
+    sandbox.spy(logger);
+    diag.setLogger(logger, DiagLogLevel.ALL);
+  });
+
+  afterEach(() => {
+    sandbox.restore();
+  });
+
+  loggerFunctions.forEach(name => {
+    const fName = name as keyof SpyLogger;
+    it(`should call global logger function "${name}" with namespace as first param`, () => {
+      const componentLogger = diag.createComponentLogger({ namespace: 'foo' });
+      componentLogger[fName]('test');
+
+      assert.strictEqual((logger[fName] as sinon.SinonSpy).callCount, 1);
+      assert.deepStrictEqual((logger[fName] as sinon.SinonSpy).args[0], [
+        'foo',
+        'test',
+      ]);
+    });
+  });
+});