refactor: ts conversion of tracing-policy

src/trace-api.ts

@@ -15,6 +15,9 @@
  */
 
 'use strict';
+
+import * as TracingPolicy from './tracing-policy';
+
 var cls = require('./cls'/*.js*/);
 var constants = require('./constants'/*.js*/);
 var is = require('is');
@@ -23,7 +26,6 @@ var util = require('./util'/*.js*/);
 var Trace = require('./trace'/*.js*/);
 var SpanData = require('./span-data'/*.js*/);
 var uuid = require('uuid');
-var TracingPolicy = require('./tracing-policy'/*.js*/);
 var semver = require('semver');
 
 var ROOT_SPAN_STACK_OFFSET = semver.satisfies(process.version, '>=8') ? 0 : 2;

src/tracing-policy.ts

@@ -14,65 +14,80 @@
  * limitations under the License.
  */
 
-'use strict';
-
-function RateLimiterPolicy(samplesPerSecond) {
-  if (samplesPerSecond > 1000) {
-    samplesPerSecond = 1000;
-  }
-  this.traceWindow = 1000 / samplesPerSecond;
-  this.nextTraceStart = Date.now();
+/**
+ * An object that determines whether a request should be traced.
+ */
+export interface Policy {
+  shouldTrace(dateMillis: number, url: string): boolean;
 }
 
-RateLimiterPolicy.prototype.shouldTrace = function(dateMillis) {
-  if (dateMillis < this.nextTraceStart) {
-    return false;
+export class RateLimiterPolicy implements Policy {
+  private traceWindow: number;
+  private nextTraceStart: number;
+
+  constructor(samplesPerSecond: number) {
+    if (samplesPerSecond > 1000) {
+      samplesPerSecond = 1000;
+    }
+    this.traceWindow = 1000 / samplesPerSecond;
+    this.nextTraceStart = Date.now();
   }
-  this.nextTraceStart = dateMillis + this.traceWindow;
-  return true;
-};
 
-function FilterPolicy(basePolicy, filterUrls) {
-  this.basePolicy = basePolicy;
-  this.filterUrls = filterUrls;
+  shouldTrace(dateMillis: number): boolean {
+    if (dateMillis < this.nextTraceStart) {
+      return false;
+    }
+    this.nextTraceStart = dateMillis + this.traceWindow;
+    return true;
+  }
 }
 
-FilterPolicy.prototype.matches = function(url) {
-  return this.filterUrls.some(function(candidate) {
-    return (typeof candidate === 'string' && candidate === url) ||
-      url.match(candidate);
-  });
-};
+export class FilterPolicy implements Policy {
+  constructor(
+    private basePolicy: Policy,
+    private filterUrls: (string | RegExp)[]
+  ) {}
 
-FilterPolicy.prototype.shouldTrace = function(dataMillis, url) {
-  return !this.matches(url) && this.basePolicy.shouldTrace(dataMillis, url);
-};
+  private matches(url: string) {
+    return this.filterUrls.some((candidate) => {
+      return (typeof candidate === 'string' && candidate === url) ||
+        !!url.match(candidate);
+    });
+  }
 
-function TraceAllPolicy() {}
+  shouldTrace(dateMillis: number, url: string) {
+    return !this.matches(url) && this.basePolicy.shouldTrace(dateMillis, url);
+  }
+}
 
-TraceAllPolicy.prototype.shouldTrace = function() { return true; };
+export class TraceAllPolicy implements Policy {
+  shouldTrace() {
+    return true;
+  }
+}
 
-function TraceNonePolicy() {}
+export class TraceNonePolicy implements Policy {
+  shouldTrace() {
+    return false;
+  }
+}
 
-TraceNonePolicy.prototype.shouldTrace = function() { return false; };
+export interface TracePolicyOptions {
+  samplingRate: number;
+  ignoreUrls?: (string | RegExp)[];
+}
 
-module.exports = {
-  TraceAllPolicy: TraceAllPolicy,
-  TraceNonePolicy: TraceNonePolicy,
-  FilterPolicy: FilterPolicy,
-  createTracePolicy: function(config) {
-    var basePolicy;
-    if (config.samplingRate < 1) {
-      basePolicy = new TraceAllPolicy();
-    } else {
-      basePolicy = new RateLimiterPolicy(config.samplingRate);
-    }
-    if (config.ignoreUrls && config.ignoreUrls.length > 0) {
-      return new FilterPolicy(basePolicy, config.ignoreUrls);
-    } else {
-      return basePolicy;
-    }
+// TODO(kjin): This could be a class as well.
+export function createTracePolicy(config: TracePolicyOptions): Policy {
+  let basePolicy;
+  if (config.samplingRate < 1) {
+    basePolicy = new TraceAllPolicy();
+  } else {
+    basePolicy = new RateLimiterPolicy(config.samplingRate);
   }
-};
-
-export default {};
+  if (config.ignoreUrls && config.ignoreUrls.length > 0) {
+    return new FilterPolicy(basePolicy, config.ignoreUrls);
+  } else {
+    return basePolicy;
+  }
+}

test/plugins/common.ts

@@ -24,6 +24,8 @@ declare global {
   }
 }
 
+import * as TracingPolicy from '../../src/tracing-policy';
+
 var proxyquire  = require('proxyquire');
 // Monkeypatch gcp-metadata to not ask for retries at all.
 proxyquire('gcp-metadata', {
@@ -42,7 +44,7 @@ if (semver.satisfies(process.version, '>=8') && process.env.GCLOUD_TRACE_NEW_CON
     return oldIt.call(this, title, cls.createNamespace().bind(fn));
   }, oldIt);
 }
-var tracePolicy = require('../../src/tracing-policy'/*.js*/);
+
 var TraceWriter = require('../../src/trace-writer'/*.js*/);
 
 var assert = require('assert');
@@ -62,7 +64,7 @@ shimmer.wrap(trace, 'start', function(original) {
       enhancedDatabaseReporting: false,
       ignoreTraceContext: false
     });
-    testTraceAgent.policy_ = new tracePolicy.TraceAllPolicy();
+    testTraceAgent.policy_ = new TracingPolicy.TraceAllPolicy();
     return result;
   };
 });

test/plugins/test-trace-grpc.ts

@@ -15,13 +15,14 @@
  */
 'use strict';
 
+import * as TracingPolicy from '../../src/tracing-policy';
+
 var assert = require('assert');
 var cls = require('../../src/cls'/*.js*/);
 var util = require('../../src/util'/*.js*/);
 var constants = require('../../src/constants'/*.js*/);
 var shimmer = require('shimmer');
 var traceLabels = require('../../src/trace-labels'/*.js*/);
-var TracingPolicy = require('../../src/tracing-policy'/*.js*/);
 var common = require('./common'/*.js*/);
 
 var versions = {

test/test-trace-api.ts

@@ -16,13 +16,14 @@
 
 'use strict';
 
+import * as TracingPolicy from '../src/tracing-policy';
+
 var assert = require('assert');
 var cls = require('../src/cls'/*.js*/);
 var common = require('./plugins/common'/*.js*/);
 var EventEmitter = require('events');
 var request = require('request');
 var TraceAgent = require('../src/trace-api'/*.js*/);
-var TracingPolicy = require('../src/tracing-policy'/*.js*/);
 var TraceWriter = require('../src/trace-writer'/*.js*/);
 
 var logger = require('@google-cloud/common').logger();

test/test-trace-policy.ts

@@ -16,33 +16,34 @@
 
 'use strict';
 
+import * as TracingPolicy from '../src/tracing-policy';
+
 var assert = require('assert');
-var tracingPolicy = require('../src/tracing-policy'/*.js*/);
 
 describe('FilterPolicy', function() {
   it('should not allow filtered urls', function() {
-    var policy = tracingPolicy.createTracePolicy({
+    var policy = TracingPolicy.createTracePolicy({
       samplingRate: 0,
       ignoreUrls: ['/_ah/health', /\/book*/]
     });
-    assert(!policy.shouldTrace(null, '/_ah/health'));
-    assert(!policy.shouldTrace(null, '/book/test'));
+    assert(!policy.shouldTrace(0, '/_ah/health'));
+    assert(!policy.shouldTrace(0, '/book/test'));
   });
 
   it('should allow non-filtered urls', function() {
-    var policy = tracingPolicy.createTracePolicy({
+    var policy = TracingPolicy.createTracePolicy({
       samplingRate: 0,
       ignoreUrls: ['/_ah/health']
     });
-    assert(policy.shouldTrace(null, '/_ah/background'));
+    assert(policy.shouldTrace(0, '/_ah/background'));
   });
 });
 
 describe('RateLimiterPolicy', function() {
   var tracesPerSecond = [10, 50, 150, 200, 500, 1000];
   tracesPerSecond.forEach(function(traceCount) {
     it('should throttle traces, ' + traceCount, function() {
-      var policy = tracingPolicy.createTracePolicy({samplingRate: traceCount});
+      var policy = TracingPolicy.createTracePolicy({samplingRate: traceCount});
       testAllowedTraces(policy, traceCount);
     });
   });