Add diagnostics channel to layers

Author: Qard

lib/router/layer.js

@@ -16,6 +16,18 @@
 var pathRegexp = require('path-to-regexp');
 var debug = require('debug')('express:router:layer');
 
+/**
+ * Diagnostic channels
+ * @private
+ */
+var onHandleRequest;
+var onHandleError;
+try {
+  var dc = require('diagnostics_channel');
+  onHandleRequest = dc.channel('express.layer.handle_request');
+  onHandleError = dc.channel('express.layer.handle_error');
+} catch (err) {}
+
 /**
  * Module variables.
  * @private
@@ -43,6 +55,7 @@ function Layer(path, options, fn) {
   this.params = undefined;
   this.path = undefined;
   this.regexp = pathRegexp(path, this.keys = [], opts);
+  this.routingKey = path;
 
   // set fast path flags
   this.regexp.fast_star = path === '*'
@@ -67,9 +80,23 @@ Layer.prototype.handle_error = function handle_error(error, req, res, next) {
     return next(error);
   }
 
+  req.layerStack = req.layerStack || [];
+  req.layerStack.push(this);
+
+  if (onHandleError && onHandleError.shouldPublish()) {
+    onHandleError.publish({
+      error: error,
+      request: req,
+      response: res,
+      layer: this
+    });
+  }
+
   try {
     fn(error, req, res, next);
+    req.layerStack.pop();
   } catch (err) {
+    req.layerStack.pop();
     next(err);
   }
 };
@@ -91,9 +118,22 @@ Layer.prototype.handle_request = function handle(req, res, next) {
     return next();
   }
 
+  req.layerStack = req.layerStack || [];
+  req.layerStack.push(this);
+
+  if (onHandleRequest && onHandleRequest.shouldPublish()) {
+    onHandleRequest.publish({
+      request: req,
+      response: res,
+      layer: this
+    });
+  }
+
   try {
     fn(req, res, next);
+    req.layerStack.pop();
   } catch (err) {
+    req.layerStack.pop();
     next(err);
   }
 };

test/diagnostics_channel.js

@@ -0,0 +1,104 @@
+
+var express = require('../')
+  , assert = require('assert');
+
+var dc = require('diagnostics_channel');
+var onHandleRequest = dc.channel('express.layer.handle_request');
+var onHandleError = dc.channel('express.layer.handle_error');
+
+function mapProp(prop) {
+  return function mapped(obj) {
+    return obj[prop];
+  };
+}
+
+function mapAndJoin(prop) {
+  return function(list) {
+    return list.map(mapProp(prop)).join('');
+  }
+}
+
+function noop() {}
+
+describe('diagnostics_channel', function () {
+  var joinLayerStack = mapAndJoin('routingKey');
+  var handleRequest;
+  var handleError;
+
+  onHandleRequest.subscribe(function (message) {
+    handleRequest = message;
+  });
+
+  onHandleError.subscribe(function (message) {
+    handleError = message;
+  });
+
+  it('use has no layers with a path', function (done) {
+    var router = new express.Router();
+
+    router.use(function (req, res) {
+      res.end();
+    });
+
+    function end() {
+      assert.strictEqual(joinLayerStack(handleRequest.request.layerStack), '/');
+      done();
+    }
+
+    router.handle({ url: '/', method: 'GET' }, { end }, noop);
+  });
+
+  it('regular routes have a layer with a path', function (done) {
+    var router = new express.Router();
+
+    router.get('/hello/:name', function (req, res) {
+      res.end();
+    });
+
+    function end() {
+      assert.strictEqual(joinLayerStack(handleRequest.request.layerStack), '/hello/:name/');
+      done();
+    }
+
+    router.handle({ url: '/hello/world', method: 'GET' }, { end }, noop);
+  });
+
+  it('nested routes have multiple layers with paths', function (done) {
+    var outer = new express.Router();
+    var inner = new express.Router();
+
+    inner.get('/:name', function (req, res) {
+      res.end();
+    });
+
+    outer.use('/hello', inner);
+
+    function end() {
+      assert.strictEqual(joinLayerStack(handleRequest.request.layerStack), '/hello/:name/');
+      done();
+    }
+
+    outer.handle({ url: '/hello/world', method: 'GET' }, { end }, noop);
+  });
+
+  it('errors send through a different channel', function (done) {
+    var router = new express.Router();
+    var error = new Error('fail');
+
+    router.get('/hello/:name', function (req, res) {
+      throw error;
+    });
+
+    router.use(function (err, req, res, next) {
+      res.end();
+    });
+
+    function end() {
+      assert.strictEqual(joinLayerStack(handleRequest.request.layerStack), '/hello/:name/');
+      assert.strictEqual(handleError.error, error);
+      done();
+    }
+
+    router.handle({ url: '/hello/world', method: 'GET' }, { end }, noop);
+  });
+});