Byebye domains

lib/helpers/child-process.js

@@ -0,0 +1,19 @@
+"use strict";
+var async = require("async");
+
+process.on('message', function(task) {
+  var hydrate = require(task.functionPath);
+  async.waterfall([
+    function startHydration(cb) {
+      cb.urlCallback = task.options.urlCallback;
+      cb.apiUrl = task.options.apiUrl;
+      hydrate(task.path, task.document, task.changes, cb);
+    }
+  ],
+  function(err, changes) {
+    process.send({
+      err: err,
+      changes: changes
+    });
+  });
+});

lib/helpers/hydrater.js

@@ -8,7 +8,7 @@
  */
 
 var async = require('async');
-var nodeDomain = require('domain');
+var shellFork = require('child_process').fork;
 var request = require('supertest');
 var crypto = require('crypto');
 var restify = require('restify');
@@ -44,38 +44,35 @@ module.exports = function(hydraterFunction, logger, errLogger) {
       /**
        * Download the file from task.file_path, store it in a temporary file if there is file_path
        */
-      function initHydration(cb) {
+      function downloadFile(cb) {
         if(task.file_path) {
-          // Download the file
-          var stream = fs.createWriteStream(path);
-
-          // Store error if statusCode !== 200
-          var err;
-          stream.on("finish", function() {
-            cb(err);
-          });
-
           var apiUrl = url.parse(task.file_path, false, true);
-          var req = request(apiUrl.protocol + "//" + apiUrl.host)
-            .get(apiUrl.path);
-
-          req.end().req.once('response', function(res) {
-            if(res.statusCode !== 200) {
-              err = new restify.BadGatewayError('Error when downloading file ' + task.file_path + ': ' + res.statusCode);
-              stream.end();
-              this.abort();
-            }
-          });
-
-          req.pipe(stream);
+          request(apiUrl.protocol + "//" + apiUrl.host)
+            .get(apiUrl.path)
+            .expect(200)
+            .end(function(err, res) {
+              if(err) {
+                err = new restify.BadGatewayError('Error when downloading file ' + task.file_path + ': ' + err);
+              }
+              cb(err, res && res.text);
+            });
         }
         else {
           cb(null);
         }
       },
+      function saveFile(res, cb) {
+        if(res) {
+          fs.writeFile(path, res, cb);
+        }
+        else {
+          cb();
+        }
+      },
       function performHydration(cb) {
-        var domain = nodeDomain.create();
-
+        var child = shellFork(__dirname + '/child-process.js', {silent: true});
+        var stderr = "";
+        var stdout = "";
         var timeout;
         /**
          * Function to call, either on domain error, on hydration error or successful hydration.
@@ -84,53 +81,73 @@ module.exports = function(hydraterFunction, logger, errLogger) {
         var cleaner = function(err, changes) {
           if(!cleaner.called) {
             cleaner.called = true;
-            domain.exit();
-            domain.dispose();
             cb(err, changes);
           }
+          clearTimeout(timeout);
         };
         cleaner.called = false;
 
-        domain.on('error', cleaner);
-
-        // Run in a domain to prevent memory leak on crash
-        domain.run(function() {
-          async.waterfall([
-            function callHydrationFunction(cb) {
-              // Give user access to the final URL callback and the API url (which can be staging, prod or anything)
-              // In case he wants to bypass us and send the changes himself
-              cb.urlCallback = task.callback;
-              cb.apiUrl = '';
-              if(task.callback) {
-                var parsed = url.parse(task.callback);
-                cb.apiUrl = parsed.protocol + "//" + parsed.host;
-              }
+        child.on('error', function(exitCode) {
+          cleaner(new HydrationError("Wild error appeared while spawning child. Exit code:" + exitCode));
+        });
 
-              // Call the real function for hydration.
-              hydraterFunction((task.file_path) ? path : null, task.document, lib.defaultChanges(), cb);
-            }
-          ], function cleanHydration(err, changes) {
-            // If the function replied with an "HydrationError", we'll wrap this in a nicely formatted document
-            // and stop the error from bubbling up.
-            if(err instanceof HydrationError) {
-              changes = {};
-              changes.hydration_errored = true;
-              changes.hydration_error = err.message;
-              err = null;
-            }
+        child.stderr.on('readable', function() {
+          var chunk;
+          while (null !== (chunk = child.stderr.read())) {
+            stderr += chunk;
+          }
+        });
+
+        child.stdout.on('readable', function() {
+          var chunk;
+          while (null !== (chunk = child.stdout.read())) {
+            stdout += chunk;
+          }
+        });
+
+        child.on('exit', function(errCode) {
+          if(errCode !== 0) {
+            cleaner(new HydrationError("Child exiting with err code: " + errCode + stdout + stderr));
+          }
+        });
+
+        // Build objects to send to child
+        var options = {};
+        options.urlCallback = task.callback;
+        options.apiUrl = '';
+        if(task.callback) {
+          var parsed = url.parse(task.callback);
+          options.apiUrl = parsed.protocol + "//" + parsed.host;
+        }
+
+        child.send({
+          functionPath: hydraterFunction,
+          path: (task.file_path) ? path : null,
+          document: task.document,
+          changes: lib.defaultChanges(),
+          options: options,
+        });
+
+        child.on('message', function(res) {
+          var err = res.err
+          // If the function replied with an "HydrationError", we'll wrap this in a nicely formatted document
+          // and stop the error from bubbling up.
+          if(err && err._hydrationError) {
+            res.changes = {};
+            res.changes.hydration_errored = true;
+            res.changes.hydration_error = res.err.message;
+            err = null;
+          }
+          cleaner(err, res.changes);
 
-            // Wait for nexttick, to end this function and be able to properly GC it on domain.dispose().
-            process.nextTick(function() {
-              cleaner(err, changes);
-            });
-          });
         });
 
         timeout = setTimeout(function() {
           if(!cleaner.called) {
             var changes = {};
             changes.hydration_errored = true;
             changes.hydration_error = "Task took too long.";
+            child.kill('SIGKILL');
             cleaner(null, changes);
           }
         }, process.env.TIMEOUT || 60 * 1000);
@@ -183,6 +200,7 @@ module.exports = function(hydraterFunction, logger, errLogger) {
         }
 
         var apiUrl = url.parse(task.callback, false, true);
+
         request(apiUrl.protocol + "//" + apiUrl.host)
           .patch(apiUrl.path)
           .send(changes)

lib/index.js

@@ -62,5 +62,6 @@ module.exports.defaultChanges = function() {
 module.exports.HydrationError = function(message) {
   this.name = 'HydrationError';
   this.message = (message || "").toString();
+  this._hydrationError = true;
 };
 util.inherits(module.exports.HydrationError, Error);