PadMessageHandler.js: convert handleUserChanges() to Promises

- the call site still expects a nodeback function, so also introduced the
  `nodeify` module to allow that function to work as expected.

src/node/handler/PadMessageHandler.js

@@ -39,6 +39,7 @@ var channels = require("channels");
 var stats = require('../stats');
 var remoteAddress = require("../utils/RemoteAddress").remoteAddress;
 const thenify = require("thenify").withCallback;
+const nodeify = require("nodeify");
 
 /**
  * A associative array that saves informations about a session
@@ -61,7 +62,11 @@ stats.gauge('totalUsers', function() {
 /**
  * A changeset queue per pad that is processed by handleUserChanges()
  */
-var padChannels = new channels.channels(thenify(handleUserChanges));
+var padChannels = new channels.channels(handleUserChangesCB);
+
+function handleUserChangesCB(data, callback) {
+  return nodeify(handleUserChanges(data), callback);
+}
 
 /**
  * Saves the Socket class we need to send and receive data from the client
@@ -591,7 +596,7 @@ function handleUserInfoUpdate(client, message)
  * @param client the client that send this message
  * @param message the message from the client
  */
-function handleUserChanges(data, cb)
+async function handleUserChanges(data)
 {
   var client = data.client
     , message = data.message
@@ -602,17 +607,17 @@ function handleUserChanges(data, cb)
   // Make sure all required fields are present
   if (message.data.baseRev == null) {
     messageLogger.warn("Dropped message, USER_CHANGES Message has no baseRev!");
-    return cb();
+    return;
   }
 
   if (message.data.apool == null) {
     messageLogger.warn("Dropped message, USER_CHANGES Message has no apool!");
-    return cb();
+    return;
   }
 
   if (message.data.changeset == null) {
     messageLogger.warn("Dropped message, USER_CHANGES Message has no changeset!");
-    return cb();
+    return;
   }
 
   // TODO: this might happen with other messages too => find one place to copy the session
@@ -620,7 +625,7 @@ function handleUserChanges(data, cb)
   // if the session was valid when the message arrived in the first place
   if (!sessioninfos[client.id]) {
     messageLogger.warn("Dropped message, disconnect happened in the mean time");
-    return cb();
+    return;
   }
 
   // get all Vars we need
@@ -632,26 +637,14 @@ function handleUserChanges(data, cb)
   // finish processing the changeset, so keep a reference to the session.
   var thisSession = sessioninfos[client.id];
 
-  var r, apool, pad;
-
   // Measure time to process edit
   var stopWatch = stats.timer('edits').start();
 
-  async.series([
   // get the pad
-    function(callback) {
+  let pad = await padManager.getPad(thisSession.padId);
-      padManager.getPad(thisSession.padId, function(err, value) {
-        if (ERR(err, callback)) return;
-
-        pad = value;
-        callback();
-      });
-    },
 
   // create the changeset
-    function(callback) {
+  try {
-      // ex. _checkChangesetAndPool
-
     try {
       // Verify that the changeset has valid syntax and is in canonical form
       Changeset.checkRep(changeset);
@@ -666,7 +659,8 @@ function handleUserChanges(data, cb)
 
       // Validate all added 'author' attribs to be the same value as the current user
       var iterator = Changeset.opIterator(Changeset.unpack(changeset).ops)
-          , op
+        , op;
+
       while (iterator.hasNext()) {
         op = iterator.next()
 
@@ -677,7 +671,7 @@ function handleUserChanges(data, cb)
         op.attribs.split('*').forEach(function(attr) {
           if (!attr) return;
 
-            attr = wireApool.getAttrib(attr)
+          attr = wireApool.getAttrib(attr);
           if (!attr) return;
 
           // the empty author is used in the clearAuthorship functionality so this should be the only exception
@@ -691,34 +685,31 @@ function handleUserChanges(data, cb)
 
       // Afaik, it copies the new attributes from the changeset, to the global Attribute Pool
       changeset = Changeset.moveOpsToNewPool(changeset, wireApool, pad.pool);
+
     } catch(e) {
       // There is an error in this changeset, so just refuse it
       client.json.send({ disconnect: "badChangeset" });
       stats.meter('failedChangesets').mark();
-        return callback(new Error("Can't apply USER_CHANGES, because "+e.message));
+      throw new Error("Can't apply USER_CHANGES, because " + e.message);
     }
 
     // ex. applyUserChanges
-      apool = pad.pool;
+    let apool = pad.pool;
-      r = baseRev;
+    let r = baseRev;
 
     // The client's changeset might not be based on the latest revision,
     // since other clients are sending changes at the same time.
     // Update the changeset so that it can be applied to the latest revision.
-      // https://github.com/caolan/async#whilst
+    while (r < pad.getHeadRevisionNumber()) {
-      async.whilst(
-        function() { return r < pad.getHeadRevisionNumber(); },
-        function(callback)
-        {
       r++;
 
-          pad.getRevisionChangeset(r, function(err, c) {
+      let c = await pad.getRevisionChangeset(r);
-            if (ERR(err, callback)) return;
 
       // At this point, both "c" (from the pad) and "changeset" (from the
       // client) are relative to revision r - 1. The follow function
       // rebases "changeset" so that it is relative to revision r
       // and can be applied after "c".
+
       try {
         // a changeset can be based on an old revision with the same changes in it
         // prevent eplite from accepting it TODO: better send the client a NEW_CHANGES
@@ -726,41 +717,23 @@ function handleUserChanges(data, cb)
         if (baseRev + 1 == r && c == changeset) {
           client.json.send({disconnect:"badChangeset"});
           stats.meter('failedChangesets').mark();
-
+          throw new Error("Won't apply USER_CHANGES, because it contains an already accepted changeset");
-                return callback(new Error("Won't apply USER_CHANGES, because it contains an already accepted changeset"));
         }
 
         changeset = Changeset.follow(c, changeset, false, apool);
       } catch(e) {
         client.json.send({disconnect:"badChangeset"});
         stats.meter('failedChangesets').mark();
-
+        throw new Error("Can't apply USER_CHANGES, because " + e.message);
-              return callback(new Error("Can't apply USER_CHANGES, because "+e.message));
+      }
     }
 
-            if ((r - baseRev) % 200 == 0) {
+    let prevText = pad.text();
-              // don't let the stack get too deep
-              async.nextTick(callback);
-            } else {
-              callback(null);
-            }
-          });
-        },
-
-        // use the callback of the series function
-        callback
-      );
-    },
-
-    // do correction changesets, and send it to all users
-    function(callback) {
-      var prevText = pad.text();
 
     if (Changeset.oldLen(changeset) != prevText.length) {
       client.json.send({disconnect:"badChangeset"});
       stats.meter('failedChangesets').mark();
-
+      throw new Error("Can't apply USER_CHANGES "+changeset+" with oldLen " + Changeset.oldLen(changeset) + " to document of length " + prevText.length);
-        return callback(new Error("Can't apply USER_CHANGES "+changeset+" with oldLen " + Changeset.oldLen(changeset) + " to document of length " + prevText.length));
     }
 
     try {
@@ -768,36 +741,26 @@ function handleUserChanges(data, cb)
     } catch(e) {
       client.json.send({ disconnect: "badChangeset" });
       stats.meter('failedChangesets').mark();
-
+      throw e;
-        return callback(e)
     }
 
-      var correctionChangeset = _correctMarkersInPad(pad.atext, pad.pool);
+    let correctionChangeset = _correctMarkersInPad(pad.atext, pad.pool);
     if (correctionChangeset) {
       pad.appendRevision(correctionChangeset);
     }
 
     // Make sure the pad always ends with an empty line.
     if (pad.text().lastIndexOf("\n") != pad.text().length-1) {
-        var nlChangeset = Changeset.makeSplice(pad.text(), pad.text().length-1,
+      var nlChangeset = Changeset.makeSplice(pad.text(), pad.text().length - 1, 0, "\n");
-                                               0, "\n");
       pad.appendRevision(nlChangeset);
     }
 
-      exports.updatePadClients(pad, function(er) {
+    await exports.updatePadClients(pad);
-        ERR(er)
+  } catch (err) {
-      });
-      callback();
-    }
-  ],
-  function(err) {
-    stopWatch.end()
-    cb();
-
-    if(err) {
     console.warn(err.stack || err);
   }
-  });
+
+  stopWatch.end();
 }
 
 exports.updatePadClients = thenify(function(pad, callback)

src/package.json

@@ -48,6 +48,7 @@
     "languages4translatewiki": "0.1.3",
     "log4js": "0.6.35",
     "measured-core": "1.11.2",
+    "nodeify": "^1.0.1",
     "npm": "6.4.1",
     "object.values": "^1.0.4",
     "request": "2.88.0",
@@ -87,4 +88,3 @@
   "version": "1.7.5",
   "license": "Apache-2.0"
 }
-