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Add some explanatory comments to handleUserChanges()

pull/1027/head
Richard Braakman 2012-09-28 22:49:20 +03:00
parent 3578e36616
commit 413ddb393e
1 changed files with 29 additions and 12 deletions
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41
src/node/handler/PadMessageHandler.js
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@ -436,15 +436,22 @@ function handleUserInfoUpdate(client, message)
}
/**
* Handles a USERINFO_UPDATE, that means that a user have changed his color or name. Anyway, we get both informations
* This Method is nearly 90% copied out of the Etherpad Source Code. So I can't tell you what happens here exactly
* Look at https://github.com/ether/pad/blob/master/etherpad/src/etherpad/collab/collab_server.js in the function applyUserChanges()
* Handles a USER_CHANGES message, where the client submits its local
* edits as a changeset.
*
* This handler's job is to update the incoming changeset so that it applies
* to the latest revision, then add it to the pad, broadcast the changes
* to all other clients, and send a confirmation to the submitting client.
*
* This function is based on a similar one in the original Etherpad.
* See https://github.com/ether/pad/blob/master/etherpad/src/etherpad/collab/collab_server.js in the function applyUserChanges()
*
* @param client the client that send this message
* @param message the message from the client
*/
function handleUserChanges(client, message)
{
//check if all ok
// Make sure all required fields are present
if(message.data.baseRev == null)
{
messageLogger.warn("Dropped message, USER_CHANGES Message has no baseRev!");
@ -487,22 +494,23 @@ function handleUserChanges(client, message)
{
//ex. _checkChangesetAndPool
//Copied from Etherpad, don't know what it does exactly
try
{
//this looks like a changeset check, it throws errors sometimes
// Verify that the changeset has valid syntax and is in canonical form
Changeset.checkRep(changeset);
// Verify that the attribute indexes used in the changeset are all
// defined in the accompanying attribute pool.
Changeset.eachAttribNumber(changeset, function(n) {
if (! wireApool.getAttrib(n)) {
throw "Attribute pool is missing attribute "+n+" for changeset "+changeset;
}
});
}
//there is an error in this changeset, so just refuse it
catch(e)
{
console.warn("Can't apply USER_CHANGES "+changeset+", cause it faild checkRep");
// There is an error in this changeset, so just refuse it
console.warn("Can't apply USER_CHANGES "+changeset+", because it failed checkRep");
client.json.send({disconnect:"badChangeset"});
return;
}
@ -515,7 +523,10 @@ function handleUserChanges(client, message)
//ex. applyUserChanges
apool = pad.pool;
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
async.whilst(
function() { return r < pad.getHeadRevisionNumber(); },
@ -526,8 +537,13 @@ function handleUserChanges(client, message)
pad.getRevisionChangeset(r, function(err, c)
{
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".
changeset = Changeset.follow(c, changeset, false, apool);
if ((r - baseRev) % 200 == 0) { // don't let the stack get too deep
async.nextTick(callback);
} else {
@ -558,7 +574,8 @@ function handleUserChanges(client, message)
if (correctionChangeset) {
pad.appendRevision(correctionChangeset);
}
// Make sure the pad always ends with an empty line.
if (pad.text().lastIndexOf("\n\n") != pad.text().length-2) {
var nlChangeset = Changeset.makeSplice(pad.text(), pad.text().length-1, 0, "\n");
pad.appendRevision(nlChangeset);