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Code Issues Releases Wiki Activity

SSE client: better state management to avoid multiple connections

This commit is contained in:
Jeremy Ruston 2024-03-25 16:43:41 +00:00
parent 7a0c43436f
commit b58cfe6324
1 changed files with 70 additions and 18 deletions
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88
plugins/tiddlywiki/multiwikiclient/multiwikiclientadaptor.js
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@ -17,6 +17,11 @@ var CONFIG_HOST_TIDDLER = "$:/config/multiwikiclient/host",
BAG_STATE_TIDDLER = "$:/state/multiwikiclient/tiddlers/bag",
REVISION_STATE_TIDDLER = "$:/state/multiwikiclient/tiddlers/revision";
var SERVER_NOT_CONNECTED = 0,
SERVER_CONNECTING_SSE = 1,
SERVER_CONNECTED_SSE = 2,
SERVER_POLLING = 3;
function MultiWikiClientAdaptor(options) {
this.wiki = options.wiki;
this.host = this.getHost();
@ -26,6 +31,7 @@ function MultiWikiClientAdaptor(options) {
this.isLoggedIn = false;
this.isReadOnly = false;
this.logoutIsAvailable = true;
this.serverUpdatesConnection = SERVER_NOT_CONNECTED;
}
MultiWikiClientAdaptor.prototype.name = "multiwikiclient";
@ -107,39 +113,85 @@ MultiWikiClientAdaptor.prototype.getStatus = function(callback) {
Get details of changed tiddlers from the server
*/
MultiWikiClientAdaptor.prototype.getUpdatedTiddlers = function(syncer,callback) {
var self = this;
// Do nothing if there's already a connection in progress.
if(this.serverUpdatesConnection !== SERVER_NOT_CONNECTED) {
return callback(null,{
modifications: [],
deletions: []
});
}
// Try to connect a server stream
this.serverUpdatesConnection = SERVER_CONNECTING_SSE;
this.connectServerStream({
syncer: syncer,
onerror: function(err) {
self.logger.log("Error connecting SSE stream",err);
// If the stream didn't work, try polling
self.serverUpdatesConnection = SERVER_POLLING;
self.pollServer({
callback: function(err,changes) {
self.serverUpdatesConnection = SERVER_NOT_CONNECTED;
callback(null,changes);
}
});
},
onopen: function() {
self.serverUpdatesConnection = SERVER_CONNECTED_SSE;
// The syncer is expecting a callback but we don't have any data to send
callback(null,{
modifications: [],
deletions: []
});
}
});
};
/*
Attempt to establish an SSE stream with the server and transfer tiddler changes. Options include:
syncer: reference to syncer object used for storing data
onopen: invoked when the stream is successfully opened
onerror: invoked if there is an error
*/
MultiWikiClientAdaptor.prototype.connectServerStream = function(options) {
var self = this;
const eventSource = new EventSource("/recipes/" + this.recipe + "/events?last_known_tiddler_id=" + this.last_known_tiddler_id);
eventSource.onerror = function(event) {
console.log("SSE connection error",event);
if(options.onerror) {
options.onerror(event);
}
}
eventSource.onopen = function(event) {
console.log("SSE connection opened",event);
if(options.onopen) {
options.onopen(event);
}
}
eventSource.onmessage = function(event) {
console.log("SSE Event",event);
};
eventSource.addEventListener("change", function(event) {
const data = $tw.utils.parseJSONSafe(event.data);
if(data) {
console.log("SSE data",data)
if(data.is_deleted) {
self.removeTiddlerInfo(data.title);
delete syncer.tiddlerInfo[data.title];
syncer.logger.log("Deleting tiddler missing from server:",data.title);
syncer.wiki.deleteTiddler(data.title);
syncer.processTaskQueue();
delete options.syncer.tiddlerInfo[data.title];
options.syncer.logger.log("Deleting tiddler missing from server:",data.title);
options.syncer.wiki.deleteTiddler(data.title);
options.syncer.processTaskQueue();
} else {
syncer.titlesToBeLoaded[data.title] = true;
syncer.processTaskQueue();
options.syncer.titlesToBeLoaded[data.title] = true;
options.syncer.processTaskQueue();
}
}
});
};
return callback(null,{
modifications: [],
deletions: []
});
/*
Poll the server for changes. Options include:
callback: invoked on completion as (err,changes)
*/
MultiWikiClientAdaptor.prototype.pollServer = function(options) {
var self = this;
$tw.utils.httpRequest({
url: this.host + "recipes/" + this.recipe + "/tiddlers.json",
data: {
@ -149,7 +201,7 @@ MultiWikiClientAdaptor.prototype.getUpdatedTiddlers = function(syncer,callback)
callback: function(err,data) {
// Check for errors
if(err) {
return callback(err);
return options.callback(err);
}
var modifications = [],
deletions = [];
@ -165,7 +217,7 @@ MultiWikiClientAdaptor.prototype.getUpdatedTiddlers = function(syncer,callback)
}
});
// Invoke the callback with the results
callback(null,{
options.callback(null,{
modifications: modifications,
deletions: deletions
});