gecko-dev/toolkit/components/social/MessagePortBase.jsm

107 lines
3.4 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// Code that is shared between clients and workers.
const EXPORTED_SYMBOLS = ["AbstractPort"];
function AbstractPort(portid) {
this._portid = portid;
this._handler = undefined;
// pending messages sent to this port before it has a message handler.
this._pendingMessagesIncoming = [];
}
AbstractPort.prototype = {
_portType: null, // set by a subclass.
// abstract methods to be overridden.
_dopost: function fw_AbstractPort_dopost(data) {
throw new Error("not implemented");
},
_onerror: function fw_AbstractPort_onerror(err) {
throw new Error("not implemented");
},
// and concrete methods shared by client and workers.
toString: function fw_AbstractPort_toString() {
return "MessagePort(portType='" + this._portType + "', portId=" + this._portid + ")";
},
_JSONParse: function fw_AbstractPort_JSONParse(data) JSON.parse(data),
_postControlMessage: function fw_AbstractPort_postControlMessage(topic, data) {
let postData = {
portTopic: topic,
portId: this._portid,
portFromType: this._portType,
data: data
};
this._dopost(postData);
},
_onmessage: function fw_AbstractPort_onmessage(data) {
// See comments in postMessage below - we work around a cloning
// issue by using JSON for these messages.
// Further, we allow the workers to override exactly how the JSON parsing
// is done - we try and do such parsing in the client window so things
// like prototype overrides on Array work as expected.
data = this._JSONParse(data);
if (!this._handler) {
this._pendingMessagesIncoming.push(data);
} else {
try {
this._handler({
data: data,
__exposedProps__: {
data: 'r'
}
});
} catch (ex) {
this._onerror(ex);
}
}
},
set onmessage(handler) { // property setter for onmessage
this._handler = handler;
while (this._pendingMessagesIncoming.length) {
this._onmessage(this._pendingMessagesIncoming.shift());
}
},
get onmessage() {
return this._handler;
},
/**
* postMessage
*
* Send data to the onmessage handler on the other end of the port. The
* data object should have a topic property.
*
* @param {jsobj} data
*/
postMessage: function fw_AbstractPort_postMessage(data) {
if (this._portid === null) {
throw new Error("port is closed");
}
// There seems to be an issue with passing objects directly and letting
// the structured clone thing work - we sometimes get:
// [Exception... "The object could not be cloned." code: "25" nsresult: "0x80530019 (DataCloneError)"]
// The best guess is that this happens when funky things have been added to the prototypes.
// It doesn't happen for our "control" messages, only in messages from
// content - so we explicitly use JSON on these messages as that avoids
// the problem.
this._postControlMessage("port-message", JSON.stringify(data));
},
close: function fw_AbstractPort_close() {
if (!this._portid) {
return; // already closed.
}
this._postControlMessage("port-close");
// and clean myself up.
this._handler = null;
this._pendingMessagesIncoming = [];
this._portid = null;
}
}