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ea6934c26d
Zulip has had a small use of WebSockets (specifically, for the code path of sending messages, via the webapp only) since ~2013. We originally added this use of WebSockets in the hope that the latency benefits of doing so would allow us to avoid implementing a markdown local echo; they were not. Further, HTTP/2 may have eliminated the latency difference we hoped to exploit by using WebSockets in any case. While we’d originally imagined using WebSockets for other endpoints, there was never a good justification for moving more components to the WebSockets system. This WebSockets code path had a lot of downsides/complexity, including: * The messy hack involving constructing an emulated request object to hook into doing Django requests. * The `message_senders` queue processor system, which increases RAM needs and must be provisioned independently from the rest of the server). * A duplicate check_send_receive_time Nagios test specific to WebSockets. * The requirement for users to have their firewalls/NATs allow WebSocket connections, and a setting to disable them for networks where WebSockets don’t work. * Dependencies on the SockJS family of libraries, which has at times been poorly maintained, and periodically throws random JavaScript exceptions in our production environments without a deep enough traceback to effectively investigate. * A total of about 1600 lines of our code related to the feature. * Increased load on the Tornado system, especially around a Zulip server restart, and especially for large installations like zulipchat.com, resulting in extra delay before messages can be sent again. As detailed in https://github.com/zulip/zulip/pull/12862#issuecomment-536152397, it appears that removing WebSockets moderately increases the time it takes for the `send_message` API query to return from the server, but does not significantly change the time between when a message is sent and when it is received by clients. We don’t understand the reason for that change (suggesting the possibility of a measurement error), and even if it is a real change, we consider that potential small latency regression to be acceptable. If we later want WebSockets, we’ll likely want to just use Django Channels. Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
55 lines
2.0 KiB
JavaScript
55 lines
2.0 KiB
JavaScript
// Miscellaneous early setup.
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$(function () {
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if (util.is_mobile()) {
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// Disable the tutorial; it's ugly on mobile.
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page_params.needs_tutorial = false;
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}
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page_params.page_load_time = new Date().getTime();
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// Display loading indicator. This disappears after the first
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// get_events completes.
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if (page_params.have_initial_messages && !page_params.needs_tutorial) {
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loading.make_indicator($('#page_loading_indicator'), {text: 'Loading...', abs_positioned: true});
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} else if (!page_params.needs_tutorial) {
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$('#first_run_message').show();
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}
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// This is an issue fix where in jQuery v3 the result of outerHeight on a node
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// that doesn’t exist is now “undefined” rather than “null”, which means it
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// will no longer cast to a Number but rather NaN. For this, we create the
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// `safeOuterHeight` and `safeOuterWidth` functions to safely return a result
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// (or 0).
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$.fn.safeOuterHeight = function () {
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return $(this).outerHeight.apply(this, arguments) || 0;
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};
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$.fn.safeOuterWidth = function () {
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return $(this).outerWidth.apply(this, arguments) || 0;
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};
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// For some reason, jQuery wants this to be attached to an element.
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$(document).ajaxError(function (event, xhr) {
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if (xhr.status === 401) {
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// We got logged out somehow, perhaps from another window or a session timeout.
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// We could display an error message, but jumping right to the login page seems
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// smoother and conveys the same information.
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window.location.replace(page_params.login_page);
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}
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});
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if (typeof $ !== 'undefined') {
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$.fn.expectOne = function () {
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if (blueslip && this.length !== 1) {
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blueslip.error("Expected one element in jQuery set, " + this.length + " found");
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}
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return this;
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};
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$.fn.within = function (sel) {
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return $(this).is(sel) || $(this).closest(sel).length;
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};
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}
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});
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