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https://github.com/bulwarkmail/native.git
synced 2026-11-02 16:07:12 +00:00
Linus Rath
9fa931c589
Coming back to the app first waited for a `Core/echo` (sometimes two: the keep-alive timer that was due fired alongside) and for the event stream to be set up before the catch-up sync started. A failed echo only led to `retrySession`, which does nothing while the session is live. On top of that, a `Core/echo` went out every 30 s although the event stream's own pings already show the server is reachable. - On resume the stream reconnects and the folders and open list are synced right away; one echo runs alongside for the connection dot. - The 30 s echo is only sent while the event stream is not open (polling fallback, reconnecting, client certificate). An open stream whose pings arrive (the live-updates handle's new `healthy`) marks the account connected instead. - Echoes never overlap, and a periodic one right after the resume one is skipped.
80 lines
2.5 KiB
TypeScript
80 lines
2.5 KiB
TypeScript
// Whether the JMAP server is reachable while the app is in the foreground,
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// for the per-account connection dot. NetInfo only knows the device is
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// online, not that the server answers.
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//
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// An open event stream already proves it: the server pings it every 30 s and
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// the stream is dropped after three missed pings. A `Core/echo` every 30 s is
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// only sent while the stream is not open (polling fallback, reconnecting,
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// client certificate), and on demand (`check`, e.g. on resume, where it runs
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// alongside the catch-up sync instead of in front of it). Checks never
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// overlap, and a periodic one is skipped right after an on-demand one.
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export const LIVENESS_INTERVAL_MS = 30_000;
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export interface LivenessOptions {
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/** One `Core/echo`: true when the server answered. */
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ping: () => Promise<boolean>;
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/** Whether the event stream is open and its pings arrive. */
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streamHealthy: () => boolean;
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/** Whether the app is in the foreground. */
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isActive: () => boolean;
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/** Whether the device has a network. */
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isOnline: () => boolean;
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/** Called with the connection state after each verdict. */
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onConnected: (connected: boolean) => void;
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intervalMs?: number;
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now?: () => number;
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}
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export interface LivenessMonitor {
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/** Check now (one `Core/echo`), unless a check is already running. */
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check: () => Promise<void>;
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stop: () => void;
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}
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export function startLivenessMonitor(opts: LivenessOptions): LivenessMonitor {
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const interval = opts.intervalMs ?? LIVENESS_INTERVAL_MS;
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const now = opts.now ?? Date.now;
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let failures = 0;
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let inFlight: Promise<void> | null = null;
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let lastCheckAt = -Infinity;
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let stopped = false;
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const check = (): Promise<void> => {
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if (inFlight) return inFlight;
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lastCheckAt = now();
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inFlight = opts.ping()
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.catch(() => false)
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.then((ok) => {
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if (stopped) return;
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failures = ok ? 0 : failures + 1;
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// One missed echo can be a blip; two in a row is a lost connection.
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opts.onConnected(failures < 2);
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})
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.finally(() => {
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inFlight = null;
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});
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return inFlight;
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};
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const timer = setInterval(() => {
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if (!opts.isActive() || !opts.isOnline()) return;
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if (opts.streamHealthy()) {
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failures = 0;
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opts.onConnected(true);
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return;
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}
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// A tick that fired late (on resume) right after the resume check.
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if (now() - lastCheckAt < interval / 2) return;
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void check();
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}, interval);
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return {
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check,
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stop: () => {
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stopped = true;
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clearInterval(timer);
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},
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};
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}
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