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Item 2: when the heartbeat checker marks a device offline it now also disconnects any socket it still holds for it, so DB-offline can't diverge from socket-state into a silent half-open (defensive — the live-socket guard already defers genuinely-live sockets). Item 3: tighten half-open detection WITHOUT reintroducing the TV-WebKit decode-load risk the 30s pong-timeout was chosen for — lower only pingInterval 30s->15s (probe more often), KEEP pingTimeout at 30s. Detection = interval+timeout = 45s (was 60s), and the client inherits these via the handshake so BOTH ends detect a dead peer ~25% sooner. (Deliberately did NOT drop pingTimeout to ~20s: MAXHUB is a video-playing TV-class device and the code comment warns tighter timeouts cause spurious drops under decode load.) Item 4: SO_KEEPALIVE on every accepted connection (lib/tcp-keepalive.js) so a half-open TCP can't persist indefinitely at the OS layer, independent of the app ping. Tests: server closes a non-ponging peer within ~pingInterval+pingTimeout while a ponging peer survives; a device whose transport dies ends offline with its connection torn down; keepalive applied to each accepted connection (and never breaks setup on error). Suite 328/328.
15 lines
681 B
JavaScript
15 lines
681 B
JavaScript
'use strict';
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// #148 Item 4 — enable TCP SO_KEEPALIVE on every accepted connection so a half-open TCP
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// (e.g. a connection severed silently by an edge firewall/NAT reap, leaving no FIN) can't
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// persist indefinitely at the OS layer, independent of the Engine.IO application ping. The
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// http/https server's 'connection' event fires with the raw net.Socket (before TLS), which
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// is where setKeepAlive belongs. Best-effort — never let it break connection setup.
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function applyTcpKeepAlive(server, idleMs) {
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server.on('connection', (socket) => {
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try { socket.setKeepAlive(true, idleMs); } catch (_) { /* best-effort */ }
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});
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}
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module.exports = { applyTcpKeepAlive };
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