From f638402e2f458a45585d6b28314a5b819a34bec4 Mon Sep 17 00:00:00 2001 From: Fedor Indutny Date: Mon, 5 Oct 2015 13:30:30 -0400 Subject: [PATCH] http: add comment about `outputSize` in res/server PR-URL: https://github.com/nodejs/node/pull/3128 --- lib/_http_outgoing.js | 7 +++++++ lib/_http_server.js | 4 ++++ 2 files changed, 11 insertions(+) diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js index 4c87a36..7bf8d56 100644 --- a/lib/_http_outgoing.js +++ b/lib/_http_outgoing.js @@ -46,9 +46,16 @@ utcDate._onTimeout = function() { function OutgoingMessage() { Stream.call(this); + // Queue that holds all currently pending data, until the response will be + // assigned to the socket (until it will its turn in the HTTP pipeline). this.output = []; this.outputEncodings = []; this.outputCallbacks = []; + + // `outputSize` is an approximate measure of how much data is queued on this + // response. `_onPendingData` will be invoked to update similar global + // per-connection counter. That counter will be used to pause/unpause the + // TCP socket and HTTP Parser and thus handle the backpressure. this.outputSize = 0; this.writable = true; diff --git a/lib/_http_server.js b/lib/_http_server.js index 2d6cb53..c11d369 100644 --- a/lib/_http_server.js +++ b/lib/_http_server.js @@ -265,6 +265,10 @@ function connectionListener(socket) { var outgoingData = 0; function updateOutgoingData(delta) { + // `outgoingData` is an approximate amount of bytes queued through all + // inactive responses. If more data than the high watermark is queued - we + // need to pause TCP socket/HTTP parser, and wait until the data will be + // sent to the client. outgoingData += delta; if (socket._paused && outgoingData < socket._writableState.highWaterMark) return socketOnDrain(); -- 2.7.4