add support for keep-alive timeout server hint

README.md

@@ -52,7 +52,8 @@ Options:
   Default: `null`.
 
 - `idleTimeout`, the timeout after which a socket with no active requests
-  will be released and no longer re-used for subsequent requests.
+  will be released and no longer re-used for subsequent requests. This value
+  is an upper bound and might be reduced by keep-alive hints from the server.
   Default: `30e3` milliseconds (30s).
 
 - `requestTimeout`, the timeout after which a request will time out, in

lib/client.js

@@ -46,6 +46,7 @@ const {
   kSocket,
   kSocketPath,
   kEnqueue,
+  kKeepAliveTimeout,
   kMaxHeadersSize,
   kHeadersTimeout
 } = require('./symbols')
@@ -133,6 +134,7 @@ class Client extends EventEmitter {
     this[kSocketPath] = socketPath
     this[kSocketTimeout] = socketTimeout == null ? 30e3 : socketTimeout
     this[kIdleTimeout] = idleTimeout == null ? 30e3 : idleTimeout
+    this[kKeepAliveTimeout] = this[kIdleTimeout]
     this[kRequestTimeout] = requestTimeout == null ? 30e3 : requestTimeout
     this[kClosed] = false
     this[kDestroyed] = false
@@ -415,6 +417,8 @@ class Parser extends HTTPParser {
 
   [HTTPParser.kOnHeadersComplete] (versionMajor, versionMinor, rawHeaders, method,
     url, statusCode, statusMessage, upgrade, shouldKeepAlive) {
+    this.headers = util.parseHeaders(rawHeaders, this.headers)
+
     const { client, socket, resumeSocket, headers } = this
     const request = client[kQueue][client[kRunningIdx]]
 
@@ -435,12 +439,22 @@ class Parser extends HTTPParser {
       return true
     }
 
+    if (headers['keep-alive']) {
+      const m = headers['keep-alive'].match(/timeout=(\d+)/)
+      if (m) {
+        // Set timeout to half of hint to account for timing inaccuracies.
+        client[kKeepAliveTimeout] = Math.min(parseInt(m[1]) * 1000 / 2, client[kIdleTimeout])
+      }
+    } else {
+      client[kKeepAliveTimeout] = client[kIdleTimeout]
+    }
+
     // TODO: More statusCode validation?
 
     if (statusCode < 200) {
       // request.onInfo(statusCode, util.parseHeaders(rawHeaders, headers))
     } else {
-      request.onHeaders(statusCode, util.parseHeaders(rawHeaders, headers), resumeSocket)
+      request.onHeaders(statusCode, headers, resumeSocket)
     }
 
     return request.method === 'HEAD' || statusCode < 200
@@ -663,6 +677,14 @@ function resume (client) {
       return
     }
 
+    if (
+      client.running === 0 &&
+      client[kSocket] &&
+      client[kSocket].timeout !== client[kKeepAliveTimeout]
+    ) {
+      client[kSocket].setTimeout(client[kKeepAliveTimeout])
+    }
+
     if (client.size === 0) {
       if (client[kClosed]) {
         client.destroy(util.nop)
@@ -675,14 +697,6 @@ function resume (client) {
       return
     }
 
-    if (
-      client.running === 0 &&
-      client[kSocket] &&
-      client[kSocket].timeout !== client[kIdleTimeout]
-    ) {
-      client[kSocket].setTimeout(client[kIdleTimeout])
-    }
-
     if (client[kRunningIdx] > 256) {
       client[kQueue].splice(0, client[kRunningIdx])
       client[kPendingIdx] -= client[kRunningIdx]

lib/symbols.js

@@ -7,6 +7,7 @@ module.exports = {
   kSocketTimeout: Symbol('socket timeout'),
   kIdleTimeout: Symbol('idle timeout'),
   kRequestTimeout: Symbol('request timeout'),
+  kKeepAliveTimeout: Symbol('keep alive timeout'),
   kServerName: Symbol('server name'),
   kTLSOpts: Symbol('TLS Options'),
   kClosed: Symbol('closed'),

test/client-keep-alive.js

@@ -0,0 +1,40 @@
+'use strict'
+
+const { test } = require('tap')
+const { Client } = require('..')
+const { createServer } = require('net')
+
+test('keep-alive header', (t) => {
+  t.plan(2)
+
+  const server = createServer((socket) => {
+    socket.write('HTTP/1.1 200 OK\r\n')
+    socket.write('Content-Length: 0\r\n')
+    socket.write('Keep-Alive: timeout=1s\r\n')
+    socket.write('Connection: keep-alive\r\n')
+    socket.write('\r\n\r\n')
+  })
+  t.teardown(server.close.bind(server))
+
+  server.listen(0, () => {
+    const client = new Client(`http://localhost:${server.address().port}`)
+    t.teardown(client.destroy.bind(client))
+
+    client.request({
+      path: '/',
+      method: 'GET',
+      idleTimeout: 30e3
+    }, (err, { body }) => {
+      t.error(err)
+      body.on('end', () => {
+        const timeout = setTimeout(() => {
+          t.fail()
+        }, 1e3)
+        client.on('disconnect', () => {
+          t.pass()
+          clearTimeout(timeout)
+        })
+      }).resume()
+    })
+  })
+})