From 817e4bb2fe0538a60f169d37e254b30e3dc3ab1d Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Tue, 7 Aug 2018 17:36:56 +0200
Subject: [PATCH] AsyncHttpClient: return from requests before body completion

Store the body completion future at the client and wait for it to
complete before issuing additional requests. This allows the body
FutureStream reader to drain the stream and read buffers to be freed
asynchronously.

Fix #8109
---
 lib/pure/httpclient.nim | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/lib/pure/httpclient.nim b/lib/pure/httpclient.nim
index 8b4fb0f8c1..72de727184 100644
--- a/lib/pure/httpclient.nim
+++ b/lib/pure/httpclient.nim
@@ -807,6 +807,7 @@ type
     lastProgressReport: float
     when SocketType is AsyncSocket:
       bodyStream: FutureStream[string]
+      parseBodyFut: Future[void]
     else:
       bodyStream: Stream
     getBody: bool ## When `false`, the body is never read in requestAux.
@@ -1066,10 +1067,14 @@ proc parseResponse(client: HttpClient | AsyncHttpClient,
   if getBody:
     when client is HttpClient:
       client.bodyStream = newStringStream()
+      result.bodyStream = client.bodyStream
+      parseBody(client, result.headers, result.version)
     else:
       client.bodyStream = newFutureStream[string]("parseResponse")
-    await parseBody(client, result.headers, result.version)
-    result.bodyStream = client.bodyStream
+      result.bodyStream = client.bodyStream
+      assert(client.parseBodyFut.isNil or client.parseBodyFut.finished)
+      client.parseBodyFut = parseBody(client, result.headers, result.version)
+        # do not wait here for the body request to complete
 
 proc newConnection(client: HttpClient | AsyncHttpClient,
                    url: Uri) {.multisync.} =
@@ -1159,6 +1164,12 @@ proc requestAux(client: HttpClient | AsyncHttpClient, url: string,
   # Helper that actually makes the request. Does not handle redirects.
   let requestUrl = parseUri(url)
 
+  when client is AsyncHttpClient:
+    if not client.parseBodyFut.isNil:
+      # let the current operation finish before making another request
+      await client.parseBodyFut
+      client.parseBodyFut = nil
+
   await newConnection(client, requestUrl)
 
   let effectiveHeaders = client.headers.override(headers)