From 0e0b64dc8563bc76a92ce7ec791ef3a80f2b26be Mon Sep 17 00:00:00 2001
From: Geoffroy Couprie <geoffroy@apollographql.com>
Date: Fri, 26 Aug 2022 12:54:01 +0200
Subject: [PATCH] patch async-compression to compress responses in streaming
 (#1604)

Fix #1572

async-compression is used in tower-http's CompressionLayer. Inside the
AsyncRead based compression code, if the underlying stream returns
Poll::Pending, it will be returned directly, while in the case of
deferred responses, the next one might come way later, so we want to
send whatever data we have available right now.
We will have to switch to an AsyncWrite interface instead, which will be
more flexible, but considering the timing of the release, this patch
will hold for now.

This uses the code from https://github.com/Nemo157/async-compression/pull/155
---
 Cargo.lock        | 3 +--
 Cargo.toml        | 8 ++++++++
 NEXT_CHANGELOG.md | 8 ++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 3acabff190..2fcb30ded0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -364,8 +364,7 @@ dependencies = [
 [[package]]
 name = "async-compression"
 version = "0.3.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "345fd392ab01f746c717b1357165b76f0b67a60192007b234058c9045fdcf695"
+source = "git+https://github.com/geal/async-compression?branch=encoder-flush#9800cd0d36be7f3414fbb98b25f9f61900ec8c7c"
 dependencies = [
  "brotli",
  "flate2",
diff --git a/Cargo.toml b/Cargo.toml
index 609df9e60c..fd3fb480e8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -32,3 +32,11 @@ members = [
 # debug = false
 strip = "debuginfo"
 incremental = false
+
+# Temporary patch to async-compression
+# It is used by tower-http's CompressionLayer. The compression code was not handling
+# the Poll::Pending result from the underlying stream, so it was accumulating the
+# entire compressed response in memory before sending it, which creates issues with
+# deferred responses getting received too late
+[patch.crates-io]
+async-compression = { git = 'https://github.com/geal/async-compression', branch = 'encoder-flush' }
\ No newline at end of file
diff --git a/NEXT_CHANGELOG.md b/NEXT_CHANGELOG.md
index fd099a2682..c33e1f427f 100644
--- a/NEXT_CHANGELOG.md
+++ b/NEXT_CHANGELOG.md
@@ -192,6 +192,14 @@ next chunk to see the delimiter.
 
 By [@Geal](https://github.com/Geal) in https://github.com/apollographql/router/pull/1596
 
+### Patch async-compression to compress responses in streaming ([PR #1604](https://github.com/apollographql/router/issues/1604))
+
+async-compression is a dependency used for response compression. Its implementation accumulates the entire compressed response
+in memory before sending it, which creates problems for deferred responses, where we want the responses to come as soon as
+possible, and not all at once after a while.
+
+By [@Geal](https://github.com/Geal) in https://github.com/apollographql/router/pull/1604
+
 ## 🛠 Maintenance
 
 ### Depend on published `router-bridge` ([PR #1613](https://github.com/apollographql/router/issues/1613))