From 53d91cd0f1295a0c3456cb1a34e5235a0316c523 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Peter=20Zeb=C3=BChr?=
 <33069501+petzeb@users.noreply.github.com>
Date: Thu, 6 Jul 2023 04:38:01 +0700
Subject: [PATCH] fix: Don't close upstream on HttpFile::Flush (#1201)

Closing the upstream on flush will effectively terminate the ongoing
curl connection. This means that we would need re-establish the
connection in order to resume writing, this is not what we want. In the
spirit of the documentation of File::Flush

```c++
/// Flush the file so that recently written data will survive an
/// application crash (but not necessarily an OS crash). For
/// instance, in LocalFile the data is flushed into the OS but not
/// necessarily to disk.
```

We will instead wait for the curl thread to finish consuming what ever
might be in the upload cache, but leave the connection open for
subsequent writes.

Fixes #1196
---
 packager/file/http_file.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packager/file/http_file.cc b/packager/file/http_file.cc
index 404ef6fb977..de6814bb970 100644
--- a/packager/file/http_file.cc
+++ b/packager/file/http_file.cc
@@ -243,6 +243,7 @@ int64_t HttpFile::Read(void* buffer, uint64_t length) {
 }
 
 int64_t HttpFile::Write(const void* buffer, uint64_t length) {
+  DCHECK(!upload_cache_.closed());
   VLOG(2) << "Writing to " << url_ << ", length=" << length;
   return upload_cache_.Write(buffer, length);
 }
@@ -253,7 +254,8 @@ int64_t HttpFile::Size() {
 }
 
 bool HttpFile::Flush() {
-  upload_cache_.Close();
+  // Wait for curl to read any data we may have buffered.
+  upload_cache_.WaitUntilEmptyOrClosed();
   return true;
 }