fix(ext/http): unify default gzip compression level (#20050)

This tweaks the HTTP response-writer in order to align the two possible
execution flows into using the same gzip default compression level, that
is `1` (otherwise the implicit default level is `6`).

1 files changed, 14 insertions, 6 deletions

diff --git a/ext/http/lib.rs b/ext/http/lib.rs
index 5a8788f92..21c051cae 100644
--- a/ext/http/lib.rs
+++ b/ext/http/lib.rs
@@ -2,6 +2,7 @@
 
 use async_compression::tokio::write::BrotliEncoder;
 use async_compression::tokio::write::GzipEncoder;
+use async_compression::Level;
 use cache_control::CacheControl;
 use deno_core::error::custom_error;
 use deno_core::error::AnyError;
@@ -702,6 +703,11 @@ fn http_response(
   compressing: bool,
   encoding: Encoding,
 ) -> Result<(HttpResponseWriter, hyper::Body), AnyError> {
+  // Gzip, after level 1, doesn't produce significant size difference.
+  // This default matches nginx default gzip compression level (1):
+  // https://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_comp_level
+  const GZIP_DEFAULT_COMPRESSION_LEVEL: u8 = 1;
+
   match data {
     Some(data) if compressing => match encoding {
       Encoding::Brotli => {
@@ -715,11 +721,10 @@ fn http_response(
         Ok((HttpResponseWriter::Closed, writer.into_inner().into()))
       }
       Encoding::Gzip => {
-        // Gzip, after level 1, doesn't produce significant size difference.
-        // Probably the reason why nginx's default gzip compression level is
-        // 1.
-        // https://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_comp_level
-        let mut writer = GzEncoder::new(Vec::new(), Compression::new(1));
+        let mut writer = GzEncoder::new(
+          Vec::new(),
+          Compression::new(GZIP_DEFAULT_COMPRESSION_LEVEL.into()),
+        );
         writer.write_all(&data)?;
         Ok((HttpResponseWriter::Closed, writer.finish()?.into()))
       }
@@ -739,7 +744,10 @@ fn http_response(
       let (_, writer) = tokio::io::split(b);
       let writer: Pin<Box<dyn tokio::io::AsyncWrite>> = match encoding {
         Encoding::Brotli => Box::pin(BrotliEncoder::new(writer)),
-        Encoding::Gzip => Box::pin(GzipEncoder::new(writer)),
+        Encoding::Gzip => Box::pin(GzipEncoder::with_quality(
+          writer,
+          Level::Precise(GZIP_DEFAULT_COMPRESSION_LEVEL.into()),
+        )),
         _ => unreachable!(), // forbidden by accepts_compression
       };
       let (stream, shutdown_handle) =