feat(object_store): use http1 by default (#5204)

* feat: use http1 by default

* add note to GCS docs

* fix docs

* simplify changes

* bring back option

object_store/src/client/mod.rs

@@ -213,7 +213,10 @@ impl Default for ClientOptions {
             http2_keep_alive_interval: None,
             http2_keep_alive_timeout: None,
             http2_keep_alive_while_idle: Default::default(),
-            http1_only: Default::default(),
+            // HTTP2 is known to be significantly slower than HTTP1, so we default
+            // to HTTP1 for now.
+            // https://github.com/apache/arrow-rs/issues/5194
+            http1_only: true.into(),
             http2_only: Default::default(),
         }
     }
@@ -350,17 +353,28 @@ impl ClientOptions {
     }
 
     /// Only use http1 connections
+    ///
+    /// This is on by default, since http2 is known to be significantly slower than http1.
     pub fn with_http1_only(mut self) -> Self {
+        self.http2_only = false.into();
         self.http1_only = true.into();
         self
     }
 
     /// Only use http2 connections
     pub fn with_http2_only(mut self) -> Self {
+        self.http1_only = false.into();
         self.http2_only = true.into();
         self
     }
 
+    /// Use http2 if supported, otherwise use http1.
+    pub fn with_allow_http2(mut self) -> Self {
+        self.http1_only = false.into();
+        self.http2_only = false.into();
+        self
+    }
+
     /// Set a proxy URL to use for requests
     pub fn with_proxy_url(mut self, proxy_url: impl Into<String>) -> Self {
         self.proxy_url = Some(proxy_url.into());

object_store/src/gcp/mod.rs

@@ -29,6 +29,13 @@
 //! to abort the upload and drop those unneeded parts. In addition, you may wish to
 //! consider implementing automatic clean up of unused parts that are older than one
 //! week.
+//!
+//! ## Using HTTP/2
+//!
+//! Google Cloud Storage supports both HTTP/2 and HTTP/1. HTTP/1 is used by default
+//! because it allows much higher throughput in our benchmarks (see
+//! [#5194](https://github.com/apache/arrow-rs/issues/5194)). HTTP/2 can be
+//! enabled by setting [crate::ClientConfigKey::Http1Only] to false.
 use std::sync::Arc;
 
 use crate::client::CredentialProvider;