perf(ext/http): faster accept-encoding parsing (#14654)

ext/http/Cargo.toml

@@ -26,7 +26,7 @@ cache_control = "0.2.0"
 deno_core = { version = "0.134.0", path = "../../core" }
 deno_websocket = { version = "0.57.0", path = "../websocket" }
 flate2 = "1.0.23"
-fly-accept-encoding = "0.2.0-alpha.5"
+fly-accept-encoding = "0.2.0"
 hyper = { version = "0.14.18", features = ["server", "stream", "http1", "http2", "runtime"] }
 mime = "0.3.16"
 percent-encoding = "2.1.0"

ext/http/lib.rs

@@ -390,31 +390,17 @@ async fn op_http_accept(
     _ => unreachable!(),
   };
 
-  {
-    let mut accept_encoding = stream.accept_encoding.borrow_mut();
-
-    // curl --compressed sends "Accept-Encoding: deflate, gzip".
-    // fly_accept_encoding::parse() returns Encoding::Deflate.
-    // Deno does not support Encoding::Deflate.
-    // So, Deno used no compression, although gzip was possible.
-    // This patch makes Deno use gzip instead in this case.
-    *accept_encoding = Encoding::Identity;
-    let mut max_qval = 0.0;
-    if let Ok(encodings) = fly_accept_encoding::encodings(request.headers()) {
-      for (encoding, qval) in encodings {
-        if let Some(enc @ (Encoding::Brotli | Encoding::Gzip)) = encoding {
-          // this logic came from fly_accept_encoding.
-          if (qval - 1.0f32).abs() < 0.01 {
-            *accept_encoding = enc;
-            break;
-          } else if qval > max_qval {
-            *accept_encoding = enc;
-            max_qval = qval;
-          }
-        }
-      }
-    }
-  }
+  stream.accept_encoding.replace({
+    let encodings = fly_accept_encoding::encodings_iter(request.headers())
+      .filter(|r| {
+        matches!(r, Ok((Some(Encoding::Brotli | Encoding::Gzip), _)))
+      });
+
+    fly_accept_encoding::preferred(encodings)
+      .ok()
+      .flatten()
+      .unwrap_or(Encoding::Identity)
+  });
 
   let method = request.method().to_string();
   let headers = req_headers(request);