Lessen pressure on the thread-local RNG

When loading HTTP requests, initialise the request ID only if devtools
are used, to lessen the pressure put on the RNG initialisation.

This tentatively fixes #11100 on OS X.

components/net/fetch/methods.rs

@@ -34,6 +34,7 @@ use std::fs::File;
 use std::io::Read;
 use std::iter::FromIterator;
 use std::mem::swap;
+use std::ops::Deref;
 use std::rc::Rc;
 use std::sync::mpsc::{channel, Sender, Receiver};
 use unicase::UniCase;
@@ -952,7 +953,9 @@ fn http_network_fetch(request: Rc<Request>,
     let url = request.current_url();
     let cancellation_listener = CancellationListener::new(None);
 
-    let request_id = uuid::Uuid::new_v4().simple().to_string();
+    let request_id = devtools_chan.as_ref().map(|_| {
+        uuid::Uuid::new_v4().simple().to_string()
+    });
 
     // XHR uses the default destination; other kinds of fetches (which haven't been implemented yet)
     // do not. Once we support other kinds of fetches we'll need to be more fine grained here
@@ -962,7 +965,7 @@ fn http_network_fetch(request: Rc<Request>,
                                            &request.headers.borrow(),
                                            &cancellation_listener, &request.body.borrow(), &request.method.borrow(),
                                            &request.pipeline_id.get(), request.redirect_count.get() + 1,
-                                           &devtools_chan, &request_id, is_xhr);
+                                           request_id.as_ref().map(Deref::deref), is_xhr);
 
     let pipeline_id = request.pipeline_id.get();
     let mut response = Response::new();
@@ -996,7 +999,7 @@ fn http_network_fetch(request: Rc<Request>,
                             // Send an HttpResponse message to devtools with the corresponding request_id
                             if let Some(pipeline_id) = pipeline_id {
                                 send_response_to_devtools(
-                                    &sender, request_id.into(),
+                                    &sender, request_id.unwrap(),
                                     meta_headers.map(Serde::into_inner),
                                     meta_status.map(Serde::into_inner),
                                     pipeline_id);

components/net/http_loader.rs

@@ -45,6 +45,7 @@ use std::collections::HashSet;
 use std::error::Error;
 use std::fmt;
 use std::io::{self, Cursor, Read, Write};
+use std::ops::Deref;
 use std::sync::mpsc::Sender;
 use std::sync::{Arc, RwLock};
 use time;
@@ -744,8 +745,7 @@ pub fn obtain_response<A>(request_factory: &HttpRequestFactory<R=A>,
                           load_data_method: &Method,
                           pipeline_id: &Option<PipelineId>,
                           iters: u32,
-                          devtools_chan: &Option<Sender<DevtoolsControlMsg>>,
-                          request_id: &str,
+                          request_id: Option<&str>,
                           is_xhr: bool)
                           -> Result<(A::R, Option<ChromeToDevtoolsControlMsg>), LoadError>
                           where A: HttpRequest + 'static  {
@@ -808,10 +808,10 @@ pub fn obtain_response<A>(request_factory: &HttpRequestFactory<R=A>,
 
         let send_end = precise_time_ms();
 
-        msg = if devtools_chan.is_some() {
+        msg = if let Some(request_id) = request_id {
             if let Some(pipeline_id) = *pipeline_id {
                 Some(prepare_devtools_request(
-                    request_id.clone().into(),
+                    request_id.into(),
                     url.clone(), method.clone(), headers,
                     request_body.clone(), pipeline_id, time::now(),
                     connect_end - connect_start, send_end - send_start, is_xhr))
@@ -968,7 +968,9 @@ pub fn load<A, B>(load_data: &LoadData,
             load_data.preserved_headers.clone()
         };
 
-        let request_id = uuid::Uuid::new_v4().simple().to_string();
+        let request_id = devtools_chan.as_ref().map(|_| {
+            uuid::Uuid::new_v4().simple().to_string()
+        });
 
         modify_request_headers(&mut request_headers, &doc_url,
                                &user_agent, load_data.referrer_policy,
@@ -992,7 +994,8 @@ pub fn load<A, B>(load_data: &LoadData,
         let (response, msg) =
             try!(obtain_response(request_factory, &doc_url, &method, &request_headers,
                                  &cancel_listener, &load_data.data, &load_data.method,
-                                 &load_data.pipeline_id, iters, &devtools_chan, &request_id, false));
+                                 &load_data.pipeline_id, iters,
+                                 request_id.as_ref().map(Deref::deref), false));
 
         process_response_headers(&response, &doc_url, &http_state.cookie_jar, &http_state.hsts_list, &load_data);
 
@@ -1092,7 +1095,7 @@ pub fn load<A, B>(load_data: &LoadData,
         if let Some(pipeline_id) = load_data.pipeline_id {
             if let Some(ref chan) = devtools_chan {
                 send_response_to_devtools(
-                    &chan, request_id,
+                    &chan, request_id.unwrap(),
                     metadata.headers.clone().map(Serde::into_inner),
                     metadata.status.clone().map(Serde::into_inner),
                     pipeline_id);

tests/wpt/metadata/html/dom/reflection-embedded.html.ini

@@ -1,7 +1,5 @@
 [reflection-embedded.html]
   type: testharness
-  disabled:
-    if os == "mac": https://github.com/servo/servo/issues/11100
   [img.dir: typeof IDL attribute]
     expected: FAIL