Provide an API to replace the host table.

components/net_traits/hosts.rs

@@ -8,9 +8,10 @@ use std::env;
 use std::fs::File;
 use std::io::{BufReader, Read};
 use std::net::IpAddr;
+use std::sync::Mutex;
 
 lazy_static! {
-    static ref HOST_TABLE: Option<HashMap<String, IpAddr>> = create_host_table();
+    static ref HOST_TABLE: Mutex<Option<HashMap<String, IpAddr>>> = Mutex::new(create_host_table());
 }
 
 fn create_host_table() -> Option<HashMap<String, IpAddr>> {
@@ -34,6 +35,10 @@ fn create_host_table() -> Option<HashMap<String, IpAddr>> {
     return Some(parse_hostsfile(&lines));
 }
 
+pub fn replace_host_table(table: HashMap<String, IpAddr>) {
+    *HOST_TABLE.lock().unwrap() = Some(table);
+}
+
 pub fn parse_hostsfile(hostsfile_content: &str) -> HashMap<String, IpAddr> {
     let mut host_table = HashMap::new();
     for line in hostsfile_content.split('\n') {
@@ -53,7 +58,7 @@ pub fn parse_hostsfile(hostsfile_content: &str) -> HashMap<String, IpAddr> {
 }
 
 pub fn replace_hosts(url: &ServoUrl) -> ServoUrl {
-    HOST_TABLE.as_ref().map_or_else(|| url.clone(), |host_table| {
+    HOST_TABLE.lock().unwrap().as_ref().map_or_else(|| url.clone(), |host_table| {
         host_replacement(host_table, url)
     })
 }