AU: Make proxy resolution asynchronous.

libcurl_http_fetcher.cc

 // Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "update_engine/libcurl_http_fetcher.h"
 
 #include <algorithm>
 #include <string>
 
 #include <base/logging.h>
 
 #include "update_engine/chrome_proxy_resolver.h"
 #include "update_engine/dbus_interface.h"
 #include "update_engine/flimflam_proxy.h"
 #include "update_engine/utils.h"
 
+using google::protobuf::NewCallback;
 using std::max;
 using std::make_pair;
 using std::string;
 
 // This is a concrete implementation of HttpFetcher that uses libcurl to do the
 // http work.
 
 namespace chromeos_update_engine {
 
 namespace {
@@ skipping 117 matching lines @@
                               "HIGH:!ADH"),
              CURLE_OK);
   }
 
   CHECK_EQ(curl_multi_add_handle(curl_multi_handle_, curl_handle_), CURLM_OK);
   transfer_in_progress_ = true;
 }
 
 // Begins the transfer, which must not have already been started.
 void LibcurlHttpFetcher::BeginTransfer(const std::string& url) {
+  CHECK(!transfer_in_progress_);
+  url_ = url;
+  if (!ResolveProxiesForUrl(
+          url_,
+          NewCallback(this, &LibcurlHttpFetcher::ProxiesResolved))) {
+    LOG(ERROR) << "Couldn't resolve proxies";
+    if (delegate_)
+      delegate_->TransferComplete(this, false);
+  }
+}
+
+void LibcurlHttpFetcher::ProxiesResolved() {
   transfer_size_ = -1;
   resume_offset_ = 0;
   retry_count_ = 0;
   no_network_retry_count_ = 0;
   http_response_code_ = 0;
   terminate_requested_ = false;
-  ResolveProxiesForUrl(url);
-  ResumeTransfer(url);
+  ResumeTransfer(url_);
   CurlPerformOnce();
 }
 
 void LibcurlHttpFetcher::ForceTransferTermination() {
   CleanUp();
   if (delegate_) {
     // Note that after the callback returns this object may be destroyed.
     delegate_->TransferTerminated(this);
   }
 }
@@ skipping 269 matching lines @@
 void LibcurlHttpFetcher::GetHttpResponseCode() {
   long http_response_code = 0;
   if (curl_easy_getinfo(curl_handle_,
                         CURLINFO_RESPONSE_CODE,
                         &http_response_code) == CURLE_OK) {
     http_response_code_ = static_cast<int>(http_response_code);
   }
 }
 
 }  // namespace chromeos_update_engine