Thread IO safety: file_util annotated, IO thread blocked from doing IO

chrome/browser/io_thread.cc

 // Copyright (c) 2010 The Chromium 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 "chrome/browser/io_thread.h"
 
 #include "base/command_line.h"
 #include "base/leak_tracker.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/stl_util-inl.h"
 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
+#include "base/thread_restrictions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/gpu_process_host.h"
 #include "chrome/browser/net/chrome_net_log.h"
 #include "chrome/browser/net/connect_interceptor.h"
 #include "chrome/browser/net/passive_log_collector.h"
 #include "chrome/browser/net/predictor_api.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/net/url_fetcher.h"
 #include "net/base/dnsrr_resolver.h"
@@ skipping 200 matching lines @@
           this,
           &IOThread::ChangedToOnTheRecordOnIOThread));
 }
 
 net::ProxyScriptFetcher* IOThread::CreateAndRegisterProxyScriptFetcher(
     URLRequestContext* url_request_context) {
   return new ManagedProxyScriptFetcher(url_request_context, this);
 }
 
 void IOThread::Init() {
+#if defined(OS_LINUX)
+  // TODO(evan): test and enable this on all platforms.
+  // Though this thread is called the "IO" thread, it actually just routes
+  // messages around; it shouldn't be allowed to perform any blocking disk I/O.
+  base::ThreadRestrictions::SetIOAllowed(false);
+#endif
+
   BrowserProcessSubThread::Init();
 
   DCHECK_EQ(MessageLoop::TYPE_IO, message_loop()->type());
 
 #if defined(USE_NSS)
   net::SetMessageLoopForOCSP();
 #endif  // defined(USE_NSS)
 
   DCHECK(!globals_);
   globals_ = new Globals;
@@ skipping 151 matching lines @@
     net::HostCache* host_cache =
         globals_->host_resolver.get()->GetAsHostResolverImpl()->cache();
     if (host_cache)
       host_cache->clear();
   }
   // Clear all of the passively logged data.
   // TODO(eroman): this is a bit heavy handed, really all we need to do is
   //               clear the data pertaining to off the record context.
   globals_->net_log->passive_collector()->Clear();
 }