Ensure that even if the HostResolver outlives the IO thread, its jobs will no...

net/base/host_resolver.cc

 // Copyright (c) 2006-2008 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 "net/base/host_resolver.h"
 
 #if defined(OS_WIN)
 #include <ws2tcpip.h>
 #include <wspiapi.h>  // Needed for Win2k compat.
 #elif defined(OS_POSIX)
@@ skipping 380 matching lines @@
   // Assigned on the worker thread, read on the origin thread.
   int error_;
   struct addrinfo* results_;
 
   DISALLOW_COPY_AND_ASSIGN(Job);
 };
 
 //-----------------------------------------------------------------------------
 
 HostResolver::HostResolver(int max_cache_entries, int cache_duration_ms)
-    : cache_(max_cache_entries, cache_duration_ms), next_request_id_(0) {
+    : cache_(max_cache_entries, cache_duration_ms), next_request_id_(0),
+      shutdown_(false) {
 #if defined(OS_WIN)
   EnsureWinsockInit();
 #endif
 }
 
 HostResolver::~HostResolver() {
   // Cancel the outstanding jobs. Those jobs may contain several attached
   // requests, which will also be cancelled.
   for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ++it)
     it->second->Cancel();
 
   // In case we are being deleted during the processing of a callback.
   if (cur_completing_job_)
     cur_completing_job_->Cancel();
 }
 
 // TODO(eroman): Don't create cache entries for hostnames which are simply IP
 // address literals.
 int HostResolver::Resolve(const RequestInfo& info,
                           AddressList* addresses,
                           CompletionCallback* callback,
                           Request** out_req) {
+  if (shutdown_)
+    return ERR_UNEXPECTED;
+
   // Choose a unique ID number for observers to see.
   int request_id = next_request_id_++;
 
   // Notify registered observers.
   NotifyObserversStartRequest(request_id, info);
 
   // If we have an unexpired cache entry, use it.
   if (info.allow_cached_response()) {
     const HostCache::Entry* cache_entry = cache_.Lookup(
         info.hostname(), base::TimeTicks::Now());
@@ skipping 76 matching lines @@
 void HostResolver::RemoveObserver(Observer* observer) {
   ObserversList::iterator it =
       std::find(observers_.begin(), observers_.end(), observer);
 
   // Observer must exist.
   DCHECK(it != observers_.end());
 
   observers_.erase(it);
 }
 
+void HostResolver::Shutdown() {
+  shutdown_ = true;
+
+  // Cancel the outstanding jobs.
+  for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ++it)
+    it->second->Cancel();
+  jobs_.clear();
+}
+
 void HostResolver::AddOutstandingJob(Job* job) {
   scoped_refptr<Job>& found_job = jobs_[job->host()];
   DCHECK(!found_job);
   found_job = job;
 }
 
 HostResolver::Job* HostResolver::FindOutstandingJob(
     const std::string& hostname) {
   JobMap::iterator it = jobs_.find(hostname);
   if (it != jobs_.end())
@@ skipping 115 matching lines @@
 
   // Clear the outstanding request information.
   cur_request_ = NULL;
   cur_request_callback_ = NULL;
 
   // Call the user's original callback.
   callback->Run(result);
 }
 
 }  // namespace net