1 files changed, 136 insertions, 0 deletions
diff --git a/net/base/host_resolver_impl.h b/net/base/host_resolver_impl.h
new file mode 100644
index 0000000..6ece456
--- /dev/null
+++ b/net/base/host_resolver_impl.h
@@ -0,0 +1,136 @@
+// 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.
+
+#ifndef NET_BASE_HOST_RESOLVER_IMPL_H_
+#define NET_BASE_HOST_RESOLVER_IMPL_H_
+
+#include <string>
+#include <vector>
+
+#include "net/base/host_cache.h"
+#include "net/base/host_resolver.h"
+#include "net/base/host_resolver_proc.h"
+
+namespace net {
+
+// For each hostname that is requested, HostResolver creates a
+// HostResolverImpl::Job. This job gets dispatched to a thread in the global
+// WorkerPool, where it runs SystemHostResolverProc(). If requests for that same
+// host are made while the job is already outstanding, then they are attached
+// to the existing job rather than creating a new one. This avoids doing
+// parallel resolves for the same host.
+//
+// The way these classes fit together is illustrated by:
+//
+//
+//            +----------- HostResolverImpl -------------+
+//            |                    |                     |
+//           Job                  Job                   Job
+//       (for host1)          (for host2)           (for hostX)
+//       /    |   |            /   |   |             /   |   |
+//   Request ... Request  Request ... Request   Request ... Request
+//  (port1)     (port2)  (port3)      (port4)  (port5)      (portX)
+//
+//
+// When a HostResolverImpl::Job finishes its work in the threadpool, the
+// callbacks of each waiting request are run on the origin thread.
+//
+// Thread safety: This class is not threadsafe, and must only be called
+// from one thread!
+//
+class HostResolverImpl : public HostResolver {
+ public:
+  // Creates a HostResolver that caches up to |max_cache_entries| for
+  // |cache_duration_ms| milliseconds. |resolver_proc| is used to perform
+  // the actual resolves; it must be thread-safe since it is run from
+  // multiple worker threads. If |resolver_proc| is NULL then the default
+  // host resolver procedure is used (which is SystemHostResolverProc except
+  // if overridden)
+  HostResolverImpl(HostResolverProc* resolver_proc,
+                   int max_cache_entries,
+                   int cache_duration_ms);
+
+  // If any completion callbacks are pending when the resolver is destroyed,
+  // the host resolutions are cancelled, and the completion callbacks will not
+  // be called.
+  virtual ~HostResolverImpl();
+
+  // HostResolver methods:
+  virtual int Resolve(const RequestInfo& info, AddressList* addresses,
+                      CompletionCallback* callback, RequestHandle* out_req);
+  virtual void CancelRequest(RequestHandle req);
+  virtual void AddObserver(Observer* observer);
+  virtual void RemoveObserver(Observer* observer);
+
+  // TODO(eroman): temp hack for http://crbug.com/15513
+  virtual void Shutdown();
+
+ private:
+  class Job;
+  class Request;
+  typedef std::vector<Request*> RequestsList;
+  typedef base::hash_map<std::string, scoped_refptr<Job> > JobMap;
+  typedef std::vector<Observer*> ObserversList;
+
+  // Returns the HostResolverProc to use for this instance.
+  HostResolverProc* effective_resolver_proc() const {
+    return resolver_proc_ ?
+        resolver_proc_.get() : HostResolverProc::GetDefault();
+  }
+
+  // Adds a job to outstanding jobs list.
+  void AddOutstandingJob(Job* job);
+
+  // Returns the outstanding job for |hostname|, or NULL if there is none.
+  Job* FindOutstandingJob(const std::string& hostname);
+
+  // Removes |job| from the outstanding jobs list.
+  void RemoveOutstandingJob(Job* job);
+
+  // Callback for when |job| has completed with |error| and |addrlist|.
+  void OnJobComplete(Job* job, int error, const AddressList& addrlist);
+
+  // Notify all observers of the start of a resolve request.
+  void NotifyObserversStartRequest(int request_id,
+                                   const RequestInfo& info);
+
+  // Notify all observers of the completion of a resolve request.
+  void NotifyObserversFinishRequest(int request_id,
+                                    const RequestInfo& info,
+                                    int error);
+
+  // Notify all observers of the cancellation of a resolve request.
+  void NotifyObserversCancelRequest(int request_id,
+                                    const RequestInfo& info);
+
+  // Cache of host resolution results.
+  HostCache cache_;
+
+  // Map from hostname to outstanding job.
+  JobMap jobs_;
+
+  // The job that OnJobComplete() is currently processing (needed in case
+  // HostResolver gets deleted from within the callback).
+  scoped_refptr<Job> cur_completing_job_;
+
+  // The observers to notify when a request starts/ends.
+  ObserversList observers_;
+
+  // Monotonically increasing ID number to assign to the next request.
+  // Observers are the only consumers of this ID number.
+  int next_request_id_;
+
+  // The procedure to use for resolving host names. This will be NULL, except
+  // in the case of unit-tests which inject custom host resolving behaviors.
+  scoped_refptr<HostResolverProc> resolver_proc_;
+
+  // TODO(eroman): temp hack for http://crbug.com/15513
+  bool shutdown_;
+
+  DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_HOST_RESOLVER_IMPL_H_