Revert of Remove the code to store and load QUIC server configs in the disk cache.

net/quic/chromium/quic_server_info.h

 // Copyright 2014 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_QUIC_CHROMIUM_QUIC_SERVER_INFO_H_
 #define NET_QUIC_CHROMIUM_QUIC_SERVER_INFO_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "net/base/completion_callback.h"
 #include "net/quic/core/quic_server_id.h"
 #include "net/quic/platform/api/quic_export.h"
 
 namespace net {
 
 // QuicServerInfo is an interface for fetching information about a QUIC server.
 // This information may be stored on disk so does not include keys or other
 // sensitive information. Primarily it's intended for caching the QUIC server's
 // crypto config.
 class QUIC_EXPORT_PRIVATE QuicServerInfo {
  public:
+  // Enum to track number of times data read/parse/write API calls of
+  // QuicServerInfo to and from disk cache is called.
+  enum QuicServerInfoAPICall {
+    QUIC_SERVER_INFO_START = 0,
+    QUIC_SERVER_INFO_WAIT_FOR_DATA_READY = 1,
+    QUIC_SERVER_INFO_PARSE = 2,
+    QUIC_SERVER_INFO_WAIT_FOR_DATA_READY_CANCEL = 3,
+    QUIC_SERVER_INFO_READY_TO_PERSIST = 4,
+    QUIC_SERVER_INFO_PERSIST = 5,
+    QUIC_SERVER_INFO_EXTERNAL_CACHE_HIT = 6,
+    QUIC_SERVER_INFO_RESET_WAIT_FOR_DATA_READY = 7,
+    QUIC_SERVER_INFO_NUM_OF_API_CALLS = 8,
+  };
+
   // Enum to track failure reasons to read/load/write of QuicServerInfo to
   // and from disk cache.
   enum FailureReason {
     WAIT_FOR_DATA_READY_INVALID_ARGUMENT_FAILURE = 0,
     GET_BACKEND_FAILURE = 1,
     OPEN_FAILURE = 2,
     CREATE_OR_OPEN_FAILURE = 3,
     PARSE_NO_DATA_FAILURE = 4,
     PARSE_FAILURE = 5,
     READ_FAILURE = 6,
     READY_TO_PERSIST_FAILURE = 7,
     PERSIST_NO_BACKEND_FAILURE = 8,
     WRITE_FAILURE = 9,
     NO_FAILURE = 10,
     PARSE_DATA_DECODE_FAILURE = 11,
     NUM_OF_FAILURES = 12,
   };
 
   explicit QuicServerInfo(const QuicServerId& server_id);
   virtual ~QuicServerInfo();
 
-  // Fetches the server config from the backing store, and returns true
-  // if the server config was found.
-  virtual bool Load() = 0;
+  // Start will commence the lookup. This must be called before any other
+  // methods. By opportunistically calling this early, it may be possible to
+  // overlap this object's lookup and reduce latency.
+  virtual void Start() = 0;
 
-  // Persist allows for the server information to be updated for future uses.
+  // WaitForDataReady returns OK if the fetch of the requested data has
+  // completed. Otherwise it returns ERR_IO_PENDING and will call |callback| on
+  // the current thread when ready.
+  //
+  // Only a single callback can be outstanding at a given time and, in the
+  // event that WaitForDataReady returns OK, it's the caller's responsibility
+  // to delete |callback|.
+  //
+  // |callback| may be NULL, in which case ERR_IO_PENDING may still be returned
+  // but, obviously, a callback will never be made.
+  virtual int WaitForDataReady(const CompletionCallback& callback) = 0;
+
+  // Reset's WaitForDataReady callback. This method shouldn't have any side
+  // effects (could be called even if HttpCache doesn't exist).
+  virtual void ResetWaitForDataReadyCallback() = 0;
+
+  // Cancel's WaitForDataReady callback. |callback| passed in WaitForDataReady
+  // will not be called.
+  virtual void CancelWaitForDataReadyCallback() = 0;
+
+  // Returns true if data is loaded from disk cache and ready (WaitForDataReady
+  // doesn't have a pending callback).
+  virtual bool IsDataReady() = 0;
+
+  // Returns true if the object is ready to persist data, in other words, if
+  // data is loaded from disk cache and ready and there are no pending writes.
+  virtual bool IsReadyToPersist() = 0;
+
+  // Persist allows for the server information to be updated for future users.
+  // This is a fire and forget operation: the caller may drop its reference
+  // from this object and the store operation will still complete. This can
+  // only be called once WaitForDataReady has returned OK or called its
+  // callback.
   virtual void Persist() = 0;
 
+  // Called whenever an external cache reuses quic server config.
+  virtual void OnExternalCacheHit() = 0;
+
   // Returns the size of dynamically allocated memory in bytes.
   virtual size_t EstimateMemoryUsage() const = 0;
 
   struct State {
     State();
     ~State();
 
     void Clear();
 
     // This class matches QuicClientCryptoConfig::CachedState.
     std::string server_config;         // A serialized handshake message.
     std::string source_address_token;  // An opaque proof of IP ownership.
     std::string cert_sct;              // Signed timestamp of the leaf cert.
     std::string chlo_hash;             // Hash of the CHLO message.
     std::vector<std::string> certs;    // A list of certificates in leaf-first
                                        // order.
     std::string server_config_sig;     // A signature of |server_config_|.
 
    private:
     DISALLOW_COPY_AND_ASSIGN(State);
   };
 
   // Once the data is ready, it can be read using the following members. These
   // members can then be updated before calling |Persist|.
   const State& state() const;
   State* mutable_state();
 
+  base::TimeTicks wait_for_data_start_time() const {
+    return wait_for_data_start_time_;
+  }
+
+  base::TimeTicks wait_for_data_end_time() const {
+    return wait_for_data_end_time_;
+  }
+
  protected:
   // Parse parses pickled data and fills out the public member fields of this
   // object. It returns true iff the parse was successful. The public member
   // fields will be set to something sane in any case.
   bool Parse(const std::string& data);
   std::string Serialize();
 
   State state_;
 
+  // Time when WaitForDataReady was called and when it has finished.
+  base::TimeTicks wait_for_data_start_time_;
+  base::TimeTicks wait_for_data_end_time_;
+
   // This is the QUIC server (hostname, port, is_https, privacy_mode) tuple for
   // which we restore the crypto_config.
   const QuicServerId server_id_;
 
  private:
   // ParseInner is a helper function for Parse.
   bool ParseInner(const std::string& data);
 
   // SerializeInner is a helper function for Serialize.
   std::string SerializeInner() const;
 
   DISALLOW_COPY_AND_ASSIGN(QuicServerInfo);
 };
 
+class QUIC_EXPORT_PRIVATE QuicServerInfoFactory {
+ public:
+  QuicServerInfoFactory() {}
+  virtual ~QuicServerInfoFactory();
+
+  // GetForServer returns a fresh, allocated QuicServerInfo for the given
+  // |server_id| or NULL on failure.
+  virtual std::unique_ptr<QuicServerInfo> GetForServer(
+      const QuicServerId& server_id) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(QuicServerInfoFactory);
+};
+
 }  // namespace net
 
 #endif  // NET_QUIC_CHROMIUM_QUIC_SERVER_INFO_H_