Fixes the cache lock issue.

net/http/http_cache_transaction.h

 // Copyright (c) 2012 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.
 
 // This file declares HttpCache::Transaction, a private class of HttpCache so
 // it should only be included by http_cache.cc
 
 #ifndef NET_HTTP_HTTP_CACHE_TRANSACTION_H_
 #define NET_HTTP_HTTP_CACHE_TRANSACTION_H_
 
@@ skipping 89 matching lines @@
   int WriteMetadata(IOBuffer* buf,
                     int buf_len,
                     const CompletionCallback& callback);
 
   // This transaction is being deleted and we are not done writing to the cache.
   // We need to indicate that the response data was truncated.  Returns true on
   // success. Keep in mind that this operation may have side effects, such as
   // deleting the active entry.
   bool AddTruncatedFlag();
 
-  HttpCache::ActiveEntry* entry() { return entry_; }
+  HttpCache::ActiveEntry* entry() const { return entry_; }
 
   // Returns the LoadState of the writer transaction of a given ActiveEntry. In
   // other words, returns the LoadState of this transaction without asking the
   // http cache, because this transaction should be the one currently writing
   // to the cache entry.
   LoadState GetWriterLoadState() const;
 
   const CompletionCallback& io_callback() { return io_callback_; }
 
+  base::WeakPtr<Transaction> GetWeakPtr() { return weak_factory_.GetWeakPtr(); }
+
   const NetLogWithSource& net_log() const;
 
   // Bypasses the cache lock whenever there is lock contention.
   void BypassLockForTest() {
     bypass_lock_for_test_ = true;
   }
 
   // Generates a failure when attempting to conditionalize a network request.
   void FailConditionalizationForTest() {
     fail_conditionalization_for_test_ = true;
@@ skipping 26 matching lines @@
   void PopulateNetErrorDetails(NetErrorDetails* details) const override;
   void SetPriority(RequestPriority priority) override;
   void SetWebSocketHandshakeStreamCreateHelper(
       WebSocketHandshakeStreamBase::CreateHelper* create_helper) override;
   void SetBeforeNetworkStartCallback(
       const BeforeNetworkStartCallback& callback) override;
   void SetBeforeHeadersSentCallback(
       const BeforeHeadersSentCallback& callback) override;
   int ResumeNetworkStart() override;
   void GetConnectionAttempts(ConnectionAttempts* out) const override;
+  RequestPriority priority() const { return priority_; }
+
+  bool shared() const { return shared_; }
+
+  // Sets shared_ to true.
+  void SetShared();
+
+  // Sets shared_ to false. Arguments tell if the transaction will continue to
+  // read from the network and whether the transaction will continue to read
+  // from the cache.
+  void ResetShared(bool continue_network_reading = false,
+                   bool continue_cache_reading = false);
+
+  // The transaction should now continue without shared writing and take the
+  // ownership of the network transaction object.
+  void ContinueWithoutSharedWriting(
+      std::unique_ptr<HttpTransaction> network_transaction,
+      bool needs_entry);
+
+  // Returns true if the transaction is eligible for reading from the
+  // network and writing to the cache along with other transactions.
+  // It is eligible if the following conditions are true:
+  // - Request’s mode is READ_WRITE. If mode is only READ then this
+  // transaction should wait until the whole response is in the cache.
+  // - Method is GET.
+  // - It is not a range request.
+  // - It is not a no-store data.
+  bool IsEligibleForSharedWriting() const;
+
+  // Any subsequent Read or IO callback should fail with the given result.
+  void SetSharedWritingFailState(int result);
 
  private:
   static const size_t kNumValidationHeaders = 2;
   // Helper struct to pair a header name with its value, for
   // headers used to validate cache entries.
   struct ValidationHeaders {
     ValidationHeaders() : initialized(false) {}
 
     std::string values[kNumValidationHeaders];
     bool initialized;
@@ skipping 33 matching lines @@
     STATE_CACHE_WRITE_RESPONSE,
     STATE_CACHE_WRITE_RESPONSE_COMPLETE,
     STATE_TRUNCATE_CACHED_DATA,
     STATE_TRUNCATE_CACHED_DATA_COMPLETE,
     STATE_TRUNCATE_CACHED_METADATA,
     STATE_TRUNCATE_CACHED_METADATA_COMPLETE,
     STATE_PARTIAL_HEADERS_RECEIVED,
     STATE_CACHE_READ_METADATA,
     STATE_CACHE_READ_METADATA_COMPLETE,
 
+    // Start states should always be before Read states.
     // These states are entered from Read/AddTruncatedFlag.
     STATE_NETWORK_READ,
     STATE_NETWORK_READ_COMPLETE,
-    STATE_CACHE_READ_DATA,
-    STATE_CACHE_READ_DATA_COMPLETE,
     STATE_CACHE_WRITE_DATA,
     STATE_CACHE_WRITE_DATA_COMPLETE,
     STATE_CACHE_WRITE_TRUNCATED_RESPONSE,
-    STATE_CACHE_WRITE_TRUNCATED_RESPONSE_COMPLETE
+    STATE_CACHE_WRITE_TRUNCATED_RESPONSE_COMPLETE,
+
+    // Shared Writing states.
+    STATE_SHARED_NETWORK_READ,
+    STATE_SHARED_NETWORK_READ_COMPLETE,
+    STATE_SHARED_NETWORK_READ_WAIT_COMPLETE,
+    STATE_SHARED_CACHE_WRITE_DATA,
+    STATE_SHARED_CACHE_WRITE_DATA_COMPLETE,
+
+    // Cache read states, also used for shared writing transactions when they
+    // are behind the data already written to the cache.
+    STATE_CACHE_READ_DATA,
+    STATE_CACHE_READ_DATA_COMPLETE,
+
+    // This state is reached for a shared writing transaction when there is a
+    // failure and any subsequent Read or IO callback should fail.
+    STATE_SHARED_READ_WRITE_FAILED
   };
 
   // Used for categorizing validation triggers in histograms.
   // NOTE: This enumeration is used in histograms, so please do not add entries
   // in the middle.
   enum ValidationCause {
     VALIDATION_CAUSE_UNDEFINED,
     VALIDATION_CAUSE_VARY_MISMATCH,
     VALIDATION_CAUSE_VALIDATE_FLAG,
     VALIDATION_CAUSE_STALE,
@@ skipping 46 matching lines @@
   int DoCacheReadMetadata();
   int DoCacheReadMetadataComplete(int result);
   int DoNetworkRead();
   int DoNetworkReadComplete(int result);
   int DoCacheReadData();
   int DoCacheReadDataComplete(int result);
   int DoCacheWriteData(int num_bytes);
   int DoCacheWriteDataComplete(int result);
   int DoCacheWriteTruncatedResponse();
   int DoCacheWriteTruncatedResponseComplete(int result);
+  int DoSharedNetworkRead();
+  int DoSharedNetworkReadComplete(int result);
+  int DoSharedNetworkReadWaitComplete(int result);
+  int DoSharedCacheWriteData(int num_bytes);
+  int DoSharedCacheWriteDataComplete(int result);
+  int DoSharedReadWriteFailed();
 
   // Sets request_ and fields derived from it.
   void SetRequest(const NetLogWithSource& net_log,
                   const HttpRequestInfo* request);
 
   // Returns true if the request should be handled exclusively by the network
   // layer (skipping the cache entirely).
   bool ShouldPassThrough();
 
   // Called to begin reading from the cache.  Returns network error code.
@@ skipping 63 matching lines @@
 
   // Helper function, should be called with result of WriteResponseInfoToEntry
   // (or the result of the callback, when WriteResponseInfoToEntry returns
   // ERR_IO_PENDING). Calls DoneWritingToEntry if |result| is not the right
   // number of bytes. It is expected that the state that calls this will
   // return whatever net error code this function returns, which currently
   // is always "OK".
   int OnWriteResponseInfoToEntryComplete(int result);
 
   // Called when we are done writing to the cache entry.
-  void DoneWritingToEntry(bool success);
+  // perform_entry_cleanup will be false if we just want to set the internal
+  // state of the transaction but do not want to invoke any cleanup operation on
+  // entry_ e.g. when it's already done by a SharedWriter callback function.
+  void DoneWritingToEntry(bool success, bool perform_entry_cleanup = true);
 
   // Returns an error to signal the caller that the current read failed. The
   // current operation |result| is also logged. If |restart| is true, the
   // transaction should be restarted.
   int OnCacheReadError(int result, bool restart);
 
   // Called when the cache lock timeout fires.
   void OnAddToEntryTimeout(base::TimeTicks start_time);
 
   // Deletes the current partial cache entry (sparse), and optionally removes
@@ skipping 14 matching lines @@
   int DoRestartPartialRequest();
 
   // Resets the relavant internal state to remove traces of internal processing
   // related to range requests. Deletes |partial_| if |delete_object| is true.
   void ResetPartialState(bool delete_object);
 
   // Resets |network_trans_|, which must be non-NULL.  Also updates
   // |old_network_trans_load_timing_|, which must be NULL when this is called.
   void ResetNetworkTransaction();
 
-  // Returns true if we should bother attempting to resume this request if it is
-  // aborted while in progress. If |has_data| is true, the size of the stored
-  // data is considered for the result.
-  bool CanResume(bool has_data);
+  void SaveNetworkTransactionInfo(const HttpTransaction* transaction);
+  void SaveSharedNetworkTransactionInfo();
+
+  // Returns the currently active network transaction.
+  // At any given point, at most one of the following can be non-null:
+  // - network_trans_(network transaction for headers),
+  // - entry_->shared_writers->network_transaction_ (network transaction for
+  // shared writing of response body).
+  HttpTransaction* GetCurrentNetworkTransaction() const;
 
   // Setter for response_ and auth_response_. It updates its cache entry status,
   // if needed.
   void SetResponse(const HttpResponseInfo& new_response);
   void SetAuthResponse(const HttpResponseInfo& new_response);
 
   void UpdateCacheEntryStatus(
       HttpResponseInfo::CacheEntryStatus new_cache_entry_status);
 
   // Sets the response.cache_entry_status to the current cache_entry_status_.
   void SyncCacheEntryStatusToResponse();
   void RecordHistograms();
 
+  // Checks if the transaction should create a SharedWriters object or not. If
+  // yes, creates one. Also checks if the transaction should continue to be part
+  // of an already created SharedWriters object or not based on its validation
+  // result.
+  void ProcessForSharedWriting();
+
+  // Returns true if the transaction is shared and still in the headers phase.
+  bool validating_shared() const;
+
+  // Destructor helper to remove the transaction from SharedWriters.
+  void RemoveTransactionFromSharedWriters();
+
+  // Helper function.
+  void OnCacheWriteDataComplete(bool was_shared, int* result);
+
   // Called to signal completion of asynchronous IO.
   void OnIOComplete(int result);
 
   State next_state_;
   const HttpRequestInfo* request_;
   RequestPriority priority_;
   NetLogWithSource net_log_;
   std::unique_ptr<HttpRequestInfo> custom_request_;
   HttpRequestHeaders request_headers_copy_;
+
   // If extra_headers specified a "if-modified-since" or "if-none-match",
   // |external_validation_| contains the value of those headers.
   ValidationHeaders external_validation_;
   base::WeakPtr<HttpCache> cache_;
   HttpCache::ActiveEntry* entry_;
   HttpCache::ActiveEntry* new_entry_;
   std::unique_ptr<HttpTransaction> network_trans_;
   CompletionCallback callback_;  // Consumer's callback.
   HttpResponseInfo response_;
   HttpResponseInfo auth_response_;
   const HttpResponseInfo* new_response_;
   std::string cache_key_;
   Mode mode_;
   bool reading_;  // We are already reading. Never reverts to false once set.
   bool invalid_range_;  // We may bypass the cache for this request.
   bool truncated_;  // We don't have all the response data.
   bool is_sparse_;  // The data is stored in sparse byte ranges.
   bool range_requested_;  // The user requested a byte range.
   bool handling_206_;  // We must deal with this 206 response.
   bool cache_pending_;  // We are waiting for the HttpCache.
   bool done_reading_;  // All available data was read.
   bool vary_mismatch_;  // The request doesn't match the stored vary data.
   bool couldnt_conditionalize_request_;
   bool bypass_lock_for_test_;  // A test is exercising the cache lock.
   bool fail_conditionalization_for_test_;  // Fail ConditionalizeRequest.
+
+  // Reads from the network and writes to the cache using a SharedWriters
+  // object.
+  bool shared_;
+
+  // Used for histograms.
+  bool initiate_shared_writing_;
+
+  // Result to be returned to the consumer on Read invocation when state is
+  // STATE_SHARED_READ_WRITE_FAILED.
+  int shared_read_write_failure_result_;
+
   scoped_refptr<IOBuffer> read_buf_;
   int io_buf_len_;
   int read_offset_;
   int effective_load_flags_;
   int write_len_;
   std::unique_ptr<PartialData> partial_;  // We are dealing with range requests.
   CompletionCallback io_callback_;
 
   // Members used to track data for histograms.
   // This cache_entry_status_ takes precedence over
@@ skipping 23 matching lines @@
   // The helper object to use to create WebSocketHandshakeStreamBase
   // objects. Only relevant when establishing a WebSocket connection.
   // This is passed to the underlying network transaction. It is stored here in
   // case the transaction does not exist yet.
   WebSocketHandshakeStreamBase::CreateHelper*
       websocket_handshake_stream_base_create_helper_;
 
   BeforeNetworkStartCallback before_network_start_callback_;
   BeforeHeadersSentCallback before_headers_sent_callback_;
 
+  bool have_full_request_headers_;
+  HttpRequestHeaders full_request_headers_;
+
   base::WeakPtrFactory<Transaction> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Transaction);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_TRANSACTION_H_