net/http/http_cache_transaction.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file declares HttpCache::Transaction, a private class of HttpCache so
   6 // it should only be included by http_cache.cc
   7
   8 #ifndef NET_HTTP_HTTP_CACHE_TRANSACTION_H_
   9 #define NET_HTTP_HTTP_CACHE_TRANSACTION_H_
  10
  11 #include <string>
  12
  13 #include "base/time/time.h"
  14 #include "net/base/completion_callback.h"
  15 #include "net/base/net_log.h"
  16 #include "net/base/request_priority.h"
  17 #include "net/http/http_cache.h"
  18 #include "net/http/http_request_headers.h"
  19 #include "net/http/http_response_info.h"
  20 #include "net/http/http_transaction.h"
  21
  22 namespace net {
  23
  24 class PartialData;
  25 struct HttpRequestInfo;
  26 struct LoadTimingInfo;
  27
  28 // This is the transaction that is returned by the HttpCache transaction
  29 // factory.
  30 class HttpCache::Transaction : public HttpTransaction {
  31  public:
  32   // The transaction has the following modes, which apply to how it may access
  33   // its cache entry.
  34   //
  35   //  o If the mode of the transaction is NONE, then it is in "pass through"
  36   //    mode and all methods just forward to the inner network transaction.
  37   //
  38   //  o If the mode of the transaction is only READ, then it may only read from
  39   //    the cache entry.
  40   //
  41   //  o If the mode of the transaction is only WRITE, then it may only write to
  42   //    the cache entry.
  43   //
  44   //  o If the mode of the transaction is READ_WRITE, then the transaction may
  45   //    optionally modify the cache entry (e.g., possibly corresponding to
  46   //    cache validation).
  47   //
  48   //  o If the mode of the transaction is UPDATE, then the transaction may
  49   //    update existing cache entries, but will never create a new entry or
  50   //    respond using the entry read from the cache.
  51   enum Mode {
  52     NONE            = 0,
  53     READ_META       = 1 << 0,
  54     READ_DATA       = 1 << 1,
  55     READ            = READ_META | READ_DATA,
  56     WRITE           = 1 << 2,
  57     READ_WRITE      = READ | WRITE,
  58     UPDATE          = READ_META | WRITE,  // READ_WRITE & ~READ_DATA
  59   };
  60
  61   Transaction(RequestPriority priority,
  62               HttpCache* cache);
  63   virtual ~Transaction();
  64
  65   Mode mode() const { return mode_; }
  66
  67   const std::string& key() const { return cache_key_; }
  68
  69   // Writes |buf_len| bytes of meta-data from the provided buffer |buf|. to the
  70   // HTTP cache entry that backs this transaction (if any).
  71   // Returns the number of bytes actually written, or a net error code. If the
  72   // operation cannot complete immediately, returns ERR_IO_PENDING, grabs a
  73   // reference to the buffer (until completion), and notifies the caller using
  74   // the provided |callback| when the operation finishes.
  75   //
  76   // The first time this method is called for a given transaction, previous
  77   // meta-data will be overwritten with the provided data, and subsequent
  78   // invocations will keep appending to the cached entry.
  79   //
  80   // In order to guarantee that the metadata is set to the correct entry, the
  81   // response (or response info) must be evaluated by the caller, for instance
  82   // to make sure that the response_time is as expected, before calling this
  83   // method.
  84   int WriteMetadata(IOBuffer* buf,
  85                     int buf_len,
  86                     const CompletionCallback& callback);
  87
  88   // This transaction is being deleted and we are not done writing to the cache.
  89   // We need to indicate that the response data was truncated.  Returns true on
  90   // success. Keep in mind that this operation may have side effects, such as
  91   // deleting the active entry.
  92   bool AddTruncatedFlag();
  93
  94   HttpCache::ActiveEntry* entry() { return entry_; }
  95
  96   // Returns the LoadState of the writer transaction of a given ActiveEntry. In
  97   // other words, returns the LoadState of this transaction without asking the
  98   // http cache, because this transaction should be the one currently writing
  99   // to the cache entry.
 100   LoadState GetWriterLoadState() const;
 101
 102   const CompletionCallback& io_callback() { return io_callback_; }
 103
 104   const BoundNetLog& net_log() const;
 105
 106   // Bypasses the cache lock whenever there is lock contention.
 107   void BypassLockForTest() {
 108     bypass_lock_for_test_ = true;
 109   }
 110
 111   // HttpTransaction methods:
 112   virtual int Start(const HttpRequestInfo* request_info,
 113                     const CompletionCallback& callback,
 114                     const BoundNetLog& net_log) OVERRIDE;
 115   virtual int RestartIgnoringLastError(
 116       const CompletionCallback& callback) OVERRIDE;
 117   virtual int RestartWithCertificate(
 118       X509Certificate* client_cert,
 119       const CompletionCallback& callback) OVERRIDE;
 120   virtual int RestartWithAuth(const AuthCredentials& credentials,
 121                               const CompletionCallback& callback) OVERRIDE;
 122   virtual bool IsReadyToRestartForAuth() OVERRIDE;
 123   virtual int Read(IOBuffer* buf,
 124                    int buf_len,
 125                    const CompletionCallback& callback) OVERRIDE;
 126   virtual void StopCaching() OVERRIDE;
 127   virtual bool GetFullRequestHeaders(
 128       HttpRequestHeaders* headers) const OVERRIDE;
 129   virtual int64 GetTotalReceivedBytes() const OVERRIDE;
 130   virtual void DoneReading() OVERRIDE;
 131   virtual const HttpResponseInfo* GetResponseInfo() const OVERRIDE;
 132   virtual LoadState GetLoadState() const OVERRIDE;
 133   virtual UploadProgress GetUploadProgress(void) const OVERRIDE;
 134   virtual void SetQuicServerInfo(QuicServerInfo* quic_server_info) OVERRIDE;
 135   virtual bool GetLoadTimingInfo(
 136       LoadTimingInfo* load_timing_info) const OVERRIDE;
 137   virtual void SetPriority(RequestPriority priority) OVERRIDE;
 138   virtual void SetWebSocketHandshakeStreamCreateHelper(
 139       net::WebSocketHandshakeStreamBase::CreateHelper* create_helper) OVERRIDE;
 140   virtual void SetBeforeNetworkStartCallback(
 141       const BeforeNetworkStartCallback& callback) OVERRIDE;
 142   virtual void SetBeforeProxyHeadersSentCallback(
 143       const BeforeProxyHeadersSentCallback& callback) OVERRIDE;
 144   virtual int ResumeNetworkStart() OVERRIDE;
 145
 146  private:
 147   static const size_t kNumValidationHeaders = 2;
 148   // Helper struct to pair a header name with its value, for
 149   // headers used to validate cache entries.
 150   struct ValidationHeaders {
 151     ValidationHeaders() : initialized(false) {}
 152
 153     std::string values[kNumValidationHeaders];
 154     bool initialized;
 155   };
 156
 157   enum State {
 158     STATE_NONE,
 159     STATE_GET_BACKEND,
 160     STATE_GET_BACKEND_COMPLETE,
 161     STATE_SEND_REQUEST,
 162     STATE_SEND_REQUEST_COMPLETE,
 163     STATE_SUCCESSFUL_SEND_REQUEST,
 164     STATE_NETWORK_READ,
 165     STATE_NETWORK_READ_COMPLETE,
 166     STATE_INIT_ENTRY,
 167     STATE_OPEN_ENTRY,
 168     STATE_OPEN_ENTRY_COMPLETE,
 169     STATE_CREATE_ENTRY,
 170     STATE_CREATE_ENTRY_COMPLETE,
 171     STATE_DOOM_ENTRY,
 172     STATE_DOOM_ENTRY_COMPLETE,
 173     STATE_ADD_TO_ENTRY,
 174     STATE_ADD_TO_ENTRY_COMPLETE,
 175     STATE_START_PARTIAL_CACHE_VALIDATION,
 176     STATE_COMPLETE_PARTIAL_CACHE_VALIDATION,
 177     STATE_UPDATE_CACHED_RESPONSE,
 178     STATE_UPDATE_CACHED_RESPONSE_COMPLETE,
 179     STATE_OVERWRITE_CACHED_RESPONSE,
 180     STATE_TRUNCATE_CACHED_DATA,
 181     STATE_TRUNCATE_CACHED_DATA_COMPLETE,
 182     STATE_TRUNCATE_CACHED_METADATA,
 183     STATE_TRUNCATE_CACHED_METADATA_COMPLETE,
 184     STATE_PARTIAL_HEADERS_RECEIVED,
 185     STATE_CACHE_READ_RESPONSE,
 186     STATE_CACHE_READ_RESPONSE_COMPLETE,
 187     STATE_CACHE_WRITE_RESPONSE,
 188     STATE_CACHE_WRITE_TRUNCATED_RESPONSE,
 189     STATE_CACHE_WRITE_RESPONSE_COMPLETE,
 190     STATE_CACHE_READ_METADATA,
 191     STATE_CACHE_READ_METADATA_COMPLETE,
 192     STATE_CACHE_QUERY_DATA,
 193     STATE_CACHE_QUERY_DATA_COMPLETE,
 194     STATE_CACHE_READ_DATA,
 195     STATE_CACHE_READ_DATA_COMPLETE,
 196     STATE_CACHE_WRITE_DATA,
 197     STATE_CACHE_WRITE_DATA_COMPLETE
 198   };
 199
 200   // Used for categorizing transactions for reporting in histograms. Patterns
 201   // cover relatively common use cases being measured and considered for
 202   // optimization. Many use cases that are more complex or uncommon are binned
 203   // as PATTERN_NOT_COVERED, and details are not reported.
 204   // NOTE: This enumeration is used in histograms, so please do not add entries
 205   // in the middle.
 206   enum TransactionPattern {
 207     PATTERN_UNDEFINED,
 208     PATTERN_NOT_COVERED,
 209     PATTERN_ENTRY_NOT_CACHED,
 210     PATTERN_ENTRY_USED,
 211     PATTERN_ENTRY_VALIDATED,
 212     PATTERN_ENTRY_UPDATED,
 213     PATTERN_ENTRY_CANT_CONDITIONALIZE,
 214     PATTERN_MAX,
 215   };
 216
 217   // This is a helper function used to trigger a completion callback.  It may
 218   // only be called if callback_ is non-null.
 219   void DoCallback(int rv);
 220
 221   // This will trigger the completion callback if appropriate.
 222   int HandleResult(int rv);
 223
 224   // Runs the state transition loop.
 225   int DoLoop(int result);
 226
 227   // Each of these methods corresponds to a State value.  If there is an
 228   // argument, the value corresponds to the return of the previous state or
 229   // corresponding callback.
 230   int DoGetBackend();
 231   int DoGetBackendComplete(int result);
 232   int DoSendRequest();
 233   int DoSendRequestComplete(int result);
 234   int DoSuccessfulSendRequest();
 235   int DoNetworkRead();
 236   int DoNetworkReadComplete(int result);
 237   int DoInitEntry();
 238   int DoOpenEntry();
 239   int DoOpenEntryComplete(int result);
 240   int DoCreateEntry();
 241   int DoCreateEntryComplete(int result);
 242   int DoDoomEntry();
 243   int DoDoomEntryComplete(int result);
 244   int DoAddToEntry();
 245   int DoAddToEntryComplete(int result);
 246   int DoStartPartialCacheValidation();
 247   int DoCompletePartialCacheValidation(int result);
 248   int DoUpdateCachedResponse();
 249   int DoUpdateCachedResponseComplete(int result);
 250   int DoOverwriteCachedResponse();
 251   int DoTruncateCachedData();
 252   int DoTruncateCachedDataComplete(int result);
 253   int DoTruncateCachedMetadata();
 254   int DoTruncateCachedMetadataComplete(int result);
 255   int DoPartialHeadersReceived();
 256   int DoCacheReadResponse();
 257   int DoCacheReadResponseComplete(int result);
 258   int DoCacheWriteResponse();
 259   int DoCacheWriteTruncatedResponse();
 260   int DoCacheWriteResponseComplete(int result);
 261   int DoCacheReadMetadata();
 262   int DoCacheReadMetadataComplete(int result);
 263   int DoCacheQueryData();
 264   int DoCacheQueryDataComplete(int result);
 265   int DoCacheReadData();
 266   int DoCacheReadDataComplete(int result);
 267   int DoCacheWriteData(int num_bytes);
 268   int DoCacheWriteDataComplete(int result);
 269
 270   // Sets request_ and fields derived from it.
 271   void SetRequest(const BoundNetLog& net_log, const HttpRequestInfo* request);
 272
 273   // Returns true if the request should be handled exclusively by the network
 274   // layer (skipping the cache entirely).
 275   bool ShouldPassThrough();
 276
 277   // Called to begin reading from the cache.  Returns network error code.
 278   int BeginCacheRead();
 279
 280   // Called to begin validating the cache entry.  Returns network error code.
 281   int BeginCacheValidation();
 282
 283   // Called to begin validating an entry that stores partial content.  Returns
 284   // a network error code.
 285   int BeginPartialCacheValidation();
 286
 287   // Validates the entry headers against the requested range and continues with
 288   // the validation of the rest of the entry.  Returns a network error code.
 289   int ValidateEntryHeadersAndContinue();
 290
 291   // Called to start requests which were given an "if-modified-since" or
 292   // "if-none-match" validation header by the caller (NOT when the request was
 293   // conditionalized internally in response to LOAD_VALIDATE_CACHE).
 294   // Returns a network error code.
 295   int BeginExternallyConditionalizedRequest();
 296
 297   // Called to restart a network transaction after an error.  Returns network
 298   // error code.
 299   int RestartNetworkRequest();
 300
 301   // Called to restart a network transaction with a client certificate.
 302   // Returns network error code.
 303   int RestartNetworkRequestWithCertificate(X509Certificate* client_cert);
 304
 305   // Called to restart a network transaction with authentication credentials.
 306   // Returns network error code.
 307   int RestartNetworkRequestWithAuth(const AuthCredentials& credentials);
 308
 309   // Called to determine if we need to validate the cache entry before using it.
 310   bool RequiresValidation();
 311
 312   // Called to make the request conditional (to ask the server if the cached
 313   // copy is valid).  Returns true if able to make the request conditional.
 314   bool ConditionalizeRequest();
 315
 316   // Makes sure that a 206 response is expected.  Returns true on success.
 317   // On success, handling_206_ will be set to true if we are processing a
 318   // partial entry.
 319   bool ValidatePartialResponse();
 320
 321   // Handles a response validation error by bypassing the cache.
 322   void IgnoreRangeRequest();
 323
 324   // Changes the response code of a range request to be 416 (Requested range not
 325   // satisfiable).
 326   void FailRangeRequest();
 327
 328   // Setups the transaction for reading from the cache entry.
 329   int SetupEntryForRead();
 330
 331   // Reads data from the network.
 332   int ReadFromNetwork(IOBuffer* data, int data_len);
 333
 334   // Reads data from the cache entry.
 335   int ReadFromEntry(IOBuffer* data, int data_len);
 336
 337   // Called to write data to the cache entry.  If the write fails, then the
 338   // cache entry is destroyed.  Future calls to this function will just do
 339   // nothing without side-effect.  Returns a network error code.
 340   int WriteToEntry(int index, int offset, IOBuffer* data, int data_len,
 341                    const CompletionCallback& callback);
 342
 343   // Called to write response_ to the cache entry. |truncated| indicates if the
 344   // entry should be marked as incomplete.
 345   int WriteResponseInfoToEntry(bool truncated);
 346
 347   // Called to append response data to the cache entry.  Returns a network error
 348   // code.
 349   int AppendResponseDataToEntry(IOBuffer* data, int data_len,
 350                                 const CompletionCallback& callback);
 351
 352   // Called when we are done writing to the cache entry.
 353   void DoneWritingToEntry(bool success);
 354
 355   // Returns an error to signal the caller that the current read failed. The
 356   // current operation |result| is also logged. If |restart| is true, the
 357   // transaction should be restarted.
 358   int OnCacheReadError(int result, bool restart);
 359
 360   // Called when the cache lock timeout fires.
 361   void OnAddToEntryTimeout(base::TimeTicks start_time);
 362
 363   // Deletes the current partial cache entry (sparse), and optionally removes
 364   // the control object (partial_).
 365   void DoomPartialEntry(bool delete_object);
 366
 367   // Performs the needed work after receiving data from the network, when
 368   // working with range requests.
 369   int DoPartialNetworkReadCompleted(int result);
 370
 371   // Performs the needed work after receiving data from the cache, when
 372   // working with range requests.
 373   int DoPartialCacheReadCompleted(int result);
 374
 375   // Restarts this transaction after deleting the cached data. It is meant to
 376   // be used when the current request cannot be fulfilled due to conflicts
 377   // between the byte range request and the cached entry.
 378   int DoRestartPartialRequest();
 379
 380   // Resets |network_trans_|, which must be non-NULL.  Also updates
 381   // |old_network_trans_load_timing_|, which must be NULL when this is called.
 382   void ResetNetworkTransaction();
 383
 384   // Returns true if we should bother attempting to resume this request if it
 385   // is aborted while in progress. If |has_data| is true, the size of the stored
 386   // data is considered for the result.
 387   bool CanResume(bool has_data);
 388
 389   void UpdateTransactionPattern(TransactionPattern new_transaction_pattern);
 390   void RecordHistograms();
 391
 392   // Called to signal completion of asynchronous IO.
 393   void OnIOComplete(int result);
 394
 395   State next_state_;
 396   const HttpRequestInfo* request_;
 397   RequestPriority priority_;
 398   BoundNetLog net_log_;
 399   scoped_ptr<HttpRequestInfo> custom_request_;
 400   HttpRequestHeaders request_headers_copy_;
 401   // If extra_headers specified a "if-modified-since" or "if-none-match",
 402   // |external_validation_| contains the value of those headers.
 403   ValidationHeaders external_validation_;
 404   base::WeakPtr<HttpCache> cache_;
 405   HttpCache::ActiveEntry* entry_;
 406   HttpCache::ActiveEntry* new_entry_;
 407   scoped_ptr<HttpTransaction> network_trans_;
 408   CompletionCallback callback_;  // Consumer's callback.
 409   HttpResponseInfo response_;
 410   HttpResponseInfo auth_response_;
 411   const HttpResponseInfo* new_response_;
 412   std::string cache_key_;
 413   Mode mode_;
 414   State target_state_;
 415   bool reading_;  // We are already reading. Never reverts to false once set.
 416   bool invalid_range_;  // We may bypass the cache for this request.
 417   bool truncated_;  // We don't have all the response data.
 418   bool is_sparse_;  // The data is stored in sparse byte ranges.
 419   bool range_requested_;  // The user requested a byte range.
 420   bool handling_206_;  // We must deal with this 206 response.
 421   bool cache_pending_;  // We are waiting for the HttpCache.
 422   bool done_reading_;  // All available data was read.
 423   bool vary_mismatch_;  // The request doesn't match the stored vary data.
 424   bool couldnt_conditionalize_request_;
 425   bool bypass_lock_for_test_;  // A test is exercising the cache lock.
 426   scoped_refptr<IOBuffer> read_buf_;
 427   int io_buf_len_;
 428   int read_offset_;
 429   int effective_load_flags_;
 430   int write_len_;
 431   scoped_ptr<PartialData> partial_;  // We are dealing with range requests.
 432   UploadProgress final_upload_progress_;
 433   base::WeakPtrFactory<Transaction> weak_factory_;
 434   CompletionCallback io_callback_;
 435
 436   // Members used to track data for histograms.
 437   TransactionPattern transaction_pattern_;
 438   base::TimeTicks entry_lock_waiting_since_;
 439   base::TimeTicks first_cache_access_since_;
 440   base::TimeTicks send_request_since_;
 441
 442   int64 total_received_bytes_;
 443
 444   // Load timing information for the last network request, if any.  Set in the
 445   // 304 and 206 response cases, as the network transaction may be destroyed
 446   // before the caller requests load timing information.
 447   scoped_ptr<LoadTimingInfo> old_network_trans_load_timing_;
 448
 449   // The helper object to use to create WebSocketHandshakeStreamBase
 450   // objects. Only relevant when establishing a WebSocket connection.
 451   // This is passed to the underlying network transaction. It is stored here in
 452   // case the transaction does not exist yet.
 453   WebSocketHandshakeStreamBase::CreateHelper*
 454       websocket_handshake_stream_base_create_helper_;
 455
 456   BeforeNetworkStartCallback before_network_start_callback_;
 457   BeforeProxyHeadersSentCallback before_proxy_headers_sent_callback_;
 458
 459   DISALLOW_COPY_AND_ASSIGN(Transaction);
 460 };
 461
 462 }  // namespace net
 463
 464 #endif  // NET_HTTP_HTTP_CACHE_TRANSACTION_H_