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   // HttpTransaction methods:
 107   virtual int Start(const HttpRequestInfo* request_info,
 108                     const CompletionCallback& callback,
 109                     const BoundNetLog& net_log) OVERRIDE;
 110   virtual int RestartIgnoringLastError(
 111       const CompletionCallback& callback) OVERRIDE;
 112   virtual int RestartWithCertificate(
 113       X509Certificate* client_cert,
 114       const CompletionCallback& callback) OVERRIDE;
 115   virtual int RestartWithAuth(const AuthCredentials& credentials,
 116                               const CompletionCallback& callback) OVERRIDE;
 117   virtual bool IsReadyToRestartForAuth() OVERRIDE;
 118   virtual int Read(IOBuffer* buf,
 119                    int buf_len,
 120                    const CompletionCallback& callback) OVERRIDE;
 121   virtual void StopCaching() OVERRIDE;
 122   virtual bool GetFullRequestHeaders(
 123       HttpRequestHeaders* headers) const OVERRIDE;
 124   virtual int64 GetTotalReceivedBytes() const OVERRIDE;
 125   virtual void DoneReading() OVERRIDE;
 126   virtual const HttpResponseInfo* GetResponseInfo() const OVERRIDE;
 127   virtual LoadState GetLoadState() const OVERRIDE;
 128   virtual UploadProgress GetUploadProgress(void) const OVERRIDE;
 129   virtual void SetQuicServerInfo(QuicServerInfo* quic_server_info) OVERRIDE;
 130   virtual bool GetLoadTimingInfo(
 131       LoadTimingInfo* load_timing_info) const OVERRIDE;
 132   virtual void SetPriority(RequestPriority priority) OVERRIDE;
 133   virtual void SetWebSocketHandshakeStreamCreateHelper(
 134       net::WebSocketHandshakeStreamBase::CreateHelper* create_helper) OVERRIDE;
 135   virtual void SetBeforeNetworkStartCallback(
 136       const BeforeNetworkStartCallback& callback) OVERRIDE;
 137   virtual int ResumeNetworkStart() OVERRIDE;
 138
 139  private:
 140   static const size_t kNumValidationHeaders = 2;
 141   // Helper struct to pair a header name with its value, for
 142   // headers used to validate cache entries.
 143   struct ValidationHeaders {
 144     ValidationHeaders() : initialized(false) {}
 145
 146     std::string values[kNumValidationHeaders];
 147     bool initialized;
 148   };
 149
 150   enum State {
 151     STATE_NONE,
 152     STATE_GET_BACKEND,
 153     STATE_GET_BACKEND_COMPLETE,
 154     STATE_SEND_REQUEST,
 155     STATE_SEND_REQUEST_COMPLETE,
 156     STATE_SUCCESSFUL_SEND_REQUEST,
 157     STATE_NETWORK_READ,
 158     STATE_NETWORK_READ_COMPLETE,
 159     STATE_INIT_ENTRY,
 160     STATE_OPEN_ENTRY,
 161     STATE_OPEN_ENTRY_COMPLETE,
 162     STATE_CREATE_ENTRY,
 163     STATE_CREATE_ENTRY_COMPLETE,
 164     STATE_DOOM_ENTRY,
 165     STATE_DOOM_ENTRY_COMPLETE,
 166     STATE_ADD_TO_ENTRY,
 167     STATE_ADD_TO_ENTRY_COMPLETE,
 168     STATE_START_PARTIAL_CACHE_VALIDATION,
 169     STATE_COMPLETE_PARTIAL_CACHE_VALIDATION,
 170     STATE_UPDATE_CACHED_RESPONSE,
 171     STATE_UPDATE_CACHED_RESPONSE_COMPLETE,
 172     STATE_OVERWRITE_CACHED_RESPONSE,
 173     STATE_TRUNCATE_CACHED_DATA,
 174     STATE_TRUNCATE_CACHED_DATA_COMPLETE,
 175     STATE_TRUNCATE_CACHED_METADATA,
 176     STATE_TRUNCATE_CACHED_METADATA_COMPLETE,
 177     STATE_PARTIAL_HEADERS_RECEIVED,
 178     STATE_CACHE_READ_RESPONSE,
 179     STATE_CACHE_READ_RESPONSE_COMPLETE,
 180     STATE_CACHE_WRITE_RESPONSE,
 181     STATE_CACHE_WRITE_TRUNCATED_RESPONSE,
 182     STATE_CACHE_WRITE_RESPONSE_COMPLETE,
 183     STATE_CACHE_READ_METADATA,
 184     STATE_CACHE_READ_METADATA_COMPLETE,
 185     STATE_CACHE_QUERY_DATA,
 186     STATE_CACHE_QUERY_DATA_COMPLETE,
 187     STATE_CACHE_READ_DATA,
 188     STATE_CACHE_READ_DATA_COMPLETE,
 189     STATE_CACHE_WRITE_DATA,
 190     STATE_CACHE_WRITE_DATA_COMPLETE
 191   };
 192
 193   // Used for categorizing transactions for reporting in histograms. Patterns
 194   // cover relatively common use cases being measured and considered for
 195   // optimization. Many use cases that are more complex or uncommon are binned
 196   // as PATTERN_NOT_COVERED, and details are not reported.
 197   // NOTE: This enumeration is used in histograms, so please do not add entries
 198   // in the middle.
 199   enum TransactionPattern {
 200     PATTERN_UNDEFINED,
 201     PATTERN_NOT_COVERED,
 202     PATTERN_ENTRY_NOT_CACHED,
 203     PATTERN_ENTRY_USED,
 204     PATTERN_ENTRY_VALIDATED,
 205     PATTERN_ENTRY_UPDATED,
 206     PATTERN_ENTRY_CANT_CONDITIONALIZE,
 207     PATTERN_MAX,
 208   };
 209
 210   // This is a helper function used to trigger a completion callback.  It may
 211   // only be called if callback_ is non-null.
 212   void DoCallback(int rv);
 213
 214   // This will trigger the completion callback if appropriate.
 215   int HandleResult(int rv);
 216
 217   // Runs the state transition loop.
 218   int DoLoop(int result);
 219
 220   // Each of these methods corresponds to a State value.  If there is an
 221   // argument, the value corresponds to the return of the previous state or
 222   // corresponding callback.
 223   int DoGetBackend();
 224   int DoGetBackendComplete(int result);
 225   int DoSendRequest();
 226   int DoSendRequestComplete(int result);
 227   int DoSuccessfulSendRequest();
 228   int DoNetworkRead();
 229   int DoNetworkReadComplete(int result);
 230   int DoInitEntry();
 231   int DoOpenEntry();
 232   int DoOpenEntryComplete(int result);
 233   int DoCreateEntry();
 234   int DoCreateEntryComplete(int result);
 235   int DoDoomEntry();
 236   int DoDoomEntryComplete(int result);
 237   int DoAddToEntry();
 238   int DoAddToEntryComplete(int result);
 239   int DoStartPartialCacheValidation();
 240   int DoCompletePartialCacheValidation(int result);
 241   int DoUpdateCachedResponse();
 242   int DoUpdateCachedResponseComplete(int result);
 243   int DoOverwriteCachedResponse();
 244   int DoTruncateCachedData();
 245   int DoTruncateCachedDataComplete(int result);
 246   int DoTruncateCachedMetadata();
 247   int DoTruncateCachedMetadataComplete(int result);
 248   int DoPartialHeadersReceived();
 249   int DoCacheReadResponse();
 250   int DoCacheReadResponseComplete(int result);
 251   int DoCacheWriteResponse();
 252   int DoCacheWriteTruncatedResponse();
 253   int DoCacheWriteResponseComplete(int result);
 254   int DoCacheReadMetadata();
 255   int DoCacheReadMetadataComplete(int result);
 256   int DoCacheQueryData();
 257   int DoCacheQueryDataComplete(int result);
 258   int DoCacheReadData();
 259   int DoCacheReadDataComplete(int result);
 260   int DoCacheWriteData(int num_bytes);
 261   int DoCacheWriteDataComplete(int result);
 262
 263   // Sets request_ and fields derived from it.
 264   void SetRequest(const BoundNetLog& net_log, const HttpRequestInfo* request);
 265
 266   // Returns true if the request should be handled exclusively by the network
 267   // layer (skipping the cache entirely).
 268   bool ShouldPassThrough();
 269
 270   // Called to begin reading from the cache.  Returns network error code.
 271   int BeginCacheRead();
 272
 273   // Called to begin validating the cache entry.  Returns network error code.
 274   int BeginCacheValidation();
 275
 276   // Called to begin validating an entry that stores partial content.  Returns
 277   // a network error code.
 278   int BeginPartialCacheValidation();
 279
 280   // Validates the entry headers against the requested range and continues with
 281   // the validation of the rest of the entry.  Returns a network error code.
 282   int ValidateEntryHeadersAndContinue();
 283
 284   // Called to start requests which were given an "if-modified-since" or
 285   // "if-none-match" validation header by the caller (NOT when the request was
 286   // conditionalized internally in response to LOAD_VALIDATE_CACHE).
 287   // Returns a network error code.
 288   int BeginExternallyConditionalizedRequest();
 289
 290   // Called to restart a network transaction after an error.  Returns network
 291   // error code.
 292   int RestartNetworkRequest();
 293
 294   // Called to restart a network transaction with a client certificate.
 295   // Returns network error code.
 296   int RestartNetworkRequestWithCertificate(X509Certificate* client_cert);
 297
 298   // Called to restart a network transaction with authentication credentials.
 299   // Returns network error code.
 300   int RestartNetworkRequestWithAuth(const AuthCredentials& credentials);
 301
 302   // Called to determine if we need to validate the cache entry before using it.
 303   bool RequiresValidation();
 304
 305   // Called to make the request conditional (to ask the server if the cached
 306   // copy is valid).  Returns true if able to make the request conditional.
 307   bool ConditionalizeRequest();
 308
 309   // Makes sure that a 206 response is expected.  Returns true on success.
 310   // On success, handling_206_ will be set to true if we are processing a
 311   // partial entry.
 312   bool ValidatePartialResponse();
 313
 314   // Handles a response validation error by bypassing the cache.
 315   void IgnoreRangeRequest();
 316
 317   // Changes the response code of a range request to be 416 (Requested range not
 318   // satisfiable).
 319   void FailRangeRequest();
 320
 321   // Setups the transaction for reading from the cache entry.
 322   int SetupEntryForRead();
 323
 324   // Reads data from the network.
 325   int ReadFromNetwork(IOBuffer* data, int data_len);
 326
 327   // Reads data from the cache entry.
 328   int ReadFromEntry(IOBuffer* data, int data_len);
 329
 330   // Called to write data to the cache entry.  If the write fails, then the
 331   // cache entry is destroyed.  Future calls to this function will just do
 332   // nothing without side-effect.  Returns a network error code.
 333   int WriteToEntry(int index, int offset, IOBuffer* data, int data_len,
 334                    const CompletionCallback& callback);
 335
 336   // Called to write response_ to the cache entry. |truncated| indicates if the
 337   // entry should be marked as incomplete.
 338   int WriteResponseInfoToEntry(bool truncated);
 339
 340   // Called to append response data to the cache entry.  Returns a network error
 341   // code.
 342   int AppendResponseDataToEntry(IOBuffer* data, int data_len,
 343                                 const CompletionCallback& callback);
 344
 345   // Called when we are done writing to the cache entry.
 346   void DoneWritingToEntry(bool success);
 347
 348   // Returns an error to signal the caller that the current read failed. The
 349   // current operation |result| is also logged. If |restart| is true, the
 350   // transaction should be restarted.
 351   int OnCacheReadError(int result, bool restart);
 352
 353   // Deletes the current partial cache entry (sparse), and optionally removes
 354   // the control object (partial_).
 355   void DoomPartialEntry(bool delete_object);
 356
 357   // Performs the needed work after receiving data from the network, when
 358   // working with range requests.
 359   int DoPartialNetworkReadCompleted(int result);
 360
 361   // Performs the needed work after receiving data from the cache, when
 362   // working with range requests.
 363   int DoPartialCacheReadCompleted(int result);
 364
 365   // Restarts this transaction after deleting the cached data. It is meant to
 366   // be used when the current request cannot be fulfilled due to conflicts
 367   // between the byte range request and the cached entry.
 368   int DoRestartPartialRequest();
 369
 370   // Resets |network_trans_|, which must be non-NULL.  Also updates
 371   // |old_network_trans_load_timing_|, which must be NULL when this is called.
 372   void ResetNetworkTransaction();
 373
 374   // Returns true if we should bother attempting to resume this request if it
 375   // is aborted while in progress. If |has_data| is true, the size of the stored
 376   // data is considered for the result.
 377   bool CanResume(bool has_data);
 378
 379   void UpdateTransactionPattern(TransactionPattern new_transaction_pattern);
 380   void RecordHistograms();
 381
 382   // Called to signal completion of asynchronous IO.
 383   void OnIOComplete(int result);
 384
 385   State next_state_;
 386   const HttpRequestInfo* request_;
 387   RequestPriority priority_;
 388   BoundNetLog net_log_;
 389   scoped_ptr<HttpRequestInfo> custom_request_;
 390   HttpRequestHeaders request_headers_copy_;
 391   // If extra_headers specified a "if-modified-since" or "if-none-match",
 392   // |external_validation_| contains the value of those headers.
 393   ValidationHeaders external_validation_;
 394   base::WeakPtr<HttpCache> cache_;
 395   HttpCache::ActiveEntry* entry_;
 396   HttpCache::ActiveEntry* new_entry_;
 397   scoped_ptr<HttpTransaction> network_trans_;
 398   CompletionCallback callback_;  // Consumer's callback.
 399   HttpResponseInfo response_;
 400   HttpResponseInfo auth_response_;
 401   const HttpResponseInfo* new_response_;
 402   std::string cache_key_;
 403   Mode mode_;
 404   State target_state_;
 405   bool reading_;  // We are already reading. Never reverts to false once set.
 406   bool invalid_range_;  // We may bypass the cache for this request.
 407   bool truncated_;  // We don't have all the response data.
 408   bool is_sparse_;  // The data is stored in sparse byte ranges.
 409   bool range_requested_;  // The user requested a byte range.
 410   bool handling_206_;  // We must deal with this 206 response.
 411   bool cache_pending_;  // We are waiting for the HttpCache.
 412   bool done_reading_;  // All available data was read.
 413   bool vary_mismatch_;  // The request doesn't match the stored vary data.
 414   bool couldnt_conditionalize_request_;
 415   scoped_refptr<IOBuffer> read_buf_;
 416   int io_buf_len_;
 417   int read_offset_;
 418   int effective_load_flags_;
 419   int write_len_;
 420   scoped_ptr<PartialData> partial_;  // We are dealing with range requests.
 421   UploadProgress final_upload_progress_;
 422   base::WeakPtrFactory<Transaction> weak_factory_;
 423   CompletionCallback io_callback_;
 424
 425   // Members used to track data for histograms.
 426   TransactionPattern transaction_pattern_;
 427   base::TimeTicks entry_lock_waiting_since_;
 428   base::TimeTicks first_cache_access_since_;
 429   base::TimeTicks send_request_since_;
 430
 431   int64 total_received_bytes_;
 432
 433   // Load timing information for the last network request, if any.  Set in the
 434   // 304 and 206 response cases, as the network transaction may be destroyed
 435   // before the caller requests load timing information.
 436   scoped_ptr<LoadTimingInfo> old_network_trans_load_timing_;
 437
 438   // The helper object to use to create WebSocketHandshakeStreamBase
 439   // objects. Only relevant when establishing a WebSocket connection.
 440   // This is passed to the underlying network transaction. It is stored here in
 441   // case the transaction does not exist yet.
 442   WebSocketHandshakeStreamBase::CreateHelper*
 443       websocket_handshake_stream_base_create_helper_;
 444
 445   BeforeNetworkStartCallback before_network_start_callback_;
 446
 447   DISALLOW_COPY_AND_ASSIGN(Transaction);
 448 };
 449
 450 }  // namespace net
 451
 452 #endif  // NET_HTTP_HTTP_CACHE_TRANSACTION_H_