Http Cache: Split HttpCache::Transaction to its own set...

net/http/http_cache_transaction.h

-// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.

[rvargas (doing something else), 2009/11/11 02:02:47]

Year already fixed.

 // 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_
+
 #include "net/http/http_cache.h"
-
-#include <algorithm>
-#include <string>
-
-#include "base/compiler_specific.h"
-
-#if defined(OS_POSIX)
-#include <unistd.h>
-#endif
-
-#include "base/message_loop.h"
-#include "base/pickle.h"
-#include "base/ref_counted.h"
-#include "base/string_util.h"
-#include "base/time.h"
-#include "net/base/io_buffer.h"
-#include "net/base/load_flags.h"
-#include "net/base/load_log.h"
-#include "net/base/net_errors.h"
-#include "net/base/ssl_cert_request_info.h"
-#include "net/disk_cache/disk_cache.h"
-#include "net/http/http_network_layer.h"
-#include "net/http/http_network_session.h"
-#include "net/http/http_request_info.h"
-#include "net/http/http_response_headers.h"
 #include "net/http/http_response_info.h"
 #include "net/http/http_transaction.h"
-#include "net/http/http_util.h"
-#include "net/http/partial_data.h"
-
-using base::Time;
 
 namespace net {
 
-// disk cache entry data indices.
-enum {
-  kResponseInfoIndex,
-  kResponseContentIndex
-};
+class HttpResponseHeaders;
+class PartialData;
 
-//-----------------------------------------------------------------------------
-
-struct HeaderNameAndValue {
-  const char* name;
-  const char* value;
-};
-
-// If the request includes one of these request headers, then avoid caching
-// to avoid getting confused.
-static const HeaderNameAndValue kPassThroughHeaders[] = {
-  { "if-unmodified-since", NULL },  // causes unexpected 412s
-  { "if-match", NULL },             // causes unexpected 412s
-  { "if-range", NULL },
-  { NULL, NULL }
-};
-
-struct ValidationHeaderInfo {
-  const char* request_header_name;
-  const char* related_response_header_name;
-};
-
-static const ValidationHeaderInfo kValidationHeaders[] = {
-  { "if-modified-since", "last-modified" },
-  { "if-none-match", "etag" },
-};
-
-// 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[ARRAYSIZE_UNSAFE(kValidationHeaders)];
-  bool initialized;
-};
-
-// If the request includes one of these request headers, then avoid reusing
-// our cached copy if any.
-static const HeaderNameAndValue kForceFetchHeaders[] = {
-  { "cache-control", "no-cache" },
-  { "pragma", "no-cache" },
-  { NULL, NULL }
-};
-
-// If the request includes one of these request headers, then force our
-// cached copy (if any) to be revalidated before reusing it.
-static const HeaderNameAndValue kForceValidateHeaders[] = {
-  { "cache-control", "max-age=0" },
-  { NULL, NULL }
-};
-
-static bool HeaderMatches(const HttpUtil::HeadersIterator& h,
-                          const HeaderNameAndValue* search) {
-  for (; search->name; ++search) {
-    if (!LowerCaseEqualsASCII(h.name_begin(), h.name_end(), search->name))
-      continue;
-
-    if (!search->value)
-      return true;
-
-    HttpUtil::ValuesIterator v(h.values_begin(), h.values_end(), ',');
-    while (v.GetNext()) {
-      if (LowerCaseEqualsASCII(v.value_begin(), v.value_end(), search->value))
-        return true;
-    }
-  }
-  return false;
-}
-
-//-----------------------------------------------------------------------------
-
-HttpCache::ActiveEntry::ActiveEntry(disk_cache::Entry* e)
-    : disk_entry(e),
-      writer(NULL),
-      will_process_pending_queue(false),
-      doomed(false) {
-}
-
-HttpCache::ActiveEntry::~ActiveEntry() {
-  if (disk_entry)
-    disk_entry->Close();
-}
-
-//-----------------------------------------------------------------------------
-
+// This is the transaction that is returned by the HttpCache transaction
+// factory.
 class HttpCache::Transaction : public HttpTransaction {
  public:
-  Transaction(HttpCache* cache, bool enable_range_support)
-      : request_(NULL),
-        cache_(cache->AsWeakPtr()),
-        entry_(NULL),
-        network_trans_(NULL),
-        callback_(NULL),
-        mode_(NONE),
-        reading_(false),
-        invalid_range_(false),
-        enable_range_support_(enable_range_support),
-        truncated_(false),
-        read_offset_(0),
-        effective_load_flags_(0),
-        final_upload_progress_(0),
-        ALLOW_THIS_IN_INITIALIZER_LIST(
-            network_info_callback_(this, &Transaction::OnNetworkInfoAvailable)),
-        ALLOW_THIS_IN_INITIALIZER_LIST(
-            network_read_callback_(this, &Transaction::OnNetworkReadCompleted)),
-        ALLOW_THIS_IN_INITIALIZER_LIST(
-            cache_read_callback_(new CancelableCompletionCallback<Transaction>(
-                this, &Transaction::OnCacheReadCompleted))),
-        ALLOW_THIS_IN_INITIALIZER_LIST(
-            cache_write_callback_(new CancelableCompletionCallback<Transaction>(
-                this, &Transaction::OnCacheWriteCompleted))),
-        ALLOW_THIS_IN_INITIALIZER_LIST(
-            entry_ready_callback_(new CancelableCompletionCallback<Transaction>(
-                this, &Transaction::OnCacheEntryReady))) {
-  }
-
-  // Clean up the transaction.
+  Transaction(HttpCache* cache, bool enable_range_support);
   virtual ~Transaction();
 
   // HttpTransaction methods:
   virtual int Start(const HttpRequestInfo*, CompletionCallback*, LoadLog*);
-  virtual int RestartIgnoringLastError(CompletionCallback*);
+  virtual int RestartIgnoringLastError(CompletionCallback* callback);
   virtual int RestartWithCertificate(X509Certificate* client_cert,
                                      CompletionCallback* callback);
   virtual int RestartWithAuth(const std::wstring& username,
                               const std::wstring& password,
                               CompletionCallback* callback);
   virtual bool IsReadyToRestartForAuth();
-  virtual int Read(IOBuffer* buf, int buf_len, CompletionCallback*);
+  virtual int Read(IOBuffer* buf, int buf_len, CompletionCallback* callback);
   virtual const HttpResponseInfo* GetResponseInfo() const;
   virtual LoadState GetLoadState() const;
   virtual uint64 GetUploadProgress(void) const;
 
   // The transaction has the following modes, which apply to how it may access
   // its cache entry.
   //
   //  o If the mode of the transaction is NONE, then it is in "pass through"
   //    mode and all methods just forward to the inner network transaction.
   //
@@ skipping 30 matching lines @@
   // Called by the HttpCache when the given disk cache entry becomes accessible
   // to the transaction.  Returns network error code.
   int EntryAvailable(ActiveEntry* entry);
 
   // 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.
   bool AddTruncatedFlag();
 
  private:
+  static const size_t kNumValidationHeaders = 2;

[eroman, 2009/11/11 03:56:35]

nit: i believe the struct declaration should precede the constant.

+  // 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;
+  };
+
   // This is a helper function used to trigger a completion callback.  It may
   // only be called if callback_ is non-null.
   void DoCallback(int rv);
 
   // This will trigger the completion callback if appropriate.
   int HandleResult(int rv);
 
   // Sets request_ and fields derived from it.
   void SetRequest(LoadLog* load_log, const HttpRequestInfo* request);
 
@@ skipping 148 matching lines @@
   CompletionCallbackImpl<Transaction> network_info_callback_;
   CompletionCallbackImpl<Transaction> network_read_callback_;
   scoped_refptr<CancelableCompletionCallback<Transaction> >
       cache_read_callback_;
   scoped_refptr<CancelableCompletionCallback<Transaction> >
       cache_write_callback_;
   scoped_refptr<CancelableCompletionCallback<Transaction> >
       entry_ready_callback_;
 };
 
-HttpCache::Transaction::~Transaction() {
-  if (cache_) {
-    if (entry_) {
-      bool cancel_request = reading_ && enable_range_support_;
-      if (cancel_request) {
-        if (partial_.get()) {
-          entry_->disk_entry->CancelSparseIO();
-        } else {
-          cancel_request &= (response_.headers->response_code() == 200);
-        }
-      }
+}  // namespace net
 
-      cache_->DoneWithEntry(entry_, this, cancel_request);
-    } else {
-      cache_->RemovePendingTransaction(this);
-    }
-  }
-
-  // If there is an outstanding callback, mark it as cancelled so running it
-  // does nothing.
-  cache_read_callback_->Cancel();
-  cache_write_callback_->Cancel();
-
-  // We could still have a cache read or write in progress, so we just null the
-  // cache_ pointer to signal that we are dead.  See DoCacheReadCompleted.
-  cache_.reset();
-}
-
-int HttpCache::Transaction::Start(const HttpRequestInfo* request,
-                                  CompletionCallback* callback,
-                                  LoadLog* load_log) {
-  DCHECK(request);
-  DCHECK(callback);
-
-  // ensure that we only have one asynchronous call at a time.
-  DCHECK(!callback_);
-
-  if (!cache_)
-    return ERR_UNEXPECTED;
-
-  SetRequest(load_log, request);
-
-  int rv;
-
-  if (!ShouldPassThrough()) {
-    cache_key_ = cache_->GenerateCacheKey(request);
-
-    // requested cache access mode
-    if (effective_load_flags_ & LOAD_ONLY_FROM_CACHE) {
-      mode_ = READ;
-    } else if (effective_load_flags_ & LOAD_BYPASS_CACHE) {
-      mode_ = WRITE;
-    } else {
-      mode_ = READ_WRITE;
-    }
-
-    // Downgrade to UPDATE if the request has been externally conditionalized.
-    if (external_validation_.initialized) {
-      if (mode_ & WRITE) {
-        // Strip off the READ_DATA bit (and maybe add back a READ_META bit
-        // in case READ was off).
-        mode_ = UPDATE;
-      } else {
-        mode_ = NONE;
-      }
-    }
-  }
-
-  // if must use cache, then we must fail.  this can happen for back/forward
-  // navigations to a page generated via a form post.
-  if (!(mode_ & READ) && effective_load_flags_ & LOAD_ONLY_FROM_CACHE)
-    return ERR_CACHE_MISS;
-
-  if (mode_ == NONE) {
-    if (partial_.get())
-      partial_->RestoreHeaders(&custom_request_->extra_headers);
-    rv = BeginNetworkRequest();
-  } else {
-    rv = AddToEntry();
-  }
-
-  // setting this here allows us to check for the existance of a callback_ to
-  // determine if we are still inside Start.
-  if (rv == ERR_IO_PENDING)
-    callback_ = callback;
-
-  return rv;
-}
-
-int HttpCache::Transaction::RestartIgnoringLastError(
-    CompletionCallback* callback) {
-  DCHECK(callback);
-
-  // ensure that we only have one asynchronous call at a time.
-  DCHECK(!callback_);
-
-  if (!cache_)
-    return ERR_UNEXPECTED;
-
-  int rv = RestartNetworkRequest();
-
-  if (rv == ERR_IO_PENDING)
-    callback_ = callback;
-
-  return rv;
-}
-
-int HttpCache::Transaction::RestartWithCertificate(
-    X509Certificate* client_cert,
-    CompletionCallback* callback) {
-  DCHECK(callback);
-
-  // ensure that we only have one asynchronous call at a time.
-  DCHECK(!callback_);
-
-  if (!cache_)
-    return ERR_UNEXPECTED;
-
-  int rv = RestartNetworkRequestWithCertificate(client_cert);
-
-  if (rv == ERR_IO_PENDING)
-    callback_ = callback;
-
-  return rv;
-}
-
-int HttpCache::Transaction::RestartWithAuth(
-    const std::wstring& username,
-    const std::wstring& password,
-    CompletionCallback* callback) {
-  DCHECK(auth_response_.headers);
-  DCHECK(callback);
-
-  // Ensure that we only have one asynchronous call at a time.
-  DCHECK(!callback_);
-
-  if (!cache_)
-    return ERR_UNEXPECTED;
-
-  // Clear the intermediate response since we are going to start over.
-  auth_response_ = HttpResponseInfo();
-
-  int rv = RestartNetworkRequestWithAuth(username, password);
-
-  if (rv == ERR_IO_PENDING)
-    callback_ = callback;
-
-  return rv;
-}
-
-bool HttpCache::Transaction::IsReadyToRestartForAuth() {
-  if (!network_trans_.get())
-    return false;
-  return network_trans_->IsReadyToRestartForAuth();
-}
-
-int HttpCache::Transaction::Read(IOBuffer* buf, int buf_len,
-                                 CompletionCallback* callback) {
-  DCHECK(buf);
-  DCHECK_GT(buf_len, 0);
-  DCHECK(callback);
-
-  DCHECK(!callback_);
-
-  if (!cache_)
-    return ERR_UNEXPECTED;
-
-  // If we have an intermediate auth response at this point, then it means the
-  // user wishes to read the network response (the error page).  If there is a
-  // previous response in the cache then we should leave it intact.
-  if (auth_response_.headers && mode_ != NONE) {
-    DCHECK(mode_ & WRITE);
-    DoneWritingToEntry(mode_ == READ_WRITE);
-    mode_ = NONE;
-  }
-
-  reading_ = true;
-  int rv;
-
-  switch (mode_) {
-    case READ_WRITE:
-      DCHECK(partial_.get());
-      if (!network_trans_.get()) {
-        // We are just reading from the cache, but we may be writing later.
-        rv = ReadFromEntry(buf, buf_len);
-        break;
-      }
-    case NONE:
-    case WRITE:
-      DCHECK(network_trans_.get());
-      rv = ReadFromNetwork(buf, buf_len);
-      break;
-    case READ:
-      rv = ReadFromEntry(buf, buf_len);
-      break;
-    default:
-      NOTREACHED();
-      rv = ERR_FAILED;
-  }
-
-  if (rv == ERR_IO_PENDING) {
-    DCHECK(!callback_);
-    callback_ = callback;
-  }
-  return rv;
-}
-
-const HttpResponseInfo* HttpCache::Transaction::GetResponseInfo() const {
-  // Null headers means we encountered an error or haven't a response yet
-  if (auth_response_.headers)
-    return &auth_response_;
-  return (response_.headers || response_.ssl_info.cert ||
-          response_.cert_request_info) ? &response_ : NULL;
-}
-
-LoadState HttpCache::Transaction::GetLoadState() const {
-  if (network_trans_.get())
-    return network_trans_->GetLoadState();
-  if (entry_ || !request_)
-    return LOAD_STATE_IDLE;
-  return LOAD_STATE_WAITING_FOR_CACHE;
-}
-
-uint64 HttpCache::Transaction::GetUploadProgress() const {
-  if (network_trans_.get())
-    return network_trans_->GetUploadProgress();
-  return final_upload_progress_;
-}
-
-int HttpCache::Transaction::AddToEntry() {
-  ActiveEntry* entry = NULL;
-
-  if (!cache_)
-    return ERR_UNEXPECTED;
-
-  if (mode_ == WRITE) {
-    cache_->DoomEntry(cache_key_);
-  } else {
-    entry = cache_->FindActiveEntry(cache_key_);
-    if (!entry) {
-      LoadLog::BeginEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_OPEN_ENTRY);
-      entry = cache_->OpenEntry(cache_key_);
-      LoadLog::EndEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_OPEN_ENTRY);
-      if (!entry) {
-        if (mode_ == READ_WRITE) {
-          mode_ = WRITE;
-        } else if (mode_ == UPDATE) {
-          // There is no cache entry to update; proceed without caching.
-          mode_ = NONE;
-          return BeginNetworkRequest();
-        } else {
-          if (cache_->mode() == PLAYBACK)
-            DLOG(INFO) << "Playback Cache Miss: " << request_->url;
-
-          // entry does not exist, and not permitted to create a new entry, so
-          // we must fail.
-          return HandleResult(ERR_CACHE_MISS);
-        }
-      }
-    }
-  }
-
-  if (mode_ == WRITE) {
-    DCHECK(!entry);
-    LoadLog::BeginEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_CREATE_ENTRY);
-    entry = cache_->CreateEntry(cache_key_);
-    LoadLog::EndEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_CREATE_ENTRY);
-    if (!entry) {
-      DLOG(WARNING) << "unable to create cache entry";
-      mode_ = NONE;
-      if (partial_.get())
-        partial_->RestoreHeaders(&custom_request_->extra_headers);
-      return BeginNetworkRequest();
-    }
-  }
-
-
-  LoadLog::BeginEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_WAITING);
-  return cache_->AddTransactionToEntry(entry, this);
-}
-
-int HttpCache::Transaction::EntryAvailable(ActiveEntry* entry) {
-  LoadLog::EndEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_WAITING);
-
-  // We now have access to the cache entry.
-  //
-  //  o if we are the writer for the transaction, then we can start the network
-  //    transaction.
-  //
-  //  o if we are a reader for the transaction, then we can start reading the
-  //    cache entry.
-  //
-  //  o if we can read or write, then we should check if the cache entry needs
-  //    to be validated and then issue a network request if needed or just read
-  //    from the cache if the cache entry is already valid.
-  //
-  //  o if we are set to UPDATE, then we are handling an externally
-  //    conditionalized request (if-modified-since / if-none-match). We read
-  //    the cache entry, and check if the request headers define a validation
-  //    request.
-  //
-  int rv;
-  entry_ = entry;
-  switch (mode_) {
-    case READ:
-      rv = BeginCacheRead();
-      break;
-    case WRITE:
-      if (partial_.get())
-        partial_->RestoreHeaders(&custom_request_->extra_headers);
-      rv = BeginNetworkRequest();
-      break;
-    case READ_WRITE:
-      rv = BeginPartialCacheValidation();
-      break;
-    case UPDATE:
-      rv = BeginExternallyConditionalizedRequest();
-      break;
-    default:
-      NOTREACHED();
-      rv = ERR_FAILED;
-  }
-  return rv;
-}
-
-bool HttpCache::Transaction::AddTruncatedFlag() {
-  DCHECK(mode_ & WRITE);
-
-  // Don't set the flag for sparse entries.
-  if (partial_.get())
-    return true;
-
-  // Double check that there is something worth keeping.
-  if (!entry_->disk_entry->GetDataSize(kResponseContentIndex))
-    return false;
-
-  truncated_ = true;
-  WriteResponseInfoToEntry(true);
-  return true;
-}
-
-void HttpCache::Transaction::DoCallback(int rv) {
-  DCHECK(rv != ERR_IO_PENDING);
-  DCHECK(callback_);
-
-  // since Run may result in Read being called, clear callback_ up front.
-  CompletionCallback* c = callback_;
-  callback_ = NULL;
-  c->Run(rv);
-}
-
-int HttpCache::Transaction::HandleResult(int rv) {
-  DCHECK(rv != ERR_IO_PENDING);
-  if (callback_)
-    DoCallback(rv);
-  return rv;
-}
-
-void HttpCache::Transaction::SetRequest(LoadLog* load_log,
-                                        const HttpRequestInfo* request) {
-  load_log_ = load_log;
-  request_ = request;
-  effective_load_flags_ = request_->load_flags;
-
-  switch (cache_->mode()) {
-    case NORMAL:
-      break;
-    case RECORD:
-      // When in record mode, we want to NEVER load from the cache.
-      // The reason for this is beacuse we save the Set-Cookie headers
-      // (intentionally).  If we read from the cache, we replay them
-      // prematurely.
-      effective_load_flags_ |= LOAD_BYPASS_CACHE;
-      break;
-    case PLAYBACK:
-      // When in playback mode, we want to load exclusively from the cache.
-      effective_load_flags_ |= LOAD_ONLY_FROM_CACHE;
-      break;
-    case DISABLE:
-      effective_load_flags_ |= LOAD_DISABLE_CACHE;
-      break;
-  }
-
-  // Some headers imply load flags.  The order here is significant.
-  //
-  //   LOAD_DISABLE_CACHE   : no cache read or write
-  //   LOAD_BYPASS_CACHE    : no cache read
-  //   LOAD_VALIDATE_CACHE  : no cache read unless validation
-  //
-  // The former modes trump latter modes, so if we find a matching header we
-  // can stop iterating kSpecialHeaders.
-  //
-  static const struct {
-    const HeaderNameAndValue* search;
-    int load_flag;
-  } kSpecialHeaders[] = {
-    { kPassThroughHeaders, LOAD_DISABLE_CACHE },
-    { kForceFetchHeaders, LOAD_BYPASS_CACHE },
-    { kForceValidateHeaders, LOAD_VALIDATE_CACHE },
-  };
-
-  std::string new_extra_headers;
-  bool range_found = false;
-  bool external_validation_error = false;
-
-  // scan request headers to see if we have any that would impact our load flags
-  HttpUtil::HeadersIterator it(request_->extra_headers.begin(),
-                               request_->extra_headers.end(),
-                               "\r\n");
-  while (it.GetNext()) {
-    if (!LowerCaseEqualsASCII(it.name(), "range")) {
-      new_extra_headers.append(it.name_begin(), it.values_end());
-      new_extra_headers.append("\r\n");
-    } else {
-      if (enable_range_support_) {
-        range_found = true;
-      } else {
-        effective_load_flags_ |= LOAD_DISABLE_CACHE;
-        continue;
-      }
-    }
-    for (size_t i = 0; i < ARRAYSIZE_UNSAFE(kSpecialHeaders); ++i) {
-      if (HeaderMatches(it, kSpecialHeaders[i].search)) {
-        effective_load_flags_ |= kSpecialHeaders[i].load_flag;
-        break;
-      }
-    }
-
-    // Check for conditionalization headers which may correspond with a
-    // cache validation request.
-    for (size_t i = 0; i < ARRAYSIZE_UNSAFE(kValidationHeaders); ++i) {
-      const ValidationHeaderInfo& info = kValidationHeaders[i];
-      if (LowerCaseEqualsASCII(it.name_begin(), it.name_end(),
-                               info.request_header_name)) {
-        if (!external_validation_.values[i].empty() || it.values().empty())
-          external_validation_error = true;
-        external_validation_.values[i] = it.values();
-        external_validation_.initialized = true;
-        break;
-      }
-    }
-  }
-
-  // We don't support ranges and validation headers.
-  if (range_found && external_validation_.initialized) {
-    LOG(WARNING) << "Byte ranges AND validation headers found.";
-    effective_load_flags_ |= LOAD_DISABLE_CACHE;
-  }
-
-  // If there is more than one validation header, we can't treat this request as
-  // a cache validation, since we don't know for sure which header the server
-  // will give us a response for (and they could be contradictory).
-  if (external_validation_error) {
-    LOG(WARNING) << "Multiple or malformed validation headers found.";
-    effective_load_flags_ |= LOAD_DISABLE_CACHE;
-  }
-
-  if (range_found && !(effective_load_flags_ & LOAD_DISABLE_CACHE)) {
-    partial_.reset(new PartialData);
-    if (partial_->Init(request_->extra_headers)) {
-      // We will be modifying the actual range requested to the server, so
-      // let's remove the header here.
-      custom_request_.reset(new HttpRequestInfo(*request_));
-      request_ = custom_request_.get();
-      custom_request_->extra_headers = new_extra_headers;
-      partial_->SetHeaders(new_extra_headers);
-    } else {
-      // The range is invalid or we cannot handle it properly.
-      LOG(WARNING) << "Invalid byte range found.";
-      effective_load_flags_ |= LOAD_DISABLE_CACHE;
-      partial_.reset(NULL);
-    }
-  }
-}
-
-bool HttpCache::Transaction::ShouldPassThrough() {
-  // We may have a null disk_cache if there is an error we cannot recover from,
-  // like not enough disk space, or sharing violations.
-  if (!cache_->disk_cache_.get())
-    return true;
-
-  // When using the record/playback modes, we always use the cache
-  // and we never pass through.
-  if (cache_->mode() == RECORD || cache_->mode() == PLAYBACK)
-    return false;
-
-  if (effective_load_flags_ & LOAD_DISABLE_CACHE)
-    return true;
-
-  if (request_->method == "GET")
-    return false;
-
-  if (request_->method == "POST" &&
-      request_->upload_data && request_->upload_data->identifier())
-    return false;
-
-  // TODO(darin): add support for caching HEAD responses
-  return true;
-}
-
-int HttpCache::Transaction::BeginCacheRead() {
-  DCHECK(mode_ == READ);
-
-  // Read response headers.
-  int rv = ReadResponseInfoFromEntry();
-  if (rv != OK)
-    return HandleResult(rv);
-
-  // We don't support any combination of LOAD_ONLY_FROM_CACHE and byte ranges.
-  if (response_.headers->response_code() == 206 || partial_.get()) {
-    NOTREACHED();
-    return HandleResult(ERR_CACHE_MISS);
-  }
-
-  // We don't have the whole resource.
-  if (truncated_)
-    return HandleResult(ERR_CACHE_MISS);
-
-  return HandleResult(rv);
-}
-
-int HttpCache::Transaction::BeginCacheValidation() {
-  DCHECK(mode_ == READ_WRITE);
-
-  if ((effective_load_flags_ & LOAD_PREFERRING_CACHE ||
-       !RequiresValidation()) && !partial_.get()) {
-    cache_->ConvertWriterToReader(entry_);
-    mode_ = READ;
-  } else {
-    // Make the network request conditional, to see if we may reuse our cached
-    // response.  If we cannot do so, then we just resort to a normal fetch.
-    // Our mode remains READ_WRITE for a conditional request.  We'll switch to
-    // either READ or WRITE mode once we hear back from the server.
-    if (!ConditionalizeRequest())
-      mode_ = WRITE;
-    return BeginNetworkRequest();
-  }
-  return HandleResult(OK);
-}
-
-int HttpCache::Transaction::BeginPartialCacheValidation() {
-  DCHECK(mode_ == READ_WRITE);
-
-  int rv = ReadResponseInfoFromEntry();
-  if (rv != OK) {
-    DCHECK(rv != ERR_IO_PENDING);
-    return HandleResult(rv);
-  }
-
-  if (response_.headers->response_code() != 206 && !partial_.get() &&
-      !truncated_)
-    return BeginCacheValidation();
-
-  if (!enable_range_support_)
-    return BeginCacheValidation();
-
-  bool byte_range_requested = partial_.get() != NULL;
-  if (byte_range_requested) {
-    if (OK != entry_->disk_entry->ReadyForSparseIO(entry_ready_callback_))
-      return ERR_IO_PENDING;
-  } else {
-    // The request is not for a range, but we have stored just ranges.
-    partial_.reset(new PartialData());
-    partial_->SetHeaders(request_->extra_headers);
-    if (!custom_request_.get()) {
-      custom_request_.reset(new HttpRequestInfo(*request_));
-      request_ = custom_request_.get();
-    }
-  }
-
-  return ValidateEntryHeadersAndContinue(byte_range_requested);
-}
-
-int HttpCache::Transaction::ValidateEntryHeadersAndContinue(
-    bool byte_range_requested) {
-  DCHECK(mode_ == READ_WRITE);
-
-  if (!cache_)
-    return HandleResult(ERR_UNEXPECTED);
-
-  if (!partial_->UpdateFromStoredHeaders(response_.headers, entry_->disk_entry,
-                                         truncated_)) {
-    // The stored data cannot be used. Get rid of it and restart this request.
-    // We need to also reset the |truncated_| flag as a new entry is created.
-    DoomPartialEntry(!byte_range_requested);
-    mode_ = WRITE;
-    truncated_ = false;
-    return AddToEntry();
-  }
-
-  if (!partial_->IsRequestedRangeOK()) {
-    // The stored data is fine, but the request may be invalid.
-    invalid_range_ = true;
-  }
-
-  return ContinuePartialCacheValidation();
-}
-
-int HttpCache::Transaction::ContinuePartialCacheValidation() {
-  DCHECK(mode_ == READ_WRITE);
-  int rv = partial_->PrepareCacheValidation(entry_->disk_entry,
-                                            &custom_request_->extra_headers);
-
-  if (!rv) {
-    // Don't invoke the callback before telling the cache we're done.
-    return rv;
-  }
-
-  if (rv < 0) {
-    DCHECK(rv != ERR_IO_PENDING);
-    return HandleResult(rv);
-  }
-
-  if (reading_ && partial_->IsCurrentRangeCached()) {
-    rv = ReadFromEntry(read_buf_, read_buf_len_);
-
-    // We are supposed to hanlde errors here.
-    if (rv < 0 && rv != ERR_IO_PENDING)
-      HandleResult(rv);
-    return rv;
-  }
-
-  return BeginCacheValidation();
-}
-
-int HttpCache::Transaction::BeginExternallyConditionalizedRequest() {
-  DCHECK_EQ(UPDATE, mode_);
-  DCHECK(external_validation_.initialized);
-
-  // Read the cached response.
-  int rv = ReadResponseInfoFromEntry();
-  if (rv != OK) {
-    DCHECK(rv != ERR_IO_PENDING);
-    return HandleResult(rv);
-  }
-
-  for (size_t i = 0;  i < ARRAYSIZE_UNSAFE(kValidationHeaders); i++) {
-    if (external_validation_.values[i].empty())
-      continue;
-    // Retrieve either the cached response's "etag" or "last-modified" header.
-    std::string validator;
-    response_.headers->EnumerateHeader(
-        NULL,
-        kValidationHeaders[i].related_response_header_name,
-        &validator);
-
-    if (response_.headers->response_code() != 200 || truncated_ ||
-        validator.empty() || validator != external_validation_.values[i]) {
-      // The externally conditionalized request is not a validation request
-      // for our existing cache entry. Proceed with caching disabled.
-      DoneWritingToEntry(true);
-    }
-  }
-
-  return BeginNetworkRequest();
-}
-
-int HttpCache::Transaction::BeginNetworkRequest() {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(!network_trans_.get());
-
-  // Create a network transaction.
-  int rv = cache_->network_layer_->CreateTransaction(&network_trans_);
-  if (rv != OK)
-    return rv;
-
-  rv = network_trans_->Start(request_, &network_info_callback_, load_log_);
-  if (rv != ERR_IO_PENDING)
-    OnNetworkInfoAvailable(rv);
-  return rv;
-}
-
-int HttpCache::Transaction::RestartNetworkRequest() {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(network_trans_.get());
-
-  int rv = network_trans_->RestartIgnoringLastError(&network_info_callback_);
-  if (rv != ERR_IO_PENDING)
-    OnNetworkInfoAvailable(rv);
-  return rv;
-}
-
-int HttpCache::Transaction::RestartNetworkRequestWithCertificate(
-    X509Certificate* client_cert) {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(network_trans_.get());
-
-  int rv = network_trans_->RestartWithCertificate(client_cert,
-                                                  &network_info_callback_);
-  if (rv != ERR_IO_PENDING)
-    OnNetworkInfoAvailable(rv);
-  return rv;
-}
-
-int HttpCache::Transaction::RestartNetworkRequestWithAuth(
-    const std::wstring& username,
-    const std::wstring& password) {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(network_trans_.get());
-
-  int rv = network_trans_->RestartWithAuth(username, password,
-                                           &network_info_callback_);
-  if (rv != ERR_IO_PENDING)
-    OnNetworkInfoAvailable(rv);
-  return rv;
-}
-
-bool HttpCache::Transaction::RequiresValidation() {
-  // TODO(darin): need to do more work here:
-  //  - make sure we have a matching request method
-  //  - watch out for cached responses that depend on authentication
-  // In playback mode, nothing requires validation.
-  if (cache_->mode() == net::HttpCache::PLAYBACK)
-    return false;
-
-  if (effective_load_flags_ & LOAD_VALIDATE_CACHE)
-    return true;
-
-  if (response_.headers->response_code() == 206 && !enable_range_support_)
-    return true;
-
-  if (response_.headers->RequiresValidation(
-          response_.request_time, response_.response_time, Time::Now()))
-    return true;
-
-  // Since Vary header computation is fairly expensive, we save it for last.
-  if (response_.vary_data.is_valid() &&
-          !response_.vary_data.MatchesRequest(*request_, *response_.headers))
-    return true;
-
-  return false;
-}
-
-bool HttpCache::Transaction::ConditionalizeRequest() {
-  DCHECK(response_.headers);
-
-  if (!enable_range_support_ && response_.headers->response_code() != 200) {
-    // This only makes sense for cached 200 responses.
-    return false;
-  }
-
-  // This only makes sense for cached 200 or 206 responses.
-  if (response_.headers->response_code() != 200 &&
-      response_.headers->response_code() != 206)
-    return false;
-
-  // Just use the first available ETag and/or Last-Modified header value.
-  // TODO(darin): Or should we use the last?
-
-  std::string etag_value;
-  response_.headers->EnumerateHeader(NULL, "etag", &etag_value);
-
-  std::string last_modified_value;
-  response_.headers->EnumerateHeader(NULL, "last-modified",
-                                     &last_modified_value);
-
-  if (etag_value.empty() && last_modified_value.empty())
-    return false;
-
-  if (!partial_.get()) {
-    // Need to customize the request, so this forces us to allocate :(
-    custom_request_.reset(new HttpRequestInfo(*request_));
-    request_ = custom_request_.get();
-  }
-  DCHECK(custom_request_.get());
-
-  if (!etag_value.empty()) {
-    if (partial_.get() && !partial_->IsCurrentRangeCached()) {
-      // We don't want to switch to WRITE mode if we don't have this block of a
-      // byte-range request because we may have other parts cached.
-      custom_request_->extra_headers.append("If-Range: ");
-    } else {
-      custom_request_->extra_headers.append("If-None-Match: ");
-    }
-    custom_request_->extra_headers.append(etag_value);
-    custom_request_->extra_headers.append("\r\n");
-    if (partial_.get() && !partial_->IsCurrentRangeCached())
-      return true;
-  }
-
-  if (!last_modified_value.empty()) {
-    if (partial_.get() && !partial_->IsCurrentRangeCached()) {
-      custom_request_->extra_headers.append("If-Range: ");
-    } else {
-      custom_request_->extra_headers.append("If-Modified-Since: ");
-    }
-    custom_request_->extra_headers.append(last_modified_value);
-    custom_request_->extra_headers.append("\r\n");
-  }
-
-  return true;
-}
-
-// We just received some headers from the server. We may have asked for a range,
-// in which case partial_ has an object. This could be the first network request
-// we make to fulfill the original request, or we may be already reading (from
-// the net and / or the cache). If we are not expecting a certain response, we
-// just bypass the cache for this request (but again, maybe we are reading), and
-// delete partial_ (so we are not able to "fix" the headers that we return to
-// the user). This results in either a weird response for the caller (we don't
-// expect it after all), or maybe a range that was not exactly what it was asked
-// for.
-//
-// For example, if the original request is for 30KB and we have the last 20KB,
-// we ask the server for the first 10KB. If the resourse has changed, we'll
-// end up forwarding the 200 back to the user (so far so good). However, if
-// we have instead the first 10KB, we end up sending back a byte range response
-// for the first 10KB, because we never asked the server for the last part. It's
-// just too complicated to restart the whole request from this point; and of
-// course, maybe we already returned the headers.
-bool HttpCache::Transaction::ValidatePartialResponse(
-    const HttpResponseHeaders* headers) {
-  int response_code = headers->response_code();
-  bool partial_content = enable_range_support_ ? response_code == 206 : false;
-
-  if (!entry_)
-    return false;
-
-  if (invalid_range_) {
-    // We gave up trying to match this request with the stored data. If the
-    // server is ok with the request, delete the entry, otherwise just ignore
-    // this request
-    if (partial_content || response_code == 200 || response_code == 304) {
-      DoomPartialEntry(true);
-      mode_ = NONE;
-    } else {
-      IgnoreRangeRequest();
-    }
-    return false;
-  }
-
-  if (!partial_.get()) {
-    // We are not expecting 206 but we may have one.
-    if (partial_content)
-      IgnoreRangeRequest();
-
-    return false;
-  }
-
-  // TODO(rvargas): Do we need to consider other results here?.
-  bool failure = response_code == 200 || response_code == 416;
-
-  if (partial_->IsCurrentRangeCached()) {
-    // We asked for "If-None-Match: " so a 206 means a new object.
-    if (partial_content)
-      failure = true;
-
-    if (response_code == 304 && partial_->ResponseHeadersOK(headers))
-      return false;
-  } else {
-    // We asked for "If-Range: " so a 206 means just another range.
-    if (partial_content && partial_->ResponseHeadersOK(headers))
-      return true;
-
-    // 304 is not expected here, but we'll spare the entry.
-  }
-
-  if (failure) {
-    // We cannot truncate this entry, it has to be deleted.
-    DoomPartialEntry(true);
-    mode_ = NONE;
-    return false;
-  }
-
-  IgnoreRangeRequest();
-  return false;
-}
-
-void HttpCache::Transaction::IgnoreRangeRequest() {
-  // We have a problem. We may or may not be reading already (in which case we
-  // returned the headers), but we'll just pretend that this request is not
-  // using the cache and see what happens. Most likely this is the first
-  // response from the server (it's not changing its mind midway, right?).
-  if (mode_ & WRITE) {
-    DoneWritingToEntry(mode_ != WRITE);
-  } else if (mode_ & READ && entry_) {
-    cache_->DoneReadingFromEntry(entry_, this);
-  }
-
-  partial_.reset(NULL);
-  entry_ = NULL;
-  mode_ = NONE;
-}
-
-int HttpCache::Transaction::ReadFromNetwork(IOBuffer* data, int data_len) {
-  int rv = network_trans_->Read(data, data_len, &network_read_callback_);
-  read_buf_ = data;
-  read_buf_len_ = data_len;
-  if (rv >= 0)
-    rv = DoNetworkReadCompleted(rv);
-  return rv;
-}
-
-int HttpCache::Transaction::ReadFromEntry(IOBuffer* data, int data_len) {
-  DCHECK(entry_);
-  int rv;
-  cache_read_callback_->AddRef();  // Balanced in OnCacheReadCompleted.
-  if (partial_.get()) {
-    rv = partial_->CacheRead(entry_->disk_entry, data, data_len,
-                            cache_read_callback_);
-  } else {
-    rv = entry_->disk_entry->ReadData(kResponseContentIndex, read_offset_,
-                                      data, data_len, cache_read_callback_);
-  }
-  read_buf_ = data;
-  read_buf_len_ = data_len;
-  if (rv != ERR_IO_PENDING)
-    cache_read_callback_->Release();
-
-  if (rv >= 0)
-    rv = DoCacheReadCompleted(rv);
-
-  return rv;
-}
-
-int HttpCache::Transaction::ReadResponseInfoFromEntry() {
-  DCHECK(entry_);
-
-  LoadLog::BeginEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_READ_INFO);
-  bool read_ok =
-      HttpCache::ReadResponseInfo(entry_->disk_entry, &response_, &truncated_);
-  LoadLog::EndEvent(load_log_, LoadLog::TYPE_HTTP_CACHE_READ_INFO);
-
-  return read_ok ? OK : ERR_CACHE_READ_FAILURE;
-}
-
-int HttpCache::Transaction::WriteToEntry(int index, int offset,
-                                         IOBuffer* data, int data_len,
-                                         CompletionCallback* callback) {
-  if (!entry_)
-    return data_len;
-
-  int rv = 0;
-  if (!partial_.get() || !data_len) {
-    rv = entry_->disk_entry->WriteData(index, offset, data, data_len, callback,
-                                       true);
-  } else {
-    rv = partial_->CacheWrite(entry_->disk_entry, data, data_len, callback);
-  }
-
-  if (rv != ERR_IO_PENDING && rv != data_len) {
-    DLOG(ERROR) << "failed to write response data to cache";
-    DoneWritingToEntry(false);
-
-    // We want to ignore errors writing to disk and just keep reading from
-    // the network.
-    rv = data_len;
-  }
-  return rv;
-}
-
-void HttpCache::Transaction::WriteResponseInfoToEntry(bool truncated) {
-  if (!entry_)
-    return;
-
-  // Do not cache no-store content (unless we are record mode).  Do not cache
-  // content with cert errors either.  This is to prevent not reporting net
-  // errors when loading a resource from the cache.  When we load a page over
-  // HTTPS with a cert error we show an SSL blocking page.  If the user clicks
-  // proceed we reload the resource ignoring the errors.  The loaded resource
-  // is then cached.  If that resource is subsequently loaded from the cache,
-  // no net error is reported (even though the cert status contains the actual
-  // errors) and no SSL blocking page is shown.  An alternative would be to
-  // reverse-map the cert status to a net error and replay the net error.
-  if ((cache_->mode() != RECORD &&
-      response_.headers->HasHeaderValue("cache-control", "no-store")) ||
-      net::IsCertStatusError(response_.ssl_info.cert_status)) {
-    DoneWritingToEntry(false);
-    return;
-  }
-
-  // When writing headers, we normally only write the non-transient
-  // headers; when in record mode, record everything.
-  bool skip_transient_headers = (cache_->mode() != RECORD);
-
-  if (truncated) {
-    DCHECK_EQ(200, response_.headers->response_code());
-  }
-
-  if (!HttpCache::WriteResponseInfo(entry_->disk_entry, &response_,
-                                    skip_transient_headers, truncated)) {
-    DLOG(ERROR) << "failed to write response info to cache";
-    DoneWritingToEntry(false);
-  }
-}
-
-int HttpCache::Transaction::AppendResponseDataToEntry(
-    IOBuffer* data, int data_len, CompletionCallback* callback) {
-  if (!entry_ || !data_len)
-    return data_len;
-
-  int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
-  return WriteToEntry(kResponseContentIndex, current_size, data, data_len,
-                      callback);
-}
-
-void HttpCache::Transaction::TruncateResponseData() {
-  if (!entry_)
-    return;
-
-  // Truncate the stream.
-  int rv = WriteToEntry(kResponseContentIndex, 0, NULL, 0, NULL);
-  DCHECK(rv != ERR_IO_PENDING);
-}
-
-void HttpCache::Transaction::DoneWritingToEntry(bool success) {
-  if (!entry_)
-    return;
-
-  if (cache_->mode() == RECORD)
-    DLOG(INFO) << "Recorded: " << request_->method << request_->url
-               << " status: " << response_.headers->response_code();
-
-  cache_->DoneWritingToEntry(entry_, success);
-  entry_ = NULL;
-  mode_ = NONE;  // switch to 'pass through' mode
-}
-
-void HttpCache::Transaction::DoomPartialEntry(bool delete_object) {
-  cache_->DoneWithEntry(entry_, this, false);
-  cache_->DoomEntry(cache_key_);
-  entry_ = NULL;
-  if (delete_object)
-    partial_.reset(NULL);
-}
-
-int HttpCache::Transaction::DoNetworkReadCompleted(int result) {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-
-  if (!cache_)
-    return HandleResult(ERR_UNEXPECTED);
-
-  cache_write_callback_->AddRef();  // Balanced in DoCacheWriteCompleted.
-
-  result = AppendResponseDataToEntry(read_buf_, result, cache_write_callback_);
-  if (result == ERR_IO_PENDING)
-    return result;
-
-  return DoCacheWriteCompleted(result);
-}
-
-int HttpCache::Transaction::DoPartialNetworkReadCompleted(int result) {
-  partial_->OnNetworkReadCompleted(result);
-
-  if (result == 0) {  // End of file.
-    if (mode_ == READ_WRITE) {
-      // We need to move on to the next range.
-      network_trans_.reset();
-      result = ContinuePartialCacheValidation();
-      if (result != OK)
-        // Any error was already handled.
-        return result;
-    }
-    DoneWritingToEntry(true);
-  }
-  return HandleResult(result);
-}
-
-int HttpCache::Transaction::DoCacheReadCompleted(int result) {
-  DCHECK(cache_);
-
-  if (!cache_)
-    return HandleResult(ERR_UNEXPECTED);
-
-  if (partial_.get())
-    return DoPartialCacheReadCompleted(result);
-
-  if (result > 0) {
-    read_offset_ += result;
-  } else if (result == 0) {  // End of file.
-    cache_->DoneReadingFromEntry(entry_, this);
-    entry_ = NULL;
-  }
-  return HandleResult(result);
-}
-
-int HttpCache::Transaction::DoPartialCacheReadCompleted(int result) {
-  partial_->OnCacheReadCompleted(result);
-
-  if (result == 0) {  // End of file.
-    if (partial_.get() && mode_ == READ_WRITE) {
-      // We need to move on to the next range.
-      result = ContinuePartialCacheValidation();
-      if (result != OK)
-        // Any error was already handled.
-        return result;
-      cache_->ConvertWriterToReader(entry_);
-    }
-    cache_->DoneReadingFromEntry(entry_, this);
-    entry_ = NULL;
-  }
-  return HandleResult(result);
-}
-
-int HttpCache::Transaction::DoCacheWriteCompleted(int result) {
-  DCHECK(cache_);
-  // Balance the AddRef from DoNetworkReadCompleted.
-  cache_write_callback_->Release();
-  if (!cache_)
-    return HandleResult(ERR_UNEXPECTED);
-
-  if (result < 0)
-    return HandleResult(result);
-
-  if (partial_.get())
-    return DoPartialNetworkReadCompleted(result);
-
-  if (result == 0)  // End of file.
-    DoneWritingToEntry(true);
-
-  return HandleResult(result);
-}
-
-void HttpCache::Transaction::OnNetworkInfoAvailable(int result) {
-  DCHECK(result != ERR_IO_PENDING);
-
-  if (!cache_) {
-    HandleResult(ERR_UNEXPECTED);
-    return;
-  }
-
-  if (result == OK) {
-    const HttpResponseInfo* new_response = network_trans_->GetResponseInfo();
-    if (new_response->headers->response_code() == 401 ||
-        new_response->headers->response_code() == 407) {
-      auth_response_ = *new_response;
-    } else {
-      bool partial_content = ValidatePartialResponse(new_response->headers);
-      if (partial_content && mode_ == READ_WRITE && !truncated_ &&
-          response_.headers->response_code() == 200) {
-        // We have stored the full entry, but it changed and the server is
-        // sending a range. We have to delete the old entry.
-        DoneWritingToEntry(false);
-      }
-
-      // Are we expecting a response to a conditional query?
-      if (mode_ == READ_WRITE || mode_ == UPDATE) {
-        if (new_response->headers->response_code() == 304 || partial_content) {
-          // Update cached response based on headers in new_response.
-          // TODO(wtc): should we update cached certificate
-          // (response_.ssl_info), too?
-          response_.headers->Update(*new_response->headers);
-          response_.response_time = new_response->response_time;
-          response_.request_time = new_response->request_time;
-
-          if (response_.headers->HasHeaderValue("cache-control", "no-store")) {
-            cache_->DoomEntry(cache_key_);
-          } else {
-            // If we are already reading, we already updated the headers for
-            // this request; doing it again will change Content-Length.
-            if (!reading_)
-              WriteResponseInfoToEntry(false);
-          }
-
-          if (mode_ == UPDATE) {
-            DCHECK(!partial_content);
-            // We got a "not modified" response and already updated the
-            // corresponding cache entry above.
-            //
-            // By closing the cached entry now, we make sure that the
-            // 304 rather than the cached 200 response, is what will be
-            // returned to the user.
-            DoneWritingToEntry(true);
-          } else if (entry_ && !partial_content) {
-            DCHECK_EQ(READ_WRITE, mode_);
-            if (!partial_.get() || partial_->IsLastRange()) {
-              cache_->ConvertWriterToReader(entry_);
-              mode_ = READ;
-            }
-            // We no longer need the network transaction, so destroy it.
-            final_upload_progress_ = network_trans_->GetUploadProgress();
-            network_trans_.reset();
-          }
-        } else {
-          mode_ = WRITE;
-        }
-      }
-
-      if (!(mode_ & READ)) {
-        // We change the value of Content-Length for partial content.
-        if (partial_content && partial_.get())
-          partial_->FixContentLength(new_response->headers);
-
-        response_ = *new_response;
-        WriteResponseInfoToEntry(truncated_);
-
-        // Truncate response data.
-        TruncateResponseData();
-
-        // If this response is a redirect, then we can stop writing now.  (We
-        // don't need to cache the response body of a redirect.)
-        if (response_.headers->IsRedirect(NULL))
-          DoneWritingToEntry(true);
-      }
-      if (reading_ && partial_.get()) {
-        if (network_trans_.get()) {
-          result = ReadFromNetwork(read_buf_, read_buf_len_);
-        } else {
-          result = ReadFromEntry(read_buf_, read_buf_len_);
-        }
-        if (result >= 0 || result == net::ERR_IO_PENDING)
-          return;
-      } else if (mode_ != NONE && partial_.get()) {
-        // We are about to return the headers for a byte-range request to the
-        // user, so let's fix them.
-        partial_->FixResponseHeaders(response_.headers);
-      }
-    }
-  } else if (IsCertificateError(result)) {
-    const HttpResponseInfo* response = network_trans_->GetResponseInfo();
-    // If we get a certificate error, then there is a certificate in ssl_info,
-    // so GetResponseInfo() should never returns NULL here.
-    DCHECK(response);
-    response_.ssl_info = response->ssl_info;
-  } else if (result == ERR_SSL_CLIENT_AUTH_CERT_NEEDED) {
-    const HttpResponseInfo* response = network_trans_->GetResponseInfo();
-    DCHECK(response);
-    response_.cert_request_info = response->cert_request_info;
-  }
-  HandleResult(result);
-}
-
-void HttpCache::Transaction::OnNetworkReadCompleted(int result) {
-  DoNetworkReadCompleted(result);
-}
-
-void HttpCache::Transaction::OnCacheReadCompleted(int result) {
-  cache_read_callback_->Release();  // Balance the AddRef from ReadFromEntry.
-  DoCacheReadCompleted(result);
-}
-
-void HttpCache::Transaction::OnCacheWriteCompleted(int result) {
-  DoCacheWriteCompleted(result);
-}
-
-void HttpCache::Transaction::OnCacheEntryReady(int result) {
-  DCHECK_EQ(OK, result);
-  ValidateEntryHeadersAndContinue(true);
-}
-
-//-----------------------------------------------------------------------------
-
-HttpCache::HttpCache(HostResolver* host_resolver,
-                     ProxyService* proxy_service,
-                     SSLConfigService* ssl_config_service,
-                     const FilePath& cache_dir,
-                     int cache_size)
-    : disk_cache_dir_(cache_dir),
-      mode_(NORMAL),
-      type_(DISK_CACHE),
-      network_layer_(HttpNetworkLayer::CreateFactory(
-          host_resolver, proxy_service, ssl_config_service)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(task_factory_(this)),
-      enable_range_support_(true),
-      cache_size_(cache_size) {
-}
-
-HttpCache::HttpCache(HttpNetworkSession* session,
-                     const FilePath& cache_dir,
-                     int cache_size)
-    : disk_cache_dir_(cache_dir),
-      mode_(NORMAL),
-      type_(DISK_CACHE),
-      network_layer_(HttpNetworkLayer::CreateFactory(session)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(task_factory_(this)),
-      enable_range_support_(true),
-      cache_size_(cache_size) {
-}
-
-HttpCache::HttpCache(HostResolver* host_resolver,
-                     ProxyService* proxy_service,
-                     SSLConfigService* ssl_config_service,
-                     int cache_size)
-    : mode_(NORMAL),
-      type_(MEMORY_CACHE),
-      network_layer_(HttpNetworkLayer::CreateFactory(
-          host_resolver, proxy_service, ssl_config_service)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(task_factory_(this)),
-      enable_range_support_(true),
-      cache_size_(cache_size) {
-}
-
-HttpCache::HttpCache(HttpTransactionFactory* network_layer,
-                     disk_cache::Backend* disk_cache)
-    : mode_(NORMAL),
-      type_(DISK_CACHE),
-      network_layer_(network_layer),
-      disk_cache_(disk_cache),
-      ALLOW_THIS_IN_INITIALIZER_LIST(task_factory_(this)),
-      enable_range_support_(true),
-      cache_size_(0) {
-}
-
-HttpCache::~HttpCache() {
-  // If we have any active entries remaining, then we need to deactivate them.
-  // We may have some pending calls to OnProcessPendingQueue, but since those
-  // won't run (due to our destruction), we can simply ignore the corresponding
-  // will_process_pending_queue flag.
-  while (!active_entries_.empty()) {
-    ActiveEntry* entry = active_entries_.begin()->second;
-    entry->will_process_pending_queue = false;
-    entry->pending_queue.clear();
-    entry->readers.clear();
-    entry->writer = NULL;
-    DeactivateEntry(entry);
-  }
-
-  ActiveEntriesSet::iterator it = doomed_entries_.begin();
-  for (; it != doomed_entries_.end(); ++it)
-    delete *it;
-}
-
-disk_cache::Backend* HttpCache::GetBackend() {
-  if (disk_cache_.get())
-    return disk_cache_.get();
-
-  DCHECK_GE(cache_size_, 0);
-  if (type_ == MEMORY_CACHE) {
-    // We may end up with no folder name and no cache if the initialization
-    // of the disk cache fails. We want to be sure that what we wanted to have
-    // was an in-memory cache.
-    disk_cache_.reset(disk_cache::CreateInMemoryCacheBackend(cache_size_));
-  } else if (!disk_cache_dir_.empty()) {
-    disk_cache_.reset(disk_cache::CreateCacheBackend(disk_cache_dir_, true,
-        cache_size_, type_));
-    disk_cache_dir_ = FilePath();  // Reclaim memory.
-  }
-  return disk_cache_.get();
-}
-
-int HttpCache::CreateTransaction(scoped_ptr<HttpTransaction>* trans) {
-  // Do lazy initialization of disk cache if needed.
-  GetBackend();
-  trans->reset(new HttpCache::Transaction(this, enable_range_support_));
-  return OK;
-}
-
-HttpCache* HttpCache::GetCache() {
-  return this;
-}
-
-HttpNetworkSession* HttpCache::GetSession() {
-  net::HttpNetworkLayer* network =
-      static_cast<net::HttpNetworkLayer*>(network_layer_.get());
-  return network->GetSession();
-}
-
-void HttpCache::Suspend(bool suspend) {
-  network_layer_->Suspend(suspend);
-}
-
-// static
-bool HttpCache::ParseResponseInfo(const char* data, int len,
-                                  HttpResponseInfo* response_info,
-                                  bool* response_truncated) {
-  Pickle pickle(data, len);
-  return response_info->InitFromPickle(pickle, response_truncated);
-}
-
-// static
-bool HttpCache::ReadResponseInfo(disk_cache::Entry* disk_entry,
-                                 HttpResponseInfo* response_info,
-                                 bool* response_truncated) {
-  int size = disk_entry->GetDataSize(kResponseInfoIndex);
-
-  scoped_refptr<IOBuffer> buffer = new IOBuffer(size);
-  int rv = disk_entry->ReadData(kResponseInfoIndex, 0, buffer, size, NULL);
-  if (rv != size) {
-    DLOG(ERROR) << "ReadData failed: " << rv;
-    return false;
-  }
-
-  return ParseResponseInfo(buffer->data(), size, response_info,
-                           response_truncated);
-}
-
-// static
-bool HttpCache::WriteResponseInfo(disk_cache::Entry* disk_entry,
-                                  const HttpResponseInfo* response_info,
-                                  bool skip_transient_headers,
-                                  bool response_truncated) {
-  Pickle pickle;
-  response_info->Persist(
-      &pickle, skip_transient_headers, response_truncated);
-
-  scoped_refptr<WrappedIOBuffer> data = new WrappedIOBuffer(
-      reinterpret_cast<const char*>(pickle.data()));
-  int len = static_cast<int>(pickle.size());
-
-  return disk_entry->WriteData(kResponseInfoIndex, 0, data, len, NULL,
-                               true) == len;
-}
-
-// Generate a key that can be used inside the cache.
-std::string HttpCache::GenerateCacheKey(const HttpRequestInfo* request) {
-  // Strip out the reference, username, and password sections of the URL.
-  std::string url = HttpUtil::SpecForRequest(request->url);
-
-  DCHECK(mode_ != DISABLE);
-  if (mode_ == NORMAL) {
-    // No valid URL can begin with numerals, so we should not have to worry
-    // about collisions with normal URLs.
-    if (request->upload_data && request->upload_data->identifier())
-      url.insert(0, StringPrintf("%lld/", request->upload_data->identifier()));
-    return url;
-  }
-
-  // In playback and record mode, we cache everything.
-
-  // Lazily initialize.
-  if (playback_cache_map_ == NULL)
-    playback_cache_map_.reset(new PlaybackCacheMap());
-
-  // Each time we request an item from the cache, we tag it with a
-  // generation number.  During playback, multiple fetches for the same
-  // item will use the same generation number and pull the proper
-  // instance of an URL from the cache.
-  int generation = 0;
-  DCHECK(playback_cache_map_ != NULL);
-  if (playback_cache_map_->find(url) != playback_cache_map_->end())
-    generation = (*playback_cache_map_)[url];
-  (*playback_cache_map_)[url] = generation + 1;
-
-  // The key into the cache is GENERATION # + METHOD + URL.
-  std::string result = IntToString(generation);
-  result.append(request->method);
-  result.append(url);
-  return result;
-}
-
-void HttpCache::DoomEntry(const std::string& key) {
-  // Need to abandon the ActiveEntry, but any transaction attached to the entry
-  // should not be impacted.  Dooming an entry only means that it will no
-  // longer be returned by FindActiveEntry (and it will also be destroyed once
-  // all consumers are finished with the entry).
-  ActiveEntriesMap::iterator it = active_entries_.find(key);
-  if (it == active_entries_.end()) {
-    disk_cache_->DoomEntry(key);
-  } else {
-    ActiveEntry* entry = it->second;
-    active_entries_.erase(it);
-
-    // We keep track of doomed entries so that we can ensure that they are
-    // cleaned up properly when the cache is destroyed.
-    doomed_entries_.insert(entry);
-
-    entry->disk_entry->Doom();
-    entry->doomed = true;
-
-    DCHECK(entry->writer || !entry->readers.empty());
-  }
-}
-
-void HttpCache::FinalizeDoomedEntry(ActiveEntry* entry) {
-  DCHECK(entry->doomed);
-  DCHECK(!entry->writer);
-  DCHECK(entry->readers.empty());
-  DCHECK(entry->pending_queue.empty());
-
-  ActiveEntriesSet::iterator it = doomed_entries_.find(entry);
-  DCHECK(it != doomed_entries_.end());
-  doomed_entries_.erase(it);
-
-  delete entry;
-}
-
-HttpCache::ActiveEntry* HttpCache::FindActiveEntry(const std::string& key) {
-  ActiveEntriesMap::const_iterator it = active_entries_.find(key);
-  return it != active_entries_.end() ? it->second : NULL;
-}
-
-HttpCache::ActiveEntry* HttpCache::OpenEntry(const std::string& key) {
-  DCHECK(!FindActiveEntry(key));
-
-  disk_cache::Entry* disk_entry;
-  if (!disk_cache_->OpenEntry(key, &disk_entry))
-    return NULL;
-
-  return ActivateEntry(key, disk_entry);
-}
-
-HttpCache::ActiveEntry* HttpCache::CreateEntry(const std::string& key) {
-  DCHECK(!FindActiveEntry(key));
-
-  disk_cache::Entry* disk_entry;
-  if (!disk_cache_->CreateEntry(key, &disk_entry))
-    return NULL;
-
-  return ActivateEntry(key, disk_entry);
-}
-
-void HttpCache::DestroyEntry(ActiveEntry* entry) {
-  if (entry->doomed) {
-    FinalizeDoomedEntry(entry);
-  } else {
-    DeactivateEntry(entry);
-  }
-}
-
-HttpCache::ActiveEntry* HttpCache::ActivateEntry(
-    const std::string& key,
-    disk_cache::Entry* disk_entry) {
-  ActiveEntry* entry = new ActiveEntry(disk_entry);
-  active_entries_[key] = entry;
-  return entry;
-}
-
-void HttpCache::DeactivateEntry(ActiveEntry* entry) {
-  DCHECK(!entry->will_process_pending_queue);
-  DCHECK(!entry->doomed);
-  DCHECK(!entry->writer);
-  DCHECK(entry->readers.empty());
-  DCHECK(entry->pending_queue.empty());
-
-  std::string key = entry->disk_entry->GetKey();
-  if (key.empty())
-    return SlowDeactivateEntry(entry);
-
-  ActiveEntriesMap::iterator it = active_entries_.find(key);
-  DCHECK(it != active_entries_.end());
-  DCHECK(it->second == entry);
-
-  active_entries_.erase(it);
-  delete entry;
-}
-
-// We don't know this entry's key so we have to find it without it.
-void HttpCache::SlowDeactivateEntry(ActiveEntry* entry) {
-  for (ActiveEntriesMap::iterator it = active_entries_.begin();
-       it != active_entries_.end(); ++it) {
-    if (it->second == entry) {
-      active_entries_.erase(it);
-      delete entry;
-      break;
-    }
-  }
-}
-
-int HttpCache::AddTransactionToEntry(ActiveEntry* entry, Transaction* trans) {
-  DCHECK(entry);
-
-  // We implement a basic reader/writer lock for the disk cache entry.  If
-  // there is already a writer, then everyone has to wait for the writer to
-  // finish before they can access the cache entry.  There can be multiple
-  // readers.
-  //
-  // NOTE: If the transaction can only write, then the entry should not be in
-  // use (since any existing entry should have already been doomed).
-
-  if (entry->writer || entry->will_process_pending_queue) {
-    entry->pending_queue.push_back(trans);
-    return ERR_IO_PENDING;
-  }
-
-  if (trans->mode() & Transaction::WRITE) {
-    // transaction needs exclusive access to the entry
-    if (entry->readers.empty()) {
-      entry->writer = trans;
-    } else {
-      entry->pending_queue.push_back(trans);
-      return ERR_IO_PENDING;
-    }
-  } else {
-    // transaction needs read access to the entry
-    entry->readers.push_back(trans);
-  }
-
-  // We do this before calling EntryAvailable to force any further calls to
-  // AddTransactionToEntry to add their transaction to the pending queue, which
-  // ensures FIFO ordering.
-  if (!entry->writer && !entry->pending_queue.empty())
-    ProcessPendingQueue(entry);
-
-  return trans->EntryAvailable(entry);
-}
-
-void HttpCache::DoneWithEntry(ActiveEntry* entry, Transaction* trans,
-                              bool cancel) {
-  // If we already posted a task to move on to the next transaction and this was
-  // the writer, there is nothing to cancel.
-  if (entry->will_process_pending_queue && entry->readers.empty())
-    return;
-
-  if (entry->writer) {
-    DCHECK(trans == entry->writer);
-
-    // Assume there was a failure.
-    bool success = false;
-    if (cancel) {
-      DCHECK(entry->disk_entry);
-      // This is a successful operation in the sense that we want to keep the
-      // entry.
-      success = trans->AddTruncatedFlag();
-    }
-    DoneWritingToEntry(entry, success);
-  } else {
-    DoneReadingFromEntry(entry, trans);
-  }
-}
-
-void HttpCache::DoneWritingToEntry(ActiveEntry* entry, bool success) {
-  DCHECK(entry->readers.empty());
-
-  entry->writer = NULL;
-
-  if (success) {
-    ProcessPendingQueue(entry);
-  } else {
-    DCHECK(!entry->will_process_pending_queue);
-
-    // We failed to create this entry.
-    TransactionList pending_queue;
-    pending_queue.swap(entry->pending_queue);
-
-    entry->disk_entry->Doom();
-    DestroyEntry(entry);
-
-    // We need to do something about these pending entries, which now need to
-    // be added to a new entry.
-    while (!pending_queue.empty()) {
-      pending_queue.front()->AddToEntry();
-      pending_queue.pop_front();
-    }
-  }
-}
-
-void HttpCache::DoneReadingFromEntry(ActiveEntry* entry, Transaction* trans) {
-  DCHECK(!entry->writer);
-
-  TransactionList::iterator it =
-      std::find(entry->readers.begin(), entry->readers.end(), trans);
-  DCHECK(it != entry->readers.end());
-
-  entry->readers.erase(it);
-
-  ProcessPendingQueue(entry);
-}
-
-void HttpCache::ConvertWriterToReader(ActiveEntry* entry) {
-  DCHECK(entry->writer);
-  DCHECK(entry->writer->mode() == Transaction::READ_WRITE);
-  DCHECK(entry->readers.empty());
-
-  Transaction* trans = entry->writer;
-
-  entry->writer = NULL;
-  entry->readers.push_back(trans);
-
-  ProcessPendingQueue(entry);
-}
-
-void HttpCache::RemovePendingTransaction(Transaction* trans) {
-  ActiveEntriesMap::const_iterator i = active_entries_.find(trans->key());
-  bool found = false;
-  if (i != active_entries_.end())
-    found = RemovePendingTransactionFromEntry(i->second, trans);
-
-  if (found)
-    return;
-
-  ActiveEntriesSet::iterator it = doomed_entries_.begin();
-  for (; it != doomed_entries_.end() && !found; ++it)
-    found = RemovePendingTransactionFromEntry(*it, trans);
-}
-
-bool HttpCache::RemovePendingTransactionFromEntry(ActiveEntry* entry,
-                                                  Transaction* trans) {
-  TransactionList& pending_queue = entry->pending_queue;
-
-  TransactionList::iterator j =
-      find(pending_queue.begin(), pending_queue.end(), trans);
-  if (j == pending_queue.end())
-    return false;
-
-  pending_queue.erase(j);
-  return true;
-}
-
-void HttpCache::ProcessPendingQueue(ActiveEntry* entry) {
-  // Multiple readers may finish with an entry at once, so we want to batch up
-  // calls to OnProcessPendingQueue.  This flag also tells us that we should
-  // not delete the entry before OnProcessPendingQueue runs.
-  if (entry->will_process_pending_queue)
-    return;
-  entry->will_process_pending_queue = true;
-
-  MessageLoop::current()->PostTask(FROM_HERE,
-      task_factory_.NewRunnableMethod(&HttpCache::OnProcessPendingQueue,
-                                      entry));
-}
-
-void HttpCache::OnProcessPendingQueue(ActiveEntry* entry) {
-  entry->will_process_pending_queue = false;
-  DCHECK(!entry->writer);
-
-  // If no one is interested in this entry, then we can de-activate it.
-  if (entry->pending_queue.empty()) {
-    if (entry->readers.empty())
-      DestroyEntry(entry);
-    return;
-  }
-
-  // Promote next transaction from the pending queue.
-  Transaction* next = entry->pending_queue.front();
-  if ((next->mode() & Transaction::WRITE) && !entry->readers.empty())
-    return;  // Have to wait.
-
-  entry->pending_queue.erase(entry->pending_queue.begin());
-
-  AddTransactionToEntry(entry, next);
-}
-
-void HttpCache::CloseIdleConnections() {
-  net::HttpNetworkLayer* network =
-      static_cast<net::HttpNetworkLayer*>(network_layer_.get());
-  HttpNetworkSession* session = network->GetSession();
-  if (session) {
-    session->tcp_socket_pool()->CloseIdleSockets();
-  }
-}
-
-//-----------------------------------------------------------------------------
-
-}  // namespace net
+#endif  // NET_HTTP_HTTP_CACHE_TRANSACTION_H_