[HttpCache::Transaction] Force states to set the next state

net/http/http_cache_transaction.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/http/http_cache_transaction.h"
 
 #include "build/build_config.h"  // For OS_POSIX
 
 #if defined(OS_POSIX)
 #include <unistd.h>
@@ skipping 694 matching lines @@
 //   BeginPartialCacheValidation() -> BeginCacheValidation() ->
 //   SetupEntryForRead()
 //
 //   Read():
 //   CacheReadData*
 //
 // 14. Cached entry more than 5 minutes old, unused_since_prefetch is true:
 //   Like examples 2-4, only CacheToggleUnusedSincePrefetch* is inserted between
 //   CacheReadResponse* and CacheDispatchValidation.
 int HttpCache::Transaction::DoLoop(int result) {
+  DCHECK(next_state_ != STATE_UNSET);
   DCHECK(next_state_ != STATE_NONE);

[Randy Smith (Not in Mondays), 2017/03/22 14:49:44]

Suggestion: DCHECK_NE for both?

[jkarlin, 2017/03/22 15:04:26]

Done.

 
   int rv = result;
   do {
     State state = next_state_;
-    next_state_ = STATE_NONE;
+    next_state_ = STATE_UNSET;
     switch (state) {
       case STATE_GET_BACKEND:
         DCHECK_EQ(OK, rv);
         rv = DoGetBackend();
         break;
       case STATE_GET_BACKEND_COMPLETE:
         rv = DoGetBackendComplete(rv);
         break;
       case STATE_INIT_ENTRY:
         DCHECK_EQ(OK, rv);
@@ skipping 141 matching lines @@
         rv = DoCacheWriteDataComplete(rv);
         break;
       case STATE_CACHE_WRITE_TRUNCATED_RESPONSE:
         DCHECK_EQ(OK, rv);
         rv = DoCacheWriteTruncatedResponse();
         break;
       case STATE_CACHE_WRITE_TRUNCATED_RESPONSE_COMPLETE:
         rv = DoCacheWriteTruncatedResponseComplete(rv);
         break;
       default:
-        NOTREACHED() << "bad state";
+        NOTREACHED() << "bad state " << state;
         rv = ERR_FAILED;
         break;
     }
+    DCHECK(next_state_ != STATE_UNSET) << "Previous state was " << state;
+
   } while (rv != ERR_IO_PENDING && next_state_ != STATE_NONE);
 
   if (rv != ERR_IO_PENDING && !callback_.is_null()) {
     read_buf_ = NULL;  // Release the buffer before invoking the callback.
     base::ResetAndReturn(&callback_).Run(rv);
   }
 
   return rv;
 }
 
@@ skipping 10 matching lines @@
                                     result);
   cache_pending_ = false;
 
   if (!ShouldPassThrough()) {
     cache_key_ = cache_->GenerateCacheKey(request_);
 
     // Requested cache access mode.
     if (effective_load_flags_ & LOAD_ONLY_FROM_CACHE) {
       if (effective_load_flags_ & LOAD_BYPASS_CACHE) {
         // The client has asked for nonsense.
+        next_state_ = STATE_NONE;
         return ERR_CACHE_MISS;
       }
       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.
@@ skipping 17 matching lines @@
   // Note that if mode_ == UPDATE (which is tied to external_validation_), the
   // transaction behaves the same for GET and HEAD requests at this point: if it
   // was not modified, the entry is updated and a response is not returned from
   // the cache. If we receive 200, it doesn't matter if there was a validation
   // header or not.
   if (request_->method == "HEAD" && mode_ == WRITE)
     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)
+  if (!(mode_ & READ) && effective_load_flags_ & LOAD_ONLY_FROM_CACHE) {
+    next_state_ = STATE_NONE;
     return ERR_CACHE_MISS;
+  }
 
   if (mode_ == NONE) {
     if (partial_) {
       partial_->RestoreHeaders(&custom_request_->extra_headers);
       partial_.reset();
     }
     next_state_ = STATE_SEND_REQUEST;
   } else {
     next_state_ = STATE_INIT_ENTRY;
   }
 
   // This is only set if we have something to do with the response.
   range_requested_ = (partial_.get() != NULL);
 
   return OK;
 }
 
 int HttpCache::Transaction::DoInitEntry() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoInitEntry");
   DCHECK(!new_entry_);
 
-  if (!cache_.get())
+  if (!cache_.get()) {
+    next_state_ = STATE_NONE;
     return ERR_UNEXPECTED;
+  }
 
   if (mode_ == WRITE) {
     next_state_ = STATE_DOOM_ENTRY;
     return OK;
   }
 
   next_state_ = STATE_OPEN_ENTRY;
   return OK;
 }
 
@@ skipping 40 matching lines @@
   }
   if (mode_ == UPDATE) {
     // There is no cache entry to update; proceed without caching.
     mode_ = NONE;
     next_state_ = STATE_SEND_REQUEST;
     return OK;
   }
 
   // The entry does not exist, and we are not permitted to create a new entry,
   // so we must fail.
+  next_state_ = STATE_NONE;
   return ERR_CACHE_MISS;
 }
 
 int HttpCache::Transaction::DoDoomEntry() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoDoomEntry");
   next_state_ = STATE_DOOM_ENTRY_COMPLETE;
   cache_pending_ = true;
   if (first_cache_access_since_.is_null())
     first_cache_access_since_ = TimeTicks::Now();
   net_log_.BeginEvent(NetLogEventType::HTTP_CACHE_DOOM_ENTRY);
@@ skipping 110 matching lines @@
 
   // If there is a failure, the cache should have taken care of new_entry_.
   new_entry_ = NULL;
 
   if (result == ERR_CACHE_RACE) {
     next_state_ = STATE_INIT_ENTRY;
     return OK;
   }
 
   if (result == ERR_CACHE_LOCK_TIMEOUT) {
-    if (mode_ == READ)
+    if (mode_ == READ) {
+      next_state_ = STATE_NONE;
       return ERR_CACHE_MISS;
+    }
 
     // The cache is busy, bypass it for this transaction.
     mode_ = NONE;
     next_state_ = STATE_SEND_REQUEST;
     if (partial_) {
       partial_->RestoreHeaders(&custom_request_->extra_headers);
       partial_.reset();
     }
     return OK;
   }
 
   open_entry_last_used_ = entry_->disk_entry->GetLastUsed();
 
+  // TODO(jkarlin): We should either handle the case or DCHECK.

[shivanisha, 2017/03/22 14:48:29]

Not sure what the "todo" suggests.

[jkarlin, 2017/03/22 15:04:26]

It's against Chromium style to NOTREACHED/DCHECK if you also handle the case
(e.g., return something) (see the condition below). So the TODO is to either
DCHECK or just handle the condition.

   if (result != OK) {
     NOTREACHED();
+    next_state_ = STATE_NONE;
     return result;
   }
 
   if (mode_ == WRITE) {
     if (partial_)
       partial_->RestoreHeaders(&custom_request_->extra_headers);
     next_state_ = STATE_SEND_REQUEST;
   } else {
     // We have to read the headers from the cached entry.
     DCHECK(mode_ & READ_META);
@@ skipping 111 matching lines @@
     case READ_WRITE:
       result = BeginPartialCacheValidation();
       break;
     case UPDATE:
       result = BeginExternallyConditionalizedRequest();
       break;
     case WRITE:
     default:
       NOTREACHED();
   }
   return result;

[shivanisha, 2017/03/22 15:19:48]

Since this Do function is setting the state in the helper functions, a dcheck
before return would be good.
DCHECK_NE(next_state_, STATE_UNSET)

[jkarlin, 2017/03/22 15:25:02]

That seems a bit redundant to me as the DCHECK will happen as soon as this
returns.

[shivanisha, 2017/03/22 15:31:53]

Makes sense.

 }
 
 int HttpCache::Transaction::DoCacheQueryData() {
   next_state_ = STATE_CACHE_QUERY_DATA_COMPLETE;
   return entry_->disk_entry->ReadyForSparseIO(io_callback_);
 }
 
 int HttpCache::Transaction::DoCacheQueryDataComplete(int result) {
   DCHECK_EQ(OK, result);
-  if (!cache_.get())
+  if (!cache_.get()) {
+    next_state_ = STATE_NONE;
     return ERR_UNEXPECTED;
+  }
 
   return ValidateEntryHeadersAndContinue();

[shivanisha, 2017/03/22 15:19:48]

Since this Do function is setting the state in the helper functions, a dcheck
before return would be good.
rv = ValidateEntryHeadersAndContinue();
DCHECK_NE(next_state_, STATE_UNSET)
return rv;

[jkarlin, 2017/03/22 15:25:02]

Acknowledged.

 }
 
 // We may end up here multiple times for a given request.
 int HttpCache::Transaction::DoStartPartialCacheValidation() {
-  if (mode_ == NONE)
+  if (mode_ == NONE) {
+    next_state_ = STATE_NONE;
     return OK;
+  }
 
   next_state_ = STATE_COMPLETE_PARTIAL_CACHE_VALIDATION;
   return partial_->ShouldValidateCache(entry_->disk_entry, io_callback_);
 }
 
 int HttpCache::Transaction::DoCompletePartialCacheValidation(int result) {
   if (!result) {
     // This is the end of the request.
     if (mode_ & WRITE) {
       DoneWritingToEntry(true);
     } else {
       cache_->DoneReadingFromEntry(entry_, this);
       entry_ = NULL;
     }
+    next_state_ = STATE_NONE;
     return result;
   }
 
-  if (result < 0)
+  if (result < 0) {
+    next_state_ = STATE_NONE;
     return result;
+  }
 
   partial_->PrepareCacheValidation(entry_->disk_entry,
                                    &custom_request_->extra_headers);
 
   if (reading_ && partial_->IsCurrentRangeCached()) {
     next_state_ = STATE_CACHE_READ_DATA;
     return OK;
   }
 
   return BeginCacheValidation();

[shivanisha, 2017/03/22 15:19:48]

Since this Do function is setting the state in the helper functions, a dcheck
before return would be good.

[jkarlin, 2017/03/22 15:25:02]

Acknowledged.

 }
 
 int HttpCache::Transaction::DoSendRequest() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoSendRequest");
   DCHECK(mode_ & WRITE || mode_ == NONE);
   DCHECK(!network_trans_.get());
 
   send_request_since_ = TimeTicks::Now();
 
   // Create a network transaction.
   int rv =
       cache_->network_layer_->CreateTransaction(priority_, &network_trans_);
-  if (rv != OK)
+  if (rv != OK) {
+    next_state_ = STATE_NONE;
     return rv;
+  }
   network_trans_->SetBeforeNetworkStartCallback(before_network_start_callback_);
   network_trans_->SetBeforeHeadersSentCallback(before_headers_sent_callback_);
 
   // Old load timing information, if any, is now obsolete.
   old_network_trans_load_timing_.reset();
   old_remote_endpoint_ = IPEndPoint();
 
   if (websocket_handshake_stream_base_create_helper_)
     network_trans_->SetWebSocketHandshakeStreamCreateHelper(
         websocket_handshake_stream_base_create_helper_);
 
   next_state_ = STATE_SEND_REQUEST_COMPLETE;
   rv = network_trans_->Start(request_, io_callback_, net_log_);
   return rv;
 }
 
 int HttpCache::Transaction::DoSendRequestComplete(int result) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoSendRequestComplete");
-  if (!cache_.get())
+  if (!cache_.get()) {
+    next_state_ = STATE_NONE;
     return ERR_UNEXPECTED;
+  }
 
   // If we tried to conditionalize the request and failed, we know
   // we won't be reading from the cache after this point.
   if (couldnt_conditionalize_request_)
     mode_ = WRITE;
 
   if (result == OK) {
     next_state_ = STATE_SUCCESSFUL_SEND_REQUEST;
     return OK;
   }
 
   const HttpResponseInfo* response = network_trans_->GetResponseInfo();
   response_.network_accessed = response->network_accessed;
 
   // Do not record requests that have network errors or restarts.
   UpdateCacheEntryStatus(CacheEntryStatus::ENTRY_OTHER);
   if (IsCertificateError(result)) {
     // If we get a certificate error, then there is a certificate in ssl_info,
     // so GetResponseInfo() should never return NULL here.
     DCHECK(response);
     response_.ssl_info = response->ssl_info;
   } else if (result == ERR_SSL_CLIENT_AUTH_CERT_NEEDED) {
     DCHECK(response);
     response_.cert_request_info = response->cert_request_info;
   } else if (response_.was_cached) {
     DoneWritingToEntry(true);
   }
 
+  next_state_ = STATE_NONE;
   return result;
 }
 
 // We received the response headers and there is no error.
 int HttpCache::Transaction::DoSuccessfulSendRequest() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoSuccessfulSendRequest");
   DCHECK(!new_response_);
   const HttpResponseInfo* new_response = network_trans_->GetResponseInfo();
 
   if (new_response->headers->response_code() == 401 ||
       new_response->headers->response_code() == 407) {
     SetAuthResponse(*new_response);
-    if (!reading_)
+    if (!reading_) {
+      next_state_ = STATE_NONE;
       return OK;
+    }
 
     // We initiated a second request the caller doesn't know about. We should be
     // able to authenticate this request because we should have authenticated
     // this URL moments ago.
     if (IsReadyToRestartForAuth()) {
       DCHECK(!response_.auth_challenge.get());
       next_state_ = STATE_SEND_REQUEST_COMPLETE;
       // In theory we should check to see if there are new cookies, but there
       // is no way to do that from here.
       return network_trans_->RestartWithAuth(AuthCredentials(), io_callback_);
     }
 
     // We have to perform cleanup at this point so that at least the next
     // request can succeed.  We do not retry at this point, because data
     // has been read and we have no way to gather credentials.  We would
     // fail again, and potentially loop.  This can happen if the credentials
     // expire while chrome is suspended.
     if (entry_)
       DoomPartialEntry(false);
     mode_ = NONE;
     partial_.reset();
     ResetNetworkTransaction();
+    next_state_ = STATE_NONE;
     return ERR_CACHE_AUTH_FAILURE_AFTER_READ;
   }
 
   new_response_ = new_response;
   if (!ValidatePartialResponse() && !auth_response_.headers.get()) {
     // Something went wrong with this request and we have to restart it.
     // If we have an authentication response, we are exposed to weird things
     // hapenning if the user cancels the authentication before we receive
     // the new response.
     net_log_.AddEvent(NetLogEventType::HTTP_CACHE_RE_SEND_PARTIAL_REQUEST);
@@ skipping 35 matching lines @@
       NonErrorResponse(new_response->headers->response_code())) {
     cache_->DoomMainEntryForUrl(request_->url);
   }
 
   RecordNoStoreHeaderHistogram(request_->load_flags, new_response);
 
   if (new_response_->headers->response_code() == 416 &&
       (request_->method == "GET" || request_->method == "POST")) {
     // If there is an active entry it may be destroyed with this transaction.
     SetResponse(*new_response_);
+    next_state_ = STATE_NONE;
     return OK;
   }
 
   // Are we expecting a response to a conditional query?
   if (mode_ == READ_WRITE || mode_ == UPDATE) {
     if (new_response->headers->response_code() == 304 || handling_206_) {
       UpdateCacheEntryStatus(CacheEntryStatus::ENTRY_VALIDATED);
       next_state_ = STATE_UPDATE_CACHED_RESPONSE;
       return OK;
     }
@@ skipping 30 matching lines @@
 
   if (response_.headers->HasHeaderValue("cache-control", "no-store")) {
     if (!entry_->doomed) {
       int ret = cache_->DoomEntry(cache_key_, NULL);
       DCHECK_EQ(OK, ret);
     }
   } else {
     // If we are already reading, we already updated the headers for this
     // request; doing it again will change Content-Length.
     if (!reading_) {
       next_state_ = STATE_CACHE_WRITE_UPDATED_RESPONSE;

[shivanisha, 2017/03/22 15:19:48]

Nothing to change here but pointing out for reference, this is one scenario
where a Do function is setting  a state in the beginning and then changing it
based on a condition.

[jkarlin, 2017/03/22 15:25:02]

Yep, it's not so great. Addressed in the follow-up CL:
https://codereview.chromium.org/2767033003/

       rv = OK;
     }
   }
   return rv;
 }
 
 int HttpCache::Transaction::DoCacheWriteUpdatedResponse() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheWriteUpdatedResponse");
 
   next_state_ = STATE_CACHE_WRITE_UPDATED_RESPONSE_COMPLETE;
@@ skipping 51 matching lines @@
   if (handling_206_ && partial_)
     partial_->FixContentLength(new_response_->headers.get());
 
   SetResponse(*new_response_);
 
   if (request_->method == "HEAD") {
     // This response is replacing the cached one.
     DoneWritingToEntry(false);
     mode_ = NONE;
     new_response_ = NULL;
+    next_state_ = STATE_NONE;
     return OK;
   }
 
   if (handling_206_ && !CanResume(false)) {
     // There is no point in storing this resource because it will never be used.
     // This may change if we support LOAD_ONLY_FROM_CACHE with sparse entries.
     DoneWritingToEntry(false);
     if (partial_)
       partial_->FixResponseHeaders(response_.headers.get(), true);
     next_state_ = STATE_PARTIAL_HEADERS_RECEIVED;
@@ skipping 59 matching lines @@
                                         result);
     }
   }
 
   next_state_ = STATE_PARTIAL_HEADERS_RECEIVED;
   return OK;
 }
 
 int HttpCache::Transaction::DoPartialHeadersReceived() {
   new_response_ = NULL;
-  if (entry_ && !partial_ && entry_->disk_entry->GetDataSize(kMetadataIndex))
-    next_state_ = STATE_CACHE_READ_METADATA;
 
-  if (!partial_)
+  if (!partial_) {
+    if (entry_ && entry_->disk_entry->GetDataSize(kMetadataIndex))
+      next_state_ = STATE_CACHE_READ_METADATA;
+    else
+      next_state_ = STATE_NONE;
     return OK;
+  }
 
   if (reading_) {
     if (network_trans_.get()) {
       next_state_ = STATE_NETWORK_READ;
     } else {
       next_state_ = STATE_CACHE_READ_DATA;
     }
   } else if (mode_ != NONE) {
     // We are about to return the headers for a byte-range request to the user,
     // so let's fix them.
     partial_->FixResponseHeaders(response_.headers.get(), true);
+    next_state_ = STATE_NONE;
+  } else {
+    next_state_ = STATE_NONE;
   }
   return OK;
 }
 
 int HttpCache::Transaction::DoCacheReadMetadata() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheReadMetadata");
   DCHECK(entry_);
   DCHECK(!response_.metadata.get());
   next_state_ = STATE_CACHE_READ_METADATA_COMPLETE;
 
   response_.metadata =
       new IOBufferWithSize(entry_->disk_entry->GetDataSize(kMetadataIndex));
 
   net_log_.BeginEvent(NetLogEventType::HTTP_CACHE_READ_INFO);
   return entry_->disk_entry->ReadData(kMetadataIndex, 0,
                                       response_.metadata.get(),
                                       response_.metadata->size(),
                                       io_callback_);
 }
 
 int HttpCache::Transaction::DoCacheReadMetadataComplete(int result) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheReadMetadataComplete");
   net_log_.EndEventWithNetErrorCode(NetLogEventType::HTTP_CACHE_READ_INFO,
                                     result);
   if (result != response_.metadata->size())
     return OnCacheReadError(result, false);
+  next_state_ = STATE_NONE;
   return OK;
 }
 
 int HttpCache::Transaction::DoNetworkRead() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoNetworkRead");
   next_state_ = STATE_NETWORK_READ_COMPLETE;
   return network_trans_->Read(read_buf_.get(), io_buf_len_, io_callback_);
 }
 
 int HttpCache::Transaction::DoNetworkReadComplete(int result) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoNetworkReadComplete");
   DCHECK(mode_ & WRITE || mode_ == NONE);
 
-  if (!cache_.get())
+  if (!cache_.get()) {
+    next_state_ = STATE_NONE;
     return ERR_UNEXPECTED;
+  }
 
   // If there is an error or we aren't saving the data, we are done; just wait
   // until the destructor runs to see if we can keep the data.
-  if (mode_ == NONE || result < 0)
+  if (mode_ == NONE || result < 0) {
+    next_state_ = STATE_NONE;
     return result;
+  }
 
   next_state_ = STATE_CACHE_WRITE_DATA;
   return result;
 }
 
 int HttpCache::Transaction::DoCacheReadData() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheReadData");
-  if (request_->method == "HEAD")
+
+  if (request_->method == "HEAD") {
+    next_state_ = STATE_NONE;
     return 0;
+  }
 
   DCHECK(entry_);
   next_state_ = STATE_CACHE_READ_DATA_COMPLETE;
 
   if (net_log_.IsCapturing())
     net_log_.BeginEvent(NetLogEventType::HTTP_CACHE_READ_DATA);
   if (partial_) {
     return partial_->CacheRead(entry_->disk_entry, read_buf_.get(), io_buf_len_,
                                io_callback_);
   }
 
   return entry_->disk_entry->ReadData(kResponseContentIndex, read_offset_,
                                       read_buf_.get(), io_buf_len_,
                                       io_callback_);
 }
 
 int HttpCache::Transaction::DoCacheReadDataComplete(int result) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheReadDataComplete");
   if (net_log_.IsCapturing()) {
     net_log_.EndEventWithNetErrorCode(NetLogEventType::HTTP_CACHE_READ_DATA,
                                       result);
   }
 
-  if (!cache_.get())
+  if (!cache_.get()) {
+    next_state_ = STATE_NONE;
     return ERR_UNEXPECTED;
+  }
 
   if (partial_) {
     // Partial requests are confusing to report in histograms because they may
     // have multiple underlying requests.
     UpdateCacheEntryStatus(CacheEntryStatus::ENTRY_OTHER);
     return DoPartialCacheReadCompleted(result);
   }
 
   if (result > 0) {
     read_offset_ += result;
   } else if (result == 0) {  // End of file.
     RecordHistograms();
     cache_->DoneReadingFromEntry(entry_, this);
     entry_ = NULL;
   } else {
     return OnCacheReadError(result, false);
   }
+
+  next_state_ = STATE_NONE;
   return result;
 }
 
 int HttpCache::Transaction::DoCacheWriteData(int num_bytes) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheWriteData");
   next_state_ = STATE_CACHE_WRITE_DATA_COMPLETE;
   write_len_ = num_bytes;
   if (entry_) {
     if (net_log_.IsCapturing())
       net_log_.BeginEvent(NetLogEventType::HTTP_CACHE_WRITE_DATA);
   }
 
   if (!entry_ || !num_bytes)
     return num_bytes;
 
   int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
   return WriteToEntry(kResponseContentIndex, current_size, read_buf_.get(),
                       num_bytes, io_callback_);
 }
 
 int HttpCache::Transaction::DoCacheWriteDataComplete(int result) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheWriteDataComplete");
   if (entry_) {
     if (net_log_.IsCapturing()) {
       net_log_.EndEventWithNetErrorCode(NetLogEventType::HTTP_CACHE_WRITE_DATA,
                                         result);
     }
   }
-  if (!cache_.get())
+  if (!cache_.get()) {
+    next_state_ = STATE_NONE;
     return ERR_UNEXPECTED;
+  }
 
   if (result != write_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.
     result = write_len_;
   } else if (!done_reading_ && entry_ && (!partial_ || truncated_)) {
     int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
@@ skipping 12 matching lines @@
 
   if (result == 0) {
     // End of file. This may be the result of a connection problem so see if we
     // have to keep the entry around to be flagged as truncated later on.
     if (done_reading_ || !entry_ || partial_ ||
         response_.headers->GetContentLength() <= 0) {
       DoneWritingToEntry(true);
     }
   }
 
+  next_state_ = STATE_NONE;
   return result;
 }
 
 int HttpCache::Transaction::DoCacheWriteTruncatedResponse() {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheWriteTruncatedResponse");
   next_state_ = STATE_CACHE_WRITE_TRUNCATED_RESPONSE_COMPLETE;
   return WriteResponseInfoToEntry(true);
 }
 
 int HttpCache::Transaction::DoCacheWriteTruncatedResponseComplete(int result) {
   TRACE_EVENT0("io", "HttpCacheTransaction::DoCacheWriteTruncatedResponse");
 
+  next_state_ = STATE_NONE;
   return OnWriteResponseInfoToEntryComplete(result);
 }
 
 //-----------------------------------------------------------------------------
 
 void HttpCache::Transaction::SetRequest(const NetLogWithSource& net_log,
                                         const HttpRequestInfo* request) {
   net_log_ = net_log;
   request_ = request;
   effective_load_flags_ = request_->load_flags;
@@ skipping 113 matching lines @@
     return false;
 
   if (request_->method == "DELETE")
     return false;
 
   return true;
 }
 
 int HttpCache::Transaction::BeginCacheRead() {
   // We don't support any combination of LOAD_ONLY_FROM_CACHE and byte ranges.
+  // TODO(jkarlin): Either handle this case or DCHECK.
   if (response_.headers->response_code() == 206 || partial_) {
     NOTREACHED();
+    next_state_ = STATE_NONE;
     return ERR_CACHE_MISS;
   }
 
   // We don't have the whole resource.
-  if (truncated_)
+  if (truncated_) {
+    next_state_ = STATE_NONE;
     return ERR_CACHE_MISS;
+  }
 
-  if (RequiresValidation() != VALIDATION_NONE)
+  if (RequiresValidation() != VALIDATION_NONE) {
+    next_state_ = STATE_NONE;
     return ERR_CACHE_MISS;
+  }
 
   if (request_->method == "HEAD")
     FixHeadersForHead();
 
   if (entry_->disk_entry->GetDataSize(kMetadataIndex))
     next_state_ = STATE_CACHE_READ_METADATA;
+  else
+    next_state_ = STATE_NONE;
 
   return OK;
 }
 
 int HttpCache::Transaction::BeginCacheValidation() {
   DCHECK_EQ(mode_, READ_WRITE);
 
   ValidationType required_validation = RequiresValidation();
 
   bool skip_validation = (required_validation == VALIDATION_NONE);
@@ skipping 500 matching lines @@
     }
   }
   cache_->ConvertWriterToReader(entry_);
   mode_ = READ;
 
   if (request_->method == "HEAD")
     FixHeadersForHead();
 
   if (entry_->disk_entry->GetDataSize(kMetadataIndex))
     next_state_ = STATE_CACHE_READ_METADATA;
+  else
+    next_state_ = STATE_NONE;
   return OK;
 }
 
 int HttpCache::Transaction::WriteToEntry(int index, int offset,
                                          IOBuffer* data, int data_len,
                                          const CompletionCallback& callback) {
   if (!entry_)
     return data_len;
 
   int rv = 0;
@@ skipping 89 matching lines @@
     DCHECK(!reading_);
     DCHECK(!network_trans_.get());
     cache_->DoneWithEntry(entry_, this, false);
     entry_ = NULL;
     is_sparse_ = false;
     partial_.reset();
     next_state_ = STATE_GET_BACKEND;
     return OK;
   }
 
+  next_state_ = STATE_NONE;
   return ERR_CACHE_READ_FAILURE;
 }
 
 void HttpCache::Transaction::OnAddToEntryTimeout(base::TimeTicks start_time) {
   if (entry_lock_waiting_since_ != start_time)
     return;
 
   DCHECK_EQ(next_state_, STATE_ADD_TO_ENTRY_COMPLETE);
 
   if (!cache_)
@@ skipping 15 matching lines @@
     partial_.reset(NULL);
 }
 
 int HttpCache::Transaction::DoPartialNetworkReadCompleted(int result) {
   partial_->OnNetworkReadCompleted(result);
 
   if (result == 0) {
     // We need to move on to the next range.
     ResetNetworkTransaction();
     next_state_ = STATE_START_PARTIAL_CACHE_VALIDATION;
+  } else {
+    next_state_ = STATE_NONE;
   }
   return result;
 }
 
 int HttpCache::Transaction::DoPartialCacheReadCompleted(int result) {
   partial_->OnCacheReadCompleted(result);
 
   if (result == 0 && mode_ == READ_WRITE) {
     // We need to move on to the next range.
     next_state_ = STATE_START_PARTIAL_CACHE_VALIDATION;
   } else if (result < 0) {
     return OnCacheReadError(result, false);
+  } else {
+    next_state_ = STATE_NONE;
   }
   return result;
 }
 
 int HttpCache::Transaction::DoRestartPartialRequest() {
   // The stored data cannot be used. Get rid of it and restart this request.
   net_log_.AddEvent(NetLogEventType::HTTP_CACHE_RESTART_PARTIAL_REQUEST);
 
   // WRITE + Doom + STATE_INIT_ENTRY == STATE_CREATE_ENTRY (without an attempt
   // to Doom the entry again).
@@ skipping 258 matching lines @@
     default:
       NOTREACHED();
   }
 }
 
 void HttpCache::Transaction::OnIOComplete(int result) {
   DoLoop(result);
 }
 
 }  // namespace net