Revert 51858 - Disk cache: Switch the disk cache to use the cache_thread.

Add an InFlightBackendIO class that handles posting of 
cacheoperations back and forth between the IO thread and 
the cachethread. 

BUG=26730
TEST=unit tests 

Review URL: http://codereview.chromium.org/2827043

TBR=rvargas@google.com
Review URL: http://codereview.chromium.org/2944002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51874 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 17 insertions, 58 deletions

diff --git a/net/tools/crash_cache/crash_cache.cc b/net/tools/crash_cache/crash_cache.cc
index 1d11013..a26c873 100644
--- a/net/tools/crash_cache/crash_cache.cc
+++ b/net/tools/crash_cache/crash_cache.cc
@@ -118,14 +118,6 @@ bool CreateTargetFolder(const FilePath& path, RankCrashes action,
   return file_util::CreateDirectory(*full_path);
 }
 
-// Makes sure that any pending task is processed.
-void FlushQueue(disk_cache::Backend* cache) {
-  TestCompletionCallback cb;
-  int rv =
-      reinterpret_cast<disk_cache::BackendImpl*>(cache)->FlushQueueForTest(&cb);
-  cb.GetResult(rv);  // Ignore the result;
-}
-
 // Generates the files for an empty and one item cache.
 int SimpleInsert(const FilePath& path, RankCrashes action,
                  base::Thread* cache_thread) {
@@ -150,7 +142,6 @@ int SimpleInsert(const FilePath& path, RankCrashes action,
     return GENERIC;
 
   entry->Close();
-  FlushQueue(cache);
 
   DCHECK(action <= disk_cache::INSERT_ONE_3);
   g_rankings_crash = action;
@@ -171,8 +162,7 @@ int SimpleRemove(const FilePath& path, RankCrashes action,
 
   TestCompletionCallback cb;
   disk_cache::Backend* cache;
-  // Use a simple LRU for eviction.
-  int rv = disk_cache::CreateCacheBackend(net::MEDIA_CACHE, path, 0, false,
+  int rv = disk_cache::CreateCacheBackend(net::DISK_CACHE, path, 0, false,
                                           cache_thread->message_loop_proxy(),
                                           &cache, &cb);
   if (cb.GetResult(rv) != net::OK || cache->GetEntryCount())
@@ -184,7 +174,6 @@ int SimpleRemove(const FilePath& path, RankCrashes action,
     return GENERIC;
 
   entry->Close();
-  FlushQueue(cache);
 
   if (action >= disk_cache::REMOVE_TAIL_1) {
     rv = cache->CreateEntry("some other key", &entry, &cb);
@@ -192,7 +181,6 @@ int SimpleRemove(const FilePath& path, RankCrashes action,
       return GENERIC;
 
     entry->Close();
-    FlushQueue(cache);
   }
 
   rv = cache->OpenEntry(kCrashEntryName, &entry, &cb);
@@ -202,7 +190,6 @@ int SimpleRemove(const FilePath& path, RankCrashes action,
   g_rankings_crash = action;
   entry->Doom();
   entry->Close();
-  FlushQueue(cache);
 
   return NOT_REACHED;
 }
@@ -214,8 +201,7 @@ int HeadRemove(const FilePath& path, RankCrashes action,
 
   TestCompletionCallback cb;
   disk_cache::Backend* cache;
-  // Use a simple LRU for eviction.
-  int rv = disk_cache::CreateCacheBackend(net::MEDIA_CACHE, path, 0, false,
+  int rv = disk_cache::CreateCacheBackend(net::DISK_CACHE, path, 0, false,
                                           cache_thread->message_loop_proxy(),
                                           &cache, &cb);
   if (cb.GetResult(rv) != net::OK || cache->GetEntryCount())
@@ -227,13 +213,11 @@ int HeadRemove(const FilePath& path, RankCrashes action,
     return GENERIC;
 
   entry->Close();
-  FlushQueue(cache);
   rv = cache->CreateEntry(kCrashEntryName, &entry, &cb);
   if (cb.GetResult(rv) != net::OK)
     return GENERIC;
 
   entry->Close();
-  FlushQueue(cache);
 
   rv = cache->OpenEntry(kCrashEntryName, &entry, &cb);
   if (cb.GetResult(rv) != net::OK)
@@ -242,7 +226,6 @@ int HeadRemove(const FilePath& path, RankCrashes action,
   g_rankings_crash = action;
   entry->Doom();
   entry->Close();
-  FlushQueue(cache);
 
   return NOT_REACHED;
 }
@@ -258,14 +241,14 @@ int LoadOperations(const FilePath& path, RankCrashes action,
   if (!cache || !cache->SetMaxSize(0x100000))
     return GENERIC;
 
-  TestCompletionCallback cb;
-  int rv = cache->Init(&cb);
-  if (cb.GetResult(rv) != net::OK || cache->GetEntryCount())
+  if (!cache->Init() || cache->GetEntryCount())
     return GENERIC;
 
   int seed = static_cast<int>(Time::Now().ToInternalValue());
   srand(seed);
 
+  TestCompletionCallback cb;
+  int rv;
   disk_cache::Entry* entry;
   for (int i = 0; i < 100; i++) {
     std::string key = GenerateKey(true);
@@ -273,13 +256,11 @@ int LoadOperations(const FilePath& path, RankCrashes action,
     if (cb.GetResult(rv) != net::OK)
       return GENERIC;
     entry->Close();
-    FlushQueue(cache);
     if (50 == i && action >= disk_cache::REMOVE_LOAD_1) {
       rv = cache->CreateEntry(kCrashEntryName, &entry, &cb);
       if (cb.GetResult(rv) != net::OK)
         return GENERIC;
       entry->Close();
-      FlushQueue(cache);
     }
   }
 
@@ -299,7 +280,6 @@ int LoadOperations(const FilePath& path, RankCrashes action,
 
   entry->Doom();
   entry->Close();
-  FlushQueue(cache);
 
   return NOT_REACHED;
 }
diff --git a/net/tools/dump_cache/upgrade.cc b/net/tools/dump_cache/upgrade.cc
index 60099b2..5a3cd67 100644
--- a/net/tools/dump_cache/upgrade.cc
+++ b/net/tools/dump_cache/upgrade.cc
@@ -104,8 +104,7 @@ enum {
   RESULT_OK = 0,
   RESULT_UNKNOWN_COMMAND,
   RESULT_INVALID_PARAMETER,
-  RESULT_NAME_OVERFLOW,
-  RESULT_PENDING  // This error code is NOT expected by the master process.
+  RESULT_NAME_OVERFLOW
 };
 
 // -----------------------------------------------------------------------
@@ -576,7 +575,6 @@ class SlaveSM : public BaseSM {
   void DoGetNextEntry();
   void DoGetPrevEntry();
   int32 GetEntryFromList();
-  void DoGetEntryComplete(int result);
   void DoCloseEntry();
   void DoGetKey();
   void DoGetUseTimes();
@@ -587,19 +585,16 @@ class SlaveSM : public BaseSM {
   void Fail();
 
   void* iterator_;
-  Message msg_;  // Used for DoReadDataComplete and DoGetEntryComplete.
+  Message msg_;  // Only used for DoReadDataComplete.
 
   net::CompletionCallbackImpl<SlaveSM> read_callback_;
-  net::CompletionCallbackImpl<SlaveSM> next_callback_;
   scoped_ptr<disk_cache::BackendImpl> cache_;
 };
 
 SlaveSM::SlaveSM(const std::wstring& path, HANDLE channel)
     : BaseSM(channel), iterator_(NULL),
       ALLOW_THIS_IN_INITIALIZER_LIST(
-          read_callback_(this, &SlaveSM::DoReadDataComplete)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(
-          next_callback_(this, &SlaveSM::DoGetEntryComplete)) {
+          read_callback_(this, &SlaveSM::DoReadDataComplete)) {
   disk_cache::Backend* cache;
   TestCompletionCallback cb;
   int rv = disk_cache::CreateCacheBackend(net::DISK_CACHE,
@@ -677,9 +672,6 @@ bool SlaveSM::DoInit() {
   DEBUGMSG("\t\t\tSlave DoInit\n");
   DCHECK(state_ == SLAVE_INITIAL);
   state_ = SLAVE_WAITING;
-  if (!cache_.get())
-    return false;
-
   return ReceiveMsg();
 }
 
@@ -708,11 +700,6 @@ void SlaveSM::DoGetPrevEntry() {
     msg.result = RESULT_UNKNOWN_COMMAND;
   } else {
     msg.result = GetEntryFromList();
-    if (msg.result == RESULT_PENDING) {
-      // We are not done yet.
-      msg_ = msg;
-      return;
-    }
     msg.long_arg1 = reinterpret_cast<int64>(entry_);
   }
   SendMsg(msg);
@@ -728,31 +715,23 @@ int32 SlaveSM::GetEntryFromList() {
   if (entry_)
     entry_->Close();
 
-  int rv;
+  bool ret;
   if (input_->msg.command == GET_NEXT_ENTRY) {
-    rv = cache_->OpenNextEntry(&iterator_,
-                               reinterpret_cast<disk_cache::Entry**>(&entry_),
-                               &next_callback_);
+    ret = cache_->OpenNextEntry(&iterator_,
+                                reinterpret_cast<disk_cache::Entry**>(&entry_));
   } else {
     DCHECK(input_->msg.command == GET_PREV_ENTRY);
-    rv = cache_->OpenPrevEntry(&iterator_,
-                               reinterpret_cast<disk_cache::Entry**>(&entry_),
-                               &next_callback_);
+    ret = cache_->OpenPrevEntry(&iterator_,
+                                reinterpret_cast<disk_cache::Entry**>(&entry_));
   }
-  DCHECK_EQ(net::ERR_IO_PENDING, rv);
-  return RESULT_PENDING;
-}
 
-void SlaveSM::DoGetEntryComplete(int result) {
-  DEBUGMSG("\t\t\tSlave DoGetEntryComplete\n");
-  if (result != net::OK) {
+  if (!ret)
     entry_ = NULL;
+
+  if (!entry_)
     DEBUGMSG("\t\t\tSlave end of list\n");
-  }
 
-  msg_.result = RESULT_OK;
-  msg_.long_arg1 = reinterpret_cast<int64>(entry_);
-  SendMsg(msg_);
+  return RESULT_OK;
 }
 
 void SlaveSM::DoCloseEntry() {