IndexedDB: Fix prefetching; cache was always being bypassed.

content/common/indexed_db/proxy_webidbcursor_impl.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 "content/common/indexed_db/proxy_webidbcursor_impl.h"
 
 #include "content/common/child_thread.h"
 #include "content/common/indexed_db/indexed_db_messages.h"
 #include "content/common/indexed_db/indexed_db_dispatcher.h"
 
 using WebKit::WebExceptionCode;
 using WebKit::WebIDBCallbacks;
 using WebKit::WebIDBKey;
 using WebKit::WebSerializedScriptValue;
 
 RendererWebIDBCursorImpl::RendererWebIDBCursorImpl(int32 idb_cursor_id)
     : idb_cursor_id_(idb_cursor_id),
       continue_count_(0),
       used_prefetches_(0),
       pending_onsuccess_callbacks_(0),
       prefetch_amount_(kMinPrefetchAmount) {
 }
 
 RendererWebIDBCursorImpl::~RendererWebIDBCursorImpl() {
   // It's not possible for there to be pending callbacks that address this
   // object since inside WebKit, they hold a reference to the object wich owns
   // this object. But, if that ever changed, then we'd need to invalidate
   // any such pointers.
+  if (idb_cursor_id_ == kInvalidIDBCursorId)
+    return;
   IndexedDBDispatcher::Send(new IndexedDBHostMsg_CursorDestroyed(
       idb_cursor_id_));
   IndexedDBDispatcher* dispatcher =
       IndexedDBDispatcher::ThreadSpecificInstance();
   dispatcher->CursorDestroyed(idb_cursor_id_);
 }
 
 unsigned short RendererWebIDBCursorImpl::direction() const {
+  if (idb_cursor_id_ == kInvalidIDBCursorId)
+    return 0;
   int direction;
   IndexedDBDispatcher::Send(
       new IndexedDBHostMsg_CursorDirection(idb_cursor_id_, &direction));
   return direction;
 }
 
 WebIDBKey RendererWebIDBCursorImpl::key() const {
   return key_;
 }
 
 WebIDBKey RendererWebIDBCursorImpl::primaryKey() const {
   return primary_key_;
 }
 
 WebSerializedScriptValue RendererWebIDBCursorImpl::value() const {
   return value_;
 }
 
 void RendererWebIDBCursorImpl::update(const WebSerializedScriptValue& value,
                                       WebIDBCallbacks* callbacks,
                                       WebExceptionCode& ec) {
+  if (idb_cursor_id_ == kInvalidIDBCursorId)
+    return;
   IndexedDBDispatcher* dispatcher =
       IndexedDBDispatcher::ThreadSpecificInstance();
   dispatcher->RequestIDBCursorUpdate(
       content::SerializedScriptValue(value), callbacks, idb_cursor_id_, &ec);
 }
 
 void RendererWebIDBCursorImpl::continueFunction(const WebIDBKey& key,
                                                 WebIDBCallbacks* callbacks,
                                                 WebExceptionCode& ec) {
   IndexedDBDispatcher* dispatcher =
       IndexedDBDispatcher::ThreadSpecificInstance();
 
-  if (key.type() == WebIDBKey::InvalidType) {
+  if (key.type() == WebIDBKey::NullType) {
     // No key, so this would qualify for a prefetch.
     ++continue_count_;
 
     if (!prefetch_keys_.empty()) {
       // We have a prefetch cache, so serve the result from that.
       CachedContinue(callbacks);
       return;
     }
 
+    if (idb_cursor_id_ == kInvalidIDBCursorId)
+      return;
+
     if (continue_count_ > kPrefetchContinueThreshold) {
       // Request pre-fetch.
       dispatcher->RequestIDBCursorPrefetch(prefetch_amount_, callbacks,
                                            idb_cursor_id_, &ec);
 
       // Increase prefetch_amount_ exponentially.
       prefetch_amount_ *= 2;
       if (prefetch_amount_ > kMaxPrefetchAmount)
         prefetch_amount_ = kMaxPrefetchAmount;
 
       return;
     }
   } else {
     // Key argument supplied. We couldn't prefetch this.
     ResetPrefetchCache();
   }
 
+  if (idb_cursor_id_ == kInvalidIDBCursorId)
+    return;
+
   dispatcher->RequestIDBCursorContinue(IndexedDBKey(key), callbacks,
                                        idb_cursor_id_, &ec);
 }
 
 void RendererWebIDBCursorImpl::deleteFunction(WebIDBCallbacks* callbacks,
                                               WebExceptionCode& ec) {
+  if (idb_cursor_id_ == kInvalidIDBCursorId)
+    return;
   IndexedDBDispatcher* dispatcher =
       IndexedDBDispatcher::ThreadSpecificInstance();
   dispatcher->RequestIDBCursorDelete(callbacks, idb_cursor_id_, &ec);
 }
 
 void RendererWebIDBCursorImpl::postSuccessHandlerCallback()
 {
   pending_onsuccess_callbacks_--;
 
   // If the onsuccess callback called continue() on the cursor again,
@@ skipping 48 matching lines @@
 
 void RendererWebIDBCursorImpl::ResetPrefetchCache() {
   continue_count_ = 0;
   prefetch_amount_ = kMinPrefetchAmount;
 
   if (!prefetch_keys_.size()) {
     // No prefetch cache, so no need to reset the cursor in the back-end.
     return;
   }
 
-  IndexedDBDispatcher* dispatcher =
-      IndexedDBDispatcher::ThreadSpecificInstance();
-  dispatcher->RequestIDBCursorPrefetchReset(used_prefetches_,
-                                            prefetch_keys_.size(),
-                                            idb_cursor_id_);
+  if (idb_cursor_id_ != kInvalidIDBCursorId) {
+    IndexedDBDispatcher* dispatcher =
+        IndexedDBDispatcher::ThreadSpecificInstance();
+    dispatcher->RequestIDBCursorPrefetchReset(used_prefetches_,
+                                              prefetch_keys_.size(),
+                                              idb_cursor_id_);
+  }
+
   prefetch_keys_.clear();
   prefetch_primary_keys_.clear();
   prefetch_values_.clear();
 
   pending_onsuccess_callbacks_ = 0;
 }