[IndexedDB] Refactoring to remove ref ptrs and host transaction ids.

content/browser/indexed_db/indexed_db_cursor.cc

Index: content/browser/indexed_db/indexed_db_cursor.cc
diff --git a/content/browser/indexed_db/indexed_db_cursor.cc b/content/browser/indexed_db/indexed_db_cursor.cc
index f4b2c5fd6f99287c7752f1e0e70c80975af8c0bf..0fe947d9f2f858a2d4914f5a7272201ef96a6835 100644
--- a/content/browser/indexed_db/indexed_db_cursor.cc
+++ b/content/browser/indexed_db/indexed_db_cursor.cc
@@ -18,6 +18,34 @@
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBDatabaseException.h"
 
 namespace content {
+namespace {
+IndexedDBDatabaseError CreateCursorClosedError() {
+  return IndexedDBDatabaseError(blink::WebIDBDatabaseExceptionUnknownError,

[jsbell, 2016/11/30 21:30:14]

Maybe add a comment that this should never be script visible: the cursor should
either be closed when it hits the end of the range (and script throws an error
before the call could be made), if the transaction has finished (ditto), or if
there's an incoming request from the front end but the transaction has aborted
on the back end; in that case the tx will already have sent an abort to the
request so this would be ignored.

[dmurph, 2016/11/30 23:13:07]

Done.

+                                "The cursor has been closed.");
+}
+
+leveldb::Status InvokeOrSucceed(base::WeakPtr<IndexedDBCursor> weak_cursor,
+                                IndexedDBTransaction::Operation operation,
+                                IndexedDBTransaction* transaction) {
+  if (weak_cursor)
+    return operation.Run(transaction);
+  return leveldb::Status::OK();
+}
+
+template <typename Functor, typename... Args>
+IndexedDBTransaction::Operation BindWeakOperation(

[jsbell, 2016/11/30 21:30:14]

Add a comment on usage here.

As an alternative to this, InvokeOrSucceed could take
std::unique_ptr<base::WeakPtr<IndexedDBCursor>> 

[dmurph, 2016/11/30 23:13:07]

Done.

+    Functor&& functor,
+    base::WeakPtr<IndexedDBCursor> weak_cursor,
+    Args&&... args) {
+  DCHECK(weak_cursor);
+  IndexedDBCursor* cursor_ptr = weak_cursor.get();
+  return base::Bind(
+      &InvokeOrSucceed, std::move(weak_cursor),
+      base::Bind(std::forward<Functor>(functor), base::Unretained(cursor_ptr),
+                 std::forward<Args>(args)...));
+}
+
+}  // namespace
 
 IndexedDBCursor::IndexedDBCursor(
     std::unique_ptr<IndexedDBBackingStore::Cursor> cursor,
@@ -28,13 +56,10 @@ IndexedDBCursor::IndexedDBCursor(
       cursor_type_(cursor_type),
       transaction_(transaction),
       cursor_(std::move(cursor)),
-      closed_(false) {
-  transaction_->RegisterOpenCursor(this);
-}
+      closed_(false),
+      ptr_factory_(this) {}
 
-IndexedDBCursor::~IndexedDBCursor() {
-  transaction_->UnregisterOpenCursor(this);
-}
+IndexedDBCursor::~IndexedDBCursor() {}
 
 void IndexedDBCursor::Continue(std::unique_ptr<IndexedDBKey> key,
                                std::unique_ptr<IndexedDBKey> primary_key,
@@ -42,19 +67,15 @@ void IndexedDBCursor::Continue(std::unique_ptr<IndexedDBKey> key,
   IDB_TRACE("IndexedDBCursor::Continue");
 
   if (closed_) {
-    callbacks->OnError(
-        IndexedDBDatabaseError(blink::WebIDBDatabaseExceptionUnknownError,
-                               "The cursor has been closed."));
+    callbacks->OnError(CreateCursorClosedError());
     return;
   }
 
   transaction_->ScheduleTask(
       task_type_,
-      base::Bind(&IndexedDBCursor::CursorIterationOperation,
-                 this,
-                 base::Passed(&key),
-                 base::Passed(&primary_key),
-                 callbacks));
+      BindWeakOperation(&IndexedDBCursor::CursorIterationOperation,
+                        ptr_factory_.GetWeakPtr(), base::Passed(&key),
+                        base::Passed(&primary_key), callbacks));
 }
 
 void IndexedDBCursor::Advance(uint32_t count,
@@ -62,16 +83,27 @@ void IndexedDBCursor::Advance(uint32_t count,
   IDB_TRACE("IndexedDBCursor::Advance");
 
   if (closed_) {
-    callbacks->OnError(
-        IndexedDBDatabaseError(blink::WebIDBDatabaseExceptionUnknownError,
-                               "The cursor has been closed."));
+    callbacks->OnError(CreateCursorClosedError());
     return;
   }
 
   transaction_->ScheduleTask(
       task_type_,
-      base::Bind(
-          &IndexedDBCursor::CursorAdvanceOperation, this, count, callbacks));
+      BindWeakOperation(&IndexedDBCursor::CursorAdvanceOperation,
+                        ptr_factory_.GetWeakPtr(), count, callbacks));
+}
+
+void IndexedDBCursor::Close() {
+  IDB_TRACE("IndexedDBCursor::Close");
+  closed_ = true;
+  cursor_.reset();
+  saved_cursor_.reset();
+  transaction_ = nullptr;
+}
+
+void IndexedDBCursor::RemoveCursorFromTransaction() {
+  if (transaction_)
+    transaction_->UnregisterOpenCursor(this);
 }
 
 leveldb::Status IndexedDBCursor::CursorAdvanceOperation(
@@ -131,18 +163,14 @@ void IndexedDBCursor::PrefetchContinue(
   IDB_TRACE("IndexedDBCursor::PrefetchContinue");
 
   if (closed_) {
-    callbacks->OnError(
-        IndexedDBDatabaseError(blink::WebIDBDatabaseExceptionUnknownError,
-                               "The cursor has been closed."));
+    callbacks->OnError(CreateCursorClosedError());
     return;
   }
 
   transaction_->ScheduleTask(
       task_type_,
-      base::Bind(&IndexedDBCursor::CursorPrefetchIterationOperation,
-                 this,
-                 number_to_fetch,
-                 callbacks));
+      BindWeakOperation(&IndexedDBCursor::CursorPrefetchIterationOperation,
+                        ptr_factory_.GetWeakPtr(), number_to_fetch, callbacks));
 }
 
 leveldb::Status IndexedDBCursor::CursorPrefetchIterationOperation(
@@ -239,11 +267,4 @@ leveldb::Status IndexedDBCursor::PrefetchReset(int used_prefetches,
   return s;
 }
 
-void IndexedDBCursor::Close() {
-  IDB_TRACE("IndexedDBCursor::Close");
-  closed_ = true;
-  cursor_.reset();
-  saved_cursor_.reset();
-}
-
 }  // namespace content