Return number of values deleted by IDBObjectStore.delete(range)

content/browser/indexed_db/indexed_db_backing_store.cc

 // Copyright (c) 2013 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/browser/indexed_db/indexed_db_backing_store.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/files/file_path.h"
@@ skipping 1345 matching lines @@
       DatabaseMetaDataKey::Encode(row_id, DatabaseMetaDataKey::USER_VERSION),
       version);
   return true;
 }
 
 // If you're deleting a range that contains user keys that have blob info, this
 // won't clean up the blobs.
 static leveldb::Status DeleteRangeBasic(LevelDBTransaction* transaction,
                                         const std::string& begin,
                                         const std::string& end,
-                                        bool upper_open) {
+                                        bool upper_open,
+                                        size_t* delete_count) {
   std::unique_ptr<LevelDBIterator> it = transaction->CreateIterator();
   leveldb::Status s;
+  if (delete_count) {

[dmurph, 2016/05/19 01:01:38]

Remove brackets here and keep on same
line.(https://google.github.io/styleguide/cppguide.html#Conditionals)

[cmumford, 2016/05/19 17:07:15]

My preference would be to make delete_count a required parameter - don't allow
it to be null.

[palakj1, 2016/05/19 23:47:52]

Done. nullptr not permitted.

+    *delete_count = 0;
+  }
   for (s = it->Seek(begin); s.ok() && it->IsValid() &&
-                                (upper_open ? CompareKeys(it->Key(), end) < 0
-                                            : CompareKeys(it->Key(), end) <= 0);
-       s = it->Next())
-    transaction->Remove(it->Key());
+                            (upper_open ? CompareKeys(it->Key(), end) < 0
+                                        : CompareKeys(it->Key(), end) <= 0);
+       s = it->Next()) {
+    if (transaction->Remove(it->Key())) {
+      if (delete_count) {
+        (*delete_count)++;
+      }
+    }
+  }
   return s;
 }
 
 static leveldb::Status DeleteBlobsInRange(
     IndexedDBBackingStore::Transaction* transaction,
     int64_t database_id,
     int64_t object_store_id,
     const std::string& start_key,
     const std::string& end_key,
     bool upper_open) {
@@ skipping 401 matching lines @@
 
   s = DeleteBlobsInObjectStore(transaction, database_id, object_store_id);
   if (!s.ok()) {
     INTERNAL_CONSISTENCY_ERROR_UNTESTED(DELETE_OBJECT_STORE);
     return s;
   }
 
   s = DeleteRangeBasic(
       leveldb_transaction,
       ObjectStoreMetaDataKey::Encode(database_id, object_store_id, 0),
-      ObjectStoreMetaDataKey::EncodeMaxKey(database_id, object_store_id),
-      true);
+      ObjectStoreMetaDataKey::EncodeMaxKey(database_id, object_store_id), true,
+      NULL);

[cmumford, 2016/05/19 17:07:15]

At a minimum s/NULL/nullptr/g.

I still prefer to pass in a local size_t variable (which would be unused in this
function). I'm just not a big fan of optional parameters as they increase
failure paths.

[palakj1, 2016/05/19 23:47:52]

Done

 
   if (s.ok()) {
     leveldb_transaction->Remove(
         ObjectStoreNamesKey::Encode(database_id, object_store_name));
 
     s = DeleteRangeBasic(
         leveldb_transaction,
         IndexFreeListKey::Encode(database_id, object_store_id, 0),
-        IndexFreeListKey::EncodeMaxKey(database_id, object_store_id),
-        true);
+        IndexFreeListKey::EncodeMaxKey(database_id, object_store_id), true,
+        NULL);
   }
 
   if (s.ok()) {
     s = DeleteRangeBasic(
         leveldb_transaction,
         IndexMetaDataKey::Encode(database_id, object_store_id, 0, 0),
-        IndexMetaDataKey::EncodeMaxKey(database_id, object_store_id),
-        true);
+        IndexMetaDataKey::EncodeMaxKey(database_id, object_store_id), true,
+        NULL);
   }
 
   if (!s.ok()) {
     INTERNAL_WRITE_ERROR_UNTESTED(DELETE_OBJECT_STORE);
     return s;
   }
 
   return ClearObjectStore(transaction, database_id, object_store_id);
 }
 
@@ skipping 123 matching lines @@
     IndexedDBBackingStore::Transaction* transaction,
     int64_t database_id,
     int64_t object_store_id) {
   IDB_TRACE("IndexedDBBackingStore::ClearObjectStore");
   if (!KeyPrefix::ValidIds(database_id, object_store_id))
     return InvalidDBKeyStatus();
   const std::string start_key =
       KeyPrefix(database_id, object_store_id).Encode();
   const std::string stop_key =
       KeyPrefix(database_id, object_store_id + 1).Encode();
-
-  leveldb::Status s =
-      DeleteRangeBasic(transaction->transaction(), start_key, stop_key, true);
+  leveldb::Status s = DeleteRangeBasic(transaction->transaction(), start_key,
+                                       stop_key, true, NULL);
   if (!s.ok()) {
     INTERNAL_WRITE_ERROR(CLEAR_OBJECT_STORE);
     return s;
   }
   return DeleteBlobsInObjectStore(transaction, database_id, object_store_id);
 }
 
 leveldb::Status IndexedDBBackingStore::DeleteRecord(
     IndexedDBBackingStore::Transaction* transaction,
     int64_t database_id,
@@ skipping 15 matching lines @@
   const std::string exists_entry_key = ExistsEntryKey::Encode(
       database_id, object_store_id, record_identifier.primary_key());
   leveldb_transaction->Remove(exists_entry_key);
   return leveldb::Status::OK();
 }
 
 leveldb::Status IndexedDBBackingStore::DeleteRange(
     IndexedDBBackingStore::Transaction* transaction,
     int64_t database_id,
     int64_t object_store_id,
-    const IndexedDBKeyRange& key_range) {
+    const IndexedDBKeyRange& key_range,
+    size_t* delete_count) {
   leveldb::Status s;
+  if (delete_count)
+    (*delete_count) = 0;  // set delete_count to 0 for empty ranges

[cmumford, 2016/05/19 17:07:15]

I think the reason to initialize delete_count is obvious so no need for comment.
Can also ditch the parenthesis do just have:

*delete_count = 0;

[palakj1, 2016/05/19 23:47:52]

Done

   std::unique_ptr<IndexedDBBackingStore::Cursor> start_cursor =
       OpenObjectStoreCursor(transaction, database_id, object_store_id,
                             key_range, blink::WebIDBCursorDirectionNext, &s);
   if (!s.ok())
     return s;
   if (!start_cursor)
     return leveldb::Status::OK();  // Empty range == delete success.
-
   std::unique_ptr<IndexedDBBackingStore::Cursor> end_cursor =
       OpenObjectStoreCursor(transaction, database_id, object_store_id,
                             key_range, blink::WebIDBCursorDirectionPrev, &s);
 
   if (!s.ok())
     return s;
   if (!end_cursor)
     return leveldb::Status::OK();  // Empty range == delete success.
 
   BlobEntryKey start_blob_key, end_blob_key;
-
   std::string start_key = ObjectStoreDataKey::Encode(
       database_id, object_store_id, start_cursor->key());
   base::StringPiece start_key_piece(start_key);
   if (!BlobEntryKey::FromObjectStoreDataKey(&start_key_piece, &start_blob_key))
     return InternalInconsistencyStatus();
   std::string stop_key = ObjectStoreDataKey::Encode(
       database_id, object_store_id, end_cursor->key());
   base::StringPiece stop_key_piece(stop_key);
   if (!BlobEntryKey::FromObjectStoreDataKey(&stop_key_piece, &end_blob_key))
     return InternalInconsistencyStatus();
 
   s = DeleteBlobsInRange(transaction,
                          database_id,
                          object_store_id,
                          start_blob_key.Encode(),
                          end_blob_key.Encode(),
                          false);
   if (!s.ok())
     return s;
-  s = DeleteRangeBasic(transaction->transaction(), start_key, stop_key, false);
+  s = DeleteRangeBasic(transaction->transaction(), start_key, stop_key, false,

[dmurph, 2016/05/19 01:01:38]

Since both of these calls are going to make delete_range=0, do you want to
create a new variable for the second one maybe? I don't think we want to add
them together, as that would double your number (is that right, josh/chris)?

IF that's so, let's just count the second one (existance table).

[cmumford, 2016/05/19 17:07:15]

jsbell please confirm, but I believe they will both return the same count, and
should *not* be summed. I'd create a variable for the second call, something
like:

size_t ignore_delete_count;

[jsbell, 2016/05/19 18:23:42]

Alternately, call the first one data_count and the second one exists_entry_count
and DCHECK_EQ(data_count, exists_entry_count)

(https://chromium.googlesource.com/chromium/src/+/master/content/browser/index...
may be useful in understanding why we have two.)

[palakj1, 2016/05/19 23:47:52]

Thanks for this bit of explanation. Changed as per jsbell's suggestion:
call the first one data_count and the second one exists_entry_count and
DCHECK_EQ(data_count, exists_entry_count)

+                       delete_count);
   if (!s.ok())
     return s;
   start_key =
       ExistsEntryKey::Encode(database_id, object_store_id, start_cursor->key());
   stop_key =
       ExistsEntryKey::Encode(database_id, object_store_id, end_cursor->key());
-  return DeleteRangeBasic(
-      transaction->transaction(), start_key, stop_key, false);
+
+  return DeleteRangeBasic(transaction->transaction(), start_key, stop_key,
+                          false, delete_count);
 }
 
 leveldb::Status IndexedDBBackingStore::GetKeyGeneratorCurrentNumber(
     IndexedDBBackingStore::Transaction* transaction,
     int64_t database_id,
     int64_t object_store_id,
     int64_t* key_generator_current_number) {
   if (!KeyPrefix::ValidIds(database_id, object_store_id))
     return InvalidDBKeyStatus();
   LevelDBTransaction* leveldb_transaction = transaction->transaction();
@@ skipping 777 matching lines @@
     int64_t index_id) {
   IDB_TRACE("IndexedDBBackingStore::DeleteIndex");
   if (!KeyPrefix::ValidIds(database_id, object_store_id, index_id))
     return InvalidDBKeyStatus();
   LevelDBTransaction* leveldb_transaction = transaction->transaction();
 
   const std::string index_meta_data_start =
       IndexMetaDataKey::Encode(database_id, object_store_id, index_id, 0);
   const std::string index_meta_data_end =
       IndexMetaDataKey::EncodeMaxKey(database_id, object_store_id, index_id);
-  leveldb::Status s = DeleteRangeBasic(
-      leveldb_transaction, index_meta_data_start, index_meta_data_end, true);
+  leveldb::Status s =
+      DeleteRangeBasic(leveldb_transaction, index_meta_data_start,
+                       index_meta_data_end, true, NULL);

[dmurph, 2016/05/19 01:01:38]

we use 'nullptr'
https://google.github.io/styleguide/cppguide.html#0_and_nullptr/NULL

[palakj1, 2016/05/19 23:47:52]

value not null anymore

 
   if (s.ok()) {
     const std::string index_data_start =
         IndexDataKey::EncodeMinKey(database_id, object_store_id, index_id);
     const std::string index_data_end =
         IndexDataKey::EncodeMaxKey(database_id, object_store_id, index_id);
-    s = DeleteRangeBasic(
-        leveldb_transaction, index_data_start, index_data_end, true);
+    s = DeleteRangeBasic(leveldb_transaction, index_data_start, index_data_end,
+                         true, NULL);
   }
 
   if (!s.ok())
     INTERNAL_WRITE_ERROR_UNTESTED(DELETE_INDEX);
 
   return s;
 }
 
 leveldb::Status IndexedDBBackingStore::PutIndexDataForRecord(
     IndexedDBBackingStore::Transaction* transaction,
@@ skipping 1597 matching lines @@
 
 IndexedDBBackingStore::Transaction::WriteDescriptor::WriteDescriptor(
     const WriteDescriptor& other) = default;
 IndexedDBBackingStore::Transaction::WriteDescriptor::~WriteDescriptor() =
     default;
 IndexedDBBackingStore::Transaction::WriteDescriptor&
     IndexedDBBackingStore::Transaction::WriteDescriptor::
     operator=(const WriteDescriptor& other) = default;
 
 }  // namespace content