IndexedDB: Optimize range deletion operations (e.g. clearing a store)

content/browser/indexed_db/leveldb/leveldb_transaction.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/leveldb/leveldb_transaction.h"
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "content/browser/indexed_db/indexed_db_tracing.h"
 #include "content/browser/indexed_db/leveldb/leveldb_database.h"
 #include "content/browser/indexed_db/leveldb/leveldb_write_batch.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 
 using base::StringPiece;
 
 namespace content {
 
 LevelDBTransaction::LevelDBTransaction(LevelDBDatabase* db)
     : db_(db),
       snapshot_(db),
       comparator_(db->Comparator()),
       data_comparator_(comparator_),
       data_(data_comparator_),
       finished_(false) {}
 
-LevelDBTransaction::Record::Record() : deleted(false) {}
+LevelDBTransaction::Record::Record() {}
 LevelDBTransaction::Record::~Record() {}
 
 LevelDBTransaction::~LevelDBTransaction() {}
 
 bool LevelDBTransaction::Set(const StringPiece& key,
                              std::string* value,
                              bool deleted) {
   DCHECK(!finished_);
   DataType::iterator it = data_.find(key);
 
@@ skipping 14 matching lines @@
 
 void LevelDBTransaction::Put(const StringPiece& key, std::string* value) {
   Set(key, value, false);
 }
 
 bool LevelDBTransaction::Remove(const StringPiece& key) {
   std::string empty;
   return !Set(key, &empty, true);
 }
 
+leveldb::Status LevelDBTransaction::RemoveRange(const StringPiece& begin,
+                                                const StringPiece& end,
+                                                bool upper_open) {
+  IDB_TRACE("LevelDBTransaction::RemoveRange");
+  data_.erase(data_.lower_bound(begin), data_.lower_bound(end));
+  if (!upper_open)
+    data_.erase(end);
+  std::unique_ptr<LevelDBIterator> it = CreateIterator();
+  leveldb::Status s;
+  for (s = it->Seek(begin);
+       s.ok() && it->IsValid() &&
+       (upper_open ? comparator_->Compare(it->Key(), end) < 0
+                   : comparator_->Compare(it->Key(), end) <= 0);
+       s = it->Next()) {
+    std::unique_ptr<Record> record = base::MakeUnique<Record>();
+    record->key = it->Key().as_string();
+    record->deleted = true;
+    data_[record->key] = std::move(record);
+  }
+  NotifyIterators();
+  return s;
+}
+
 leveldb::Status LevelDBTransaction::Get(const StringPiece& key,
                                         std::string* value,
                                         bool* found) {
   *found = false;
   DCHECK(!finished_);
   std::string string_key(key.begin(), key.end() - key.begin());
   DataType::const_iterator it = data_.find(string_key);
 
   if (it != data_.end()) {
     if (it->second->deleted)
@@ skipping 414 matching lines @@
 
   leveldb::Status s = db_->Write(*write_batch_);
   if (s.ok()) {
     finished_ = true;
     write_batch_->Clear();
   }
   return s;
 }
 
 }  // namespace content