Revert of [SyncFS] Introduce DatabaseWrapper class (https://codereview.chromium.org/415033002/)

Reason for revert:
Broke compile on DrMemory bots.

Original issue's description:
> [SyncFS] Introduce DatabaseWrapper class.
> 
> DatabaseWrapper class wraps leveldb::DB and leveldb::WriteBatch class.
> DatabaseWrapper has following features.
> - Simple interfaces for many usages.
> - I/O seems synchronous, with caching pending transactions on memory.
> 
> 
> 
> BUG=347425
> TEST=./unit_tests --gtest_filter="DatabaseWrapper*"
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=286451

TBR=nhiroki@chromium.org,tzik@chromium.org,peria@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=398820

Review URL: https://codereview.chromium.org/423423002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@286483 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 0 insertions, 481 deletions

diff --git a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc b/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc
deleted file mode 100644
index d18325d..0000000
--- a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc
+++ /dev/null
@@ -1,188 +0,0 @@
-// Copyright 2014 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 "chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h"
-
-#include <map>
-#include <set>
-#include <string>
-
-#include "base/logging.h"
-#include "third_party/leveldatabase/src/include/leveldb/db.h"
-#include "third_party/leveldatabase/src/include/leveldb/iterator.h"
-#include "third_party/leveldatabase/src/include/leveldb/slice.h"
-#include "third_party/leveldatabase/src/include/leveldb/status.h"
-#include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
-
-namespace sync_file_system {
-namespace drive_backend {
-
-LevelDBWrapper::Iterator::Iterator(LevelDBWrapper* db)
-    : db_(db),
-      db_iterator_(db->db_->NewIterator(leveldb::ReadOptions())),
-      map_iterator_(db->pending_.end()) {}
-
-LevelDBWrapper::Iterator::~Iterator() {}
-
-bool LevelDBWrapper::Iterator::Valid() {
-  return map_iterator_ != db_->pending_.end() ||
-      db_iterator_->Valid();
-}
-
-void LevelDBWrapper::Iterator::Seek(const std::string& target) {
-  map_iterator_ = db_->pending_.lower_bound(target);
-  db_iterator_->Seek(target);
-  AdvanceIterators();
-}
-
-void LevelDBWrapper::Iterator::Next() {
-  if (map_iterator_ == db_->pending_.end()) {
-    if (db_iterator_->Valid())
-      db_iterator_->Next();
-    return;
-  }
-
-  if (db_iterator_->Valid()) {
-    int comp = db_iterator_->key().compare(map_iterator_->first);
-    if (comp <= 0)
-      db_iterator_->Next();
-    if (comp >= 0)
-      ++map_iterator_;
-  }
-
-  AdvanceIterators();
-}
-
-leveldb::Slice LevelDBWrapper::Iterator::key() {
-  DCHECK(Valid());
-
-  if (!db_iterator_->Valid())
-    return map_iterator_->first;
-  if (map_iterator_ == db_->pending_.end())
-    return db_iterator_->key();
-
-  const leveldb::Slice db_key = db_iterator_->key();
-  const leveldb::Slice map_key = map_iterator_->first;
-  return (db_key.compare(map_key) < 0) ? db_key : map_key;
-}
-
-leveldb::Slice LevelDBWrapper::Iterator::value() {
-  DCHECK(Valid());
-
-  if (!db_iterator_->Valid())
-    return map_iterator_->second.second;
-  if (map_iterator_ == db_->pending_.end())
-    return db_iterator_->value();
-
-  const leveldb::Slice db_key = db_iterator_->key();
-  const leveldb::Slice map_key = map_iterator_->first;
-  if (db_key.compare(map_key) < 0)
-    return db_iterator_->value();
-
-  DCHECK(map_iterator_->second.first == PUT);
-  return map_iterator_->second.second;
-}
-
-void LevelDBWrapper::Iterator::AdvanceIterators() {
-  // Iterator is valid iff any of below holds:
-  // - |db_itr.key| < |map_itr.key| OR |map_itr| == end()
-  // - (|db_itr.key| >= |map_itr.key| OR !|db_itr|->IsValid())
-  //   AND |map_itr.operation| == PUT
-
-  if (map_iterator_ == db_->pending_.end())
-    return;
-
-  while (map_iterator_ != db_->pending_.end() && db_iterator_->Valid()) {
-    int cmp_key = db_iterator_->key().compare(map_iterator_->first);
-    if (cmp_key < 0 || map_iterator_->second.first == PUT)
-      return;
-    // |db_itr.key| >= |map_itr.key| && |map_itr.operation| != PUT
-    if (cmp_key == 0)
-      db_iterator_->Next();
-    ++map_iterator_;
-  }
-
-  if (db_iterator_->Valid())
-    return;
-
-  while (map_iterator_ != db_->pending_.end() &&
-         map_iterator_->second.first == DELETE)
-    ++map_iterator_;
-}
-
-// ---------------------------------------------------------------------------
-// LevelDBWrapper class
-// ---------------------------------------------------------------------------
-LevelDBWrapper::LevelDBWrapper(scoped_ptr<leveldb::DB> db)
-    : db_(db.Pass()) {
-  DCHECK(db_);
-}
-
-LevelDBWrapper::~LevelDBWrapper() {}
-
-void LevelDBWrapper::Put(const std::string& key,
-                         const std::string& value) {
-  pending_[key] = Transaction(PUT, value);
-}
-
-void LevelDBWrapper::Delete(const std::string& key) {
-  pending_[key] = Transaction(DELETE, std::string());
-}
-
-leveldb::Status LevelDBWrapper::Get(const std::string& key,
-                                    std::string* value) {
-  PendingOperationMap::iterator itr = pending_.find(key);
-  if (itr == pending_.end())
-    return db_->Get(leveldb::ReadOptions(), key, value);
-
-  const Transaction& transaction = itr->second;
-  switch (transaction.first) {
-    case PUT:
-      *value = transaction.second;
-      return leveldb::Status();
-    case DELETE:
-      return leveldb::Status::NotFound(leveldb::Slice());
-  }
-  NOTREACHED();
-  return leveldb::Status::NotSupported("Not supported operation.");
-}
-
-scoped_ptr<LevelDBWrapper::Iterator> LevelDBWrapper::NewIterator() {
-  return make_scoped_ptr(new Iterator(this));
-}
-
-leveldb::Status LevelDBWrapper::Commit() {
-  leveldb::WriteBatch batch;
-  for (PendingOperationMap::iterator itr = pending_.begin();
-       itr != pending_.end(); ++itr) {
-    const leveldb::Slice key(itr->first);
-    const Transaction& transaction = itr->second;
-    switch (transaction.first) {
-      case PUT:
-        batch.Put(key, transaction.second);
-        break;
-      case DELETE:
-        batch.Delete(key);
-        break;
-    }
-  }
-
-  leveldb::Status status = db_->Write(leveldb::WriteOptions(), &batch);
-  // TODO(peria): Decide what to do depending on |status|.
-  if (status.ok())
-    Clear();
-
-  return status;
-}
-
-void LevelDBWrapper::Clear() {
-  pending_.clear();
-}
-
-leveldb::DB* LevelDBWrapper::GetLevelDBForTesting() {
-  return db_.get();
-}
-
-}  // namespace drive_backend
-}  // namespace sync_file_system
diff --git a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h b/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h
deleted file mode 100644
index 321bb1086..0000000
--- a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h
+++ /dev/null
@@ -1,102 +0,0 @@
-// Copyright 2014 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.
-
-#ifndef CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_LEVELDB_WRAPPER_H_
-#define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_LEVELDB_WRAPPER_H_
-
-#include <map>
-#include <string>
-
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "third_party/leveldatabase/src/include/leveldb/slice.h"
-
-namespace leveldb {
-class DB;
-class Iterator;
-class Slice;
-class Status;
-class WriteBatch;
-}
-
-namespace sync_file_system {
-namespace drive_backend {
-
-class SliceComparator {
- public:
-  bool operator()(const leveldb::Slice& a, const leveldb::Slice& b) const {
-    return a.compare(b) < 0;
-  }
-};
-
-// LevelDBWrapper class wraps leveldb::DB and leveldb::WriteBatch to provide
-// transparent access to pre-commit data.
-// Put() and Delete() update data on memory, and Get() can access to those data
-// and also data on disk.  Those data on memory are written down on disk when
-// Commit() is called.
-class LevelDBWrapper {
- private:
-  enum Operation {
-    PUT,
-    DELETE,
-  };
-  typedef std::pair<Operation, std::string> Transaction;
-  typedef std::map<std::string, Transaction, SliceComparator>
-      PendingOperationMap;
-
- public:
-  class Iterator {
-   public:
-    explicit Iterator(LevelDBWrapper* db);
-    ~Iterator();
-
-    bool Valid();
-    void Seek(const std::string& target);
-    void Next();
-    leveldb::Slice key();
-    leveldb::Slice value();
-
-   private:
-    // Advances internal iterators to be valid.
-    void AdvanceIterators();
-
-    LevelDBWrapper* db_;  // do not own
-    scoped_ptr<leveldb::Iterator> db_iterator_;
-    PendingOperationMap::iterator map_iterator_;
-
-    DISALLOW_COPY_AND_ASSIGN(Iterator);
-  };
-
-  explicit LevelDBWrapper(scoped_ptr<leveldb::DB> db);
-  ~LevelDBWrapper();
-
-  // Wrapping methods of leveldb::WriteBatch
-  void Put(const std::string& key, const std::string& value);
-  void Delete(const std::string& key);
-
-  // Wrapping methods of leveldb::DB
-  leveldb::Status Get(const std::string& key, std::string* value);
-  scoped_ptr<Iterator> NewIterator();
-
-  // Commits pending transactions to |db_| and clears cached transactions.
-  // Returns true if the commitment succeeds.
-  leveldb::Status Commit();
-
-  // Clears pending transactions.
-  void Clear();
-
-  leveldb::DB* GetLevelDBForTesting();
-
- private:
-  scoped_ptr<leveldb::DB> db_;
-
-  PendingOperationMap pending_;
-
-  DISALLOW_COPY_AND_ASSIGN(LevelDBWrapper);
-};
-
-}  // namespace drive_backend
-}  // namespace sync_file_system
-
-#endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_LEVELDB_WRAPPER_H_
diff --git a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper_unittest.cc b/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper_unittest.cc
deleted file mode 100644
index 808d442..0000000
--- a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper_unittest.cc
+++ /dev/null
@@ -1,188 +0,0 @@
-// Copyright 2014 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 "chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h"
-
-#include <string>
-
-#include "base/files/scoped_temp_dir.h"
-#include "base/logging.h"
-#include "base/strings/string_number_conversions.h"
-#include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/leveldatabase/src/helpers/memenv/memenv.h"
-#include "third_party/leveldatabase/src/include/leveldb/db.h"
-#include "third_party/leveldatabase/src/include/leveldb/env.h"
-
-namespace sync_file_system {
-namespace drive_backend {
-
-struct TestData {
-  const std::string key;
-  const std::string value;
-};
-
-class LevelDBWrapperTest : public testing::Test {
- public:
-  virtual ~LevelDBWrapperTest() {}
-
-  virtual void SetUp() OVERRIDE {
-    ASSERT_TRUE(database_dir_.CreateUniqueTempDir());
-    in_memory_env_.reset(leveldb::NewMemEnv(leveldb::Env::Default()));
-    InitializeLevelDB();
-  }
-
-  virtual void TearDown() OVERRIDE {
-    db_.reset();
-    in_memory_env_.reset();
-  }
-
-  void CreateDefaultDatabase() {
-    leveldb::DB* db = db_->GetLevelDBForTesting();
-
-    // Expected contents are
-    // {"a": "1", "ab": "0", "bb": "3", "d": "4"}
-    const char* keys[] = {"ab", "a", "d", "bb", "d"};
-    for (size_t i = 0; i < arraysize(keys); ++i) {
-      leveldb::Status status =
-          db->Put(leveldb::WriteOptions(), keys[i], base::Int64ToString(i));
-      ASSERT_TRUE(status.ok());
-    }
-  }
-
-  LevelDBWrapper* GetDB() {
-    return db_.get();
-  }
-
-  void CheckDBContents(const TestData expects[], size_t size) {
-    DCHECK(db_);
-
-    scoped_ptr<LevelDBWrapper::Iterator> itr = db_->NewIterator();
-    // TODO(peria): Use itr->SeekToFirst(), if available.
-    itr->Seek(std::string());
-    for (size_t i = 0; i < size; ++i) {
-      ASSERT_TRUE(itr->Valid());
-      EXPECT_EQ(expects[i].key, itr->key().ToString());
-      EXPECT_EQ(expects[i].value, itr->value().ToString());
-      itr->Next();
-    }
-    EXPECT_FALSE(itr->Valid());
-  }
-
- private:
-  void InitializeLevelDB() {
-    leveldb::DB* db = NULL;
-    leveldb::Options options;
-    options.create_if_missing = true;
-    options.max_open_files = 0;  // Use minimum.
-    options.env = in_memory_env_.get();
-    leveldb::Status status =
-        leveldb::DB::Open(options, database_dir_.path().AsUTF8Unsafe(), &db);
-    ASSERT_TRUE(status.ok());
-
-    db_.reset(new LevelDBWrapper(make_scoped_ptr(db)));
-  }
-
-  base::ScopedTempDir database_dir_;
-  scoped_ptr<leveldb::Env> in_memory_env_;
-  scoped_ptr<LevelDBWrapper> db_;
-};
-
-TEST_F(LevelDBWrapperTest, IteratorTest) {
-  CreateDefaultDatabase();
-  scoped_ptr<LevelDBWrapper::Iterator> itr = GetDB()->NewIterator();
-
-  itr->Seek("a");
-  EXPECT_TRUE(itr->Valid());
-  EXPECT_EQ("a", itr->key().ToString());
-  EXPECT_EQ("1", itr->value().ToString());
-
-  itr->Next();
-  EXPECT_TRUE(itr->Valid());
-  EXPECT_EQ("ab", itr->key().ToString());
-  EXPECT_EQ("0", itr->value().ToString());
-
-  itr->Seek("b");
-  EXPECT_TRUE(itr->Valid());
-  EXPECT_EQ("bb", itr->key().ToString());
-  EXPECT_EQ("3", itr->value().ToString());
-
-  itr->Next();
-  EXPECT_TRUE(itr->Valid());
-  EXPECT_EQ("d", itr->key().ToString());
-  EXPECT_EQ("4", itr->value().ToString());
-
-  itr->Next();
-  EXPECT_FALSE(itr->Valid());
-}
-
-TEST_F(LevelDBWrapperTest, PutTest) {
-  TestData merged_data[] = {{"a", "1"}, {"aa", "new0"}, {"ab", "0"},
-                            {"bb", "new2"}, {"c", "new1"}, {"d", "4"}};
-  TestData orig_data[] = {{"a", "1"}, {"ab", "0"}, {"bb", "3"}, {"d", "4"}};
-
-  CreateDefaultDatabase();
-
-  // Add pending transactions.
-  GetDB()->Put("aa", "new0");
-  GetDB()->Put("c", "new1");
-  GetDB()->Put("bb", "new2");  // Overwrite an entry.
-
-  SCOPED_TRACE("PutTest_Pending");
-  CheckDBContents(merged_data, arraysize(merged_data));
-
-  // Remove all pending transactions.
-  GetDB()->Clear();
-
-  SCOPED_TRACE("PutTest_Clear");
-  CheckDBContents(orig_data, arraysize(orig_data));
-
-  // Add pending transactions again, with commiting.
-  GetDB()->Put("aa", "new0");
-  GetDB()->Put("c", "new1");
-  GetDB()->Put("bb", "new2");
-  GetDB()->Commit();
-  GetDB()->Clear();  // Clear just in case.
-
-  SCOPED_TRACE("PutTest_Commit");
-  CheckDBContents(merged_data, arraysize(merged_data));
-}
-
-TEST_F(LevelDBWrapperTest, DeleteTest) {
-  TestData merged_data[] = {{"a", "1"}, {"aa", "new0"}, {"bb", "new2"},
-                            {"d", "4"}};
-  TestData orig_data[] = {{"a", "1"}, {"ab", "0"}, {"bb", "3"}, {"d", "4"}};
-
-  CreateDefaultDatabase();
-
-  // Add pending transactions.
-  GetDB()->Put("aa", "new0");
-  GetDB()->Put("c", "new1");
-  GetDB()->Put("bb", "new2");  // Overwrite an entry.
-  GetDB()->Delete("c");        // Remove a pending entry.
-  GetDB()->Delete("ab");       // Remove a committed entry.
-
-  SCOPED_TRACE("DeleteTest_Pending");
-  CheckDBContents(merged_data, arraysize(merged_data));
-
-  // Remove all pending transactions.
-  GetDB()->Clear();
-
-  SCOPED_TRACE("DeleteTest_Clear");
-  CheckDBContents(orig_data, arraysize(orig_data));
-
-  // Add pending transactions again, with commiting.
-  GetDB()->Put("aa", "new0");
-  GetDB()->Put("c", "new1");
-  GetDB()->Put("bb", "new2");
-  GetDB()->Delete("c");
-  GetDB()->Delete("ab");
-  GetDB()->Commit();
-  GetDB()->Clear();
-
-  SCOPED_TRACE("DeleteTest_Commit");
-  CheckDBContents(merged_data, arraysize(merged_data));
-}
-
-}  // namespace drive_backend
-}  // namespace sync_file_system
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index ebc4183..552575e 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1569,8 +1569,6 @@
       'browser/sync_file_system/drive_backend/drive_uploader_wrapper.h',
       'browser/sync_file_system/drive_backend/folder_creator.cc',
       'browser/sync_file_system/drive_backend/folder_creator.h',
-      'browser/sync_file_system/drive_backend/leveldb_wrapper.cc',
-      'browser/sync_file_system/drive_backend/leveldb_wrapper.h',
       'browser/sync_file_system/drive_backend/list_changes_task.cc',
       'browser/sync_file_system/drive_backend/list_changes_task.h',
       'browser/sync_file_system/drive_backend/local_to_remote_syncer.cc',
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 836f85d..741daf7 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -1397,7 +1397,6 @@
         'browser/sync_file_system/drive_backend/fake_drive_uploader.h',
         'browser/sync_file_system/drive_backend/fake_sync_worker.cc',
         'browser/sync_file_system/drive_backend/fake_sync_worker.h',
-        'browser/sync_file_system/drive_backend/leveldb_wrapper_unittest.cc',
         'browser/sync_file_system/drive_backend/list_changes_task_unittest.cc',
         'browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc',
         'browser/sync_file_system/drive_backend/metadata_database_index_on_disk_unittest.cc',