Migrate the IndexedDB backend from Blink to Chromium

content/browser/indexed_db/leveldb/leveldb_database.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_database.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram.h"
+#include "base/string16.h"
+#include "base/sys_info.h"
+#include "base/utf_string_conversions.h"
+#include "content/browser/indexed_db/leveldb/leveldb_comparator.h"
+#include "content/browser/indexed_db/leveldb/leveldb_iterator.h"
+#include "content/browser/indexed_db/leveldb/leveldb_slice.h"
+#include "content/browser/indexed_db/leveldb/leveldb_write_batch.h"
+#include "third_party/leveldatabase/env_idb.h"
+#include "third_party/leveldatabase/src/helpers/memenv/memenv.h"
+#include "third_party/leveldatabase/src/include/leveldb/comparator.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "third_party/leveldatabase/src/include/leveldb/env.h"
+#include "third_party/leveldatabase/src/include/leveldb/slice.h"
+
+namespace content {
+
+static leveldb::Slice MakeSlice(const std::vector<char>& value) {
+  return leveldb::Slice(value.data(), value.size());
+}
+
+static leveldb::Slice MakeSlice(const LevelDBSlice& s) {
+  return leveldb::Slice(s.begin(), s.end() - s.begin());
+}
+
+static LevelDBSlice MakeLevelDBSlice(const leveldb::Slice& s) {
+  return LevelDBSlice(s.data(), s.data() + s.size());
+}
+
+class ComparatorAdapter : public leveldb::Comparator {
+ public:
+  ComparatorAdapter(const LevelDBComparator* comparator)
+      : comparator_(comparator) {}
+
+  virtual int Compare(const leveldb::Slice& a, const leveldb::Slice& b) const
+      OVERRIDE {
+    return comparator_->Compare(MakeLevelDBSlice(a), MakeLevelDBSlice(b));
+  }
+
+  virtual const char* Name() const OVERRIDE { return comparator_->Name(); }
+
+  // TODO: Support the methods below in the future.
+  virtual void FindShortestSeparator(std::string* start,
+                                     const leveldb::Slice& limit) const
+      OVERRIDE {}
+  virtual void FindShortSuccessor(std::string* key) const OVERRIDE {}
+
+ private:
+  const LevelDBComparator* comparator_;
+};
+
+LevelDBSnapshot::LevelDBSnapshot(LevelDBDatabase* db)
+    : db_(db->db_.get()), snapshot_(db_->GetSnapshot()) {}
+
+LevelDBSnapshot::~LevelDBSnapshot() { db_->ReleaseSnapshot(snapshot_); }
+
+LevelDBDatabase::LevelDBDatabase() {}
+
+LevelDBDatabase::~LevelDBDatabase() {
+  // db_'s destructor uses comparator_adapter_; order of deletion is important.
+  db_.reset();
+  comparator_adapter_.reset();
+  env_.reset();
+}
+
+static leveldb::Status OpenDB(leveldb::Comparator* comparator,
+                              leveldb::Env* env,
+                              const base::FilePath& path,
+                              leveldb::DB** db) {
+  leveldb::Options options;
+  options.comparator = comparator;
+  options.create_if_missing = true;
+  options.paranoid_checks = true;
+
+  // Marking compression as explicitly off so snappy support can be
+  // compiled in for other leveldb clients without implicitly enabling
+  // it for IndexedDB. http://crbug.com/81384
+  options.compression = leveldb::kNoCompression;
+
+  // 20 max_open_files is the minimum LevelDB allows but its cache behaves
+  // poorly with less than 4 files per shard. As of this writing the latest
+  // leveldb (1.9) hardcodes 16 shards. See
+  // https://code.google.com/p/chromium/issues/detail?id=227313#c11
+  options.max_open_files = 80;
+  options.env = env;
+
+  // ChromiumEnv assumes UTF8, converts back to FilePath before using.
+  return leveldb::DB::Open(options, path.AsUTF8Unsafe(), db);
+}
+
+bool LevelDBDatabase::Destroy(const base::FilePath& file_name) {
+  leveldb::Options options;
+  options.env = leveldb::IDBEnv();
+  // ChromiumEnv assumes UTF8, converts back to FilePath before using.
+  const leveldb::Status s =
+      leveldb::DestroyDB(file_name.AsUTF8Unsafe(), options);
+  return s.ok();
+}
+
+static void HistogramFreeSpace(const char* type,
+                               const base::FilePath& file_name) {
+  string16 name = ASCIIToUTF16("WebCore.IndexedDB.LevelDB.Open") +
+                  ASCIIToUTF16(type) + ASCIIToUTF16("FreeDiskSpace");
+  long long free_disk_space_in_k_bytes =
+      base::SysInfo::AmountOfFreeDiskSpace(file_name) / 1024;
+  if (free_disk_space_in_k_bytes < 0) {
+    base::Histogram::FactoryGet(
+        "WebCore.IndexedDB.LevelDB.FreeDiskSpaceFailure",
+        1,
+        2 /*boundary*/,
+        2 /*boundary*/ + 1,
+        base::HistogramBase::kUmaTargetedHistogramFlag)->Add(1 /*sample*/);
+    return;
+  }
+  int clamped_disk_space_k_bytes =
+      free_disk_space_in_k_bytes > INT_MAX ? INT_MAX
+                                           : free_disk_space_in_k_bytes;
+  const uint64_t histogram_max = static_cast<uint64_t>(1e9);
+  COMPILE_ASSERT(histogram_max <= INT_MAX, histogram_max_too_big);
+  base::Histogram::FactoryGet(UTF16ToUTF8(name),
+                              1,
+                              histogram_max,
+                              11 /*buckets*/,
+                              base::HistogramBase::kUmaTargetedHistogramFlag)
+      ->Add(clamped_disk_space_k_bytes);
+}
+
+static void HistogramLevelDBError(const char* histogram_name,
+                                  const leveldb::Status& s) {
+  DCHECK(!s.ok());
+  enum {
+    LevelDBNotFound,
+    LevelDBCorruption,
+    LevelDBIOError,
+    LevelDBOther,
+    LevelDBMaxError
+  };
+  int leveldb_error = LevelDBOther;
+  if (s.IsNotFound())
+    leveldb_error = LevelDBNotFound;
+  else if (s.IsCorruption())
+    leveldb_error = LevelDBCorruption;
+  else if (s.IsIOError())
+    leveldb_error = LevelDBIOError;
+  base::Histogram::FactoryGet(histogram_name,
+                              1,
+                              LevelDBMaxError,
+                              LevelDBMaxError + 1,
+                              base::HistogramBase::kUmaTargetedHistogramFlag)
+      ->Add(leveldb_error);
+}
+
+scoped_ptr<LevelDBDatabase> LevelDBDatabase::Open(
+    const base::FilePath& file_name,
+    const LevelDBComparator* comparator) {
+  scoped_ptr<ComparatorAdapter> comparator_adapter(
+      new ComparatorAdapter(comparator));
+
+  leveldb::DB* db;
+  const leveldb::Status s =
+      OpenDB(comparator_adapter.get(), leveldb::IDBEnv(), file_name, &db);
+
+  if (!s.ok()) {
+    HistogramLevelDBError("WebCore.IndexedDB.LevelDBOpenErrors", s);
+    HistogramFreeSpace("Failure", file_name);
+
+    LOG(ERROR) << "Failed to open LevelDB database from "
+               << file_name.AsUTF8Unsafe() << "," << s.ToString();
+    return scoped_ptr<LevelDBDatabase>();
+  }
+
+  HistogramFreeSpace("Success", file_name);
+
+  scoped_ptr<LevelDBDatabase> result(new LevelDBDatabase);
+  result->db_ = make_scoped_ptr(db);
+  result->comparator_adapter_ = comparator_adapter.Pass();
+  result->comparator_ = comparator;
+
+  return result.Pass();
+}
+
+scoped_ptr<LevelDBDatabase> LevelDBDatabase::OpenInMemory(
+    const LevelDBComparator* comparator) {
+  scoped_ptr<ComparatorAdapter> comparator_adapter(
+      new ComparatorAdapter(comparator));
+  scoped_ptr<leveldb::Env> in_memory_env(leveldb::NewMemEnv(leveldb::IDBEnv()));
+
+  leveldb::DB* db;
+  const leveldb::Status s = OpenDB(
+      comparator_adapter.get(), in_memory_env.get(), base::FilePath(), &db);
+
+  if (!s.ok()) {
+    LOG(ERROR) << "Failed to open in-memory LevelDB database: " << s.ToString();
+    return scoped_ptr<LevelDBDatabase>();
+  }
+
+  scoped_ptr<LevelDBDatabase> result(new LevelDBDatabase);
+  result->env_ = in_memory_env.Pass();
+  result->db_ = make_scoped_ptr(db);
+  result->comparator_adapter_ = comparator_adapter.Pass();
+  result->comparator_ = comparator;
+
+  return result.Pass();
+}
+
+bool LevelDBDatabase::Put(const LevelDBSlice& key,
+                          const std::vector<char>& value) {
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+
+  const leveldb::Status s =
+      db_->Put(write_options, MakeSlice(key), MakeSlice(value));
+  if (s.ok())
+    return true;
+  LOG(ERROR) << "LevelDB put failed: " << s.ToString();
+  return false;
+}
+
+bool LevelDBDatabase::Remove(const LevelDBSlice& key) {
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+
+  const leveldb::Status s = db_->Delete(write_options, MakeSlice(key));
+  if (s.ok())
+    return true;
+  if (s.IsNotFound())
+    return false;
+  LOG(ERROR) << "LevelDB remove failed: " << s.ToString();
+  return false;
+}
+
+bool LevelDBDatabase::Get(const LevelDBSlice& key,
+                          std::vector<char>& value,
+                          bool& found,
+                          const LevelDBSnapshot* snapshot) {
+  found = false;
+  std::string result;
+  leveldb::ReadOptions read_options;
+  read_options.verify_checksums =
+      true;  // TODO: Disable this if the performance impact is too great.
+  read_options.snapshot = snapshot ? snapshot->snapshot_ : 0;
+
+  const leveldb::Status s = db_->Get(read_options, MakeSlice(key), &result);
+  if (s.ok()) {
+    found = true;
+    value.clear();
+    value.insert(value.end(), result.begin(), result.end());
+    return true;
+  }
+  if (s.IsNotFound())
+    return true;
+  LOG(ERROR) << "LevelDB get failed: " << s.ToString();
+  return false;
+}
+
+bool LevelDBDatabase::Write(LevelDBWriteBatch& write_batch) {
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+
+  const leveldb::Status s =
+      db_->Write(write_options, write_batch.write_batch_.get());
+  if (s.ok())
+    return true;
+  HistogramLevelDBError("WebCore.IndexedDB.LevelDBWriteErrors", s);
+  LOG(ERROR) << "LevelDB write failed: " << s.ToString();
+  return false;
+}
+
+namespace {
+class IteratorImpl : public LevelDBIterator {
+ public:
+  virtual ~IteratorImpl() {}
+
+  virtual bool IsValid() const OVERRIDE;
+  virtual void SeekToLast() OVERRIDE;
+  virtual void Seek(const LevelDBSlice& target) OVERRIDE;
+  virtual void Next() OVERRIDE;
+  virtual void Prev() OVERRIDE;
+  virtual LevelDBSlice Key() const OVERRIDE;
+  virtual LevelDBSlice Value() const OVERRIDE;
+
+ private:
+  friend class content::LevelDBDatabase;
+  IteratorImpl(scoped_ptr<leveldb::Iterator>);
+  void CheckStatus();
+
+  scoped_ptr<leveldb::Iterator> iterator_;
+};
+}
+
+IteratorImpl::IteratorImpl(scoped_ptr<leveldb::Iterator> it)
+    : iterator_(it.Pass()) {}
+
+void IteratorImpl::CheckStatus() {
+  const leveldb::Status s = iterator_->status();
+  if (!s.ok())
+    LOG(ERROR) << "LevelDB iterator error: " << s.ToString();
+}
+
+bool IteratorImpl::IsValid() const { return iterator_->Valid(); }
+
+void IteratorImpl::SeekToLast() {
+  iterator_->SeekToLast();
+  CheckStatus();
+}
+
+void IteratorImpl::Seek(const LevelDBSlice& target) {
+  iterator_->Seek(MakeSlice(target));
+  CheckStatus();
+}
+
+void IteratorImpl::Next() {
+  DCHECK(IsValid());
+  iterator_->Next();
+  CheckStatus();
+}
+
+void IteratorImpl::Prev() {
+  DCHECK(IsValid());
+  iterator_->Prev();
+  CheckStatus();
+}
+
+LevelDBSlice IteratorImpl::Key() const {
+  DCHECK(IsValid());
+  return MakeLevelDBSlice(iterator_->key());
+}
+
+LevelDBSlice IteratorImpl::Value() const {
+  DCHECK(IsValid());
+  return MakeLevelDBSlice(iterator_->value());
+}
+
+scoped_ptr<LevelDBIterator> LevelDBDatabase::CreateIterator(
+    const LevelDBSnapshot* snapshot) {
+  leveldb::ReadOptions read_options;
+  read_options.verify_checksums =
+      true;  // TODO: Disable this if the performance impact is too great.
+  read_options.snapshot = snapshot ? snapshot->snapshot_ : 0;
+  scoped_ptr<leveldb::Iterator> i(db_->NewIterator(read_options));
+  if (!i)  // TODO: Double check if we actually need to check this.
+    return scoped_ptr<LevelDBIterator>();
+  return scoped_ptr<LevelDBIterator>(new IteratorImpl(i.Pass()));
+}
+
+const LevelDBComparator* LevelDBDatabase::Comparator() const {
+  return comparator_;
+}
+
+}  // namespace content