Source/WebCore/platform/leveldb/LevelDBDatabase.cpp

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
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 *     notice, this list of conditions and the following disclaimer in the
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 *
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"
#include "LevelDBDatabase.h"

#if USE(LEVELDB)

#include "LevelDBComparator.h"
#include "LevelDBIterator.h"
#include "LevelDBSlice.h"
#include "LevelDBWriteBatch.h"
#include "Logging.h"
#include <helpers/memenv/memenv.h>
#include <leveldb/comparator.h>
#include <leveldb/db.h>
#include <leveldb/env.h>
#include <leveldb/slice.h>
#include <string>
#include <wtf/PassOwnPtr.h>
#include <wtf/text/CString.h>
#include <wtf/text/WTFString.h>

namespace WebCore {

static leveldb::Slice makeSlice(const 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());
}

static Vector<char> makeVector(const std::string& s)
{
    Vector<char> res;
    res.append(s.c_str(), s.length());
    return res;
}

class ComparatorAdapter : public leveldb::Comparator {
public:
    ComparatorAdapter(const LevelDBComparator* comparator)
        : m_comparator(comparator)
    {
    }

    virtual int Compare(const leveldb::Slice& a, const leveldb::Slice& b) const
    {
        return m_comparator->compare(makeLevelDBSlice(a), makeLevelDBSlice(b));
    }

    virtual const char* Name() const { return m_comparator->name(); }

    // FIXME: Support the methods below in the future.
    virtual void FindShortestSeparator(std::string* start, const leveldb::Slice& limit) const { }
    virtual void FindShortSuccessor(std::string* key) const { }

private:
    const LevelDBComparator* m_comparator;
};

LevelDBDatabase::LevelDBDatabase()
{
}

LevelDBDatabase::~LevelDBDatabase()
{
    // m_db's destructor uses m_comparatorAdapter; order of deletion is important.
    m_db.clear();
    m_comparatorAdapter.clear();
    m_env.clear();
}

static leveldb::Status openDB(leveldb::Comparator* comparator, leveldb::Env* env, const String& path, leveldb::DB** db)
{
    leveldb::Options options;
    options.comparator = comparator;
    options.create_if_missing = true;
    options.paranoid_checks = true;
    options.env = env;

    return leveldb::DB::Open(options, path.utf8().data(), db);
}

PassOwnPtr<LevelDBDatabase> LevelDBDatabase::open(const String& fileName, const LevelDBComparator* comparator)
{
    OwnPtr<ComparatorAdapter> comparatorAdapter = adoptPtr(new ComparatorAdapter(comparator));

    leveldb::DB* db;
    const leveldb::Status s = openDB(comparatorAdapter.get(), leveldb::Env::Default(), fileName, &db);

    if (!s.ok()) {
        LOG_ERROR("Failed to open LevelDB database from %s: %s", fileName.ascii().data(), s.ToString().c_str());
        return nullptr;
    }

    OwnPtr<LevelDBDatabase> result = adoptPtr(new LevelDBDatabase);
    result->m_db = adoptPtr(db);
    result->m_comparatorAdapter = comparatorAdapter.release();
    result->m_comparator = comparator;

    return result.release();
}

PassOwnPtr<LevelDBDatabase> LevelDBDatabase::openInMemory(const LevelDBComparator* comparator)
{
    OwnPtr<ComparatorAdapter> comparatorAdapter = adoptPtr(new ComparatorAdapter(comparator));
    OwnPtr<leveldb::Env> inMemoryEnv = adoptPtr(leveldb::NewMemEnv(leveldb::Env::Default()));

    leveldb::DB* db;
    const leveldb::Status s = openDB(comparatorAdapter.get(), inMemoryEnv.get(), String(), &db);

    if (!s.ok()) {
        LOG_ERROR("Failed to open in-memory LevelDB database: %s", s.ToString().c_str());
        return nullptr;
    }

    OwnPtr<LevelDBDatabase> result = adoptPtr(new LevelDBDatabase);
    result->m_env = inMemoryEnv.release();
    result->m_db = adoptPtr(db);
    result->m_comparatorAdapter = comparatorAdapter.release();
    result->m_comparator = comparator;

    return result.release();
}

bool LevelDBDatabase::put(const LevelDBSlice& key, const Vector<char>& value)
{
    leveldb::WriteOptions writeOptions;
    writeOptions.sync = true;

    const leveldb::Status s = m_db->Put(writeOptions, makeSlice(key), makeSlice(value));
    if (s.ok())
        return true;
    LOG_ERROR("LevelDB put failed: %s", s.ToString().c_str());
    return false;
}

bool LevelDBDatabase::remove(const LevelDBSlice& key)
{
    leveldb::WriteOptions writeOptions;
    writeOptions.sync = true;

    const leveldb::Status s = m_db->Delete(writeOptions, makeSlice(key));
    if (s.ok())
        return true;
    if (s.IsNotFound())
        return false;
    LOG_ERROR("LevelDB remove failed: %s", s.ToString().c_str());
    return false;
}

bool LevelDBDatabase::get(const LevelDBSlice& key, Vector<char>& value)
{
    std::string result;
    leveldb::ReadOptions readOptions;
    readOptions.verify_checksums = true; // FIXME: Disable this if the performance impact is too great.

    const leveldb::Status s = m_db->Get(readOptions, makeSlice(key), &result);
    if (s.ok()) {
        value = makeVector(result);
        return true;
    }
    if (s.IsNotFound())
        return false;
    LOG_ERROR("LevelDB get failed: %s", s.ToString().c_str());
    return false;
}

bool LevelDBDatabase::write(LevelDBWriteBatch& writeBatch)
{
    leveldb::WriteOptions writeOptions;
    writeOptions.sync = true;

    const leveldb::Status s = m_db->Write(writeOptions, writeBatch.m_writeBatch.get());
    if (s.ok())
        return true;
    LOG_ERROR("LevelDB write failed: %s", s.ToString().c_str());
    return false;
}

namespace {
class IteratorImpl : public LevelDBIterator {
public:
    ~IteratorImpl() { };

    virtual bool isValid() const;
    virtual void seekToLast();
    virtual void seek(const LevelDBSlice& target);
    virtual void next();
    virtual void prev();
    virtual LevelDBSlice key() const;
    virtual LevelDBSlice value() const;

private:
    friend class WebCore::LevelDBDatabase;
    IteratorImpl(PassOwnPtr<leveldb::Iterator>);
    void checkStatus();

    OwnPtr<leveldb::Iterator> m_iterator;
};
}

IteratorImpl::IteratorImpl(PassOwnPtr<leveldb::Iterator> it)
    : m_iterator(it)
{
}

void IteratorImpl::checkStatus()
{
    const leveldb::Status s = m_iterator->status();
    if (!s.ok())
        LOG_ERROR("LevelDB iterator error: %s", s.ToString().c_str());
}

bool IteratorImpl::isValid() const
{
    return m_iterator->Valid();
}

void IteratorImpl::seekToLast()
{
    m_iterator->SeekToLast();
    checkStatus();
}

void IteratorImpl::seek(const LevelDBSlice& target)
{
    m_iterator->Seek(makeSlice(target));
    checkStatus();
}

void IteratorImpl::next()
{
    ASSERT(isValid());
    m_iterator->Next();
    checkStatus();
}

void IteratorImpl::prev()
{
    ASSERT(isValid());
    m_iterator->Prev();
    checkStatus();
}

LevelDBSlice IteratorImpl::key() const
{
    ASSERT(isValid());
    return makeLevelDBSlice(m_iterator->key());
}

LevelDBSlice IteratorImpl::value() const
{
    ASSERT(isValid());
    return makeLevelDBSlice(m_iterator->value());
}

PassOwnPtr<LevelDBIterator> LevelDBDatabase::createIterator()
{
    leveldb::ReadOptions readOptions;
    readOptions.verify_checksums = true; // FIXME: Disable this if the performance impact is too great.
    OwnPtr<leveldb::Iterator> i = adoptPtr(m_db->NewIterator(readOptions));
    if (!i) // FIXME: Double check if we actually need to check this.
        return nullptr;
    return adoptPtr(new IteratorImpl(i.release()));
}

const LevelDBComparator* LevelDBDatabase::comparator() const
{
    return m_comparator;
}

}

#endif