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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
#ifndef LEVEL_DB_STORE_H
#define LEVEL_DB_STORE_H
#include "include/types.h"
#include "include/buffer.h"
#include "KeyValueDB.h"
#include <set>
#include <map>
#include <string>
#include <tr1/memory>
#include <boost/scoped_ptr.hpp>
#include "leveldb/db.h"
#include "leveldb/write_batch.h"
#include "leveldb/slice.h"
/**
* Uses LevelDB to implement the KeyValueDB interface
*/
class LevelDBStore : public KeyValueDB {
string path;
boost::scoped_ptr<leveldb::DB> db;
public:
LevelDBStore(const string &path) : path(path) {}
/// Opens underlying db
int init(ostream &out);
class LevelDBTransactionImpl : public KeyValueDB::TransactionImpl {
public:
leveldb::WriteBatch bat;
list<bufferlist> buffers;
list<string> keys;
LevelDBStore *db;
LevelDBTransactionImpl(LevelDBStore *db) : db(db) {}
void set(
const string &prefix,
const std::map<string, bufferlist> &to_set
);
void rmkeys(
const string &prefix,
const std::set<string> &keys
);
void rmkeys_by_prefix(
const string &prefix
);
};
KeyValueDB::Transaction get_transaction() {
return std::tr1::shared_ptr< LevelDBTransactionImpl >(
new LevelDBTransactionImpl(this));
}
int submit_transaction(KeyValueDB::Transaction t) {
LevelDBTransactionImpl * _t =
static_cast<LevelDBTransactionImpl *>(t.get());
leveldb::Status s = db->Write(leveldb::WriteOptions(), &(_t->bat));
return s.ok() ? 0 : -1;
}
int submit_transaction_sync(KeyValueDB::Transaction t) {
LevelDBTransactionImpl * _t =
static_cast<LevelDBTransactionImpl *>(t.get());
leveldb::WriteOptions options;
options.sync = true;
leveldb::Status s = db->Write(options, &(_t->bat));
return s.ok() ? 0 : -1;
}
int get(
const string &prefix,
const std::set<string> &key,
std::map<string, bufferlist> *out
);
class LevelDBIteratorImpl : public KeyValueDB::IteratorImpl {
boost::scoped_ptr<leveldb::Iterator> dbiter;
const string prefix;
public:
LevelDBIteratorImpl(leveldb::Iterator *iter, const string &prefix) :
dbiter(iter), prefix(prefix) {}
int seek_to_first() {
leveldb::Slice slice_prefix(prefix);
dbiter->Seek(slice_prefix);
return dbiter->status().ok() ? 0 : -1;
}
int seek_to_last() {
string limit = past_prefix(prefix);
leveldb::Slice slice_limit(limit);
dbiter->Seek(slice_limit);
if (!dbiter->Valid()) {
dbiter->SeekToLast();
} else {
dbiter->Prev();
}
return dbiter->status().ok() ? 0 : -1;
}
int upper_bound(const string &after) {
lower_bound(after);
if (valid() && key() == after)
next();
return dbiter->status().ok() ? 0 : -1;
}
int lower_bound(const string &to) {
string bound = combine_strings(prefix, to);
leveldb::Slice slice_bound(bound);
dbiter->Seek(slice_bound);
return dbiter->status().ok() ? 0 : -1;
}
bool valid() {
return dbiter->Valid() && in_prefix(prefix, dbiter->key());
}
int next() {
if (valid())
dbiter->Next();
return dbiter->status().ok() ? 0 : -1;
}
int prev() {
if (valid())
dbiter->Prev();
return dbiter->status().ok() ? 0 : -1;
}
string key() {
string out_key;
split_key(dbiter->key(), 0, &out_key);
return out_key;
}
bufferlist value() {
return to_bufferlist(dbiter->value());
}
int status() {
return dbiter->status().ok() ? 0 : -1;
}
};
Iterator get_iterator(const string &prefix) {
return std::tr1::shared_ptr<LevelDBIteratorImpl>(
new LevelDBIteratorImpl(
db->NewIterator(leveldb::ReadOptions()),
prefix));
}
/// Utility
static string combine_strings(const string &prefix, const string &value);
static int split_key(leveldb::Slice in, string *prefix, string *key);
static bufferlist to_bufferlist(leveldb::Slice in);
static bool in_prefix(const string &prefix, leveldb::Slice key) {
return (key.compare(leveldb::Slice(past_prefix(prefix))) < 0) &&
(key.compare(leveldb::Slice(prefix)) > 0);
}
static string past_prefix(const string prefix) {
string limit = prefix;
limit.push_back(1);
return limit;
}
};
#endif
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