r1

src/leveldbwrapper.h

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+// Copyright (c) 2012-2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_LEVELDBWRAPPER_H
+#define BITCOIN_LEVELDBWRAPPER_H
+
+#include "clientversion.h"
+#include "serialize.h"
+#include "streams.h"
+#include "util.h"
+#include "version.h"
+
+#include <boost/filesystem/path.hpp>
+
+#include <leveldb/db.h>
+#include <leveldb/write_batch.h>
+
+class leveldb_error : public std::runtime_error
+{
+public:
+    leveldb_error(const std::string& msg) : std::runtime_error(msg) {}
+};
+
+void HandleError(const leveldb::Status& status);
+
+/** Batch of changes queued to be written to a CLevelDBWrapper */
+class CLevelDBBatch
+{
+    friend class CLevelDBWrapper;
+
+private:
+    leveldb::WriteBatch batch;
+
+public:
+    template <typename K, typename V>
+    void Write(const K& key, const V& value)
+    {
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(ssKey.GetSerializeSize(key));
+        ssKey << key;
+        leveldb::Slice slKey(&ssKey[0], ssKey.size());
+
+        CDataStream ssValue(SER_DISK, CLIENT_VERSION);
+        ssValue.reserve(ssValue.GetSerializeSize(value));
+        ssValue << value;
+        leveldb::Slice slValue(&ssValue[0], ssValue.size());
+
+        batch.Put(slKey, slValue);
+    }
+
+    template <typename K>
+    void Erase(const K& key)
+    {
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(ssKey.GetSerializeSize(key));
+        ssKey << key;
+        leveldb::Slice slKey(&ssKey[0], ssKey.size());
+
+        batch.Delete(slKey);
+    }
+};
+
+class CLevelDBWrapper
+{
+private:
+    //! custom environment this database is using (may be NULL in case of default environment)
+    leveldb::Env* penv;
+
+    //! database options used
+    leveldb::Options options;
+
+    //! options used when reading from the database
+    leveldb::ReadOptions readoptions;
+
+    //! options used when iterating over values of the database
+    leveldb::ReadOptions iteroptions;
+
+    //! options used when writing to the database
+    leveldb::WriteOptions writeoptions;
+
+    //! options used when sync writing to the database
+    leveldb::WriteOptions syncoptions;
+
+    //! the database itself
+    leveldb::DB* pdb;
+
+public:
+    CLevelDBWrapper(const boost::filesystem::path& path, size_t nCacheSize, bool fMemory = false, bool fWipe = false);
+    ~CLevelDBWrapper();
+
+    template <typename K, typename V>
+    bool Read(const K& key, V& value) const
+    {
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(ssKey.GetSerializeSize(key));
+        ssKey << key;
+        leveldb::Slice slKey(&ssKey[0], ssKey.size());
+
+        std::string strValue;
+        leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
+        if (!status.ok()) {
+            if (status.IsNotFound())
+                return false;
+            LogPrintf("LevelDB read failure: %s\n", status.ToString());
+            HandleError(status);
+        }
+        try {
+            CDataStream ssValue(strValue.data(), strValue.data() + strValue.size(), SER_DISK, CLIENT_VERSION);
+            ssValue >> value;
+        } catch (const std::exception&) {
+            return false;
+        }
+        return true;
+    }
+
+    template <typename K, typename V>
+    bool Write(const K& key, const V& value, bool fSync = false)
+    {
+        CLevelDBBatch batch;
+        batch.Write(key, value);
+        return WriteBatch(batch, fSync);
+    }
+
+    template <typename K>
+    bool Exists(const K& key) const
+    {
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(ssKey.GetSerializeSize(key));
+        ssKey << key;
+        leveldb::Slice slKey(&ssKey[0], ssKey.size());
+
+        std::string strValue;
+        leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
+        if (!status.ok()) {
+            if (status.IsNotFound())
+                return false;
+            LogPrintf("LevelDB read failure: %s\n", status.ToString());
+            HandleError(status);
+        }
+        return true;
+    }
+
+    template <typename K>
+    bool Erase(const K& key, bool fSync = false)
+    {
+        CLevelDBBatch batch;
+        batch.Erase(key);
+        return WriteBatch(batch, fSync);
+    }
+
+    bool WriteBatch(CLevelDBBatch& batch, bool fSync = false);
+
+    // not available for LevelDB; provide for compatibility with BDB
+    bool Flush()
+    {
+        return true;
+    }
+
+    bool Sync()
+    {
+        CLevelDBBatch batch;
+        return WriteBatch(batch, true);
+    }
+
+    // not exactly clean encapsulation, but it's easiest for now
+    leveldb::Iterator* NewIterator()
+    {
+        return pdb->NewIterator(iteroptions);
+    }
+};
+
+#endif // BITCOIN_LEVELDBWRAPPER_H