LevelDB block and coin databases

Split off CBlockTreeDB and CCoinsViewDB into txdb-*.{cpp,h} files,
implemented by either LevelDB or BDB.

Based on code from earlier commits by Mike Hearn in his leveldb
branch.

src/txdb-leveldb.cpp

@@ -0,0 +1,151 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2012 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "txdb-leveldb.h"
+#include "main.h"
+
+using namespace std;
+
+void static BatchWriteCoins(CLevelDBBatch &batch, const uint256 &hash, const CCoins &coins) {
+    if (coins.IsPruned())
+        batch.Erase(make_pair('c', hash));
+    else
+        batch.Write(make_pair('c', hash), coins);
+}
+
+void static BatchWriteHashBestChain(CLevelDBBatch &batch, const uint256 &hash) {
+    batch.Write('B', hash);
+}
+
+CCoinsViewDB::CCoinsViewDB() : db(GetDataDir() / "coins") {
+}
+
+bool CCoinsViewDB::GetCoins(uint256 txid, CCoins &coins) { 
+    return db.Read(make_pair('c', txid), coins); 
+}
+
+bool CCoinsViewDB::SetCoins(uint256 txid, const CCoins &coins) {
+    CLevelDBBatch batch;
+    BatchWriteCoins(batch, txid, coins);
+    return db.WriteBatch(batch);
+}
+
+bool CCoinsViewDB::HaveCoins(uint256 txid) {
+    return db.Exists(make_pair('c', txid)); 
+}
+
+CBlockIndex *CCoinsViewDB::GetBestBlock() {
+    uint256 hashBestChain;
+    if (!db.Read('B', hashBestChain))
+        return NULL;
+    std::map<uint256, CBlockIndex*>::iterator it = mapBlockIndex.find(hashBestChain);
+    if (it == mapBlockIndex.end())
+        return NULL;
+    return it->second;
+}
+
+bool CCoinsViewDB::SetBestBlock(CBlockIndex *pindex) {
+    CLevelDBBatch batch;
+    BatchWriteHashBestChain(batch, pindex->GetBlockHash()); 
+    return db.WriteBatch(batch);
+}
+
+bool CCoinsViewDB::BatchWrite(const std::map<uint256, CCoins> &mapCoins, CBlockIndex *pindex) {
+    printf("Committing %u changed transactions to coin database...\n", (unsigned int)mapCoins.size());
+
+    CLevelDBBatch batch;
+    for (std::map<uint256, CCoins>::const_iterator it = mapCoins.begin(); it != mapCoins.end(); it++)
+        BatchWriteCoins(batch, it->first, it->second);
+    BatchWriteHashBestChain(batch, pindex->GetBlockHash());
+
+    return db.WriteBatch(batch);
+}
+
+bool CBlockTreeDB::WriteBlockIndex(const CDiskBlockIndex& blockindex)
+{
+    return Write(make_pair('b', blockindex.GetBlockHash()), blockindex);
+}
+
+bool CBlockTreeDB::ReadBestInvalidWork(CBigNum& bnBestInvalidWork)
+{
+    return Read('I', bnBestInvalidWork);
+}
+
+bool CBlockTreeDB::WriteBestInvalidWork(const CBigNum& bnBestInvalidWork)
+{
+    return Write('I', bnBestInvalidWork);
+}
+
+bool CBlockTreeDB::WriteBlockFileInfo(int nFile, const CBlockFileInfo &info) {
+    return Write(make_pair('f', nFile), info);
+}
+
+bool CBlockTreeDB::ReadBlockFileInfo(int nFile, CBlockFileInfo &info) {
+    return Read(make_pair('f', nFile), info);
+}
+
+bool CBlockTreeDB::WriteLastBlockFile(int nFile) {
+    return Write('l', nFile);
+}
+
+bool CBlockTreeDB::ReadLastBlockFile(int &nFile) {
+    return Read('l', nFile);
+}
+
+bool CBlockTreeDB::LoadBlockIndexGuts()
+{
+    leveldb::Iterator *pcursor = NewIterator();
+
+    CDataStream ssKeySet(SER_DISK, CLIENT_VERSION);
+    ssKeySet << make_pair('b', uint256(0));
+    pcursor->Seek(ssKeySet.str());
+
+    // Load mapBlockIndex
+    while (pcursor->Valid()) {
+        try {
+            leveldb::Slice slKey = pcursor->key();
+            CDataStream ssKey(slKey.data(), slKey.data()+slKey.size(), SER_DISK, CLIENT_VERSION);
+            char chType;
+            ssKey >> chType;
+            if (chType == 'b' && !fRequestShutdown) {
+                leveldb::Slice slValue = pcursor->value();
+                CDataStream ssValue(slValue.data(), slValue.data()+slValue.size(), SER_DISK, CLIENT_VERSION);
+                CDiskBlockIndex diskindex;
+                ssValue >> diskindex;
+
+                // Construct block index object
+                CBlockIndex* pindexNew = InsertBlockIndex(diskindex.GetBlockHash());
+                pindexNew->pprev          = InsertBlockIndex(diskindex.hashPrev);
+                pindexNew->nHeight        = diskindex.nHeight;
+                pindexNew->nFile          = diskindex.nFile;
+                pindexNew->nDataPos       = diskindex.nDataPos;
+                pindexNew->nUndoPos       = diskindex.nUndoPos;
+                pindexNew->nVersion       = diskindex.nVersion;
+                pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
+                pindexNew->nTime          = diskindex.nTime;
+                pindexNew->nBits          = diskindex.nBits;
+                pindexNew->nNonce         = diskindex.nNonce;
+                pindexNew->nStatus        = diskindex.nStatus;
+                pindexNew->nTx            = diskindex.nTx;
+
+                // Watch for genesis block
+                if (pindexGenesisBlock == NULL && diskindex.GetBlockHash() == hashGenesisBlock)
+                    pindexGenesisBlock = pindexNew;
+
+                if (!pindexNew->CheckIndex())
+                    return error("LoadBlockIndex() : CheckIndex failed: %s", pindexNew->ToString().c_str());
+
+                pcursor->Next();
+            } else {
+                break; // if shutdown requested or finished loading block index
+            }
+        } catch (std::exception &e) {
+            return error("%s() : deserialize error", __PRETTY_FUNCTION__);
+        }
+    }
+    delete pcursor;
+
+    return true;
+}