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/main.cpp

@@ -6,6 +6,7 @@
 #include "alert.h"
 #include "checkpoints.h"
 #include "db.h"
+#include "txdb.h"
 #include "net.h"
 #include "init.h"
 #include "ui_interface.h"
@@ -1719,6 +1720,7 @@ bool SetBestChain(CBlockIndex* pindexNew)
     bool fIsInitialDownload = IsInitialBlockDownload();
     if (!fIsInitialDownload || view.GetCacheSize()>5000) {
         FlushBlockFile();
+        pblocktree->Sync();
         if (!view.Flush())
             return false;
     }
@@ -2203,6 +2205,116 @@ FILE *OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly) {
     return OpenDiskFile(pos, "rev", fReadOnly);
 }
 
+CBlockIndex * InsertBlockIndex(uint256 hash)
+{
+    if (hash == 0)
+        return NULL;
+
+    // Return existing
+    map<uint256, CBlockIndex*>::iterator mi = mapBlockIndex.find(hash);
+    if (mi != mapBlockIndex.end())
+        return (*mi).second;
+
+    // Create new
+    CBlockIndex* pindexNew = new CBlockIndex();
+    if (!pindexNew)
+        throw runtime_error("LoadBlockIndex() : new CBlockIndex failed");
+    mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
+    pindexNew->phashBlock = &((*mi).first);
+
+    return pindexNew;
+}
+
+bool static LoadBlockIndexDB()
+{
+    if (!pblocktree->LoadBlockIndexGuts())
+        return false;
+
+    if (fRequestShutdown)
+        return true;
+
+    // Calculate bnChainWork
+    vector<pair<int, CBlockIndex*> > vSortedByHeight;
+    vSortedByHeight.reserve(mapBlockIndex.size());
+    BOOST_FOREACH(const PAIRTYPE(uint256, CBlockIndex*)& item, mapBlockIndex)
+    {
+        CBlockIndex* pindex = item.second;
+        vSortedByHeight.push_back(make_pair(pindex->nHeight, pindex));
+    }
+    sort(vSortedByHeight.begin(), vSortedByHeight.end());
+    BOOST_FOREACH(const PAIRTYPE(int, CBlockIndex*)& item, vSortedByHeight)
+    {
+        CBlockIndex* pindex = item.second;
+        pindex->bnChainWork = (pindex->pprev ? pindex->pprev->bnChainWork : 0) + pindex->GetBlockWork();
+        pindex->nChainTx = (pindex->pprev ? pindex->pprev->nChainTx : 0) + pindex->nTx;
+        if ((pindex->nStatus & BLOCK_VALID_MASK) >= BLOCK_VALID_TRANSACTIONS && !(pindex->nStatus & BLOCK_FAILED_MASK))
+            setBlockIndexValid.insert(pindex);
+    }
+
+    // Load block file info
+    pblocktree->ReadLastBlockFile(nLastBlockFile);
+    printf("LoadBlockIndex(): last block file = %i\n", nLastBlockFile);
+    if (pblocktree->ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile))
+        printf("LoadBlockIndex(): last block file: %s\n", infoLastBlockFile.ToString().c_str());
+ 
+    // Load hashBestChain pointer to end of best chain
+    pindexBest = pcoinsTip->GetBestBlock();
+    if (pindexBest == NULL)
+    {
+        if (pindexGenesisBlock == NULL)
+            return true;
+    }
+    hashBestChain = pindexBest->GetBlockHash();
+    nBestHeight = pindexBest->nHeight;
+    bnBestChainWork = pindexBest->bnChainWork;
+
+    // set 'next' pointers in best chain
+    CBlockIndex *pindex = pindexBest;
+    while(pindex != NULL && pindex->pprev != NULL) {
+         CBlockIndex *pindexPrev = pindex->pprev;
+         pindexPrev->pnext = pindex;
+         pindex = pindexPrev;
+    }
+    printf("LoadBlockIndex(): hashBestChain=%s  height=%d date=%s\n",
+        hashBestChain.ToString().substr(0,20).c_str(), nBestHeight,
+        DateTimeStrFormat("%x %H:%M:%S", pindexBest->GetBlockTime()).c_str());
+
+    // Load bnBestInvalidWork, OK if it doesn't exist
+    pblocktree->ReadBestInvalidWork(bnBestInvalidWork);
+
+    // Verify blocks in the best chain
+    int nCheckLevel = GetArg("-checklevel", 1);
+    int nCheckDepth = GetArg( "-checkblocks", 2500);
+    if (nCheckDepth == 0)
+        nCheckDepth = 1000000000; // suffices until the year 19000
+    if (nCheckDepth > nBestHeight)
+        nCheckDepth = nBestHeight;
+    printf("Verifying last %i blocks at level %i\n", nCheckDepth, nCheckLevel);
+    CBlockIndex* pindexFork = NULL;
+    for (CBlockIndex* pindex = pindexBest; pindex && pindex->pprev; pindex = pindex->pprev)
+    {
+        if (fRequestShutdown || pindex->nHeight < nBestHeight-nCheckDepth)
+            break;
+        CBlock block;
+        if (!block.ReadFromDisk(pindex))
+            return error("LoadBlockIndex() : block.ReadFromDisk failed");
+        // check level 1: verify block validity
+        if (nCheckLevel>0 && !block.CheckBlock())
+        {
+            printf("LoadBlockIndex() : *** found bad block at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString().c_str());
+            pindexFork = pindex->pprev;
+        }
+        // TODO: stronger verifications
+    }
+    if (pindexFork && !fRequestShutdown)
+    {
+        // TODO: reorg back
+        return error("LoadBlockIndex(): chain database corrupted");
+    }
+
+    return true;
+}
+
 bool LoadBlockIndex(bool fAllowNew)
 {
     if (fTestNet)