Batch block connection during IBD

During the initial block download (or -loadblock), delay connection
of new blocks a bit, and perform them in a single action. This reduces
the load on the database engine, as subsequent blocks often update an
earlier block's transaction already.

src/db.cpp

@@ -79,8 +79,8 @@ bool CDBEnv::Open(boost::filesystem::path pathEnv_)
     dbenv.set_cachesize(nDbCache / 1024, (nDbCache % 1024)*1048576, 1);
     dbenv.set_lg_bsize(1048576);
     dbenv.set_lg_max(10485760);
-    dbenv.set_lk_max_locks(10000);
-    dbenv.set_lk_max_objects(10000);
+    dbenv.set_lk_max_locks(40000);
+    dbenv.set_lk_max_objects(40000);
     dbenv.set_errfile(fopen(pathErrorFile.string().c_str(), "a")); /// debug
     dbenv.set_flags(DB_AUTO_COMMIT, 1);
     dbenv.set_flags(DB_TXN_WRITE_NOSYNC, 1);
@@ -279,14 +279,10 @@ static bool IsChainFile(std::string strFile)
     return false;
 }
 
-void CDB::Close()
+void CDB::Flush()
 {
-    if (!pdb)
-        return;
     if (activeTxn)
-        activeTxn->abort();
-    activeTxn = NULL;
-    pdb = NULL;
+        return;
 
     // Flush database activity from memory pool to disk log
     unsigned int nMinutes = 0;
@@ -298,6 +294,18 @@ void CDB::Close()
         nMinutes = 5;
 
     bitdb.dbenv.txn_checkpoint(nMinutes ? GetArg("-dblogsize", 100)*1024 : 0, nMinutes, 0);
+}
+
+void CDB::Close()
+{
+    if (!pdb)
+        return;
+    if (activeTxn)
+        activeTxn->abort();
+    activeTxn = NULL;
+    pdb = NULL;
+
+    Flush();
 
     {
         LOCK(bitdb.cs_db);
@@ -537,6 +545,42 @@ bool CChainDB::ReadLastBlockFile(int &nFile) {
     return Read('l', nFile);
 }
 
+CCoinsViewDB::CCoinsViewDB() : db("cr+") {}
+bool CCoinsViewDB::GetCoins(uint256 txid, CCoins &coins) { return db.ReadCoins(txid, coins); }
+bool CCoinsViewDB::SetCoins(uint256 txid, const CCoins &coins) { return db.WriteCoins(txid, coins); }
+bool CCoinsViewDB::HaveCoins(uint256 txid) { return db.HaveCoins(txid); }
+CBlockIndex *CCoinsViewDB::GetBestBlock() {
+    uint256 hashBestChain;
+    if (!db.ReadHashBestChain(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) { return db.WriteHashBestChain(pindex->GetBlockHash()); }
+bool CCoinsViewDB::BatchWrite(const std::map<uint256, CCoins> &mapCoins, CBlockIndex *pindex) {
+    printf("Committing %u changed transactions to coin database...\n", (unsigned int)mapCoins.size());
+
+    if (!db.TxnBegin())
+        return false;
+    bool fOk = true;
+    for (std::map<uint256, CCoins>::const_iterator it = mapCoins.begin(); it != mapCoins.end(); it++) {
+        fOk = db.WriteCoins(it->first, it->second);
+        if (!fOk)
+            break;
+    }
+    if (fOk)
+        fOk = db.WriteHashBestChain(pindex->GetBlockHash());
+
+    if (!fOk)
+        db.TxnAbort();
+    else
+        fOk = db.TxnCommit();
+
+    return fOk;
+}
+
 CBlockIndex static * InsertBlockIndex(uint256 hash)
 {
     if (hash == 0)
@@ -557,7 +601,7 @@ CBlockIndex static * InsertBlockIndex(uint256 hash)
     return pindexNew;
 }
 
-bool LoadBlockIndex(CCoinsDB &coindb, CChainDB &chaindb)
+bool LoadBlockIndex(CChainDB &chaindb)
 {
     if (!chaindb.LoadBlockIndexGuts())
         return false;
@@ -587,26 +631,23 @@ bool LoadBlockIndex(CCoinsDB &coindb, CChainDB &chaindb)
         printf("LoadBlockIndex(): last block file: %s\n", infoLastBlockFile.ToString().c_str());
 
     // Load hashBestChain pointer to end of best chain
-    if (!coindb.ReadHashBestChain(hashBestChain))
+    pindexBest = pcoinsTip->GetBestBlock();
+    if (pindexBest == NULL)
     {
         if (pindexGenesisBlock == NULL)
             return true;
         return error("CTxDB::LoadBlockIndex() : hashBestChain not loaded");
     }
-    std::map<uint256, CBlockIndex*>::iterator it = mapBlockIndex.find(hashBestChain);
-    if (it == mapBlockIndex.end()) {
-        return error("CTxDB::LoadBlockIndex() : hashBestChain not found in the block index");
-    } else {
-        // set 'next' pointers in best chain
-        CBlockIndex *pindex = it->second;
-        while(pindex != NULL && pindex->pprev != NULL) {
-             CBlockIndex *pindexPrev = pindex->pprev;
-             pindexPrev->pnext = pindex;
-             pindex = pindexPrev;
-        }
-        pindexBest = it->second;
-        nBestHeight = pindexBest->nHeight;
-        bnBestChainWork = pindexBest->bnChainWork;
+    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,

src/db.h

@@ -102,6 +102,7 @@ class CDB
     explicit CDB(const char* pszFile, const char* pszMode="r+");
     ~CDB() { Close(); }
 public:
+    void Flush();
     void Close();
 private:
     CDB(const CDB&);
@@ -330,6 +331,23 @@ class CCoinsDB : public CDB
     bool WriteHashBestChain(uint256 hashBestChain);
 };
 
+
+/** CCoinsView backed by a CCoinsDB */
+class CCoinsViewDB : public CCoinsView
+{
+protected:
+    CCoinsDB db;
+public:
+    CCoinsViewDB();
+    bool GetCoins(uint256 txid, CCoins &coins);
+    bool SetCoins(uint256 txid, const CCoins &coins);
+    bool HaveCoins(uint256 txid);
+    CBlockIndex *GetBestBlock();
+    bool SetBestBlock(CBlockIndex *pindex);
+    bool BatchWrite(const std::map<uint256, CCoins> &mapCoins, CBlockIndex *pindex);
+};
+
+
 /** Access to the block database (chain.dat) */
 class CChainDB : public CDB
 {
@@ -350,7 +368,7 @@ class CChainDB : public CDB
 };
 
 
-bool LoadBlockIndex(CCoinsDB &coinsdb, CChainDB &chaindb);
+bool LoadBlockIndex(CChainDB &chaindb);
 
 
 /** Access to the (IP) address database (peers.dat) */

src/init.cpp

@@ -50,6 +50,8 @@ void StartShutdown()
 #endif
 }
 
+static CCoinsViewDB *pcoinsdbview;
+
 void Shutdown(void* parg)
 {
     static CCriticalSection cs_Shutdown;
@@ -74,6 +76,12 @@ void Shutdown(void* parg)
         nTransactionsUpdated++;
         bitdb.Flush(false);
         StopNode();
+        {
+            LOCK(cs_main);
+            pcoinsTip->Flush();
+            delete pcoinsTip;
+            delete pcoinsdbview;
+        }
         bitdb.Flush(true);
         boost::filesystem::remove(GetPidFile());
         UnregisterWallet(pwalletMain);
@@ -298,6 +306,7 @@ std::string HelpMessage()
     return strUsage;
 }
 
+
 /** Initialize bitcoin.
  *  @pre Parameters should be parsed and config file should be read.
  */
@@ -641,6 +650,9 @@ bool AppInit2()
     uiInterface.InitMessage(_("Loading block index..."));
     printf("Loading block index...\n");
     nStart = GetTimeMillis();
+    pcoinsdbview = new CCoinsViewDB();
+    pcoinsTip = new CCoinsViewCache(*pcoinsdbview);
+
     if (!LoadBlockIndex())
         return InitError(_("Error loading blkindex.dat"));