Ultraprune

This switches bitcoin's transaction/block verification logic to use a
"coin database", which contains all unredeemed transaction output scripts,
amounts and heights.

The name ultraprune comes from the fact that instead of a full transaction
index, we only (need to) keep an index with unspent outputs. For now, the
blocks themselves are kept as usual, although they are only necessary for
serving, rescanning and reorganizing.

The basic datastructures are CCoins (representing the coins of a single
transaction), and CCoinsView (representing a state of the coins database).
There are several implementations for CCoinsView. A dummy, one backed by
the coins database (coins.dat), one backed by the memory pool, and one
that adds a cache on top of it. FetchInputs, ConnectInputs, ConnectBlock,
DisconnectBlock, ... now operate on a generic CCoinsView.

The block switching logic now builds a single cached CCoinsView with
changes to be committed to the database before any changes are made.
This means no uncommitted changes are ever read from the database, and
should ease the transition to another database layer which does not
support transactions (but does support atomic writes), like LevelDB.

For the getrawtransaction() RPC call, access to a txid-to-disk index
would be preferable. As this index is not necessary or even useful
for any other part of the implementation, it is not provided. Instead,
getrawtransaction() uses the coin database to find the block height,
and then scans that block to find the requested transaction. This is
slow, but should suffice for debug purposes.

1 files changed, 19 insertions, 44 deletions

diff --git a/src/wallet.cpp b/src/wallet.cpp
index 1a6a1082b1..9b2960f64e 100644
--- a/src/wallet.cpp
+++ b/src/wallet.cpp
@@ -685,7 +685,7 @@ void CWalletTx::GetAccountAmounts(const string& strAccount, int64& nReceived,
     }
 }
 
-void CWalletTx::AddSupportingTransactions(CTxDB& txdb)
+void CWalletTx::AddSupportingTransactions()
 {
     vtxPrev.clear();
 
@@ -696,7 +696,6 @@ void CWalletTx::AddSupportingTransactions(CTxDB& txdb)
         BOOST_FOREACH(const CTxIn& txin, vin)
             vWorkQueue.push_back(txin.prevout.hash);
 
-        // This critsect is OK because txdb is already open
         {
             LOCK(pwallet->cs_wallet);
             map<uint256, const CMerkleTx*> mapWalletPrev;
@@ -720,15 +719,6 @@ void CWalletTx::AddSupportingTransactions(CTxDB& txdb)
                 {
                     tx = *mapWalletPrev[hash];
                 }
-                else if (!fClient && txdb.ReadDiskTx(hash, tx))
-                {
-                    ;
-                }
-                else
-                {
-                    printf("ERROR: AddSupportingTransactions() : unsupported transaction\n");
-                    continue;
-                }
 
                 int nDepth = tx.SetMerkleBranch();
                 vtxPrev.push_back(tx);
@@ -775,49 +765,36 @@ int CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate)
     return ret;
 }
 
-int CWallet::ScanForWalletTransaction(const uint256& hashTx)
-{
-    CTransaction tx;
-    tx.ReadFromDisk(COutPoint(hashTx, 0));
-    if (AddToWalletIfInvolvingMe(tx, NULL, true, true))
-        return 1;
-    return 0;
-}
-
 void CWallet::ReacceptWalletTransactions()
 {
-    CTxDB txdb("r");
+    CCoinsDB coinsdb("r");
     bool fRepeat = true;
     while (fRepeat)
     {
         LOCK(cs_wallet);
         fRepeat = false;
-        vector<CDiskTxPos> vMissingTx;
+        bool fMissing = false;
         BOOST_FOREACH(PAIRTYPE(const uint256, CWalletTx)& item, mapWallet)
         {
             CWalletTx& wtx = item.second;
             if (wtx.IsCoinBase() && wtx.IsSpent(0))
                 continue;
 
-            CTxIndex txindex;
+            CCoins coins;
             bool fUpdated = false;
-            if (txdb.ReadTxIndex(wtx.GetHash(), txindex))
+            bool fNotFound = coinsdb.ReadCoins(wtx.GetHash(), coins);
+            if (!fNotFound || wtx.GetDepthInMainChain() > 0)
             {
                 // Update fSpent if a tx got spent somewhere else by a copy of wallet.dat
-                if (txindex.vSpent.size() != wtx.vout.size())
-                {
-                    printf("ERROR: ReacceptWalletTransactions() : txindex.vSpent.size() %"PRIszu" != wtx.vout.size() %"PRIszu"\n", txindex.vSpent.size(), wtx.vout.size());
-                    continue;
-                }
-                for (unsigned int i = 0; i < txindex.vSpent.size(); i++)
+                for (unsigned int i = 0; i < wtx.vout.size(); i++)
                 {
                     if (wtx.IsSpent(i))
                         continue;
-                    if (!txindex.vSpent[i].IsNull() && IsMine(wtx.vout[i]))
+                    if ((i >= coins.vout.size() || coins.vout[i].IsNull()) && IsMine(wtx.vout[i]))
                     {
                         wtx.MarkSpent(i);
                         fUpdated = true;
-                        vMissingTx.push_back(txindex.vSpent[i]);
+                        fMissing = true;
                     }
                 }
                 if (fUpdated)
@@ -831,10 +808,10 @@ void CWallet::ReacceptWalletTransactions()
             {
                 // Re-accept any txes of ours that aren't already in a block
                 if (!wtx.IsCoinBase())
-                    wtx.AcceptWalletTransaction(txdb, false);
+                    wtx.AcceptWalletTransaction(coinsdb, false);
             }
         }
-        if (!vMissingTx.empty())
+        if (fMissing)
         {
             // TODO: optimize this to scan just part of the block chain?
             if (ScanForWalletTransactions(pindexGenesisBlock))
@@ -843,21 +820,21 @@ void CWallet::ReacceptWalletTransactions()
     }
 }
 
-void CWalletTx::RelayWalletTransaction(CTxDB& txdb)
+void CWalletTx::RelayWalletTransaction(CCoinsDB& coinsdb)
 {
     BOOST_FOREACH(const CMerkleTx& tx, vtxPrev)
     {
         if (!tx.IsCoinBase())
         {
             uint256 hash = tx.GetHash();
-            if (!txdb.ContainsTx(hash))
+            if (!coinsdb.HaveCoins(hash))
                 RelayMessage(CInv(MSG_TX, hash), (CTransaction)tx);
         }
     }
     if (!IsCoinBase())
     {
         uint256 hash = GetHash();
-        if (!txdb.ContainsTx(hash))
+        if (!coinsdb.HaveCoins(hash))
         {
             printf("Relaying wtx %s\n", hash.ToString().substr(0,10).c_str());
             RelayMessage(CInv(MSG_TX, hash), (CTransaction)*this);
@@ -867,8 +844,8 @@ void CWalletTx::RelayWalletTransaction(CTxDB& txdb)
 
 void CWalletTx::RelayWalletTransaction()
 {
-   CTxDB txdb("r");
-   RelayWalletTransaction(txdb);
+   CCoinsDB coinsdb("r");
+   RelayWalletTransaction(coinsdb);
 }
 
 void CWallet::ResendWalletTransactions()
@@ -891,7 +868,7 @@ void CWallet::ResendWalletTransactions()
 
     // Rebroadcast any of our txes that aren't in a block yet
     printf("ResendWalletTransactions()\n");
-    CTxDB txdb("r");
+    CCoinsDB coinsdb("r");
     {
         LOCK(cs_wallet);
         // Sort them in chronological order
@@ -907,7 +884,7 @@ void CWallet::ResendWalletTransactions()
         BOOST_FOREACH(PAIRTYPE(const unsigned int, CWalletTx*)& item, mapSorted)
         {
             CWalletTx& wtx = *item.second;
-            wtx.RelayWalletTransaction(txdb);
+            wtx.RelayWalletTransaction(coinsdb);
         }
     }
 }
@@ -1162,8 +1139,6 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, int64> >& vecSend, CW
 
     {
         LOCK2(cs_main, cs_wallet);
-        // txdb must be opened before the mapWallet lock
-        CTxDB txdb("r");
         {
             nFeeRet = nTransactionFee;
             loop
@@ -1253,7 +1228,7 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, int64> >& vecSend, CW
                 }
 
                 // Fill vtxPrev by copying from previous transactions vtxPrev
-                wtxNew.AddSupportingTransactions(txdb);
+                wtxNew.AddSupportingTransactions();
                 wtxNew.fTimeReceivedIsTxTime = true;
 
                 break;