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, 43 insertions, 44 deletions

diff --git a/src/rpcrawtransaction.cpp b/src/rpcrawtransaction.cpp
index cb5bae62da..c62898316c 100644
--- a/src/rpcrawtransaction.cpp
+++ b/src/rpcrawtransaction.cpp
@@ -118,7 +118,7 @@ Value getrawtransaction(const Array& params, bool fHelp)
 
     CTransaction tx;
     uint256 hashBlock = 0;
-    if (!GetTransaction(hash, tx, hashBlock))
+    if (!GetTransaction(hash, tx, hashBlock, true))
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No information available about transaction");
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
@@ -335,26 +335,22 @@ Value signrawtransaction(const Array& params, bool fHelp)
     bool fComplete = true;
 
     // Fetch previous transactions (inputs):
-    map<COutPoint, CScript> mapPrevOut;
-    for (unsigned int i = 0; i < mergedTx.vin.size(); i++)
+    CCoinsView viewDummy;
+    CCoinsViewCache view(viewDummy);
     {
-        CTransaction tempTx;
-        MapPrevTx mapPrevTx;
-        CTxDB txdb("r");
-        map<uint256, CTxIndex> unused;
-        bool fInvalid;
-
-        // FetchInputs aborts on failure, so we go one at a time.
-        tempTx.vin.push_back(mergedTx.vin[i]);
-        tempTx.FetchInputs(txdb, unused, false, false, mapPrevTx, fInvalid);
-
-        // Copy results into mapPrevOut:
-        BOOST_FOREACH(const CTxIn& txin, tempTx.vin)
-        {
+        LOCK(mempool.cs);
+        CCoinsDB coinsdb("r");
+        CCoinsViewDB viewDB(coinsdb);
+        CCoinsViewMemPool viewMempool(viewDB, mempool);
+        view.SetBackend(viewMempool); // temporarily switch cache backend to db+mempool view
+
+        BOOST_FOREACH(const CTxIn& txin, mergedTx.vin) {
             const uint256& prevHash = txin.prevout.hash;
-            if (mapPrevTx.count(prevHash) && mapPrevTx[prevHash].second.vout.size()>txin.prevout.n)
-                mapPrevOut[txin.prevout] = mapPrevTx[prevHash].second.vout[txin.prevout.n].scriptPubKey;
+            CCoins coins;
+            view.GetCoins(prevHash, coins); // this is certainly allowed to fail
         }
+
+        view.SetBackend(viewDummy); // switch back to avoid locking db/mempool too long
     }
 
     // Add previous txouts given in the RPC call:
@@ -386,20 +382,19 @@ Value signrawtransaction(const Array& params, bool fHelp)
             vector<unsigned char> pkData(ParseHex(pkHex));
             CScript scriptPubKey(pkData.begin(), pkData.end());
 
-            COutPoint outpoint(txid, nOut);
-            if (mapPrevOut.count(outpoint))
-            {
-                // Complain if scriptPubKey doesn't match
-                if (mapPrevOut[outpoint] != scriptPubKey)
-                {
+            CCoins coins;
+            if (view.GetCoins(txid, coins)) {
+                if (coins.IsAvailable(nOut) && coins.vout[nOut].scriptPubKey != scriptPubKey) {
                     string err("Previous output scriptPubKey mismatch:\n");
-                    err = err + mapPrevOut[outpoint].ToString() + "\nvs:\n"+
+                    err = err + coins.vout[nOut].scriptPubKey.ToString() + "\nvs:\n"+
                         scriptPubKey.ToString();
                     throw JSONRPCError(RPC_DESERIALIZATION_ERROR, err);
                 }
+                // what todo if txid is known, but the actual output isn't?
             }
-            else
-                mapPrevOut[outpoint] = scriptPubKey;
+            coins.vout[nOut].scriptPubKey = scriptPubKey;
+            coins.vout[nOut].nValue = 0; // we don't know the actual output value
+            view.SetCoins(txid, coins);
         }
     }
 
@@ -452,12 +447,13 @@ Value signrawtransaction(const Array& params, bool fHelp)
     for (unsigned int i = 0; i < mergedTx.vin.size(); i++)
     {
         CTxIn& txin = mergedTx.vin[i];
-        if (mapPrevOut.count(txin.prevout) == 0)
+        CCoins coins;
+        if (!view.GetCoins(txin.prevout.hash, coins) || !coins.IsAvailable(txin.prevout.n))
         {
             fComplete = false;
             continue;
         }
-        const CScript& prevPubKey = mapPrevOut[txin.prevout];
+        const CScript& prevPubKey = coins.vout[txin.prevout.n].scriptPubKey;
 
         txin.scriptSig.clear();
         // Only sign SIGHASH_SINGLE if there's a corresponding output:
@@ -505,24 +501,27 @@ Value sendrawtransaction(const Array& params, bool fHelp)
     }
     uint256 hashTx = tx.GetHash();
 
-    // See if the transaction is already in a block
-    // or in the memory pool:
-    CTransaction existingTx;
-    uint256 hashBlock = 0;
-    if (GetTransaction(hashTx, existingTx, hashBlock))
+    bool fHave = false;
+    CCoins existingCoins;
     {
-        if (hashBlock != 0)
-            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, string("transaction already in block ")+hashBlock.GetHex());
+        CCoinsDB coinsdb("r");
+        {
+            CCoinsViewDB coinsviewDB(coinsdb);
+            CCoinsViewMemPool coinsview(coinsviewDB, mempool);
+            fHave = coinsview.GetCoins(hashTx, existingCoins);
+        }
+        if (!fHave) {
+            // push to local node
+            if (!tx.AcceptToMemoryPool(coinsdb))
+                throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX rejected");
+        }
+    }
+    if (fHave) {
+        if (existingCoins.nHeight < 1000000000)
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "transaction already in block chain");
         // Not in block, but already in the memory pool; will drop
         // through to re-relay it.
-    }
-    else
-    {
-        // push to local node
-        CTxDB txdb("r");
-        if (!tx.AcceptToMemoryPool(txdb))
-            throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX rejected");
-
+    } else {
         SyncWithWallets(tx, NULL, true);
     }
     RelayMessage(CInv(MSG_TX, hashTx), tx);