Add optional transaction index to databases

By specifying -txindex when initializing the database, a txid-to-diskpos
index is maintained in the blktree database. This database is used to
help answering getrawtransaction() RPC queries, when enabled.

Changing the -txindex value requires a -reindex; the client will abort
at startup if the database and the specified -txindex mismatch.

1 files changed, 40 insertions, 4 deletions

diff --git a/src/main.cpp b/src/main.cpp
index a6394e0bff..46ed6c56a5 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -45,6 +45,7 @@ int nScriptCheckThreads = 0;
 bool fImporting = false;
 bool fReindex = false;
 bool fBenchmark = false;
+bool fTxIndex = false;
 unsigned int nCoinCacheSize = 5000;
 
 CMedianFilter<int> cPeerBlockCounts(8, 0); // Amount of blocks that other nodes claim to have
@@ -949,6 +950,25 @@ bool GetTransaction(const uint256 &hash, CTransaction &txOut, uint256 &hashBlock
             }
         }
 
+        if (fTxIndex) {
+            CDiskTxPos postx;
+            if (pblocktree->ReadTxIndex(hash, postx)) {
+                CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
+                CBlockHeader header;
+                try {
+                    file >> header;
+                    fseek(file, postx.nTxOffset, SEEK_CUR);
+                    file >> txOut;
+                } catch (std::exception &e) {
+                    return error("%s() : deserialize or I/O error", __PRETTY_FUNCTION__);
+                }
+                hashBlock = header.GetHash();
+                if (txOut.GetHash() != hash)
+                    return error("%s() : txid mismatch", __PRETTY_FUNCTION__);
+                return true;
+            }
+        }
+
         if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
             int nHeight = -1;
             {
@@ -1632,6 +1652,9 @@ bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJust
     int64 nFees = 0;
     int nInputs = 0;
     unsigned int nSigOps = 0;
+    CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(vtx.size()));
+    std::vector<std::pair<uint256, CDiskTxPos> > vPos;
+    vPos.reserve(vtx.size());
     for (unsigned int i=0; i<vtx.size(); i++)
     {
 
@@ -1671,6 +1694,8 @@ bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJust
         if (!tx.IsCoinBase())
             blockundo.vtxundo.push_back(txundo);
 
+        vPos.push_back(std::make_pair(GetTxHash(i), pos));
+        pos.nTxOffset += ::GetSerializeSize(tx, SER_DISK, CLIENT_VERSION);
     }
     int64 nTime = GetTimeMicros() - nStart;
     if (fBenchmark)
@@ -1710,6 +1735,9 @@ bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJust
             return error("ConnectBlock() : WriteBlockIndex failed");
     }
 
+    if (fTxIndex)
+        pblocktree->WriteTxIndex(vPos);
+
     // add this block to the view's block chain
     if (!view.SetBestBlock(pindex))
         return false;
@@ -2554,6 +2582,10 @@ bool static LoadBlockIndexDB()
     pblocktree->ReadReindexing(fReindexing);
     fReindex |= fReindexing;
 
+    // Check whether we have a transaction index
+    pblocktree->ReadFlag("txindex", fTxIndex);
+    printf("LoadBlockIndex(): transaction index %s\n", fTxIndex ? "enabled" : "disabled");
+
     // Load hashBestChain pointer to end of best chain
     pindexBest = pcoinsTip->GetBestBlock();
     if (pindexBest == NULL)
@@ -2658,13 +2690,10 @@ bool LoadBlockIndex()
         hashGenesisBlock = uint256("000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943");
     }
 
-    if (fReindex)
-        return true;
-
     //
     // Load block index from databases
     //
-    if (!LoadBlockIndexDB())
+    if (!fReindex && !LoadBlockIndexDB())
         return false;
 
     //
@@ -2672,6 +2701,13 @@ bool LoadBlockIndex()
     //
     if (mapBlockIndex.empty())
     {
+        fTxIndex = GetBoolArg("-txindex", false);
+        pblocktree->WriteFlag("txindex", fTxIndex);
+        printf("Initializing databases...\n");
+
+        if (fReindex)
+            return true;
+
         // Genesis Block:
         // CBlock(hash=000000000019d6, ver=1, hashPrevBlock=00000000000000, hashMerkleRoot=4a5e1e, nTime=1231006505, nBits=1d00ffff, nNonce=2083236893, vtx=1)
         //   CTransaction(hash=4a5e1e, ver=1, vin.size=1, vout.size=1, nLockTime=0)