Switch CCoinsView and chainstate db from per-txid to per-txout

This patch makes several related changes:
* Changes the CCoinsView virtual methods (GetCoins, HaveCoins, ...)
  to be COutPoint/Coin-based rather than txid/CCoins-based.
* Changes the chainstate db to a new incompatible format that is also
  COutPoint/Coin based.
* Implements reconstruction code for hash_serialized_2.
* Adapts the coins_tests unit tests (thanks to Russell Yanofsky).

A side effect of the new CCoinsView model is that we can no longer
use the (unreliable) test for transaction outputs in the UTXO set
to determine whether we already have a particular transaction.

1 files changed, 27 insertions, 27 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index b295a7f86e..cf4dab420e 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -268,15 +268,15 @@ bool CheckSequenceLocks(const CTransaction &tx, int flags, LockPoints* lp, bool
         prevheights.resize(tx.vin.size());
         for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
             const CTxIn& txin = tx.vin[txinIndex];
-            CCoins coins;
-            if (!viewMemPool.GetCoins(txin.prevout.hash, coins)) {
+            Coin coin;
+            if (!viewMemPool.GetCoins(txin.prevout, coin)) {
                 return error("%s: Missing input", __func__);
             }
-            if (coins.nHeight == MEMPOOL_HEIGHT) {
+            if (coin.nHeight == MEMPOOL_HEIGHT) {
                 // Assume all mempool transaction confirm in the next block
                 prevheights[txinIndex] = tip->nHeight + 1;
             } else {
-                prevheights[txinIndex] = coins.nHeight;
+                prevheights[txinIndex] = coin.nHeight;
             }
         }
         lockPair = CalculateSequenceLocks(tx, flags, &prevheights, index);
@@ -315,9 +315,9 @@ void LimitMempoolSize(CTxMemPool& pool, size_t limit, unsigned long age) {
         LogPrint(BCLog::MEMPOOL, "Expired %i transactions from the memory pool\n", expired);
     }
 
-    std::vector<uint256> vNoSpendsRemaining;
+    std::vector<COutPoint> vNoSpendsRemaining;
     pool.TrimToSize(limit, &vNoSpendsRemaining);
-    BOOST_FOREACH(const uint256& removed, vNoSpendsRemaining)
+    BOOST_FOREACH(const COutPoint& removed, vNoSpendsRemaining)
         pcoinsTip->Uncache(removed);
 }
 
@@ -344,7 +344,7 @@ static bool IsCurrentForFeeEstimation()
 
 bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const CTransactionRef& ptx, bool fLimitFree,
                               bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
-                              bool fOverrideMempoolLimit, const CAmount& nAbsurdFee, std::vector<uint256>& vHashTxnToUncache)
+                              bool fOverrideMempoolLimit, const CAmount& nAbsurdFee, std::vector<COutPoint>& vHashTxnToUncache)
 {
     const CTransaction& tx = *ptx;
     const uint256 hash = tx.GetHash();
@@ -437,30 +437,30 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         view.SetBackend(viewMemPool);
 
         // do we already have it?
-        bool fHadTxInCache = pcoinsTip->HaveCoinsInCache(hash);
-        if (view.HaveCoins(hash)) {
-            if (!fHadTxInCache)
-                vHashTxnToUncache.push_back(hash);
-            return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-known");
+        for (size_t out = 0; out < tx.vout.size(); out++) {
+            COutPoint outpoint(hash, out);
+            bool fHadTxInCache = pcoinsTip->HaveCoinsInCache(outpoint);
+            if (view.HaveCoins(outpoint)) {
+                if (!fHadTxInCache) {
+                    vHashTxnToUncache.push_back(outpoint);
+                }
+                return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-known");
+            }
         }
 
         // do all inputs exist?
-        // Note that this does not check for the presence of actual outputs (see the next check for that),
-        // and only helps with filling in pfMissingInputs (to determine missing vs spent).
         BOOST_FOREACH(const CTxIn txin, tx.vin) {
-            if (!pcoinsTip->HaveCoinsInCache(txin.prevout.hash))
-                vHashTxnToUncache.push_back(txin.prevout.hash);
-            if (!view.HaveCoins(txin.prevout.hash)) {
-                if (pfMissingInputs)
+            if (!pcoinsTip->HaveCoinsInCache(txin.prevout)) {
+                vHashTxnToUncache.push_back(txin.prevout);
+            }
+            if (!view.HaveCoins(txin.prevout)) {
+                if (pfMissingInputs) {
                     *pfMissingInputs = true;
+                }
                 return false; // fMissingInputs and !state.IsInvalid() is used to detect this condition, don't set state.Invalid()
             }
         }
 
-        // are the actual inputs available?
-        if (!view.HaveInputs(tx))
-            return state.Invalid(false, REJECT_DUPLICATE, "bad-txns-inputs-spent");
-
         // Bring the best block into scope
         view.GetBestBlock();
 
@@ -763,10 +763,10 @@ bool AcceptToMemoryPoolWithTime(CTxMemPool& pool, CValidationState &state, const
                         bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
                         bool fOverrideMempoolLimit, const CAmount nAbsurdFee)
 {
-    std::vector<uint256> vHashTxToUncache;
+    std::vector<COutPoint> vHashTxToUncache;
     bool res = AcceptToMemoryPoolWorker(pool, state, tx, fLimitFree, pfMissingInputs, nAcceptTime, plTxnReplaced, fOverrideMempoolLimit, nAbsurdFee, vHashTxToUncache);
     if (!res) {
-        BOOST_FOREACH(const uint256& hashTx, vHashTxToUncache)
+        BOOST_FOREACH(const COutPoint& hashTx, vHashTxToUncache)
             pcoinsTip->Uncache(hashTx);
     }
     // After we've (potentially) uncached entries, ensure our coins cache is still within its size limits
@@ -1762,12 +1762,12 @@ bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode, int n
     }
     // Flush best chain related state. This can only be done if the blocks / block index write was also done.
     if (fDoFullFlush) {
-        // Typical CCoins structures on disk are around 128 bytes in size.
+        // Typical Coin structures on disk are around 48 bytes in size.
         // Pushing a new one to the database can cause it to be written
         // twice (once in the log, and once in the tables). This is already
         // an overestimation, as most will delete an existing entry or
         // overwrite one. Still, use a conservative safety factor of 2.
-        if (!CheckDiskSpace(128 * 2 * 2 * pcoinsTip->GetCacheSize()))
+        if (!CheckDiskSpace(48 * 2 * 2 * pcoinsTip->GetCacheSize()))
             return state.Error("out of disk space");
         // Flush the chainstate (which may refer to block index entries).
         if (!pcoinsTip->Flush())
@@ -1848,7 +1848,7 @@ void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
             }
         }
     }
-    LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu date='%s' progress=%f cache=%.1fMiB(%utx)", __func__,
+    LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu date='%s' progress=%f cache=%.1fMiB(%utxo)", __func__,
       chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(), chainActive.Tip()->nVersion,
       log(chainActive.Tip()->nChainWork.getdouble())/log(2.0), (unsigned long)chainActive.Tip()->nChainTx,
       DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),