Move CCoins-related logic to coins.{cpp.h}

1 files changed, 356 insertions, 0 deletions

diff --git a/src/coins.h b/src/coins.h
new file mode 100644
index 0000000000..2c72ee88e1
--- /dev/null
+++ b/src/coins.h
@@ -0,0 +1,356 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#ifndef BITCOIN_COINS_H
+#define BITCOIN_COINS_H
+
+#include "core.h"
+#include "serialize.h"
+#include "uint256.h"
+
+#include <assert.h>
+#include <stdint.h>
+
+#include <boost/foreach.hpp>
+
+/** pruned version of CTransaction: only retains metadata and unspent transaction outputs
+ *
+ * Serialized format:
+ * - VARINT(nVersion)
+ * - VARINT(nCode)
+ * - unspentness bitvector, for vout[2] and further; least significant byte first
+ * - the non-spent CTxOuts (via CTxOutCompressor)
+ * - VARINT(nHeight)
+ *
+ * The nCode value consists of:
+ * - bit 1: IsCoinBase()
+ * - bit 2: vout[0] is not spent
+ * - bit 4: vout[1] is not spent
+ * - The higher bits encode N, the number of non-zero bytes in the following bitvector.
+ *   - In case both bit 2 and bit 4 are unset, they encode N-1, as there must be at
+ *     least one non-spent output).
+ *
+ * Example: 0104835800816115944e077fe7c803cfa57f29b36bf87c1d358bb85e
+ *          <><><--------------------------------------------><---->
+ *          |  \                  |                             /
+ *    version   code             vout[1]                  height
+ *
+ *    - version = 1
+ *    - code = 4 (vout[1] is not spent, and 0 non-zero bytes of bitvector follow)
+ *    - unspentness bitvector: as 0 non-zero bytes follow, it has length 0
+ *    - vout[1]: 835800816115944e077fe7c803cfa57f29b36bf87c1d35
+ *               * 8358: compact amount representation for 60000000000 (600 BTC)
+ *               * 00: special txout type pay-to-pubkey-hash
+ *               * 816115944e077fe7c803cfa57f29b36bf87c1d35: address uint160
+ *    - height = 203998
+ *
+ *
+ * Example: 0109044086ef97d5790061b01caab50f1b8e9c50a5057eb43c2d9563a4eebbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa486af3b
+ *          <><><--><--------------------------------------------------><----------------------------------------------><---->
+ *         /  \   \                     |                                                           |                     /
+ *  version  code  unspentness       vout[4]                                                     vout[16]           height
+ *
+ *  - version = 1
+ *  - code = 9 (coinbase, neither vout[0] or vout[1] are unspent,
+ *                2 (1, +1 because both bit 2 and bit 4 are unset) non-zero bitvector bytes follow)
+ *  - unspentness bitvector: bits 2 (0x04) and 14 (0x4000) are set, so vout[2+2] and vout[14+2] are unspent
+ *  - vout[4]: 86ef97d5790061b01caab50f1b8e9c50a5057eb43c2d9563a4ee
+ *             * 86ef97d579: compact amount representation for 234925952 (2.35 BTC)
+ *             * 00: special txout type pay-to-pubkey-hash
+ *             * 61b01caab50f1b8e9c50a5057eb43c2d9563a4ee: address uint160
+ *  - vout[16]: bbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa4
+ *              * bbd123: compact amount representation for 110397 (0.001 BTC)
+ *              * 00: special txout type pay-to-pubkey-hash
+ *              * 8c988f1a4a4de2161e0f50aac7f17e7f9555caa4: address uint160
+ *  - height = 120891
+ */
+class CCoins
+{
+public:
+    // whether transaction is a coinbase
+    bool fCoinBase;
+
+    // unspent transaction outputs; spent outputs are .IsNull(); spent outputs at the end of the array are dropped
+    std::vector<CTxOut> vout;
+
+    // at which height this transaction was included in the active block chain
+    int nHeight;
+
+    // version of the CTransaction; accesses to this value should probably check for nHeight as well,
+    // as new tx version will probably only be introduced at certain heights
+    int nVersion;
+
+    // construct a CCoins from a CTransaction, at a given height
+    CCoins(const CTransaction &tx, int nHeightIn) : fCoinBase(tx.IsCoinBase()), vout(tx.vout), nHeight(nHeightIn), nVersion(tx.nVersion) {
+        ClearUnspendable();
+    }
+
+    // empty constructor
+    CCoins() : fCoinBase(false), vout(0), nHeight(0), nVersion(0) { }
+
+    // remove spent outputs at the end of vout
+    void Cleanup() {
+        while (vout.size() > 0 && vout.back().IsNull())
+            vout.pop_back();
+        if (vout.empty())
+            std::vector<CTxOut>().swap(vout);
+    }
+
+    void ClearUnspendable() {
+        BOOST_FOREACH(CTxOut &txout, vout) {
+            if (txout.scriptPubKey.IsUnspendable())
+                txout.SetNull();
+        }
+        Cleanup();
+    }
+
+    void swap(CCoins &to) {
+        std::swap(to.fCoinBase, fCoinBase);
+        to.vout.swap(vout);
+        std::swap(to.nHeight, nHeight);
+        std::swap(to.nVersion, nVersion);
+    }
+
+    // equality test
+    friend bool operator==(const CCoins &a, const CCoins &b) {
+         // Empty CCoins objects are always equal.
+         if (a.IsPruned() && b.IsPruned())
+             return true;
+         return a.fCoinBase == b.fCoinBase &&
+                a.nHeight == b.nHeight &&
+                a.nVersion == b.nVersion &&
+                a.vout == b.vout;
+    }
+    friend bool operator!=(const CCoins &a, const CCoins &b) {
+        return !(a == b);
+    }
+
+    void CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const;
+
+    bool IsCoinBase() const {
+        return fCoinBase;
+    }
+
+    unsigned int GetSerializeSize(int nType, int nVersion) const {
+        unsigned int nSize = 0;
+        unsigned int nMaskSize = 0, nMaskCode = 0;
+        CalcMaskSize(nMaskSize, nMaskCode);
+        bool fFirst = vout.size() > 0 && !vout[0].IsNull();
+        bool fSecond = vout.size() > 1 && !vout[1].IsNull();
+        assert(fFirst || fSecond || nMaskCode);
+        unsigned int nCode = 8*(nMaskCode - (fFirst || fSecond ? 0 : 1)) + (fCoinBase ? 1 : 0) + (fFirst ? 2 : 0) + (fSecond ? 4 : 0);
+        // version
+        nSize += ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion);
+        // size of header code
+        nSize += ::GetSerializeSize(VARINT(nCode), nType, nVersion);
+        // spentness bitmask
+        nSize += nMaskSize;
+        // txouts themself
+        for (unsigned int i = 0; i < vout.size(); i++)
+            if (!vout[i].IsNull())
+                nSize += ::GetSerializeSize(CTxOutCompressor(REF(vout[i])), nType, nVersion);
+        // height
+        nSize += ::GetSerializeSize(VARINT(nHeight), nType, nVersion);
+        return nSize;
+    }
+
+    template<typename Stream>
+    void Serialize(Stream &s, int nType, int nVersion) const {
+        unsigned int nMaskSize = 0, nMaskCode = 0;
+        CalcMaskSize(nMaskSize, nMaskCode);
+        bool fFirst = vout.size() > 0 && !vout[0].IsNull();
+        bool fSecond = vout.size() > 1 && !vout[1].IsNull();
+        assert(fFirst || fSecond || nMaskCode);
+        unsigned int nCode = 8*(nMaskCode - (fFirst || fSecond ? 0 : 1)) + (fCoinBase ? 1 : 0) + (fFirst ? 2 : 0) + (fSecond ? 4 : 0);
+        // version
+        ::Serialize(s, VARINT(this->nVersion), nType, nVersion);
+        // header code
+        ::Serialize(s, VARINT(nCode), nType, nVersion);
+        // spentness bitmask
+        for (unsigned int b = 0; b<nMaskSize; b++) {
+            unsigned char chAvail = 0;
+            for (unsigned int i = 0; i < 8 && 2+b*8+i < vout.size(); i++)
+                if (!vout[2+b*8+i].IsNull())
+                    chAvail |= (1 << i);
+            ::Serialize(s, chAvail, nType, nVersion);
+        }
+        // txouts themself
+        for (unsigned int i = 0; i < vout.size(); i++) {
+            if (!vout[i].IsNull())
+                ::Serialize(s, CTxOutCompressor(REF(vout[i])), nType, nVersion);
+        }
+        // coinbase height
+        ::Serialize(s, VARINT(nHeight), nType, nVersion);
+    }
+
+    template<typename Stream>
+    void Unserialize(Stream &s, int nType, int nVersion) {
+        unsigned int nCode = 0;
+        // version
+        ::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
+        // header code
+        ::Unserialize(s, VARINT(nCode), nType, nVersion);
+        fCoinBase = nCode & 1;
+        std::vector<bool> vAvail(2, false);
+        vAvail[0] = nCode & 2;
+        vAvail[1] = nCode & 4;
+        unsigned int nMaskCode = (nCode / 8) + ((nCode & 6) != 0 ? 0 : 1);
+        // spentness bitmask
+        while (nMaskCode > 0) {
+            unsigned char chAvail = 0;
+            ::Unserialize(s, chAvail, nType, nVersion);
+            for (unsigned int p = 0; p < 8; p++) {
+                bool f = (chAvail & (1 << p)) != 0;
+                vAvail.push_back(f);
+            }
+            if (chAvail != 0)
+                nMaskCode--;
+        }
+        // txouts themself
+        vout.assign(vAvail.size(), CTxOut());
+        for (unsigned int i = 0; i < vAvail.size(); i++) {
+            if (vAvail[i])
+                ::Unserialize(s, REF(CTxOutCompressor(vout[i])), nType, nVersion);
+        }
+        // coinbase height
+        ::Unserialize(s, VARINT(nHeight), nType, nVersion);
+        Cleanup();
+    }
+
+    // mark an outpoint spent, and construct undo information
+    bool Spend(const COutPoint &out, CTxInUndo &undo);
+
+    // mark a vout spent
+    bool Spend(int nPos);
+
+    // check whether a particular output is still available
+    bool IsAvailable(unsigned int nPos) const {
+        return (nPos < vout.size() && !vout[nPos].IsNull());
+    }
+
+    // check whether the entire CCoins is spent
+    // note that only !IsPruned() CCoins can be serialized
+    bool IsPruned() const {
+        BOOST_FOREACH(const CTxOut &out, vout)
+            if (!out.IsNull())
+                return false;
+        return true;
+    }
+};
+
+
+struct CCoinsStats
+{
+    int nHeight;
+    uint256 hashBlock;
+    uint64_t nTransactions;
+    uint64_t nTransactionOutputs;
+    uint64_t nSerializedSize;
+    uint256 hashSerialized;
+    int64_t nTotalAmount;
+
+    CCoinsStats() : nHeight(0), hashBlock(0), nTransactions(0), nTransactionOutputs(0), nSerializedSize(0), hashSerialized(0), nTotalAmount(0) {}
+};
+
+
+/** Abstract view on the open txout dataset. */
+class CCoinsView
+{
+public:
+    // Retrieve the CCoins (unspent transaction outputs) for a given txid
+    virtual bool GetCoins(const uint256 &txid, CCoins &coins);
+
+    // Modify the CCoins for a given txid
+    virtual bool SetCoins(const uint256 &txid, const CCoins &coins);
+
+    // Just check whether we have data for a given txid.
+    // This may (but cannot always) return true for fully spent transactions
+    virtual bool HaveCoins(const uint256 &txid);
+
+    // Retrieve the block hash whose state this CCoinsView currently represents
+    virtual uint256 GetBestBlock();
+
+    // Modify the currently active block hash
+    virtual bool SetBestBlock(const uint256 &hashBlock);
+
+    // Do a bulk modification (multiple SetCoins + one SetBestBlock)
+    virtual bool BatchWrite(const std::map<uint256, CCoins> &mapCoins, const uint256 &hashBlock);
+
+    // Calculate statistics about the unspent transaction output set
+    virtual bool GetStats(CCoinsStats &stats);
+
+    // As we use CCoinsViews polymorphically, have a virtual destructor
+    virtual ~CCoinsView() {}
+};
+
+
+/** CCoinsView backed by another CCoinsView */
+class CCoinsViewBacked : public CCoinsView
+{
+protected:
+    CCoinsView *base;
+
+public:
+    CCoinsViewBacked(CCoinsView &viewIn);
+    bool GetCoins(const uint256 &txid, CCoins &coins);
+    bool SetCoins(const uint256 &txid, const CCoins &coins);
+    bool HaveCoins(const uint256 &txid);
+    uint256 GetBestBlock();
+    bool SetBestBlock(const uint256 &hashBlock);
+    void SetBackend(CCoinsView &viewIn);
+    bool BatchWrite(const std::map<uint256, CCoins> &mapCoins, const uint256 &hashBlock);
+    bool GetStats(CCoinsStats &stats);
+};
+
+
+/** CCoinsView that adds a memory cache for transactions to another CCoinsView */
+class CCoinsViewCache : public CCoinsViewBacked
+{
+protected:
+    uint256 hashBlock;
+    std::map<uint256,CCoins> cacheCoins;
+
+public:
+    CCoinsViewCache(CCoinsView &baseIn, bool fDummy = false);
+
+    // Standard CCoinsView methods
+    bool GetCoins(const uint256 &txid, CCoins &coins);
+    bool SetCoins(const uint256 &txid, const CCoins &coins);
+    bool HaveCoins(const uint256 &txid);
+    uint256 GetBestBlock();
+    bool SetBestBlock(const uint256 &hashBlock);
+    bool BatchWrite(const std::map<uint256, CCoins> &mapCoins, const uint256 &hashBlock);
+
+    // Return a modifiable reference to a CCoins. Check HaveCoins first.
+    // Many methods explicitly require a CCoinsViewCache because of this method, to reduce
+    // copying.
+    CCoins &GetCoins(const uint256 &txid);
+
+    // Push the modifications applied to this cache to its base.
+    // Failure to call this method before destruction will cause the changes to be forgotten.
+    bool Flush();
+
+    // Calculate the size of the cache (in number of transactions)
+    unsigned int GetCacheSize();
+
+    /** Amount of bitcoins coming in to a transaction
+        Note that lightweight clients may not know anything besides the hash of previous transactions,
+        so may not be able to calculate this.
+
+        @param[in] tx	transaction for which we are checking input total
+        @return	Sum of value of all inputs (scriptSigs)
+        @see CTransaction::FetchInputs
+     */
+    int64_t GetValueIn(const CTransaction& tx);
+
+    // Check whether all prevouts of the transaction are present in the UTXO set represented by this view
+    bool HaveInputs(const CTransaction& tx);
+
+    const CTxOut &GetOutputFor(const CTxIn& input);
+
+private:
+    std::map<uint256,CCoins>::iterator FetchCoins(const uint256 &txid);
+};
+
+#endif