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coins.h
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// 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)
*/
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);
// Return priority of tx at height nHeight
double GetPriority(const CTransaction &tx, int nHeight);
const CTxOut &GetOutputFor(const CTxIn& input);
private:
std::map<uint256,CCoins>::iterator FetchCoins(const uint256 &txid);
};
#endif

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