Merge pull request #4796

e8b5f0d Move CBlockIndex, CChain and related code out of main (jtimon)
6db83db Decouple CChain from mapBlockIndex (jtimon)

6 files changed, 461 insertions, 442 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 94a582dfac..2c64cb74a0 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -67,6 +67,7 @@ BITCOIN_CORE_H = \
   allocators.h \
   base58.h \
   bloom.h \
+  chain.h \
   chainparams.h \
   chainparamsbase.h \
   chainparamsseeds.h \
@@ -145,6 +146,7 @@ libbitcoin_server_a_SOURCES = \
   addrman.cpp \
   alert.cpp \
   bloom.cpp \
+  chain.cpp \
   checkpoints.cpp \
   init.cpp \
   leveldbwrapper.cpp \
diff --git a/src/chain.cpp b/src/chain.cpp
new file mode 100644
index 0000000000..bcb497b2d4
--- /dev/null
+++ b/src/chain.cpp
@@ -0,0 +1,59 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "chain.h"
+
+using namespace std;
+
+// CChain implementation
+
+CBlockIndex *CChain::SetTip(CBlockIndex *pindex) {
+    if (pindex == NULL) {
+        vChain.clear();
+        return NULL;
+    }
+    vChain.resize(pindex->nHeight + 1);
+    while (pindex && vChain[pindex->nHeight] != pindex) {
+        vChain[pindex->nHeight] = pindex;
+        pindex = pindex->pprev;
+    }
+    return pindex;
+}
+
+CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const {
+    int nStep = 1;
+    std::vector<uint256> vHave;
+    vHave.reserve(32);
+
+    if (!pindex)
+        pindex = Tip();
+    while (pindex) {
+        vHave.push_back(pindex->GetBlockHash());
+        // Stop when we have added the genesis block.
+        if (pindex->nHeight == 0)
+            break;
+        // Exponentially larger steps back, plus the genesis block.
+        int nHeight = std::max(pindex->nHeight - nStep, 0);
+        if (Contains(pindex)) {
+            // Use O(1) CChain index if possible.
+            pindex = (*this)[nHeight];
+        } else {
+            // Otherwise, use O(log n) skiplist.
+            pindex = pindex->GetAncestor(nHeight);
+        }
+        if (vHave.size() > 10)
+            nStep *= 2;
+    }
+
+    return CBlockLocator(vHave);
+}
+
+const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
+    if (pindex->nHeight > Height())
+        pindex = pindex->GetAncestor(Height());
+    while (pindex && !Contains(pindex))
+        pindex = pindex->pprev;
+    return pindex;
+}
diff --git a/src/chain.h b/src/chain.h
new file mode 100644
index 0000000000..91bdf38347
--- /dev/null
+++ b/src/chain.h
@@ -0,0 +1,390 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 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 H_BITCOIN_CHAIN
+#define H_BITCOIN_CHAIN
+
+#include "core.h"
+#include "pow.h"
+#include "uint256.h"
+
+#include <vector>
+
+#include <boost/foreach.hpp>
+
+struct CDiskBlockPos
+{
+    int nFile;
+    unsigned int nPos;
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(VARINT(nFile));
+        READWRITE(VARINT(nPos));
+    }
+
+    CDiskBlockPos() {
+        SetNull();
+    }
+
+    CDiskBlockPos(int nFileIn, unsigned int nPosIn) {
+        nFile = nFileIn;
+        nPos = nPosIn;
+    }
+
+    friend bool operator==(const CDiskBlockPos &a, const CDiskBlockPos &b) {
+        return (a.nFile == b.nFile && a.nPos == b.nPos);
+    }
+
+    friend bool operator!=(const CDiskBlockPos &a, const CDiskBlockPos &b) {
+        return !(a == b);
+    }
+
+    void SetNull() { nFile = -1; nPos = 0; }
+    bool IsNull() const { return (nFile == -1); }
+};
+
+enum BlockStatus {
+    BLOCK_VALID_UNKNOWN      =    0,
+    BLOCK_VALID_HEADER       =    1, // parsed, version ok, hash satisfies claimed PoW, 1 <= vtx count <= max, timestamp not in future
+    BLOCK_VALID_TREE         =    2, // parent found, difficulty matches, timestamp >= median previous, checkpoint
+    BLOCK_VALID_TRANSACTIONS =    3, // only first tx is coinbase, 2 <= coinbase input script length <= 100, transactions valid, no duplicate txids, sigops, size, merkle root
+    BLOCK_VALID_CHAIN        =    4, // outputs do not overspend inputs, no double spends, coinbase output ok, immature coinbase spends, BIP30
+    BLOCK_VALID_SCRIPTS      =    5, // scripts/signatures ok
+    BLOCK_VALID_MASK         =   BLOCK_VALID_HEADER | BLOCK_VALID_TREE | BLOCK_VALID_TRANSACTIONS |
+                                 BLOCK_VALID_CHAIN | BLOCK_VALID_SCRIPTS,
+
+    BLOCK_HAVE_DATA          =    8, // full block available in blk*.dat
+    BLOCK_HAVE_UNDO          =   16, // undo data available in rev*.dat
+    BLOCK_HAVE_MASK          =   BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO,
+
+    BLOCK_FAILED_VALID       =   32, // stage after last reached validness failed
+    BLOCK_FAILED_CHILD       =   64, // descends from failed block
+    BLOCK_FAILED_MASK        =   BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
+};
+
+/** The block chain is a tree shaped structure starting with the
+ * genesis block at the root, with each block potentially having multiple
+ * candidates to be the next block. A blockindex may have multiple pprev pointing
+ * to it, but at most one of them can be part of the currently active branch.
+ */
+class CBlockIndex
+{
+public:
+    // pointer to the hash of the block, if any. memory is owned by this CBlockIndex
+    const uint256* phashBlock;
+
+    // pointer to the index of the predecessor of this block
+    CBlockIndex* pprev;
+
+    // pointer to the index of some further predecessor of this block
+    CBlockIndex* pskip;
+
+    // height of the entry in the chain. The genesis block has height 0
+    int nHeight;
+
+    // Which # file this block is stored in (blk?????.dat)
+    int nFile;
+
+    // Byte offset within blk?????.dat where this block's data is stored
+    unsigned int nDataPos;
+
+    // Byte offset within rev?????.dat where this block's undo data is stored
+    unsigned int nUndoPos;
+
+    // (memory only) Total amount of work (expected number of hashes) in the chain up to and including this block
+    uint256 nChainWork;
+
+    // Number of transactions in this block.
+    // Note: in a potential headers-first mode, this number cannot be relied upon
+    unsigned int nTx;
+
+    // (memory only) Number of transactions in the chain up to and including this block
+    unsigned int nChainTx; // change to 64-bit type when necessary; won't happen before 2030
+
+    // Verification status of this block. See enum BlockStatus
+    unsigned int nStatus;
+
+    // block header
+    int nVersion;
+    uint256 hashMerkleRoot;
+    unsigned int nTime;
+    unsigned int nBits;
+    unsigned int nNonce;
+
+    // (memory only) Sequencial id assigned to distinguish order in which blocks are received.
+    uint32_t nSequenceId;
+
+    void SetNull()
+    {
+        phashBlock = NULL;
+        pprev = NULL;
+        pskip = NULL;
+        nHeight = 0;
+        nFile = 0;
+        nDataPos = 0;
+        nUndoPos = 0;
+        nChainWork = 0;
+        nTx = 0;
+        nChainTx = 0;
+        nStatus = 0;
+        nSequenceId = 0;
+
+        nVersion       = 0;
+        hashMerkleRoot = 0;
+        nTime          = 0;
+        nBits          = 0;
+        nNonce         = 0;
+    }
+
+    CBlockIndex()
+    {
+        SetNull();
+    }
+
+    CBlockIndex(CBlockHeader& block)
+    {
+        SetNull();
+
+        nVersion       = block.nVersion;
+        hashMerkleRoot = block.hashMerkleRoot;
+        nTime          = block.nTime;
+        nBits          = block.nBits;
+        nNonce         = block.nNonce;
+    }
+
+    CDiskBlockPos GetBlockPos() const {
+        CDiskBlockPos ret;
+        if (nStatus & BLOCK_HAVE_DATA) {
+            ret.nFile = nFile;
+            ret.nPos  = nDataPos;
+        }
+        return ret;
+    }
+
+    CDiskBlockPos GetUndoPos() const {
+        CDiskBlockPos ret;
+        if (nStatus & BLOCK_HAVE_UNDO) {
+            ret.nFile = nFile;
+            ret.nPos  = nUndoPos;
+        }
+        return ret;
+    }
+
+    CBlockHeader GetBlockHeader() const
+    {
+        CBlockHeader block;
+        block.nVersion       = nVersion;
+        if (pprev)
+            block.hashPrevBlock = pprev->GetBlockHash();
+        block.hashMerkleRoot = hashMerkleRoot;
+        block.nTime          = nTime;
+        block.nBits          = nBits;
+        block.nNonce         = nNonce;
+        return block;
+    }
+
+    uint256 GetBlockHash() const
+    {
+        return *phashBlock;
+    }
+
+    int64_t GetBlockTime() const
+    {
+        return (int64_t)nTime;
+    }
+
+    uint256 GetBlockWork() const
+    {
+        return GetProofIncrement(nBits);
+    }
+
+    enum { nMedianTimeSpan=11 };
+
+    int64_t GetMedianTimePast() const
+    {
+        int64_t pmedian[nMedianTimeSpan];
+        int64_t* pbegin = &pmedian[nMedianTimeSpan];
+        int64_t* pend = &pmedian[nMedianTimeSpan];
+
+        const CBlockIndex* pindex = this;
+        for (int i = 0; i < nMedianTimeSpan && pindex; i++, pindex = pindex->pprev)
+            *(--pbegin) = pindex->GetBlockTime();
+
+        std::sort(pbegin, pend);
+        return pbegin[(pend - pbegin)/2];
+    }
+
+    /**
+     * Returns true if there are nRequired or more blocks of minVersion or above
+     * in the last Params().ToCheckBlockUpgradeMajority() blocks, starting at pstart 
+     * and going backwards.
+     */
+    static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart,
+                                unsigned int nRequired);
+
+    std::string ToString() const
+    {
+        return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
+            pprev, nHeight,
+            hashMerkleRoot.ToString(),
+            GetBlockHash().ToString());
+    }
+
+    // Check whether this block index entry is valid up to the passed validity level.
+    bool IsValid(enum BlockStatus nUpTo = BLOCK_VALID_TRANSACTIONS) const
+    {
+        assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
+        if (nStatus & BLOCK_FAILED_MASK)
+            return false;
+        return ((nStatus & BLOCK_VALID_MASK) >= nUpTo);
+    }
+
+    // Raise the validity level of this block index entry.
+    // Returns true if the validity was changed.
+    bool RaiseValidity(enum BlockStatus nUpTo)
+    {
+        assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
+        if (nStatus & BLOCK_FAILED_MASK)
+            return false;
+        if ((nStatus & BLOCK_VALID_MASK) < nUpTo) {
+            nStatus = (nStatus & ~BLOCK_VALID_MASK) | nUpTo;
+            return true;
+        }
+        return false;
+    }
+
+    // Build the skiplist pointer for this entry.
+    void BuildSkip();
+
+    // Efficiently find an ancestor of this block.
+    CBlockIndex* GetAncestor(int height);
+    const CBlockIndex* GetAncestor(int height) const;
+};
+
+/** Used to marshal pointers into hashes for db storage. */
+class CDiskBlockIndex : public CBlockIndex
+{
+public:
+    uint256 hashPrev;
+
+    CDiskBlockIndex() {
+        hashPrev = 0;
+    }
+
+    explicit CDiskBlockIndex(CBlockIndex* pindex) : CBlockIndex(*pindex) {
+        hashPrev = (pprev ? pprev->GetBlockHash() : 0);
+    }
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        if (!(nType & SER_GETHASH))
+            READWRITE(VARINT(nVersion));
+
+        READWRITE(VARINT(nHeight));
+        READWRITE(VARINT(nStatus));
+        READWRITE(VARINT(nTx));
+        if (nStatus & (BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO))
+            READWRITE(VARINT(nFile));
+        if (nStatus & BLOCK_HAVE_DATA)
+            READWRITE(VARINT(nDataPos));
+        if (nStatus & BLOCK_HAVE_UNDO)
+            READWRITE(VARINT(nUndoPos));
+
+        // block header
+        READWRITE(this->nVersion);
+        READWRITE(hashPrev);
+        READWRITE(hashMerkleRoot);
+        READWRITE(nTime);
+        READWRITE(nBits);
+        READWRITE(nNonce);
+    }
+
+    uint256 GetBlockHash() const
+    {
+        CBlockHeader block;
+        block.nVersion        = nVersion;
+        block.hashPrevBlock   = hashPrev;
+        block.hashMerkleRoot  = hashMerkleRoot;
+        block.nTime           = nTime;
+        block.nBits           = nBits;
+        block.nNonce          = nNonce;
+        return block.GetHash();
+    }
+
+
+    std::string ToString() const
+    {
+        std::string str = "CDiskBlockIndex(";
+        str += CBlockIndex::ToString();
+        str += strprintf("\n                hashBlock=%s, hashPrev=%s)",
+            GetBlockHash().ToString(),
+            hashPrev.ToString());
+        return str;
+    }
+};
+
+/** An in-memory indexed chain of blocks. */
+class CChain {
+private:
+    std::vector<CBlockIndex*> vChain;
+
+public:
+    /** Returns the index entry for the genesis block of this chain, or NULL if none. */
+    CBlockIndex *Genesis() const {
+        return vChain.size() > 0 ? vChain[0] : NULL;
+    }
+
+    /** Returns the index entry for the tip of this chain, or NULL if none. */
+    CBlockIndex *Tip() const {
+        return vChain.size() > 0 ? vChain[vChain.size() - 1] : NULL;
+    }
+
+    /** Returns the index entry at a particular height in this chain, or NULL if no such height exists. */
+    CBlockIndex *operator[](int nHeight) const {
+        if (nHeight < 0 || nHeight >= (int)vChain.size())
+            return NULL;
+        return vChain[nHeight];
+    }
+
+    /** Compare two chains efficiently. */
+    friend bool operator==(const CChain &a, const CChain &b) {
+        return a.vChain.size() == b.vChain.size() &&
+               a.vChain[a.vChain.size() - 1] == b.vChain[b.vChain.size() - 1];
+    }
+
+    /** Efficiently check whether a block is present in this chain. */
+    bool Contains(const CBlockIndex *pindex) const {
+        return (*this)[pindex->nHeight] == pindex;
+    }
+
+    /** Find the successor of a block in this chain, or NULL if the given index is not found or is the tip. */
+    CBlockIndex *Next(const CBlockIndex *pindex) const {
+        if (Contains(pindex))
+            return (*this)[pindex->nHeight + 1];
+        else
+            return NULL;
+    }
+
+    /** Return the maximal height in the chain. Is equal to chain.Tip() ? chain.Tip()->nHeight : -1. */
+    int Height() const {
+        return vChain.size() - 1;
+    }
+
+    /** Set/initialize a chain with a given tip. Returns the forking point. */
+    CBlockIndex *SetTip(CBlockIndex *pindex);
+
+    /** Return a CBlockLocator that refers to a block in this chain (by default the tip). */
+    CBlockLocator GetLocator(const CBlockIndex *pindex = NULL) const;
+
+    /** Find the last common block between this chain and a block index entry. */
+    const CBlockIndex *FindFork(const CBlockIndex *pindex) const;
+};
+
+#endif 
diff --git a/src/init.cpp b/src/init.cpp
index 27594ecbe3..85f4d360d2 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1159,7 +1159,7 @@ bool AppInit2(boost::thread_group& threadGroup)
             CWalletDB walletdb(strWalletFile);
             CBlockLocator locator;
             if (walletdb.ReadBestBlock(locator))
-                pindexRescan = chainActive.FindFork(locator);
+                pindexRescan = FindForkInGlobalIndex(chainActive, locator);
             else
                 pindexRescan = chainActive.Genesis();
         }
diff --git a/src/main.cpp b/src/main.cpp
index 60e2a56795..9a4271eda2 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -391,72 +391,19 @@ void UnregisterNodeSignals(CNodeSignals& nodeSignals)
     nodeSignals.FinalizeNode.disconnect(&FinalizeNode);
 }
 
-//////////////////////////////////////////////////////////////////////////////
-//
-// CChain implementation
-//
-
-CBlockIndex *CChain::SetTip(CBlockIndex *pindex) {
-    if (pindex == NULL) {
-        vChain.clear();
-        return NULL;
-    }
-    vChain.resize(pindex->nHeight + 1);
-    while (pindex && vChain[pindex->nHeight] != pindex) {
-        vChain[pindex->nHeight] = pindex;
-        pindex = pindex->pprev;
-    }
-    return pindex;
-}
-
-CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const {
-    int nStep = 1;
-    std::vector<uint256> vHave;
-    vHave.reserve(32);
-
-    if (!pindex)
-        pindex = Tip();
-    while (pindex) {
-        vHave.push_back(pindex->GetBlockHash());
-        // Stop when we have added the genesis block.
-        if (pindex->nHeight == 0)
-            break;
-        // Exponentially larger steps back, plus the genesis block.
-        int nHeight = std::max(pindex->nHeight - nStep, 0);
-        if (Contains(pindex)) {
-            // Use O(1) CChain index if possible.
-            pindex = (*this)[nHeight];
-        } else {
-            // Otherwise, use O(log n) skiplist.
-            pindex = pindex->GetAncestor(nHeight);
-        }
-        if (vHave.size() > 10)
-            nStep *= 2;
-    }
-
-    return CBlockLocator(vHave);
-}
-
-CBlockIndex *CChain::FindFork(const CBlockLocator &locator) const {
+CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)
+{
     // Find the first block the caller has in the main chain
     BOOST_FOREACH(const uint256& hash, locator.vHave) {
         BlockMap::iterator mi = mapBlockIndex.find(hash);
         if (mi != mapBlockIndex.end())
         {
             CBlockIndex* pindex = (*mi).second;
-            if (Contains(pindex))
+            if (chain.Contains(pindex))
                 return pindex;
         }
     }
-    return Genesis();
-}
-
-const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
-    if (pindex->nHeight > Height())
-        pindex = pindex->GetAncestor(Height());
-    while (pindex && !Contains(pindex))
-        pindex = pindex->pprev;
-    return pindex;
+    return chain.Genesis();
 }
 
 CCoinsViewCache *pcoinsTip = NULL;
@@ -3709,7 +3656,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         LOCK(cs_main);
 
         // Find the last block the caller has in the main chain
-        CBlockIndex* pindex = chainActive.FindFork(locator);
+        CBlockIndex* pindex = FindForkInGlobalIndex(chainActive, locator);
 
         // Send the rest of the chain
         if (pindex)
@@ -3756,7 +3703,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         else
         {
             // Find the last block the caller has in the main chain
-            pindex = chainActive.FindFork(locator);
+            pindex = FindForkInGlobalIndex(chainActive, locator);
             if (pindex)
                 pindex = chainActive.Next(pindex);
         }
diff --git a/src/main.h b/src/main.h
index 5acc551793..c75841538f 100644
--- a/src/main.h
+++ b/src/main.h
@@ -10,6 +10,7 @@
 #include "config/bitcoin-config.h"
 #endif
 
+#include "chain.h"
 #include "chainparams.h"
 #include "coins.h"
 #include "core.h"
@@ -113,7 +114,6 @@ static const uint64_t nMinDiskSpace = 52428800;
 
 
 class CBlockTreeDB;
-struct CDiskBlockPos;
 class CTxUndo;
 class CScriptCheck;
 class CValidationState;
@@ -189,51 +189,11 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
                         bool* pfMissingInputs, bool fRejectInsaneFee=false);
 
 
-
-
-
-
-
-
 struct CNodeStateStats {
     int nMisbehavior;
     int nSyncHeight;
 };
 
-struct CDiskBlockPos
-{
-    int nFile;
-    unsigned int nPos;
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(VARINT(nFile));
-        READWRITE(VARINT(nPos));
-    }
-
-    CDiskBlockPos() {
-        SetNull();
-    }
-
-    CDiskBlockPos(int nFileIn, unsigned int nPosIn) {
-        nFile = nFileIn;
-        nPos = nPosIn;
-    }
-
-    friend bool operator==(const CDiskBlockPos &a, const CDiskBlockPos &b) {
-        return (a.nFile == b.nFile && a.nPos == b.nPos);
-    }
-
-    friend bool operator!=(const CDiskBlockPos &a, const CDiskBlockPos &b) {
-        return !(a == b);
-    }
-
-    void SetNull() { nFile = -1; nPos = 0; }
-    bool IsNull() const { return (nFile == -1); }
-};
-
 struct CDiskTxPos : public CDiskBlockPos
 {
     unsigned int nTxOffset; // after header
@@ -545,288 +505,6 @@ public:
      }
 };
 
-enum BlockStatus {
-    BLOCK_VALID_UNKNOWN      =    0,
-    BLOCK_VALID_HEADER       =    1, // parsed, version ok, hash satisfies claimed PoW, 1 <= vtx count <= max, timestamp not in future
-    BLOCK_VALID_TREE         =    2, // parent found, difficulty matches, timestamp >= median previous, checkpoint
-    BLOCK_VALID_TRANSACTIONS =    3, // only first tx is coinbase, 2 <= coinbase input script length <= 100, transactions valid, no duplicate txids, sigops, size, merkle root
-    BLOCK_VALID_CHAIN        =    4, // outputs do not overspend inputs, no double spends, coinbase output ok, immature coinbase spends, BIP30
-    BLOCK_VALID_SCRIPTS      =    5, // scripts/signatures ok
-    BLOCK_VALID_MASK         =   BLOCK_VALID_HEADER | BLOCK_VALID_TREE | BLOCK_VALID_TRANSACTIONS |
-                                 BLOCK_VALID_CHAIN | BLOCK_VALID_SCRIPTS,
-
-    BLOCK_HAVE_DATA          =    8, // full block available in blk*.dat
-    BLOCK_HAVE_UNDO          =   16, // undo data available in rev*.dat
-    BLOCK_HAVE_MASK          =   BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO,
-
-    BLOCK_FAILED_VALID       =   32, // stage after last reached validness failed
-    BLOCK_FAILED_CHILD       =   64, // descends from failed block
-    BLOCK_FAILED_MASK        =   BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
-};
-
-/** The block chain is a tree shaped structure starting with the
- * genesis block at the root, with each block potentially having multiple
- * candidates to be the next block. A blockindex may have multiple pprev pointing
- * to it, but at most one of them can be part of the currently active branch.
- */
-class CBlockIndex
-{
-public:
-    // pointer to the hash of the block, if any. memory is owned by this CBlockIndex
-    const uint256* phashBlock;
-
-    // pointer to the index of the predecessor of this block
-    CBlockIndex* pprev;
-
-    // pointer to the index of some further predecessor of this block
-    CBlockIndex* pskip;
-
-    // height of the entry in the chain. The genesis block has height 0
-    int nHeight;
-
-    // Which # file this block is stored in (blk?????.dat)
-    int nFile;
-
-    // Byte offset within blk?????.dat where this block's data is stored
-    unsigned int nDataPos;
-
-    // Byte offset within rev?????.dat where this block's undo data is stored
-    unsigned int nUndoPos;
-
-    // (memory only) Total amount of work (expected number of hashes) in the chain up to and including this block
-    uint256 nChainWork;
-
-    // Number of transactions in this block.
-    // Note: in a potential headers-first mode, this number cannot be relied upon
-    unsigned int nTx;
-
-    // (memory only) Number of transactions in the chain up to and including this block
-    unsigned int nChainTx; // change to 64-bit type when necessary; won't happen before 2030
-
-    // Verification status of this block. See enum BlockStatus
-    unsigned int nStatus;
-
-    // block header
-    int nVersion;
-    uint256 hashMerkleRoot;
-    unsigned int nTime;
-    unsigned int nBits;
-    unsigned int nNonce;
-
-    // (memory only) Sequencial id assigned to distinguish order in which blocks are received.
-    uint32_t nSequenceId;
-
-    void SetNull()
-    {
-        phashBlock = NULL;
-        pprev = NULL;
-        pskip = NULL;
-        nHeight = 0;
-        nFile = 0;
-        nDataPos = 0;
-        nUndoPos = 0;
-        nChainWork = 0;
-        nTx = 0;
-        nChainTx = 0;
-        nStatus = 0;
-        nSequenceId = 0;
-
-        nVersion       = 0;
-        hashMerkleRoot = 0;
-        nTime          = 0;
-        nBits          = 0;
-        nNonce         = 0;
-    }
-
-    CBlockIndex()
-    {
-        SetNull();
-    }
-
-    CBlockIndex(CBlockHeader& block)
-    {
-        SetNull();
-
-        nVersion       = block.nVersion;
-        hashMerkleRoot = block.hashMerkleRoot;
-        nTime          = block.nTime;
-        nBits          = block.nBits;
-        nNonce         = block.nNonce;
-    }
-
-    CDiskBlockPos GetBlockPos() const {
-        CDiskBlockPos ret;
-        if (nStatus & BLOCK_HAVE_DATA) {
-            ret.nFile = nFile;
-            ret.nPos  = nDataPos;
-        }
-        return ret;
-    }
-
-    CDiskBlockPos GetUndoPos() const {
-        CDiskBlockPos ret;
-        if (nStatus & BLOCK_HAVE_UNDO) {
-            ret.nFile = nFile;
-            ret.nPos  = nUndoPos;
-        }
-        return ret;
-    }
-
-    CBlockHeader GetBlockHeader() const
-    {
-        CBlockHeader block;
-        block.nVersion       = nVersion;
-        if (pprev)
-            block.hashPrevBlock = pprev->GetBlockHash();
-        block.hashMerkleRoot = hashMerkleRoot;
-        block.nTime          = nTime;
-        block.nBits          = nBits;
-        block.nNonce         = nNonce;
-        return block;
-    }
-
-    uint256 GetBlockHash() const
-    {
-        return *phashBlock;
-    }
-
-    int64_t GetBlockTime() const
-    {
-        return (int64_t)nTime;
-    }
-
-    uint256 GetBlockWork() const
-    {
-        return GetProofIncrement(nBits);
-    }
-
-    enum { nMedianTimeSpan=11 };
-
-    int64_t GetMedianTimePast() const
-    {
-        int64_t pmedian[nMedianTimeSpan];
-        int64_t* pbegin = &pmedian[nMedianTimeSpan];
-        int64_t* pend = &pmedian[nMedianTimeSpan];
-
-        const CBlockIndex* pindex = this;
-        for (int i = 0; i < nMedianTimeSpan && pindex; i++, pindex = pindex->pprev)
-            *(--pbegin) = pindex->GetBlockTime();
-
-        std::sort(pbegin, pend);
-        return pbegin[(pend - pbegin)/2];
-    }
-
-    /**
-     * Returns true if there are nRequired or more blocks of minVersion or above
-     * in the last Params().ToCheckBlockUpgradeMajority() blocks, starting at pstart 
-     * and going backwards.
-     */
-    static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart,
-                                unsigned int nRequired);
-
-    std::string ToString() const
-    {
-        return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
-            pprev, nHeight,
-            hashMerkleRoot.ToString(),
-            GetBlockHash().ToString());
-    }
-
-    // Check whether this block index entry is valid up to the passed validity level.
-    bool IsValid(enum BlockStatus nUpTo = BLOCK_VALID_TRANSACTIONS) const
-    {
-        assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
-        if (nStatus & BLOCK_FAILED_MASK)
-            return false;
-        return ((nStatus & BLOCK_VALID_MASK) >= nUpTo);
-    }
-
-    // Raise the validity level of this block index entry.
-    // Returns true if the validity was changed.
-    bool RaiseValidity(enum BlockStatus nUpTo)
-    {
-        assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
-        if (nStatus & BLOCK_FAILED_MASK)
-            return false;
-        if ((nStatus & BLOCK_VALID_MASK) < nUpTo) {
-            nStatus = (nStatus & ~BLOCK_VALID_MASK) | nUpTo;
-            return true;
-        }
-        return false;
-    }
-
-    // Build the skiplist pointer for this entry.
-    void BuildSkip();
-
-    // Efficiently find an ancestor of this block.
-    CBlockIndex* GetAncestor(int height);
-    const CBlockIndex* GetAncestor(int height) const;
-};
-
-/** Used to marshal pointers into hashes for db storage. */
-class CDiskBlockIndex : public CBlockIndex
-{
-public:
-    uint256 hashPrev;
-
-    CDiskBlockIndex() {
-        hashPrev = 0;
-    }
-
-    explicit CDiskBlockIndex(CBlockIndex* pindex) : CBlockIndex(*pindex) {
-        hashPrev = (pprev ? pprev->GetBlockHash() : 0);
-    }
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        if (!(nType & SER_GETHASH))
-            READWRITE(VARINT(nVersion));
-
-        READWRITE(VARINT(nHeight));
-        READWRITE(VARINT(nStatus));
-        READWRITE(VARINT(nTx));
-        if (nStatus & (BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO))
-            READWRITE(VARINT(nFile));
-        if (nStatus & BLOCK_HAVE_DATA)
-            READWRITE(VARINT(nDataPos));
-        if (nStatus & BLOCK_HAVE_UNDO)
-            READWRITE(VARINT(nUndoPos));
-
-        // block header
-        READWRITE(this->nVersion);
-        READWRITE(hashPrev);
-        READWRITE(hashMerkleRoot);
-        READWRITE(nTime);
-        READWRITE(nBits);
-        READWRITE(nNonce);
-    }
-
-    uint256 GetBlockHash() const
-    {
-        CBlockHeader block;
-        block.nVersion        = nVersion;
-        block.hashPrevBlock   = hashPrev;
-        block.hashMerkleRoot  = hashMerkleRoot;
-        block.nTime           = nTime;
-        block.nBits           = nBits;
-        block.nNonce          = nNonce;
-        return block.GetHash();
-    }
-
-
-    std::string ToString() const
-    {
-        std::string str = "CDiskBlockIndex(";
-        str += CBlockIndex::ToString();
-        str += strprintf("\n                hashBlock=%s, hashPrev=%s)",
-            GetBlockHash().ToString(),
-            hashPrev.ToString());
-        return str;
-    }
-};
-
 /** Capture information about block/transaction validation */
 class CValidationState {
 private:
@@ -898,65 +576,8 @@ public:
     bool VerifyDB(CCoinsView *coinsview, int nCheckLevel, int nCheckDepth);
 };
 
-/** An in-memory indexed chain of blocks. */
-class CChain {
-private:
-    std::vector<CBlockIndex*> vChain;
-
-public:
-    /** Returns the index entry for the genesis block of this chain, or NULL if none. */
-    CBlockIndex *Genesis() const {
-        return vChain.size() > 0 ? vChain[0] : NULL;
-    }
-
-    /** Returns the index entry for the tip of this chain, or NULL if none. */
-    CBlockIndex *Tip() const {
-        return vChain.size() > 0 ? vChain[vChain.size() - 1] : NULL;
-    }
-
-    /** Returns the index entry at a particular height in this chain, or NULL if no such height exists. */
-    CBlockIndex *operator[](int nHeight) const {
-        if (nHeight < 0 || nHeight >= (int)vChain.size())
-            return NULL;
-        return vChain[nHeight];
-    }
-
-    /** Compare two chains efficiently. */
-    friend bool operator==(const CChain &a, const CChain &b) {
-        return a.vChain.size() == b.vChain.size() &&
-               a.vChain[a.vChain.size() - 1] == b.vChain[b.vChain.size() - 1];
-    }
-
-    /** Efficiently check whether a block is present in this chain. */
-    bool Contains(const CBlockIndex *pindex) const {
-        return (*this)[pindex->nHeight] == pindex;
-    }
-
-    /** Find the successor of a block in this chain, or NULL if the given index is not found or is the tip. */
-    CBlockIndex *Next(const CBlockIndex *pindex) const {
-        if (Contains(pindex))
-            return (*this)[pindex->nHeight + 1];
-        else
-            return NULL;
-    }
-
-    /** Return the maximal height in the chain. Is equal to chain.Tip() ? chain.Tip()->nHeight : -1. */
-    int Height() const {
-        return vChain.size() - 1;
-    }
-
-    /** Set/initialize a chain with a given tip. Returns the forking point. */
-    CBlockIndex *SetTip(CBlockIndex *pindex);
-
-    /** Return a CBlockLocator that refers to a block in this chain (by default the tip). */
-    CBlockLocator GetLocator(const CBlockIndex *pindex = NULL) const;
-
-    /** Find the last common block between this chain and a locator. */
-    CBlockIndex *FindFork(const CBlockLocator &locator) const;
-
-    /** Find the last common block between this chain and a block index entry. */
-    const CBlockIndex *FindFork(const CBlockIndex *pindex) const;
-};
+/** Find the last common block between the parameter chain and a locator. */
+CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator);
 
 /** The currently-connected chain of blocks. */
 extern CChain chainActive;