From 4c6d41b8b653ef90639b1a32f6aab0bb1cef90c5 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 10 Oct 2013 23:07:44 +0200
Subject: Refactor/encapsulate chain globals into a CChain class

---
 src/main.h | 83 +++++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 53 insertions(+), 30 deletions(-)

(limited to 'src/main.h')

diff --git a/src/main.h b/src/main.h
index 83b0d07f63..46d629044a 100644
--- a/src/main.h
+++ b/src/main.h
@@ -74,14 +74,8 @@ extern CScript COINBASE_FLAGS;
 
 extern CCriticalSection cs_main;
 extern std::map<uint256, CBlockIndex*> mapBlockIndex;
-extern std::vector<CBlockIndex*> vBlockIndexByHeight;
 extern std::set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexValid;
-extern CBlockIndex* pindexGenesisBlock;
-extern int nBestHeight;
-extern uint256 nBestChainWork;
 extern uint256 nBestInvalidWork;
-extern uint256 hashBestChain;
-extern CBlockIndex* pindexBest;
 extern unsigned int nTransactionsUpdated;
 extern uint64 nLastBlockTx;
 extern uint64 nLastBlockSize;
@@ -153,8 +147,6 @@ void UnloadBlockIndex();
 bool VerifyDB(int nCheckLevel, int nCheckDepth);
 /** Print the loaded block tree */
 void PrintBlockTree();
-/** Find a block by height in the currently-connected chain */
-CBlockIndex* FindBlockByHeight(int nHeight);
 /** Process protocol messages received from a given node */
 bool ProcessMessages(CNode* pfrom);
 /** Send queued protocol messages to be sent to a give node */
@@ -819,15 +811,6 @@ public:
         return (CBigNum(1)<<256) / (bnTarget+1);
     }
 
-    bool IsInMainChain() const
-    {
-        return nHeight < (int)vBlockIndexByHeight.size() && vBlockIndexByHeight[nHeight] == this;
-    }
-
-    CBlockIndex *GetNextInMainChain() const {
-        return nHeight+1 >= (int)vBlockIndexByHeight.size() ? NULL : vBlockIndexByHeight[nHeight+1];
-    }
-
     bool CheckIndex() const
     {
         return CheckProofOfWork(GetBlockHash(), nBits);
@@ -849,17 +832,7 @@ public:
         return pbegin[(pend - pbegin)/2];
     }
 
-    int64 GetMedianTime() const
-    {
-        const CBlockIndex* pindex = this;
-        for (int i = 0; i < nMedianTimeSpan/2; i++)
-        {
-            if (!pindex->GetNextInMainChain())
-                return GetBlockTime();
-            pindex = pindex->GetNextInMainChain();
-        }
-        return pindex->GetMedianTimePast();
-    }
+    int64 GetMedianTime() const;
 
     /**
      * Returns true if there are nRequired or more blocks of minVersion or above
@@ -870,8 +843,8 @@ public:
 
     std::string ToString() const
     {
-        return strprintf("CBlockIndex(pprev=%p, pnext=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
-            pprev, GetNextInMainChain(), nHeight,
+        return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
+            pprev, nHeight,
             hashMerkleRoot.ToString().c_str(),
             GetBlockHash().ToString().c_str());
     }
@@ -1011,9 +984,59 @@ public:
     }
 };
 
+/** 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);
+};
 
+/** The currently-connected chain of blocks. */
+extern CChain chainActive;
 
 
 
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