Merge pull request #3839

fd704c7 move pow constants to chainparams (jtimon)
df852d2 Refactor proof of work related functions out of main (jtimon)

11 files changed, 163 insertions, 124 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 5ecded442c..7e7fa0c3ca 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -71,6 +71,7 @@ BITCOIN_CORE_H = \
   netbase.h \
   net.h \
   noui.h \
+  pow.h \
   protocol.h \
   rpcclient.h \
   rpcprotocol.h \
@@ -121,6 +122,7 @@ libbitcoin_server_a_SOURCES = \
   miner.cpp \
   net.cpp \
   noui.cpp \
+  pow.cpp \
   rpcblockchain.cpp \
   rpcmining.cpp \
   rpcmisc.cpp \
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index afbae6fc57..eb56af750e 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -117,6 +117,8 @@ public:
         nRejectBlockOutdatedMajority = 950;
         nToCheckBlockUpgradeMajority = 1000;
         nMinerThreads = 0;
+        nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
+        nTargetSpacing = 10 * 60;
 
         // Build the genesis block. Note that the output of the genesis coinbase cannot
         // be spent as it did not originally exist in the database.
@@ -204,6 +206,9 @@ public:
         nEnforceBlockUpgradeMajority = 51;
         nRejectBlockOutdatedMajority = 75;
         nToCheckBlockUpgradeMajority = 100;
+        nMinerThreads = 0;
+        nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
+        nTargetSpacing = 10 * 60;
         strDataDir = "testnet3";
 
         // Modify the testnet genesis block so the timestamp is valid for a later start.
@@ -251,6 +256,8 @@ public:
         nRejectBlockOutdatedMajority = 950;
         nToCheckBlockUpgradeMajority = 1000;
         nMinerThreads = 1;
+        nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
+        nTargetSpacing = 10 * 60;
         bnProofOfWorkLimit = ~uint256(0) >> 1;
         genesis.nTime = 1296688602;
         genesis.nBits = 0x207fffff;
diff --git a/src/chainparams.h b/src/chainparams.h
index c0a6ebda6b..e9774bbfa2 100644
--- a/src/chainparams.h
+++ b/src/chainparams.h
@@ -70,6 +70,9 @@ public:
     bool AllowMinDifficultyBlocks() const { return fAllowMinDifficultyBlocks; }
     /* Make standard checks */
     bool RequireStandard() const { return fRequireStandard; }
+    int64_t TargetTimespan() const { return nTargetTimespan; }
+    int64_t TargetSpacing() const { return nTargetSpacing; }
+    int64_t Interval() const { return nTargetTimespan / nTargetSpacing; }
     const std::string& DataDir() const { return strDataDir; }
     /* Make miner stop after a block is found. In RPC, don't return
      * until nGenProcLimit blocks are generated */
@@ -95,6 +98,8 @@ protected:
     int nEnforceBlockUpgradeMajority;
     int nRejectBlockOutdatedMajority;
     int nToCheckBlockUpgradeMajority;
+    int64_t nTargetTimespan;
+    int64_t nTargetSpacing;
     std::string strDataDir;
     int nMinerThreads;
     std::vector<CDNSSeedData> vSeeds;
diff --git a/src/main.cpp b/src/main.cpp
index d3f04b95fa..ea47601081 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -12,6 +12,7 @@
 #include "checkqueue.h"
 #include "init.h"
 #include "net.h"
+#include "pow.h"
 #include "txdb.h"
 #include "txmempool.h"
 #include "ui_interface.h"
@@ -1194,118 +1195,6 @@ int64_t GetBlockValue(int nHeight, int64_t nFees)
     return nSubsidy + nFees;
 }
 
-static const int64_t nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
-static const int64_t nTargetSpacing = 10 * 60;
-static const int64_t nInterval = nTargetTimespan / nTargetSpacing;
-
-//
-// minimum amount of work that could possibly be required nTime after
-// minimum work required was nBase
-//
-unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime)
-{
-    const uint256 &bnLimit = Params().ProofOfWorkLimit();
-    // Testnet has min-difficulty blocks
-    // after nTargetSpacing*2 time between blocks:
-    if (Params().AllowMinDifficultyBlocks() && nTime > nTargetSpacing*2)
-        return bnLimit.GetCompact();
-
-    uint256 bnResult;
-    bnResult.SetCompact(nBase);
-    while (nTime > 0 && bnResult < bnLimit)
-    {
-        // Maximum 400% adjustment...
-        bnResult *= 4;
-        // ... in best-case exactly 4-times-normal target time
-        nTime -= nTargetTimespan*4;
-    }
-    if (bnResult > bnLimit)
-        bnResult = bnLimit;
-    return bnResult.GetCompact();
-}
-
-unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock)
-{
-    unsigned int nProofOfWorkLimit = Params().ProofOfWorkLimit().GetCompact();
-
-    // Genesis block
-    if (pindexLast == NULL)
-        return nProofOfWorkLimit;
-
-    // Only change once per interval
-    if ((pindexLast->nHeight+1) % nInterval != 0)
-    {
-        if (Params().AllowMinDifficultyBlocks())
-        {
-            // Special difficulty rule for testnet:
-            // If the new block's timestamp is more than 2* 10 minutes
-            // then allow mining of a min-difficulty block.
-            if (pblock->nTime > pindexLast->nTime + nTargetSpacing*2)
-                return nProofOfWorkLimit;
-            else
-            {
-                // Return the last non-special-min-difficulty-rules-block
-                const CBlockIndex* pindex = pindexLast;
-                while (pindex->pprev && pindex->nHeight % nInterval != 0 && pindex->nBits == nProofOfWorkLimit)
-                    pindex = pindex->pprev;
-                return pindex->nBits;
-            }
-        }
-        return pindexLast->nBits;
-    }
-
-    // Go back by what we want to be 14 days worth of blocks
-    const CBlockIndex* pindexFirst = pindexLast;
-    for (int i = 0; pindexFirst && i < nInterval-1; i++)
-        pindexFirst = pindexFirst->pprev;
-    assert(pindexFirst);
-
-    // Limit adjustment step
-    int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
-    LogPrintf("  nActualTimespan = %d  before bounds\n", nActualTimespan);
-    if (nActualTimespan < nTargetTimespan/4)
-        nActualTimespan = nTargetTimespan/4;
-    if (nActualTimespan > nTargetTimespan*4)
-        nActualTimespan = nTargetTimespan*4;
-
-    // Retarget
-    uint256 bnNew;
-    uint256 bnOld;
-    bnNew.SetCompact(pindexLast->nBits);
-    bnOld = bnNew;
-    bnNew *= nActualTimespan;
-    bnNew /= nTargetTimespan;
-
-    if (bnNew > Params().ProofOfWorkLimit())
-        bnNew = Params().ProofOfWorkLimit();
-
-    /// debug print
-    LogPrintf("GetNextWorkRequired RETARGET\n");
-    LogPrintf("nTargetTimespan = %d    nActualTimespan = %d\n", nTargetTimespan, nActualTimespan);
-    LogPrintf("Before: %08x  %s\n", pindexLast->nBits, bnOld.ToString());
-    LogPrintf("After:  %08x  %s\n", bnNew.GetCompact(), bnNew.ToString());
-
-    return bnNew.GetCompact();
-}
-
-bool CheckProofOfWork(uint256 hash, unsigned int nBits)
-{
-    bool fNegative;
-    bool fOverflow;
-    uint256 bnTarget;
-    bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
-
-    // Check range
-    if (fNegative || bnTarget == 0 || fOverflow || bnTarget > Params().ProofOfWorkLimit())
-        return error("CheckProofOfWork() : nBits below minimum work");
-
-    // Check proof of work matches claimed amount
-    if (hash > bnTarget)
-        return error("CheckProofOfWork() : hash doesn't match nBits");
-
-    return true;
-}
-
 bool IsInitialBlockDownload()
 {
     LOCK(cs_main);
diff --git a/src/main.h b/src/main.h
index 27041a0026..9858bcfd69 100644
--- a/src/main.h
+++ b/src/main.h
@@ -146,10 +146,6 @@ bool ProcessMessages(CNode* pfrom);
 bool SendMessages(CNode* pto, bool fSendTrickle);
 /** Run an instance of the script checking thread */
 void ThreadScriptCheck();
-/** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
-bool CheckProofOfWork(uint256 hash, unsigned int nBits);
-/** Calculate the minimum amount of work a received block needs, without knowing its direct parent */
-unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime);
 /** Check whether we are doing an initial block download (synchronizing from disk or network) */
 bool IsInitialBlockDownload();
 /** Format a string that describes several potential problems detected by the core */
@@ -159,7 +155,6 @@ bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock, b
 /** Find the best known block, and make it the tip of the block chain */
 bool ActivateBestChain(CValidationState &state);
 int64_t GetBlockValue(int nHeight, int64_t nFees);
-unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock);
 
 void UpdateTime(CBlockHeader& block, const CBlockIndex* pindexPrev);
 
@@ -812,11 +807,6 @@ public:
         return (~bnTarget / (bnTarget + 1)) + 1;
     }
 
-    bool CheckIndex() const
-    {
-        return CheckProofOfWork(GetBlockHash(), nBits);
-    }
-
     enum { nMedianTimeSpan=11 };
 
     int64_t GetMedianTimePast() const
diff --git a/src/miner.cpp b/src/miner.cpp
index 6b1f58b229..19b4694357 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -9,6 +9,7 @@
 #include "hash.h"
 #include "main.h"
 #include "net.h"
+#include "pow.h"
 #ifdef ENABLE_WALLET
 #include "wallet.h"
 #endif
diff --git a/src/pow.cpp b/src/pow.cpp
new file mode 100644
index 0000000000..952250decd
--- /dev/null
+++ b/src/pow.cpp
@@ -0,0 +1,119 @@
+// 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 "pow.h"
+
+#include "chainparams.h"
+#include "core.h"
+#include "main.h"
+#include "uint256.h"
+
+unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock)
+{
+    unsigned int nProofOfWorkLimit = Params().ProofOfWorkLimit().GetCompact();
+
+    // Genesis block
+    if (pindexLast == NULL)
+        return nProofOfWorkLimit;
+
+    // Only change once per interval
+    if ((pindexLast->nHeight+1) % Params().Interval() != 0)
+    {
+        if (Params().AllowMinDifficultyBlocks())
+        {
+            // Special difficulty rule for testnet:
+            // If the new block's timestamp is more than 2* 10 minutes
+            // then allow mining of a min-difficulty block.
+            if (pblock->nTime > pindexLast->nTime + Params().TargetSpacing()*2)
+                return nProofOfWorkLimit;
+            else
+            {
+                // Return the last non-special-min-difficulty-rules-block
+                const CBlockIndex* pindex = pindexLast;
+                while (pindex->pprev && pindex->nHeight % Params().Interval() != 0 && pindex->nBits == nProofOfWorkLimit)
+                    pindex = pindex->pprev;
+                return pindex->nBits;
+            }
+        }
+        return pindexLast->nBits;
+    }
+
+    // Go back by what we want to be 14 days worth of blocks
+    const CBlockIndex* pindexFirst = pindexLast;
+    for (int i = 0; pindexFirst && i < Params().Interval()-1; i++)
+        pindexFirst = pindexFirst->pprev;
+    assert(pindexFirst);
+
+    // Limit adjustment step
+    int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
+    LogPrintf("  nActualTimespan = %d  before bounds\n", nActualTimespan);
+    if (nActualTimespan < Params().TargetTimespan()/4)
+        nActualTimespan = Params().TargetTimespan()/4;
+    if (nActualTimespan > Params().TargetTimespan()*4)
+        nActualTimespan = Params().TargetTimespan()*4;
+
+    // Retarget
+    uint256 bnNew;
+    uint256 bnOld;
+    bnNew.SetCompact(pindexLast->nBits);
+    bnOld = bnNew;
+    bnNew *= nActualTimespan;
+    bnNew /= Params().TargetTimespan();
+
+    if (bnNew > Params().ProofOfWorkLimit())
+        bnNew = Params().ProofOfWorkLimit();
+
+    /// debug print
+    LogPrintf("GetNextWorkRequired RETARGET\n");
+    LogPrintf("Params().TargetTimespan() = %d    nActualTimespan = %d\n", Params().TargetTimespan(), nActualTimespan);
+    LogPrintf("Before: %08x  %s\n", pindexLast->nBits, bnOld.ToString());
+    LogPrintf("After:  %08x  %s\n", bnNew.GetCompact(), bnNew.ToString());
+
+    return bnNew.GetCompact();
+}
+
+bool CheckProofOfWork(uint256 hash, unsigned int nBits)
+{
+    bool fNegative;
+    bool fOverflow;
+    uint256 bnTarget;
+    bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
+
+    // Check range
+    if (fNegative || bnTarget == 0 || fOverflow || bnTarget > Params().ProofOfWorkLimit())
+        return error("CheckProofOfWork() : nBits below minimum work");
+
+    // Check proof of work matches claimed amount
+    if (hash > bnTarget)
+        return error("CheckProofOfWork() : hash doesn't match nBits");
+
+    return true;
+}
+
+//
+// minimum amount of work that could possibly be required nTime after
+// minimum work required was nBase
+//
+unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime)
+{
+    const uint256 &bnLimit = Params().ProofOfWorkLimit();
+    // Testnet has min-difficulty blocks
+    // after Params().TargetSpacing()*2 time between blocks:
+    if (Params().AllowMinDifficultyBlocks() && nTime > Params().TargetSpacing()*2)
+        return bnLimit.GetCompact();
+
+    uint256 bnResult;
+    bnResult.SetCompact(nBase);
+    while (nTime > 0 && bnResult < bnLimit)
+    {
+        // Maximum 400% adjustment...
+        bnResult *= 4;
+        // ... in best-case exactly 4-times-normal target time
+        nTime -= Params().TargetTimespan()*4;
+    }
+    if (bnResult > bnLimit)
+        bnResult = bnLimit;
+    return bnResult.GetCompact();
+}
diff --git a/src/pow.h b/src/pow.h
new file mode 100644
index 0000000000..0ce5b48766
--- /dev/null
+++ b/src/pow.h
@@ -0,0 +1,23 @@
+
+// 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 BITCOIN_POW_H
+#define BITCOIN_POW_H
+
+#include <stdint.h>
+
+class CBlockIndex;
+class CBlockHeader;
+class uint256;
+
+unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock);
+
+/** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
+bool CheckProofOfWork(uint256 hash, unsigned int nBits);
+/** Calculate the minimum amount of work a received block needs, without knowing its direct parent */
+unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime);
+
+#endif
diff --git a/src/rpcmining.cpp b/src/rpcmining.cpp
index a1410f0e41..f60070eb5b 100644
--- a/src/rpcmining.cpp
+++ b/src/rpcmining.cpp
@@ -9,6 +9,7 @@
 #include "net.h"
 #include "main.h"
 #include "miner.h"
+#include "pow.h"
 #ifdef ENABLE_WALLET
 #include "db.h"
 #include "wallet.h"
diff --git a/src/test/DoS_tests.cpp b/src/test/DoS_tests.cpp
index 3a45844411..d512053051 100644
--- a/src/test/DoS_tests.cpp
+++ b/src/test/DoS_tests.cpp
@@ -11,6 +11,7 @@
 #include "keystore.h"
 #include "main.h"
 #include "net.h"
+#include "pow.h"
 #include "script.h"
 #include "serialize.h"
 
diff --git a/src/txdb.cpp b/src/txdb.cpp
index 4eab8525a5..92137f71ff 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -6,6 +6,7 @@
 #include "txdb.h"
 
 #include "core.h"
+#include "pow.h"
 #include "uint256.h"
 
 #include <stdint.h>
@@ -212,8 +213,8 @@ bool CBlockTreeDB::LoadBlockIndexGuts()
                 pindexNew->nStatus        = diskindex.nStatus;
                 pindexNew->nTx            = diskindex.nTx;
 
-                if (!pindexNew->CheckIndex())
-                    return error("LoadBlockIndex() : CheckIndex failed: %s", pindexNew->ToString());
+                if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits))
+                    return error("LoadBlockIndex() : CheckProofOfWork failed: %s", pindexNew->ToString());
 
                 pcursor->Next();
             } else {