Added excess orphan block pruning

src/init.cpp

@@ -611,8 +611,9 @@ std::string HelpMessage()
       "  -dnsseed         \t  "   + _("Find peers using DNS lookup (default: 1)") + "\n" +
       "  -banscore=<n>    \t  "   + _("Threshold for disconnecting misbehaving peers (default: 100)") + "\n" +
       "  -bantime=<n>     \t  "   + _("Number of seconds to keep misbehaving peers from reconnecting (default: 86400)") + "\n" +
-      "  -maxreceivebuffer=<n>\t  " + _("Maximum per-connection receive buffer, <n>*1000 bytes (default: 10000)") + "\n" +
-      "  -maxsendbuffer=<n>\t  "   + _("Maximum per-connection send buffer, <n>*1000 bytes (default: 10000)") + "\n" +
+      "  -maxreceivebuffer=<n>\t " + _("Maximum per-connection receive buffer, <n>*1000 bytes (default: 10000)") + "\n" +
+      "  -maxsendbuffer=<n>\t    "   + _("Maximum per-connection send buffer, <n>*1000 bytes (default: 10000)") + "\n" +
+      "  -maxorphanblocks=<n>\t  "  + _("Maximum number of orphan blocks to store in the memory (default: 750)") + "\n" +
 #ifdef USE_UPNP
 #if USE_UPNP
       "  -upnp            \t  "   + _("Use Universal Plug and Play to map the listening port (default: 1)") + "\n" +

src/main.cpp

@@ -15,6 +15,7 @@
 #include <boost/filesystem.hpp>
 #include <boost/filesystem/fstream.hpp>
 #include <math.h>       /* pow */
+#include <cstdlib>      /* std::rand() */
 
 #include "dcrypt.h"
 
@@ -72,7 +73,20 @@ const uint64 POB_POS_TARGET_SWITCH_TIME = 1407110400; //Mon, 04 Aug 2014 00:00:0
 CMedianFilter<int> cPeerBlockCounts(5, 0); // Amount of blocks that other nodes claim to have
 
 map<uint256, CBlock*> mapOrphanBlocks;
-multimap<uint256, CBlock*> mapOrphanBlocksByPrev;
+
+struct CBlockOrphan
+{
+  CBlockOrphan(uint256 hash, CBlock *blockptr)
+  {
+    hashBlock = hash;
+    pblock = blockptr;
+  }
+
+  uint256 hashBlock;
+  CBlock *pblock;
+};
+multimap<uint256, CBlockOrphan> mapOrphanBlocksByPrev;
+
 set<pair<COutPoint, unsigned int> > setStakeSeenOrphan;
 map<uint256, uint256> mapProofOfStake;
 set<pair<COutPoint, unsigned int> > setStakeSeen;
@@ -945,6 +959,36 @@ uint256 static GetOrphanRoot(const CBlock *pblock)
   return pblock->GetHash();
 }
 
+// Remove a random orphan block (which does not have any dependent orphans).
+void static PruneOrphanBlocks()
+{
+  if(mapOrphanBlocksByPrev.size() <= (size_t)std::max((int64)0, GetArg("-maxorphanblocks", DEFAULT_MAX_ORPHAN_BLOCKS)))
+    return;
+
+  // Pick a random orphan block.
+  int pos = std::rand() % mapOrphanBlocksByPrev.size();
+  multimap<uint256, CBlockOrphan>::iterator it = mapOrphanBlocksByPrev.begin();
+  while(pos--) 
+    it++;
+
+  // As long as this block has other orphans depending on it, move to one of those successors.
+  do 
+  {
+    multimap<uint256, CBlockOrphan>::iterator it2 = mapOrphanBlocksByPrev.find(it->second.hashBlock);
+
+    if (it2 == mapOrphanBlocksByPrev.end())
+      break;
+    it = it2;
+  }while(1);
+
+  delete it->second.pblock;
+
+  uint256 hash = it->second.hashBlock;
+  mapOrphanBlocksByPrev.erase(it);
+  mapOrphanBlocks.erase(hash);
+  printf("PruneOrphanBlocks() : Removed orphan block %s\n", hash.ToString().c_str());
+}
+
 // slimcoin: find block wanted by given orphan block
 uint256 WantedByOrphan(const CBlock *pblockOrphan)
 {
@@ -2594,6 +2638,9 @@ bool ProcessBlock(CNode *pfrom, CBlock *pblock)
   //If we do not already have its previous block, shunt it off to holding area until we get it
   if(!mapBlockIndex.count(pblock->hashPrevBlock))
   {
+    //makes space for this orphan block if there are more than DEFAULT_MAX_ORPHAN_BLOCKS orphan blocks
+    PruneOrphanBlocks();
+
     printf("ProcessBlock: ORPHAN BLOCK, prev=%s\n", pblock->hashPrevBlock.ToString().substr(0,20).c_str());
     CBlock *pblock2 = new CBlock(*pblock);
 
@@ -2628,7 +2675,7 @@ bool ProcessBlock(CNode *pfrom, CBlock *pblock)
     }
 
     mapOrphanBlocks.insert(make_pair(hash, pblock2));
-    mapOrphanBlocksByPrev.insert(make_pair(pblock2->hashPrevBlock, pblock2));
+    mapOrphanBlocksByPrev.insert(make_pair(pblock2->hashPrevBlock, CBlockOrphan(hash, pblock2)));
 
     // Ask this guy to fill in what we're missing
     if(pfrom)
@@ -2655,11 +2702,11 @@ bool ProcessBlock(CNode *pfrom, CBlock *pblock)
   {
     uint256 hashPrev = vWorkQueue[i];
 
-    for(multimap<uint256, CBlock*>::iterator mi = mapOrphanBlocksByPrev.lower_bound(hashPrev);
+    for(multimap<uint256, CBlockOrphan>::iterator mi = mapOrphanBlocksByPrev.lower_bound(hashPrev);
          mi != mapOrphanBlocksByPrev.upper_bound(hashPrev); ++mi)
     {
-      CBlock *pblockOrphan = (*mi).second;
-      uint256 pblockOrphanHash = pblockOrphan->GetHash();
+      uint256 pblockOrphanHash = (*mi).second.hashBlock;
+      CBlock *pblockOrphan = (*mi).second.pblock;
 
       if(pblockOrphan->AcceptBlock())
         vWorkQueue.push_back(pblockOrphanHash);

src/main.h

@@ -49,6 +49,8 @@ static const int64 MAX_MONEY = 250000000 * COIN;
 static const int64 MAX_MINT_PROOF_OF_WORK = 50 * COIN;
 static const int64 MAX_MINT_PROOF_OF_BURN = 250 * COIN;
 static const int64 MIN_TXOUT_AMOUNT = MIN_TX_FEE;
+// Default for -maxorphanblocks, maximum number of orphan blocks kept in memory
+static const unsigned int DEFAULT_MAX_ORPHAN_BLOCKS = 750;
 inline bool MoneyRange(int64 nValue) { return (nValue >= 0 && nValue <= MAX_MONEY); }
 static const int COINBASE_MATURITY_SLM = 500;
 // Threshold for nLockTime: below this value it is interpreted as block number, otherwise as UNIX timestamp.