Avoid download more than one thousand blocks in advance.

libethereum/EthereumHost.cpp

@@ -48,6 +48,7 @@ EthereumHost::EthereumHost(BlockChain const& _ch, TransactionQueue& _tq, BlockQu
 	m_bq		(_bq),
 	m_networkId	(_networkId)
 {
+	m_bq.onReady([=](){ if (readyForMore()) m_continueSync = true; });
 	m_latestBlockSent = _ch.currentHash();
 	m_hashMan.reset(m_chain.number() + 1);
 }
@@ -105,6 +106,12 @@ void EthereumHost::doWork()
 		}
 	}
 
+	if (m_continueSync)
+	{
+		m_continueSync = false;
+		continueSync();
+	}
+
 	foreachPeer([](EthereumPeer* _p) { _p->tick(); });
 
 //	return netChange;
@@ -589,6 +596,11 @@ void EthereumHost::continueSync()
 	});
 }
 
+bool EthereumHost::readyForMore() const
+{
+	return m_bq.status().verified + m_bq.status().verifying + m_bq.status().unverified < 1024;
+}
+
 void EthereumHost::continueSync(EthereumPeer* _peer)
 {
 	assert(_peer->m_asking == Asking::Nothing);
@@ -642,7 +654,10 @@ void EthereumHost::continueSync(EthereumPeer* _peer)
 		}
 	}
 	else if (m_needSyncBlocks && peerCanHelp(_peer)) // Check if this peer can help with downloading blocks
-		_peer->requestBlocks();
+	{
+		if (readyForMore())
+			_peer->requestBlocks();
+	}
 	else
 		_peer->setIdle();
 }

libethereum/EthereumHost.h

@@ -126,6 +126,7 @@ private:
 	bool peerShouldGrabChain(EthereumPeer* _peer) const;
 	bool peerCanHelp(EthereumPeer* _peer) const;
 	void estimatePeerHashes(EthereumPeer* _peer);
+	bool readyForMore() const;
 
 	BlockChain const& m_chain;
 	TransactionQueue& m_tq;					///< Maintains a list of incoming transactions not yet in a block on the blockchain.
@@ -152,6 +153,7 @@ private:
 	h256s m_hashes;								///< List of hashes with unknown block numbers. Used for PV60 chain downloading and catching up to a particular unknown
 	unsigned m_estimatedHashes = 0;				///< Number of estimated hashes for the last peer over PV60. Used for status reporting only.
 	bool m_syncingV61 = false;					///< True if recent activity was over pv61+. Used for status reporting only.
+	bool m_continueSync = false;				///< True when the block queue has processed a block; we should restart grabbing blocks.
 };
 
 }