ethmonitor: ensure trail is always distance apart from head, or do no… (#23)

Author: pkieltyka

ethmonitor/chain.go

@@ -80,6 +80,7 @@ func (c *Chain) Head() *Block {
 }
 
 func (c *Chain) Blocks() []*Block {
+	// TODO: this lock is pointless
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	return c.blocks

ethmonitor/ethmonitor.go

@@ -378,8 +378,14 @@ func (m *Monitor) broadcast(events Blocks) {
 		return
 	}
 
+	head := m.chain.Head()
+
 	if m.sentBlockNumber == nil {
-		m.sentBlockNumber = big.NewInt(0).SetUint64(m.chain.Head().NumberU64() - uint64(numBlocksBehindHead))
+		m.sentBlockNumber = big.NewInt(0).Sub(head.Number(), big.NewInt(int64(numBlocksBehindHead+1)))
+	}
+
+	if big.NewInt(0).Sub(head.Number(), m.sentBlockNumber).Cmp(big.NewInt(int64(numBlocksBehindHead))) < 0 {
+		return
 	} else {
 		m.sentBlockNumber = big.NewInt(0).Add(m.sentBlockNumber, big.NewInt(1))
 	}