miner: clean up unconfirmed mined block tracking

1 files changed, 116 insertions, 0 deletions

diff --git a/miner/pending.go b/miner/pending.go
new file mode 100644
index 000000000..e4668d8d9
--- /dev/null
+++ b/miner/pending.go
@@ -0,0 +1,116 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package miner
+
+import (
+	"container/ring"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+// pendingBlock is a small collection of metadata about a locally mined block
+// that is placed into a pending set for canonical chain inclusion tracking.
+type pendingBlock struct {
+	index uint64
+	hash  common.Hash
+}
+
+// pendingBlockSet implements a data structure to maintain locally mined blocks
+// have have not yet reached enough maturity to guarantee chain inclusion. It is
+// used by the miner to provide logs to the user when a previously mined block
+// has a high enough guarantee to not be reorged out of te canonical chain.
+type pendingBlockSet struct {
+	chain  *core.BlockChain // Blockchain to verify canonical status through
+	depth  uint             // Depth after which to discard previous blocks
+	blocks *ring.Ring       // Block infos to allow canonical chain cross checks
+	lock   sync.RWMutex     // Protects the fields from concurrent access
+}
+
+// newPendingBlockSet returns new data structure to track currently pending blocks.
+func newPendingBlockSet(chain *core.BlockChain, depth uint) *pendingBlockSet {
+	return &pendingBlockSet{
+		chain: chain,
+		depth: depth,
+	}
+}
+
+// Insert adds a new block to the set of pending ones.
+func (set *pendingBlockSet) Insert(index uint64, hash common.Hash) {
+	// If a new block was mined locally, shift out any old enough blocks
+	set.Shift(index)
+
+	// Create the new item as its own ring
+	item := ring.New(1)
+	item.Value = &pendingBlock{
+		index: index,
+		hash:  hash,
+	}
+	// Set as the initial ring or append to the end
+	set.lock.Lock()
+	defer set.lock.Unlock()
+
+	if set.blocks == nil {
+		set.blocks = item
+	} else {
+		set.blocks.Move(-1).Link(item)
+	}
+	// Display a log for the user to notify of a new mined block pending
+	glog.V(logger.Info).Infof("🔨  mined potential block #%d [%x…], waiting for %d blocks to confirm", index, hash.Bytes()[:4], set.depth)
+}
+
+// Shift drops all pending blocks from the set which exceed the pending sets depth
+// allowance, checking them against the canonical chain for inclusion or staleness
+// report.
+func (set *pendingBlockSet) Shift(height uint64) {
+	set.lock.Lock()
+	defer set.lock.Unlock()
+
+	// Short circuit if there are no pending blocks to shift
+	if set.blocks == nil {
+		return
+	}
+	// Otherwise shift all blocks below the depth allowance
+	for set.blocks != nil {
+		// Retrieve the next pending block and abort if too fresh
+		next := set.blocks.Value.(*pendingBlock)
+		if next.index+uint64(set.depth) > height {
+			break
+		}
+		// Block seems to exceed depth allowance, check for canonical status
+		header := set.chain.GetHeaderByNumber(next.index)
+		switch {
+		case header == nil:
+			glog.V(logger.Warn).Infof("failed to retrieve header of mined block #%d [%x…]", next.index, next.hash.Bytes()[:4])
+		case header.Hash() == next.hash:
+			glog.V(logger.Info).Infof("🔗  mined block #%d [%x…] reached canonical chain", next.index, next.hash.Bytes()[:4])
+		default:
+			glog.V(logger.Info).Infof("⑂ mined block #%d [%x…] became a side fork", next.index, next.hash.Bytes()[:4])
+		}
+		// Drop the block out of the ring
+		if set.blocks.Value == set.blocks.Next().Value {
+			set.blocks = nil
+		} else {
+			set.blocks = set.blocks.Move(-1)
+			set.blocks.Unlink(1)
+			set.blocks = set.blocks.Move(1)
+		}
+	}
+}