lbcd/blockchain/accept.go
Olaoluwa Osuntokun 1914200080
blockchain: introduce SequenceLocks for relative lock-time calcs
This commit introduces the concept of “sequence locks” borrowed from
Bitcoin Core for converting an input’s relative time-locks to an
absolute value based on a particular block for input maturity
evaluation.

A sequence lock is computed as the most distant maturity height/time
amongst all the referenced outputs within a particular transaction.

A transaction with sequence locks activated within any of its inputs
can *only* be included within a block if from the point-of-view of that
block either the time-based or height-based maturity for all referenced
inputs has been met.

A transaction with sequence locks can only be accepted to the mempool
iff from the point-of-view of the *next* (yet to be found block) all
referenced inputs within the transaction are mature.
2016-10-26 21:48:44 -07:00

77 lines
2.7 KiB
Go

// Copyright (c) 2013-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package blockchain
import "github.com/btcsuite/btcutil"
// maybeAcceptBlock potentially accepts a block into the block chain and, if
// accepted, returns whether or not it is on the main chain. It performs
// several validation checks which depend on its position within the block chain
// before adding it. The block is expected to have already gone through
// ProcessBlock before calling this function with it.
//
// The flags modify the behavior of this function as follows:
// - BFDryRun: The memory chain index will not be pruned and no accept
// notification will be sent since the block is not being accepted.
//
// The flags are also passed to checkBlockContext and connectBestChain. See
// their documentation for how the flags modify their behavior.
//
// This function MUST be called with the chain state lock held (for writes).
func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) (bool, error) {
dryRun := flags&BFDryRun == BFDryRun
// Get a block node for the block previous to this one. Will be nil
// if this is the genesis block.
prevNode, err := b.getPrevNodeFromBlock(block)
if err != nil {
log.Errorf("getPrevNodeFromBlock: %v", err)
return false, err
}
// The height of this block is one more than the referenced previous
// block.
blockHeight := int32(0)
if prevNode != nil {
blockHeight = prevNode.height + 1
}
block.SetHeight(blockHeight)
// The block must pass all of the validation rules which depend on the
// position of the block within the block chain.
err = b.checkBlockContext(block, prevNode, flags)
if err != nil {
return false, err
}
// Create a new block node for the block and add it to the in-memory
// block chain (could be either a side chain or the main chain).
blockHeader := &block.MsgBlock().Header
newNode := newBlockNode(blockHeader, block.Hash(), blockHeight)
if prevNode != nil {
newNode.parent = prevNode
newNode.height = blockHeight
newNode.workSum.Add(prevNode.workSum, newNode.workSum)
}
// Connect the passed block to the chain while respecting proper chain
// selection according to the chain with the most proof of work. This
// also handles validation of the transaction scripts.
isMainChain, err := b.connectBestChain(newNode, block, flags)
if err != nil {
return false, err
}
// Notify the caller that the new block was accepted into the block
// chain. The caller would typically want to react by relaying the
// inventory to other peers.
if !dryRun {
b.chainLock.Unlock()
b.sendNotification(NTBlockAccepted, block)
b.chainLock.Lock()
}
return isMainChain, nil
}