52cddc19cd
The block index now tracks the set of dirty block nodes with status changes that haven't been persisted and flushes the changes to the DB at the appropriate times.
93 lines
3.4 KiB
Go
93 lines
3.4 KiB
Go
// Copyright (c) 2013-2017 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package blockchain
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import (
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"fmt"
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"github.com/btcsuite/btcd/database"
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"github.com/btcsuite/btcutil"
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)
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// maybeAcceptBlock potentially accepts a block into the block chain and, if
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// accepted, returns whether or not it is on the main chain. It performs
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// several validation checks which depend on its position within the block chain
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// before adding it. The block is expected to have already gone through
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// ProcessBlock before calling this function with it.
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//
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// The flags are also passed to checkBlockContext and connectBestChain. See
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// their documentation for how the flags modify their behavior.
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//
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// This function MUST be called with the chain state lock held (for writes).
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func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) (bool, error) {
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// The height of this block is one more than the referenced previous
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// block.
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prevHash := &block.MsgBlock().Header.PrevBlock
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prevNode := b.index.LookupNode(prevHash)
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if prevNode == nil {
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str := fmt.Sprintf("previous block %s is unknown", prevHash)
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return false, ruleError(ErrPreviousBlockUnknown, str)
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} else if b.index.NodeStatus(prevNode).KnownInvalid() {
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str := fmt.Sprintf("previous block %s is known to be invalid", prevHash)
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return false, ruleError(ErrInvalidAncestorBlock, str)
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}
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blockHeight := prevNode.height + 1
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block.SetHeight(blockHeight)
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// The block must pass all of the validation rules which depend on the
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// position of the block within the block chain.
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err := b.checkBlockContext(block, prevNode, flags)
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if err != nil {
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return false, err
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}
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// Insert the block into the database if it's not already there. Even
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// though it is possible the block will ultimately fail to connect, it
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// has already passed all proof-of-work and validity tests which means
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// it would be prohibitively expensive for an attacker to fill up the
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// disk with a bunch of blocks that fail to connect. This is necessary
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// since it allows block download to be decoupled from the much more
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// expensive connection logic. It also has some other nice properties
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// such as making blocks that never become part of the main chain or
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// blocks that fail to connect available for further analysis.
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err = b.db.Update(func(dbTx database.Tx) error {
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return dbStoreBlock(dbTx, block)
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})
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if err != nil {
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return false, err
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}
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// Create a new block node for the block and add it to the node index. Even
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// if the block ultimately gets connected to the main chain, it starts out
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// on a side chain.
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blockHeader := &block.MsgBlock().Header
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newNode := newBlockNode(blockHeader, prevNode)
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newNode.status = statusDataStored
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b.index.AddNode(newNode)
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err = b.index.flushToDB()
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if err != nil {
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return false, err
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}
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// Connect the passed block to the chain while respecting proper chain
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// selection according to the chain with the most proof of work. This
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// also handles validation of the transaction scripts.
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isMainChain, err := b.connectBestChain(newNode, block, flags)
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if err != nil {
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return false, err
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}
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// Notify the caller that the new block was accepted into the block
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// chain. The caller would typically want to react by relaying the
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// inventory to other peers.
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b.chainLock.Unlock()
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b.sendNotification(NTBlockAccepted, block)
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b.chainLock.Lock()
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return isMainChain, nil
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}
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