github.com/BlockABC/godash@v0.0.0-20191112120524-f4aa3a32c566/blockchain/accept.go (about)

     1  // Copyright (c) 2013-2016 The btcsuite developers
     2  // Copyright (c) 2016 The Dash developers
     3  // Use of this source code is governed by an ISC
     4  // license that can be found in the LICENSE file.
     5  
     6  package blockchain
     7  
     8  import "github.com/BlockABC/godashutil"
     9  
    10  // maybeAcceptBlock potentially accepts a block into the memory block chain.
    11  // It performs several validation checks which depend on its position within
    12  // the block chain before adding it.  The block is expected to have already gone
    13  // through ProcessBlock before calling this function with it.
    14  //
    15  // The flags modify the behavior of this function as follows:
    16  //  - BFDryRun: The memory chain index will not be pruned and no accept
    17  //    notification will be sent since the block is not being accepted.
    18  //
    19  // The flags are also passed to checkBlockContext and connectBestChain.  See
    20  // their documentation for how the flags modify their behavior.
    21  //
    22  // This function MUST be called with the chain state lock held (for writes).
    23  func (b *BlockChain) maybeAcceptBlock(block *godashutil.Block, flags BehaviorFlags) error {
    24  	dryRun := flags&BFDryRun == BFDryRun
    25  
    26  	// Get a block node for the block previous to this one.  Will be nil
    27  	// if this is the genesis block.
    28  	prevNode, err := b.getPrevNodeFromBlock(block)
    29  	if err != nil {
    30  		log.Errorf("getPrevNodeFromBlock: %v", err)
    31  		return err
    32  	}
    33  
    34  	// The height of this block is one more than the referenced previous
    35  	// block.
    36  	blockHeight := int32(0)
    37  	if prevNode != nil {
    38  		blockHeight = prevNode.height + 1
    39  	}
    40  	block.SetHeight(blockHeight)
    41  
    42  	// The block must pass all of the validation rules which depend on the
    43  	// position of the block within the block chain.
    44  	err = b.checkBlockContext(block, prevNode, flags)
    45  	if err != nil {
    46  		return err
    47  	}
    48  
    49  	// Prune block nodes which are no longer needed before creating
    50  	// a new node.
    51  	if !dryRun {
    52  		err = b.pruneBlockNodes()
    53  		if err != nil {
    54  			return err
    55  		}
    56  	}
    57  
    58  	// Create a new block node for the block and add it to the in-memory
    59  	// block chain (could be either a side chain or the main chain).
    60  	blockHeader := &block.MsgBlock().Header
    61  	newNode := newBlockNode(blockHeader, block.Sha(), blockHeight)
    62  	if prevNode != nil {
    63  		newNode.parent = prevNode
    64  		newNode.height = blockHeight
    65  		newNode.workSum.Add(prevNode.workSum, newNode.workSum)
    66  	}
    67  
    68  	// Connect the passed block to the chain while respecting proper chain
    69  	// selection according to the chain with the most proof of work.  This
    70  	// also handles validation of the transaction scripts.
    71  	err = b.connectBestChain(newNode, block, flags)
    72  	if err != nil {
    73  		return err
    74  	}
    75  
    76  	// Notify the caller that the new block was accepted into the block
    77  	// chain.  The caller would typically want to react by relaying the
    78  	// inventory to other peers.
    79  	if !dryRun {
    80  		b.chainLock.Unlock()
    81  		b.sendNotification(NTBlockAccepted, block)
    82  		b.chainLock.Lock()
    83  	}
    84  
    85  	return nil
    86  }