Golang ShaHash.IsEqual方法代碼示例

// PushGetBlocksMsg sends a getblocks message for the provided block locator
// and stop hash.  It will ignore back-to-back duplicate requests.
func (p *peer) PushGetBlocksMsg(locator btcchain.BlockLocator, stopHash *btcwire.ShaHash) error {
	// Extract the begin hash from the block locator, if one was specified,
	// to use for filtering duplicate getblocks requests.
	// request.
	var beginHash *btcwire.ShaHash
	if len(locator) > 0 {
		beginHash = locator[0]
	}

	// Filter duplicate getblocks requests.
	if p.prevGetBlocksStop != nil && p.prevGetBlocksBegin != nil &&
		beginHash != nil && stopHash.IsEqual(p.prevGetBlocksStop) &&
		beginHash.IsEqual(p.prevGetBlocksBegin) {

		log.Tracef("PEER: Filtering duplicate [getblocks] with begin "+
			"hash %v, stop hash %v", beginHash, stopHash)
		return nil
	}

	// Construct the getblocks request and queue it to be sent.
	msg := btcwire.NewMsgGetBlocks(stopHash)
	for _, hash := range locator {
		err := msg.AddBlockLocatorHash(hash)
		if err != nil {
			return err
		}
	}
	p.QueueMessage(msg, nil)

	// Update the previous getblocks request information for filtering
	// duplicates.
	p.prevGetBlocksBegin = beginHash
	p.prevGetBlocksStop = stopHash
	return nil
}

// BlockLocatorFromHash returns a block locator for the passed block hash.
// See BlockLocator for details on the algotirhm used to create a block locator.
//
// In addition to the general algorithm referenced above, there are a couple of
// special cases which are handled:
//
//  - If the genesis hash is passed, there are no previous hashes to add and
//    therefore the block locator will only consist of the genesis hash
//  - If the passed hash is not currently known, the block locator will only
//    consist of the passed hash
func (b *BlockChain) BlockLocatorFromHash(hash *btcwire.ShaHash) BlockLocator {
	// The locator contains the requested hash at the very least.
	locator := make(BlockLocator, 0, btcwire.MaxBlockLocatorsPerMsg)
	locator = append(locator, hash)

	// Nothing more to do if a locator for the genesis hash was requested.
	if hash.IsEqual(b.chainParams().GenesisHash) {
		return locator
	}

	// Attempt to find the height of the block that corresponds to the
	// passed hash, and if it's on a side chain, also find the height at
	// which it forks from the main chain.
	blockHeight := int64(-1)
	forkHeight := int64(-1)
	node, exists := b.index[*hash]
	if !exists {
		// Try to look up the height for passed block hash.  Assume an
		// error means it doesn't exist and just return the locator for
		// the block itself.
		block, err := b.db.FetchBlockBySha(hash)
		if err != nil {
			return locator
		}
		blockHeight = block.Height()

	} else {
		blockHeight = node.height

		// Find the height at which this node forks from the main chain
		// if the node is on a side chain.
		if !node.inMainChain {
			for n := node; n.parent != nil; n = n.parent {
				if n.inMainChain {
					forkHeight = n.height
					break
				}
			}
		}
	}

	// Generate the block locators according to the algorithm described in
	// in the BlockLocator comment and make sure to leave room for the
	// final genesis hash.
	iterNode := node
	increment := int64(1)
	for len(locator) < btcwire.MaxBlockLocatorsPerMsg-1 {
		// Once there are 10 locators, exponentially increase the
		// distance between each block locator.
		if len(locator) > 10 {
			increment *= 2
		}
		blockHeight -= increment
		if blockHeight < 1 {
			break
		}

		// As long as this is still on the side chain, walk backwards
		// along the side chain nodes to each block height.
		if forkHeight != -1 && blockHeight > forkHeight {
			// Intentionally use parent field instead of the
			// getPrevNodeFromNode function since we don't want to
			// dynamically load nodes when building block locators.
			// Side chain blocks should always be in memory already,
			// and if they aren't for some reason it's ok to skip
			// them.
			for iterNode != nil && blockHeight > iterNode.height {
				iterNode = iterNode.parent
			}
			if iterNode != nil && iterNode.height == blockHeight {
				locator = append(locator, iterNode.hash)
			}
			continue
		}

		// The desired block height is in the main chain, so look it up
		// from the main chain database.
		h, err := b.db.FetchBlockShaByHeight(blockHeight)
		if err != nil {
			// This shouldn't happen and it's ok to ignore block
			// locators, so just continue to the next one.
			log.Warnf("Lookup of known valid height failed %v",
				blockHeight)
			continue
		}
		locator = append(locator, h)
	}

	// Append the appropriate genesis block.
	locator = append(locator, b.chainParams().GenesisHash)
//.........這裏部分代碼省略.........