Golang Db.FetchBlockBySha方法代码示例

func getHeight(database database.Db, str string) (int64, error) {
	argtype, idx, sha, err := parsesha(str)
	if err != nil {
		log.Warnf("unable to decode [%v] %v", str, err)
		return 0, err
	}

	switch argtype {
	case ArgSha:
		// nothing to do
		blk, err := database.FetchBlockBySha(sha)
		if err != nil {
			log.Warnf("unable to locate block sha %v err %v",
				sha, err)
			return 0, err
		}
		idx = blk.Height()
	case ArgHeight:
	}
	return idx, nil
}

func DumpBlock(database database.Db, height int64, fo io.Writer, rflag bool, fflag bool, tflag bool) error {
	sha, err := database.FetchBlockShaByHeight(height)

	if err != nil {
		return err
	}
	blk, err := database.FetchBlockBySha(sha)
	if err != nil {
		log.Warnf("Failed to fetch block %v, err %v", sha, err)
		return err
	}
	rblk, err := blk.Bytes()
	blkid := blk.Height()

	if rflag {
		log.Infof("Block %v depth %v %v", sha, blkid, spew.Sdump(rblk))
	}

	mblk := blk.MsgBlock()
	if fflag {
		log.Infof("Block %v depth %v %v", sha, blkid, spew.Sdump(mblk))
	}
	if tflag {
		log.Infof("Num transactions %v", len(mblk.Transactions))
		for i, tx := range mblk.Transactions {
			txsha := tx.TxSha()
			log.Infof("tx %v: %v", i, &txsha)

		}
	}
	if fo != nil {
		// generate and write header values
		binary.Write(fo, binary.LittleEndian, uint32(wire.SimNet))
		binary.Write(fo, binary.LittleEndian, uint32(len(rblk)))

		// write block
		fo.Write(rblk)
	}
	return nil
}

// findCandidates searches the chain backwards for checkpoint candidates and
// returns a slice of found candidates, if any.  It also stops searching for
// candidates at the last checkpoint that is already hard coded into chain
// since there is no point in finding candidates before already existing
// checkpoints.
func findCandidates(db database.Db, latestHash *chainhash.Hash) ([]*chaincfg.Checkpoint, error) {
	// Start with the latest block of the main chain.
	block, err := db.FetchBlockBySha(latestHash)
	if err != nil {
		return nil, err
	}

	// Setup chain and get the latest checkpoint.  Ignore notifications
	// since they aren't needed for this util.
	chain := blockchain.New(db, nil, activeNetParams, nil, nil)
	latestCheckpoint := chain.LatestCheckpoint()
	if latestCheckpoint == nil {
		// Set the latest checkpoint to the genesis block if there isn't
		// already one.
		latestCheckpoint = &chaincfg.Checkpoint{
			Hash:   activeNetParams.GenesisHash,
			Height: 0,
		}
	}

	// The latest known block must be at least the last known checkpoint
	// plus required checkpoint confirmations.
	checkpointConfirmations := int64(blockchain.CheckpointConfirmations)
	requiredHeight := latestCheckpoint.Height + checkpointConfirmations
	if block.Height() < requiredHeight {
		return nil, fmt.Errorf("the block database is only at height "+
			"%d which is less than the latest checkpoint height "+
			"of %d plus required confirmations of %d",
			block.Height(), latestCheckpoint.Height,
			checkpointConfirmations)
	}

	// For the first checkpoint, the required height is any block after the
	// genesis block, so long as the chain has at least the required number
	// of confirmations (which is enforced above).
	if len(activeNetParams.Checkpoints) == 0 {
		requiredHeight = 1
	}

	// Indeterminate progress setup.
	numBlocksToTest := block.Height() - requiredHeight
	progressInterval := (numBlocksToTest / 100) + 1 // min 1
	fmt.Print("Searching for candidates")
	defer fmt.Println()

	// Loop backwards through the chain to find checkpoint candidates.
	candidates := make([]*chaincfg.Checkpoint, 0, cfg.NumCandidates)
	numTested := int64(0)
	for len(candidates) < cfg.NumCandidates && block.Height() > requiredHeight {
		// Display progress.
		if numTested%progressInterval == 0 {
			fmt.Print(".")
		}

		// Determine if this block is a checkpoint candidate.
		isCandidate, err := chain.IsCheckpointCandidate(block)
		if err != nil {
			return nil, err
		}

		// All checks passed, so this node seems like a reasonable
		// checkpoint candidate.
		if isCandidate {
			checkpoint := chaincfg.Checkpoint{
				Height: block.Height(),
				Hash:   block.Sha(),
			}
			candidates = append(candidates, &checkpoint)
		}

		prevHash := &block.MsgBlock().Header.PrevBlock
		block, err = db.FetchBlockBySha(prevHash)
		if err != nil {
			return nil, err
		}
		numTested++
	}
	return candidates, nil
}