lbcd/example_test.go

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// Copyright (c) 2014 Conformal Systems LLC.
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package btcchain_test
import (
"fmt"
"github.com/conformal/btcchain"
"github.com/conformal/btcdb"
_ "github.com/conformal/btcdb/memdb"
"github.com/conformal/btcnet"
"github.com/conformal/btcutil"
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"math/big"
)
// This example demonstrates how to create a new chain instance and use
// ProcessBlock to attempt to attempt add a block to the chain. As the package
// overview documentation describes, this includes all of the Bitcoin consensus
// rules. This example intentionally attempts to insert a duplicate genesis
// block to illustrate how an invalid block is handled.
func ExampleBlockChain_ProcessBlock() {
// Create a new database to store the accepted blocks into. Typically
// this would be opening an existing database and would not use memdb
// which is a memory-only database backend, but we create a new db
// here so this is a complete working example.
db, err := btcdb.CreateDB("memdb")
if err != nil {
fmt.Printf("Failed to create database: %v\n", err)
return
}
defer db.Close()
// Insert the main network genesis block. This is part of the initial
// database setup. Like above, this typically would not be needed when
// opening an existing database.
genesisBlock := btcutil.NewBlock(btcnet.MainNetParams.GenesisBlock)
_, err = db.InsertBlock(genesisBlock)
if err != nil {
fmt.Printf("Failed to insert genesis block: %v\n", err)
return
}
// Create a new BlockChain instance using the underlying database for
// the main bitcoin network and ignore notifications.
chain := btcchain.New(db, &btcnet.MainNetParams, nil)
// Create a new median time source that is required by the upcoming
// call to ProcessBlock. Ordinarily this would also add time values
// obtained from other peers on the network so the local time is
// adjusted to be in agreement with other peers.
timeSource := btcchain.NewMedianTime()
// Process a block. For this example, we are going to intentionally
// cause an error by trying to process the genesis block which already
// exists.
isOrphan, err := chain.ProcessBlock(genesisBlock, timeSource, btcchain.BFNone)
if err != nil {
fmt.Printf("Failed to process block: %v\n", err)
return
}
fmt.Printf("Block accepted. Is it an orphan?: %v", isOrphan)
// Output:
// Failed to process block: already have block 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
}
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// This example demonstrates how to convert the compact "bits" in a block header
// which represent the target difficulty to a big integer and display it using
// the typical hex notation.
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func ExampleCompactToBig() {
// Convert the bits from block 300000 in the main block chain.
bits := uint32(419465580)
targetDifficulty := btcchain.CompactToBig(bits)
// Display it in hex.
fmt.Printf("%064x\n", targetDifficulty.Bytes())
// Output:
// 0000000000000000896c00000000000000000000000000000000000000000000
}
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// This example demonstrates how to convert a target difficulty into the compact
// "bits" in a block header which represent that target difficulty .
func ExampleBigToCompact() {
// Convert the target difficulty from block 300000 in the main block
// chain to compact form.
t := "0000000000000000896c00000000000000000000000000000000000000000000"
targetDifficulty, success := new(big.Int).SetString(t, 16)
if !success {
fmt.Println("invalid target difficulty")
return
}
bits := btcchain.BigToCompact(targetDifficulty)
fmt.Println(bits)
// Output:
// 419465580
}