893802fc06
This updates all users of the github.com/decred/dcrd/databasev/2 module to use the recently introduced v3 version. Replace directives are added as needed to ease development while the final version of the database/v3 v3.0.0 isn't tagged. The relevant documentation is also updated to use the new database/v3 module.
104 lines
3.7 KiB
Go
104 lines
3.7 KiB
Go
// Copyright (c) 2014-2016 The btcsuite developers
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// Copyright (c) 2015-2021 The Decred 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_test
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import (
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"context"
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"fmt"
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"os"
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"path/filepath"
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"github.com/decred/dcrd/blockchain/v4"
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"github.com/decred/dcrd/chaincfg/v3"
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"github.com/decred/dcrd/database/v3"
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_ "github.com/decred/dcrd/database/v3/ffldb"
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"github.com/decred/dcrd/dcrutil/v4"
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"github.com/syndtr/goleveldb/leveldb"
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"github.com/syndtr/goleveldb/leveldb/filter"
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"github.com/syndtr/goleveldb/leveldb/opt"
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)
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// This example demonstrates how to create a new chain instance and use
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// ProcessBlock to attempt to add a block to the chain. As the package
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// overview documentation describes, this includes all of the Decred consensus
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// rules. This example intentionally attempts to insert a duplicate genesis
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// block to illustrate how an invalid block is handled.
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func ExampleBlockChain_ProcessBlock() {
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// Create a new database to store the accepted blocks into. Typically
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// this would be opening an existing database and would not be deleting
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// and creating a new database like this, but it is done here so this is
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// a complete working example and does not leave temporary files laying
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// around.
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mainNetParams := chaincfg.MainNetParams()
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dbPath := filepath.Join(os.TempDir(), "exampleprocessblock")
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_ = os.RemoveAll(dbPath)
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db, err := database.Create("ffldb", dbPath, mainNetParams.Net)
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if err != nil {
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fmt.Printf("Failed to create database: %v\n", err)
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return
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}
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defer os.RemoveAll(dbPath)
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defer db.Close()
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// Additionally, create a new database to store the UTXO set.
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utxoDbPath := filepath.Join(os.TempDir(), "exampleprocessblockutxodb")
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_ = os.RemoveAll(utxoDbPath)
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opts := opt.Options{
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Strict: opt.DefaultStrict,
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Compression: opt.NoCompression,
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Filter: filter.NewBloomFilter(10),
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}
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utxoDb, err := leveldb.OpenFile(utxoDbPath, &opts)
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if err != nil {
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fmt.Printf("Failed to create UTXO database: %v\n", err)
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return
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}
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defer os.RemoveAll(utxoDbPath)
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defer utxoDb.Close()
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// Create a new BlockChain instance using the underlying database for
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// the main bitcoin network. This example does not demonstrate some
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// of the other available configuration options such as specifying a
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// notification callback and signature cache. Also, the caller would
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// ordinarily keep a reference to the median time source and add time
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// values obtained from other peers on the network so the local time is
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// adjusted to be in agreement with other peers.
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chain, err := blockchain.New(context.Background(),
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&blockchain.Config{
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DB: db,
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ChainParams: mainNetParams,
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TimeSource: blockchain.NewMedianTime(),
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UtxoCache: blockchain.NewUtxoCache(&blockchain.UtxoCacheConfig{
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Backend: blockchain.NewLevelDbUtxoBackend(utxoDb),
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FlushBlockDB: func() error {
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return nil
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},
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MaxSize: 100 * 1024 * 1024, // 100 MiB
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}),
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})
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if err != nil {
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fmt.Printf("Failed to create chain instance: %v\n", err)
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return
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}
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// Process a block. For this example, intentionally cause an error by
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// trying to process the genesis block which already exists.
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genesisBlock := dcrutil.NewBlock(mainNetParams.GenesisBlock)
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forkLen, err := chain.ProcessBlock(genesisBlock,
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blockchain.BFNone)
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if err != nil {
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fmt.Printf("Failed to create chain instance: %v\n", err)
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return
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}
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isMainChain := forkLen == 0
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fmt.Printf("Block accepted. Is it on the main chain?: %v", isMainChain)
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// This output is dependent on the genesis block, and needs to be
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// updated if the mainnet genesis block is updated.
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// Output:
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// Failed to process block: already have block 267a53b5ee86c24a48ec37aee4f4e7c0c4004892b7259e695e9f5b321f1ab9d2
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}
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