func assertAddrIndexTipIsUpdated(db database.Db, t *testing.T, newestSha *wire.ShaHash, newestBlockIdx int32) {
	// Safe to ignore error, since height will be < 0 in "error" case.
	sha, height, _ := db.FetchAddrIndexTip()
	if newestBlockIdx != height {
		t.Fatalf("Height of address index tip failed to update, "+
			"expected %v, got %v", newestBlockIdx, height)
	}
	if !bytes.Equal(newestSha.Bytes(), sha.Bytes()) {
		t.Fatalf("Sha of address index tip failed to update, "+
			"expected %v, got %v", newestSha, sha)
	}
}

// fetchTxStoreMain fetches transaction data about the provided set of
// transactions from the point of view of the end of the main chain.  It takes
// a flag which specifies whether or not fully spent transaction should be
// included in the results.
func fetchTxStoreMain(db database.Db, txSet map[wire.ShaHash]struct{}, includeSpent bool) TxStore {
	// Just return an empty store now if there are no requested hashes.
	txStore := make(TxStore)
	if len(txSet) == 0 {
		return txStore
	}

	// The transaction store map needs to have an entry for every requested
	// transaction.  By default, all the transactions are marked as missing.
	// Each entry will be filled in with the appropriate data below.
	txList := make([]*wire.ShaHash, 0, len(txSet))
	for hash := range txSet {
		hashCopy := hash
		txStore[hash] = &TxData{Hash: &hashCopy, Err: database.ErrTxShaMissing}
		txList = append(txList, &hashCopy)
	}

	// Ask the database (main chain) for the list of transactions.  This
	// will return the information from the point of view of the end of the
	// main chain.  Choose whether or not to include fully spent
	// transactions depending on the passed flag.
	var txReplyList []*database.TxListReply
	if includeSpent {
		txReplyList = db.FetchTxByShaList(txList)
	} else {
		txReplyList = db.FetchUnSpentTxByShaList(txList)
	}
	for _, txReply := range txReplyList {
		// Lookup the existing results entry to modify.  Skip
		// this reply if there is no corresponding entry in
		// the transaction store map which really should not happen, but
		// be safe.
		txD, ok := txStore[*txReply.Sha]
		if !ok {
			continue
		}

		// Fill in the transaction details.  A copy is used here since
		// there is no guarantee the returned data isn't cached and
		// this code modifies the data.  A bug caused by modifying the
		// cached data would likely be difficult to track down and could
		// cause subtle errors, so avoid the potential altogether.
		txD.Err = txReply.Err
		if txReply.Err == nil {
			txD.Tx = btcutil.NewTx(txReply.Tx)
			txD.BlockHeight = txReply.Height
			txD.Spent = make([]bool, len(txReply.TxSpent))
			copy(txD.Spent, txReply.TxSpent)
		}
	}

	return txStore
}

// testNewestShaEmpty ensures that NewestSha returns the values expected by
// the interface contract.
func testNewestShaEmpty(t *testing.T, db database.Db) {
	sha, height, err := db.NewestSha()
	if err != nil {
		t.Errorf("NewestSha error %v", err)
	}
	if !sha.IsEqual(&zeroHash) {
		t.Errorf("NewestSha wrong hash got: %s, want %s", sha, &zeroHash)

	}
	if height != -1 {
		t.Errorf("NewestSha wrong height got: %d, want %d", height, -1)
	}
}

func testFetchHeightRange(t *testing.T, db database.Db, blocks []*btcutil.Block) {

	var testincrement int32 = 50
	var testcnt int32 = 100

	shanames := make([]*wire.ShaHash, len(blocks))

	nBlocks := int32(len(blocks))

	for i := range blocks {
		shanames[i] = blocks[i].Sha()
	}

	for startheight := int32(0); startheight < nBlocks; startheight += testincrement {
		endheight := startheight + testcnt

		if endheight > nBlocks {
			endheight = database.AllShas
		}

		shalist, err := db.FetchHeightRange(startheight, endheight)
		if err != nil {
			t.Errorf("FetchHeightRange: unexpected failure looking up shas %v", err)
		}

		if endheight == database.AllShas {
			if int32(len(shalist)) != nBlocks-startheight {
				t.Errorf("FetchHeightRange: expected A %v shas, got %v", nBlocks-startheight, len(shalist))
			}
		} else {
			if int32(len(shalist)) != testcnt {
				t.Errorf("FetchHeightRange: expected %v shas, got %v", testcnt, len(shalist))
			}
		}

		for i := range shalist {
			sha0 := *shanames[int32(i)+startheight]
			sha1 := shalist[i]
			if sha0 != sha1 {
				t.Errorf("FetchHeightRange: mismatch sha at %v requested range %v %v: %v %v ", int32(i)+startheight, startheight, endheight, sha0, sha1)
			}
		}
	}

}

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

	switch argtype {
	case argSha:
		// nothing to do
	case argHeight:
		sha, err = db.FetchBlockShaByHeight(idx)
		if err != nil {
			return wire.ShaHash{}, err
		}
	}
	if sha == nil {
		fmt.Printf("wtf sha is nil but err is %v", err)
	}
	return *sha, nil
}

// chainSetup is used to create a new db and chain instance with the genesis
// block already inserted.  In addition to the new chain instnce, it returns
// a teardown function the caller should invoke when done testing to clean up.
func chainSetup(dbName string) (*blockchain.BlockChain, func(), error) {
	if !isSupportedDbType(testDbType) {
		return nil, nil, fmt.Errorf("unsupported db type %v", testDbType)
	}

	// Handle memory database specially since it doesn't need the disk
	// specific handling.
	var db database.Db
	var teardown func()
	if testDbType == "memdb" {
		ndb, err := database.CreateDB(testDbType)
		if err != nil {
			return nil, nil, fmt.Errorf("error creating db: %v", err)
		}
		db = ndb

		// Setup a teardown function for cleaning up.  This function is
		// returned to the caller to be invoked when it is done testing.
		teardown = func() {
			db.Close()
		}
	} else {
		// Create the root directory for test databases.
		if !fileExists(testDbRoot) {
			if err := os.MkdirAll(testDbRoot, 0700); err != nil {
				err := fmt.Errorf("unable to create test db "+
					"root: %v", err)
				return nil, nil, err
			}
		}

		// Create a new database to store the accepted blocks into.
		dbPath := filepath.Join(testDbRoot, dbName)
		_ = os.RemoveAll(dbPath)
		ndb, err := database.CreateDB(testDbType, dbPath)
		if err != nil {
			return nil, nil, fmt.Errorf("error creating db: %v", err)
		}
		db = ndb

		// Setup a teardown function for cleaning up.  This function is
		// returned to the caller to be invoked when it is done testing.
		teardown = func() {
			dbVersionPath := filepath.Join(testDbRoot, dbName+".ver")
			db.Sync()
			db.Close()
			os.RemoveAll(dbPath)
			os.Remove(dbVersionPath)
			os.RemoveAll(testDbRoot)
		}
	}

	// Insert the main network genesis block.  This is part of the initial
	// database setup.
	genesisBlock := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
	_, err := db.InsertBlock(genesisBlock)
	if err != nil {
		teardown()
		err := fmt.Errorf("failed to insert genesis block: %v", err)
		return nil, nil, err
	}

	chain := blockchain.New(db, &chaincfg.MainNetParams, nil, nil)
	return chain, teardown, nil
}

// testAddrIndexOperations ensures that all normal operations concerning
// the optional address index function correctly.
func testAddrIndexOperations(t *testing.T, db database.Db, newestBlock *btcutil.Block, newestSha *wire.ShaHash, newestBlockIdx int32) {
	// Metadata about the current addr index state should be unset.
	sha, height, err := db.FetchAddrIndexTip()
	if err != database.ErrAddrIndexDoesNotExist {
		t.Fatalf("Address index metadata shouldn't be in db, hasn't been built up yet.")
	}

	var zeroHash wire.ShaHash
	if !sha.IsEqual(&zeroHash) {
		t.Fatalf("AddrIndexTip wrong hash got: %s, want %s", sha, &zeroHash)

	}

	if height != -1 {
		t.Fatalf("Addrindex not built up, yet a block index tip has been set to: %d.", height)
	}

	// Test enforcement of constraints for "limit" and "skip"
	var fakeAddr btcutil.Address
	_, _, err = db.FetchTxsForAddr(fakeAddr, -1, 0, false)
	if err == nil {
		t.Fatalf("Negative value for skip passed, should return an error")
	}

	_, _, err = db.FetchTxsForAddr(fakeAddr, 0, -1, false)
	if err == nil {
		t.Fatalf("Negative value for limit passed, should return an error")
	}

	// Simple test to index outputs(s) of the first tx.
	testIndex := make(database.BlockAddrIndex)
	testTx, err := newestBlock.Tx(0)
	if err != nil {
		t.Fatalf("Block has no transactions, unable to test addr "+
			"indexing, err %v", err)
	}

	// Extract the dest addr from the tx.
	_, testAddrs, _, err := txscript.ExtractPkScriptAddrs(testTx.MsgTx().TxOut[0].PkScript, &chaincfg.MainNetParams)
	if err != nil {
		t.Fatalf("Unable to decode tx output, err %v", err)
	}

	// Extract the hash160 from the output script.
	var hash160Bytes [ripemd160.Size]byte
	testHash160 := testAddrs[0].(*btcutil.AddressPubKey).AddressPubKeyHash().ScriptAddress()
	copy(hash160Bytes[:], testHash160[:])

	// Create a fake index.
	blktxLoc, _ := newestBlock.TxLoc()
	testIndex[hash160Bytes] = []*wire.TxLoc{&blktxLoc[0]}

	// Insert our test addr index into the DB.
	err = db.UpdateAddrIndexForBlock(newestSha, newestBlockIdx, testIndex)
	if err != nil {
		t.Fatalf("UpdateAddrIndexForBlock: failed to index"+
			" addrs for block #%d (%s) "+
			"err %v", newestBlockIdx, newestSha, err)
	}

	// Chain Tip of address should've been updated.
	assertAddrIndexTipIsUpdated(db, t, newestSha, newestBlockIdx)

	// Check index retrieval.
	txReplies, _, err := db.FetchTxsForAddr(testAddrs[0], 0, 1000, false)
	if err != nil {
		t.Fatalf("FetchTxsForAddr failed to correctly fetch txs for an "+
			"address, err %v", err)
	}
	// Should have one reply.
	if len(txReplies) != 1 {
		t.Fatalf("Failed to properly index tx by address.")
	}

	// Our test tx and indexed tx should have the same sha.
	indexedTx := txReplies[0]
	if !bytes.Equal(indexedTx.Sha.Bytes(), testTx.Sha().Bytes()) {
		t.Fatalf("Failed to fetch proper indexed tx. Expected sha %v, "+
			"fetched %v", testTx.Sha(), indexedTx.Sha)
	}

	// Shut down DB.
	db.Sync()
	db.Close()

	// Re-Open, tip still should be updated to current height and sha.
	db, err = database.OpenDB("leveldb", "tstdbopmode")
	if err != nil {
		t.Fatalf("Unable to re-open created db, err %v", err)
	}
	assertAddrIndexTipIsUpdated(db, t, newestSha, newestBlockIdx)

	// Delete the entire index.
	err = db.DeleteAddrIndex()
	if err != nil {
		t.Fatalf("Couldn't delete address index, err %v", err)
	}

//.........这里部分代码省略.........

// 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 btcchain
// since there is no point in finding candidates before already existing
// checkpoints.
func findCandidates(db database.Db, latestHash *wire.ShaHash) ([]*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, activeNetParams, nil, nil)
	latestCheckpoint := chain.LatestCheckpoint()
	if latestCheckpoint == nil {
		return nil, fmt.Errorf("unable to retrieve latest checkpoint")
	}

	// The latest known block must be at least the last known checkpoint
	// plus required checkpoint confirmations.
	checkpointConfirmations := int32(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)
	}

	// 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 := int32(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
}