func ExampleTx_CopyFile() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Create a bucket and a key.
	db.Update(func(tx *bolt.Tx) error {
		tx.CreateBucket([]byte("widgets"))
		tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
		return nil
	})

	// Copy the database to another file.
	toFile := tempfile()
	db.View(func(tx *bolt.Tx) error { return tx.CopyFile(toFile, 0666) })
	defer os.Remove(toFile)

	// Open the cloned database.
	db2, _ := bolt.Open(toFile, 0666, nil)
	defer db2.Close()

	// Ensure that the key exists in the copy.
	db2.View(func(tx *bolt.Tx) error {
		value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
		fmt.Printf("The value for 'foo' in the clone is: %s\n", value)
		return nil
	})

	// Output:
	// The value for 'foo' in the clone is: bar
}

// Ensure that a re-opened database is consistent.
func TestOpen_Check(t *testing.T) {
	path := tempfile()
	defer os.Remove(path)

	db, err := bolt.Open(path, 0666, nil)
	ok(t, err)
	ok(t, db.View(func(tx *bolt.Tx) error { return <-tx.Check() }))
	db.Close()

	db, err = bolt.Open(path, 0666, nil)
	ok(t, err)
	ok(t, db.View(func(tx *bolt.Tx) error { return <-tx.Check() }))
	db.Close()
}

// Ensure that a database that is too small returns an error.
func TestDB_Open_FileTooSmall(t *testing.T) {
	path := tempfile()
	defer os.Remove(path)

	db, err := bolt.Open(path, 0666, nil)
	ok(t, err)
	db.Close()

	// corrupt the database
	ok(t, os.Truncate(path, int64(os.Getpagesize())))

	db, err = bolt.Open(path, 0666, nil)
	equals(t, errors.New("file size too small"), err)
}

func NewBoltStore(path string) (*BoltStore, error) {
	db, err := bolt.Open(path, 0600, nil)
	if err != nil {
		return nil, err
	}

	db.Update(func(tx *bolt.Tx) error {
		tx.CreateBucketIfNotExists(boltBucketUsers)
		tx.CreateBucketIfNotExists(boltBucketUsernameIndex)
		tx.CreateBucketIfNotExists(boltBucketTokenIndex)
		tx.CreateBucketIfNotExists(boltBucketSettings)
		tx.CreateBucketIfNotExists(boltBucketSettingUserIDIndex)
		tx.CreateBucketIfNotExists(boltBucketCasts)
		tx.CreateBucketIfNotExists(boltBucketCastURLIndex)
		tx.CreateBucketIfNotExists(boltBucketEpisodes)
		tx.CreateBucketIfNotExists(boltBucketEpisodeCastIDIndex)
		tx.CreateBucketIfNotExists(boltBucketEpisodeGUIDIndex)
		tx.CreateBucketIfNotExists(boltBucketEpisodeCrawlTSIndex)
		tx.CreateBucketIfNotExists(boltBucketEvents)
		tx.CreateBucketIfNotExists(boltBucketLabels)
		tx.CreateBucketIfNotExists(boltBucketLabelUserIDIndex)
		tx.CreateBucketIfNotExists(boltBucketLabelNameIndex)
		tx.CreateBucketIfNotExists(boltBucketLabelRootIndex)
		return nil
	})

	return &BoltStore{
		db: db,
	}, nil
}

// Keys retrieves a list of keys for a given bucket.
func Keys(path, name string) {
	if _, err := os.Stat(path); os.IsNotExist(err) {
		fatal(err)
		return
	}

	db, err := bolt.Open(path, 0600, nil)
	if err != nil {
		fatal(err)
		return
	}
	defer db.Close()

	err = db.View(func(tx *bolt.Tx) error {
		// Find bucket.
		b := tx.Bucket([]byte(name))
		if b == nil {
			fatalf("bucket not found: %s", name)
			return nil
		}

		// Iterate over each key.
		return b.ForEach(func(key, _ []byte) error {
			println(string(key))
			return nil
		})
	})
	if err != nil {
		fatal(err)
		return
	}
}

func ExampleTx_Rollback() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Create a bucket.
	db.Update(func(tx *bolt.Tx) error {
		_, err := tx.CreateBucket([]byte("widgets"))
		return err
	})

	// Set a value for a key.
	db.Update(func(tx *bolt.Tx) error {
		return tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
	})

	// Update the key but rollback the transaction so it never saves.
	tx, _ := db.Begin(true)
	b := tx.Bucket([]byte("widgets"))
	b.Put([]byte("foo"), []byte("baz"))
	tx.Rollback()

	// Ensure that our original value is still set.
	db.View(func(tx *bolt.Tx) error {
		value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
		fmt.Printf("The value for 'foo' is still: %s\n", value)
		return nil
	})

	// Output:
	// The value for 'foo' is still: bar
}

// NewTestDB returns a new instance of TestDB.
func NewTestDB() *TestDB {
	db, err := bolt.Open(tempfile(), 0666, nil)
	if err != nil {
		panic("cannot open db: " + err.Error())
	}
	return &TestDB{db}
}

func ExampleDB_Begin_ReadOnly() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Create a bucket.
	db.Update(func(tx *bolt.Tx) error {
		_, err := tx.CreateBucket([]byte("widgets"))
		return err
	})

	// Create several keys in a transaction.
	tx, _ := db.Begin(true)
	b := tx.Bucket([]byte("widgets"))
	b.Put([]byte("john"), []byte("blue"))
	b.Put([]byte("abby"), []byte("red"))
	b.Put([]byte("zephyr"), []byte("purple"))
	tx.Commit()

	// Iterate over the values in sorted key order.
	tx, _ = db.Begin(false)
	c := tx.Bucket([]byte("widgets")).Cursor()
	for k, v := c.First(); k != nil; k, v = c.Next() {
		fmt.Printf("%s likes %s\n", k, v)
	}
	tx.Rollback()

	// Output:
	// abby likes red
	// john likes blue
	// zephyr likes purple
}

func ExampleDB_View() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Insert data into a bucket.
	db.Update(func(tx *bolt.Tx) error {
		tx.CreateBucket([]byte("people"))
		b := tx.Bucket([]byte("people"))
		b.Put([]byte("john"), []byte("doe"))
		b.Put([]byte("susy"), []byte("que"))
		return nil
	})

	// Access data from within a read-only transactional block.
	db.View(func(tx *bolt.Tx) error {
		v := tx.Bucket([]byte("people")).Get([]byte("john"))
		fmt.Printf("John's last name is %s.\n", v)
		return nil
	})

	// Output:
	// John's last name is doe.
}

func ExampleDB_Update() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Execute several commands within a write transaction.
	err := db.Update(func(tx *bolt.Tx) error {
		b, err := tx.CreateBucket([]byte("widgets"))
		if err != nil {
			return err
		}
		if err := b.Put([]byte("foo"), []byte("bar")); err != nil {
			return err
		}
		return nil
	})

	// If our transactional block didn't return an error then our data is saved.
	if err == nil {
		db.View(func(tx *bolt.Tx) error {
			value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
			fmt.Printf("The value of 'foo' is: %s\n", value)
			return nil
		})
	}

	// Output:
	// The value of 'foo' is: bar
}

func ExampleBucket_ForEach() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Insert data into a bucket.
	db.Update(func(tx *bolt.Tx) error {
		tx.CreateBucket([]byte("animals"))
		b := tx.Bucket([]byte("animals"))
		b.Put([]byte("dog"), []byte("fun"))
		b.Put([]byte("cat"), []byte("lame"))
		b.Put([]byte("liger"), []byte("awesome"))

		// Iterate over items in sorted key order.
		b.ForEach(func(k, v []byte) error {
			fmt.Printf("A %s is %s.\n", k, v)
			return nil
		})
		return nil
	})

	// Output:
	// A cat is lame.
	// A dog is fun.
	// A liger is awesome.
}

func ExampleBucket_Put() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Start a write transaction.
	db.Update(func(tx *bolt.Tx) error {
		// Create a bucket.
		tx.CreateBucket([]byte("widgets"))

		// Set the value "bar" for the key "foo".
		tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
		return nil
	})

	// Read value back in a different read-only transaction.
	db.View(func(tx *bolt.Tx) error {
		value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
		fmt.Printf("The value of 'foo' is: %s\n", value)
		return nil
	})

	// Output:
	// The value of 'foo' is: bar
}

// Ensure that a database can be opened without error.
func TestOpen(t *testing.T) {
	path := tempfile()
	defer os.Remove(path)
	db, err := bolt.Open(path, 0666, nil)
	assert(t, db != nil, "")
	ok(t, err)
	equals(t, db.Path(), path)
	ok(t, db.Close())
}

// Ensure that the database returns an error if the file handle cannot be open.
func TestDB_Open_FileError(t *testing.T) {
	path := tempfile()
	defer os.Remove(path)

	_, err := bolt.Open(path+"/youre-not-my-real-parent", 0666, nil)
	assert(t, err.(*os.PathError) != nil, "")
	equals(t, path+"/youre-not-my-real-parent", err.(*os.PathError).Path)
	equals(t, "open", err.(*os.PathError).Op)
}

// open creates and opens a Bolt database in the temp directory.
func open(fn func(*bolt.DB, string)) {
	path := tempfile()
	defer os.RemoveAll(path)

	db, err := bolt.Open(path, 0600, nil)
	if err != nil {
		panic("db open error: " + err.Error())
	}
	fn(db, path)
}

// Ensure that opening an already open database file will timeout.
func TestOpen_Timeout(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("timeout not supported on windows")
	}

	path := tempfile()
	defer os.Remove(path)

	// Open a data file.
	db0, err := bolt.Open(path, 0666, nil)
	assert(t, db0 != nil, "")
	ok(t, err)

	// Attempt to open the database again.
	start := time.Now()
	db1, err := bolt.Open(path, 0666, &bolt.Options{Timeout: 100 * time.Millisecond})
	assert(t, db1 == nil, "")
	equals(t, bolt.ErrTimeout, err)
	assert(t, time.Since(start) > 100*time.Millisecond, "")

	db0.Close()
}

// Ensure that opening a database beyond the max step size does not increase its size.
// https://github.com/boltdb/bolt/issues/303
func TestOpen_Size_Large(t *testing.T) {
	if testing.Short() {
		t.Skip("short mode")
	}

	// Open a data file.
	db := NewTestDB()
	path := db.Path()
	defer db.Close()

	// Insert until we get above the minimum 4MB size.
	var index uint64
	for i := 0; i < 10000; i++ {
		ok(t, db.Update(func(tx *bolt.Tx) error {
			b, _ := tx.CreateBucketIfNotExists([]byte("data"))
			for j := 0; j < 1000; j++ {
				ok(t, b.Put(u64tob(index), make([]byte, 50)))
				index++
			}
			return nil
		}))
	}

	// Close database and grab the size.
	db.DB.Close()
	sz := fileSize(path)
	if sz == 0 {
		t.Fatalf("unexpected new file size: %d", sz)
	} else if sz < (1 << 30) {
		t.Fatalf("expected larger initial size: %d", sz)
	}

	// Reopen database, update, and check size again.
	db0, err := bolt.Open(path, 0666, nil)
	ok(t, err)
	ok(t, db0.Update(func(tx *bolt.Tx) error { return tx.Bucket([]byte("data")).Put([]byte{0}, []byte{0}) }))
	ok(t, db0.Close())
	newSz := fileSize(path)
	if newSz == 0 {
		t.Fatalf("unexpected new file size: %d", newSz)
	}

	// Compare the original size with the new size.
	if sz != newSz {
		t.Fatalf("unexpected file growth: %d => %d", sz, newSz)
	}
}

// Pages prints a list of all pages in a database.
func Pages(path string) {
	if _, err := os.Stat(path); os.IsNotExist(err) {
		fatal(err)
		return
	}

	db, err := bolt.Open(path, 0600, nil)
	if err != nil {
		fatal(err)
		return
	}
	defer db.Close()

	println("ID       TYPE       ITEMS  OVRFLW")
	println("======== ========== ====== ======")

	db.Update(func(tx *bolt.Tx) error {
		var id int
		for {
			p, err := tx.Page(id)
			if err != nil {
				fatalf("page error: %d: %s", id, err)
			} else if p == nil {
				break
			}

			// Only display count and overflow if this is a non-free page.
			var count, overflow string
			if p.Type != "free" {
				count = strconv.Itoa(p.Count)
				if p.OverflowCount > 0 {
					overflow = strconv.Itoa(p.OverflowCount)
				}
			}

			// Print table row.
			printf("%-8d %-10s %-6s %-6s\n", p.ID, p.Type, count, overflow)

			// Move to the next non-overflow page.
			id += 1
			if p.Type != "free" {
				id += p.OverflowCount
			}
		}
		return nil
	})
}

// Info prints basic information about a database.
func Info(path string) {
	if _, err := os.Stat(path); os.IsNotExist(err) {
		fatal(err)
		return
	}

	db, err := bolt.Open(path, 0600, nil)
	if err != nil {
		fatal(err)
		return
	}
	defer db.Close()

	// Print basic database info.
	var info = db.Info()
	printf("Page Size: %d\n", info.PageSize)
}

func ExampleBucket_Delete() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Start a write transaction.
	db.Update(func(tx *bolt.Tx) error {
		// Create a bucket.
		tx.CreateBucket([]byte("widgets"))
		b := tx.Bucket([]byte("widgets"))

		// Set the value "bar" for the key "foo".
		b.Put([]byte("foo"), []byte("bar"))

		// Retrieve the key back from the database and verify it.
		value := b.Get([]byte("foo"))
		fmt.Printf("The value of 'foo' was: %s\n", value)
		return nil
	})

	// Delete the key in a different write transaction.
	db.Update(func(tx *bolt.Tx) error {
		return tx.Bucket([]byte("widgets")).Delete([]byte("foo"))
	})

	// Retrieve the key again.
	db.View(func(tx *bolt.Tx) error {
		value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
		if value == nil {
			fmt.Printf("The value of 'foo' is now: nil\n")
		}
		return nil
	})

	// Output:
	// The value of 'foo' was: bar
	// The value of 'foo' is now: nil
}