示例#1
0
文件: db_test.go 项目: brb/bolt
// 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)
}
示例#2
0
文件: db_test.go 项目: brb/bolt
// 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()
}
示例#3
0
文件: bucket_test.go 项目: brb/bolt
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.
}
示例#4
0
文件: bucket_test.go 项目: brb/bolt
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
}
示例#5
0
文件: db_test.go 项目: brb/bolt
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
}
示例#6
0
文件: db_test.go 项目: brb/bolt
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.
}
示例#7
0
文件: db_test.go 项目: brb/bolt
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
}
示例#8
0
文件: db_test.go 项目: brb/bolt
// 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}
}
示例#9
0
文件: main.go 项目: brb/bolt
// Run executes the command.
func (cmd *InfoCommand) Run(args ...string) error {
	// Parse flags.
	fs := flag.NewFlagSet("", flag.ContinueOnError)
	help := fs.Bool("h", false, "")
	if err := fs.Parse(args); err != nil {
		return err
	} else if *help {
		fmt.Fprintln(cmd.Stderr, cmd.Usage())
		return ErrUsage
	}

	// Require database path.
	path := fs.Arg(0)
	if path == "" {
		return ErrPathRequired
	} else if _, err := os.Stat(path); os.IsNotExist(err) {
		return ErrFileNotFound
	}

	// Open the database.
	db, err := bolt.Open(path, 0666, nil)
	if err != nil {
		return err
	}
	defer db.Close()

	// Print basic database info.
	info := db.Info()
	fmt.Fprintf(cmd.Stdout, "Page Size: %d\n", info.PageSize)

	return nil
}
示例#10
0
文件: db_test.go 项目: brb/bolt
// 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)
}
示例#11
0
文件: db_test.go 项目: brb/bolt
// 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())
}
示例#12
0
func ExampleDB_Batch() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

	// Start our web server
	count := counter{db}
	srv := httptest.NewServer(count)
	defer srv.Close()

	// Decrease the batch size to make things more interesting.
	db.MaxBatchSize = 3

	// Get every path multiple times concurrently.
	const clients = 10
	paths := []string{
		"/foo",
		"/bar",
		"/baz",
		"/quux",
		"/thud",
		"/xyzzy",
	}
	errors := make(chan error, clients)
	for i := 0; i < clients; i++ {
		go func(id int) {
			errors <- client(id, srv.URL, paths)
		}(i)
	}
	// Check all responses to make sure there's no error.
	for i := 0; i < clients; i++ {
		if err := <-errors; err != nil {
			fmt.Printf("client error: %v", err)
			return
		}
	}

	// Check the final result
	db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte("hits"))
		c := b.Cursor()
		for k, v := c.First(); k != nil; k, v = c.Next() {
			fmt.Printf("hits to %s: %d\n", k, decode(v))
		}
		return nil
	})

	// Output:
	// hits to /bar: 10
	// hits to /baz: 10
	// hits to /foo: 10
	// hits to /quux: 10
	// hits to /thud: 10
	// hits to /xyzzy: 10
}
示例#13
0
文件: main.go 项目: brb/bolt
// Run executes the command.
func (cmd *CheckCommand) Run(args ...string) error {
	// Parse flags.
	fs := flag.NewFlagSet("", flag.ContinueOnError)
	help := fs.Bool("h", false, "")
	if err := fs.Parse(args); err != nil {
		return err
	} else if *help {
		fmt.Fprintln(cmd.Stderr, cmd.Usage())
		return ErrUsage
	}

	// Require database path.
	path := fs.Arg(0)
	if path == "" {
		return ErrPathRequired
	} else if _, err := os.Stat(path); os.IsNotExist(err) {
		return ErrFileNotFound
	}

	// Open database.
	db, err := bolt.Open(path, 0666, nil)
	if err != nil {
		return err
	}
	defer db.Close()

	// Perform consistency check.
	return db.View(func(tx *bolt.Tx) error {
		var count int
		ch := tx.Check()
	loop:
		for {
			select {
			case err, ok := <-ch:
				if !ok {
					break loop
				}
				fmt.Fprintln(cmd.Stdout, err)
				count++
			}
		}

		// Print summary of errors.
		if count > 0 {
			fmt.Fprintf(cmd.Stdout, "%d errors found\n", count)
			return ErrCorrupt
		}

		// Notify user that database is valid.
		fmt.Fprintln(cmd.Stdout, "OK")
		return nil
	})
}
示例#14
0
文件: main_test.go 项目: brb/bolt
// MustOpen creates a Bolt database in a temporary location.
func MustOpen(mode os.FileMode, options *bolt.Options) *DB {
	// Create temporary path.
	f, _ := ioutil.TempFile("", "bolt-")
	f.Close()
	os.Remove(f.Name())

	db, err := bolt.Open(f.Name(), mode, options)
	if err != nil {
		panic(err.Error())
	}
	return &DB{DB: db, Path: f.Name()}
}
示例#15
0
文件: db_test.go 项目: brb/bolt
// 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()
}
示例#16
0
文件: db_test.go 项目: brb/bolt
// Ensure that opening a database beyond the max step size does not increase its size.
// https://github.com/brb/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)
	}
}
示例#17
0
文件: main.go 项目: brb/bolt
// Run executes the "bench" command.
func (cmd *BenchCommand) Run(args ...string) error {
	// Parse CLI arguments.
	options, err := cmd.ParseFlags(args)
	if err != nil {
		return err
	}

	// Remove path if "-work" is not set. Otherwise keep path.
	if options.Work {
		fmt.Fprintf(cmd.Stdout, "work: %s\n", options.Path)
	} else {
		defer os.Remove(options.Path)
	}

	// Create database.
	db, err := bolt.Open(options.Path, 0666, nil)
	if err != nil {
		return err
	}
	db.NoSync = options.NoSync
	defer db.Close()

	// Write to the database.
	var results BenchResults
	if err := cmd.runWrites(db, options, &results); err != nil {
		return fmt.Errorf("write: ", err)
	}

	// Read from the database.
	if err := cmd.runReads(db, options, &results); err != nil {
		return fmt.Errorf("bench: read: %s", err)
	}

	// Print results.
	fmt.Fprintf(os.Stderr, "# Write\t%v\t(%v/op)\t(%v op/sec)\n", results.WriteDuration, results.WriteOpDuration(), results.WriteOpsPerSecond())
	fmt.Fprintf(os.Stderr, "# Read\t%v\t(%v/op)\t(%v op/sec)\n", results.ReadDuration, results.ReadOpDuration(), results.ReadOpsPerSecond())
	fmt.Fprintln(os.Stderr, "")
	return nil
}
示例#18
0
文件: bucket_test.go 项目: brb/bolt
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
}
示例#19
0
文件: cursor_test.go 项目: brb/bolt
func ExampleCursor_reverse() {
	// Open the database.
	db, _ := bolt.Open(tempfile(), 0666, nil)
	defer os.Remove(db.Path())
	defer db.Close()

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

		// Insert data into a bucket.
		b := tx.Bucket([]byte("animals"))
		b.Put([]byte("dog"), []byte("fun"))
		b.Put([]byte("cat"), []byte("lame"))
		b.Put([]byte("liger"), []byte("awesome"))

		// Create a cursor for iteration.
		c := b.Cursor()

		// Iterate over items in reverse sorted key order. This starts
		// from the last key/value pair and updates the k/v variables to
		// the previous key/value on each iteration.
		//
		// The loop finishes at the beginning of the cursor when a nil key
		// is returned.
		for k, v := c.Last(); k != nil; k, v = c.Prev() {
			fmt.Printf("A %s is %s.\n", k, v)
		}

		return nil
	})

	// Output:
	// A liger is awesome.
	// A dog is fun.
	// A cat is lame.
}
示例#20
0
文件: db_test.go 项目: brb/bolt
// Ensure that opening a database does not increase its size.
// https://github.com/brb/bolt/issues/291
func TestOpen_Size(t *testing.T) {
	// Open a data file.
	db := NewTestDB()
	path := db.Path()
	defer db.Close()

	// Insert until we get above the minimum 4MB size.
	ok(t, db.Update(func(tx *bolt.Tx) error {
		b, _ := tx.CreateBucketIfNotExists([]byte("data"))
		for i := 0; i < 10000; i++ {
			ok(t, b.Put([]byte(fmt.Sprintf("%04d", i)), make([]byte, 1000)))
		}
		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)
	}

	// 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)
	}
}
示例#21
0
文件: db_test.go 项目: brb/bolt
// Ensure that opening a database with a bad path returns an error.
func TestOpen_BadPath(t *testing.T) {
	db, err := bolt.Open("", 0666, nil)
	assert(t, err != nil, "err: %s", err)
	assert(t, db == nil, "")
}
示例#22
0
文件: main.go 项目: brb/bolt
// Run executes the command.
func (cmd *PagesCommand) Run(args ...string) error {
	// Parse flags.
	fs := flag.NewFlagSet("", flag.ContinueOnError)
	help := fs.Bool("h", false, "")
	if err := fs.Parse(args); err != nil {
		return err
	} else if *help {
		fmt.Fprintln(cmd.Stderr, cmd.Usage())
		return ErrUsage
	}

	// Require database path.
	path := fs.Arg(0)
	if path == "" {
		return ErrPathRequired
	} else if _, err := os.Stat(path); os.IsNotExist(err) {
		return ErrFileNotFound
	}

	// Open database.
	db, err := bolt.Open(path, 0666, nil)
	if err != nil {
		return err
	}
	defer func() { _ = db.Close() }()

	// Write header.
	fmt.Fprintln(cmd.Stdout, "ID       TYPE       ITEMS  OVRFLW")
	fmt.Fprintln(cmd.Stdout, "======== ========== ====== ======")

	return db.Update(func(tx *bolt.Tx) error {
		var id int
		for {
			p, err := tx.Page(id)
			if err != nil {
				return &PageError{ID: id, Err: 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.
			fmt.Fprintf(cmd.Stdout, "%-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
	})
}
示例#23
0
文件: main.go 项目: brb/bolt
// Run executes the command.
func (cmd *StatsCommand) Run(args ...string) error {
	// Parse flags.
	fs := flag.NewFlagSet("", flag.ContinueOnError)
	help := fs.Bool("h", false, "")
	if err := fs.Parse(args); err != nil {
		return err
	} else if *help {
		fmt.Fprintln(cmd.Stderr, cmd.Usage())
		return ErrUsage
	}

	// Require database path.
	path, prefix := fs.Arg(0), fs.Arg(1)
	if path == "" {
		return ErrPathRequired
	} else if _, err := os.Stat(path); os.IsNotExist(err) {
		return ErrFileNotFound
	}

	// Open database.
	db, err := bolt.Open(path, 0666, nil)
	if err != nil {
		return err
	}
	defer db.Close()

	return db.View(func(tx *bolt.Tx) error {
		var s bolt.BucketStats
		var count int
		if err := tx.ForEach(func(name []byte, b *bolt.Bucket) error {
			if bytes.HasPrefix(name, []byte(prefix)) {
				s.Add(b.Stats())
				count += 1
			}
			return nil
		}); err != nil {
			return err
		}

		fmt.Fprintf(cmd.Stdout, "Aggregate statistics for %d buckets\n\n", count)

		fmt.Fprintln(cmd.Stdout, "Page count statistics")
		fmt.Fprintf(cmd.Stdout, "\tNumber of logical branch pages: %d\n", s.BranchPageN)
		fmt.Fprintf(cmd.Stdout, "\tNumber of physical branch overflow pages: %d\n", s.BranchOverflowN)
		fmt.Fprintf(cmd.Stdout, "\tNumber of logical leaf pages: %d\n", s.LeafPageN)
		fmt.Fprintf(cmd.Stdout, "\tNumber of physical leaf overflow pages: %d\n", s.LeafOverflowN)

		fmt.Fprintln(cmd.Stdout, "Tree statistics")
		fmt.Fprintf(cmd.Stdout, "\tNumber of keys/value pairs: %d\n", s.KeyN)
		fmt.Fprintf(cmd.Stdout, "\tNumber of levels in B+tree: %d\n", s.Depth)

		fmt.Fprintln(cmd.Stdout, "Page size utilization")
		fmt.Fprintf(cmd.Stdout, "\tBytes allocated for physical branch pages: %d\n", s.BranchAlloc)
		var percentage int
		if s.BranchAlloc != 0 {
			percentage = int(float32(s.BranchInuse) * 100.0 / float32(s.BranchAlloc))
		}
		fmt.Fprintf(cmd.Stdout, "\tBytes actually used for branch data: %d (%d%%)\n", s.BranchInuse, percentage)
		fmt.Fprintf(cmd.Stdout, "\tBytes allocated for physical leaf pages: %d\n", s.LeafAlloc)
		percentage = 0
		if s.LeafAlloc != 0 {
			percentage = int(float32(s.LeafInuse) * 100.0 / float32(s.LeafAlloc))
		}
		fmt.Fprintf(cmd.Stdout, "\tBytes actually used for leaf data: %d (%d%%)\n", s.LeafInuse, percentage)

		fmt.Fprintln(cmd.Stdout, "Bucket statistics")
		fmt.Fprintf(cmd.Stdout, "\tTotal number of buckets: %d\n", s.BucketN)
		percentage = int(float32(s.InlineBucketN) * 100.0 / float32(s.BucketN))
		fmt.Fprintf(cmd.Stdout, "\tTotal number on inlined buckets: %d (%d%%)\n", s.InlineBucketN, percentage)
		percentage = 0
		if s.LeafInuse != 0 {
			percentage = int(float32(s.InlineBucketInuse) * 100.0 / float32(s.LeafInuse))
		}
		fmt.Fprintf(cmd.Stdout, "\tBytes used for inlined buckets: %d (%d%%)\n", s.InlineBucketInuse, percentage)

		return nil
	})
}
示例#24
0
文件: db_test.go 项目: brb/bolt
// Ensure that a database can be opened in read-only mode by multiple processes
// and that a database can not be opened in read-write mode and in read-only
// mode at the same time.
func TestOpen_ReadOnly(t *testing.T) {
	bucket, key, value := []byte(`bucket`), []byte(`key`), []byte(`value`)

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

	// Open in read-write mode.
	db, err := bolt.Open(path, 0666, nil)
	ok(t, db.Update(func(tx *bolt.Tx) error {
		b, err := tx.CreateBucket(bucket)
		if err != nil {
			return err
		}
		return b.Put(key, value)
	}))
	assert(t, db != nil, "")
	assert(t, !db.IsReadOnly(), "")
	ok(t, err)
	ok(t, db.Close())

	// Open in read-only mode.
	db0, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
	ok(t, err)
	defer db0.Close()

	// Opening in read-write mode should return an error.
	_, err = bolt.Open(path, 0666, &bolt.Options{Timeout: time.Millisecond * 100})
	assert(t, err != nil, "")

	// And again (in read-only mode).
	db1, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
	ok(t, err)
	defer db1.Close()

	// Verify both read-only databases are accessible.
	for _, db := range []*bolt.DB{db0, db1} {
		// Verify is is in read only mode indeed.
		assert(t, db.IsReadOnly(), "")

		// Read-only databases should not allow updates.
		assert(t,
			bolt.ErrDatabaseReadOnly == db.Update(func(*bolt.Tx) error {
				panic(`should never get here`)
			}),
			"")

		// Read-only databases should not allow beginning writable txns.
		_, err = db.Begin(true)
		assert(t, bolt.ErrDatabaseReadOnly == err, "")

		// Verify the data.
		ok(t, db.View(func(tx *bolt.Tx) error {
			b := tx.Bucket(bucket)
			if b == nil {
				return fmt.Errorf("expected bucket `%s`", string(bucket))
			}

			got := string(b.Get(key))
			expected := string(value)
			if got != expected {
				return fmt.Errorf("expected `%s`, got `%s`", expected, got)
			}
			return nil
		}))
	}
}