README
¶
seekstream
seekstream allows seeking on non-seekable io.ReadCloser source by buffering read data using memory or temp file.
var source io.ReadCloser // non-seekable
var buffer seekstream.Buffer
...
var rs io.ReadSeekCloser = seekstream.New(source, buffer) // seekable
MemoryBuffer
Use NewMemoryBuffer(size) if total size is known and can be fit inside memory:
package main
import (
"github.com/cshum/imagor/seekstream"
...
)
func Test(t *testing.T) {
source := io.NopCloser(bytes.NewBuffer([]byte("0123456789")))
rs := seekstream.New(source, seekstream.NewMemoryBuffer(10))
defer rs.Close()
b := make([]byte, 4)
_, _ = rs.Read(b)
assert.Equal(t, "0123", string(b))
b = make([]byte, 3)
_, _ = rs.Seek(-2, io.SeekCurrent)
_, _ = rs.Read(b)
assert.Equal(t, "234", string(b))
b = make([]byte, 4)
_, _ = rs.Seek(-5, io.SeekEnd)
_, _ = rs.Read(b)
assert.Equal(t, "5678", string(b))
}
TempFileBuffer
Use NewTempFileBuffer(dir, pattern) if total size is not known or does not fit inside memory:
package main
import (
"github.com/cshum/imagor/seekstream"
...
)
func Test(t *testing.T) {
source := io.NopCloser(bytes.NewBuffer([]byte("0123456789")))
buffer, err := seekstream.NewTempFileBuffer("", "seekstream-")
assert.NoError(t, err)
rs := seekstream.New(source, buffer)
defer rs.Close()
...
}
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Buffer ¶
type Buffer interface {
io.ReadWriteSeeker
Clear()
}
Buffer is the underlying buffer interface for allowing the non-seekable source to become seekable
type MemoryBuffer ¶
type MemoryBuffer struct {
// contains filtered or unexported fields
}
MemoryBuffer Buffer implementation using memory buffer suitable for known size that can be fit inside memory
func NewMemoryBuffer ¶
func NewMemoryBuffer(size int64) *MemoryBuffer
NewMemoryBuffer new memory buffer providing data size
func (*MemoryBuffer) Read ¶
func (r *MemoryBuffer) Read(b []byte) (n int, err error)
Read implements the io.Reader interface.
type SeekStream ¶
type SeekStream struct {
// contains filtered or unexported fields
}
SeekStream allows seeking on non-seekable io.ReadCloser source by buffering read data using memory or temp file.
func New ¶
func New(source io.ReadCloser, buffer Buffer) *SeekStream
New SeekStream proving io.ReadCloser source and buffer interface
func (*SeekStream) Close ¶
func (s *SeekStream) Close() (err error)
Close implements the io.Closer interface.
func (*SeekStream) Len ¶
func (s *SeekStream) Len() int
Len returns the number of bytes of the unread portion of buffer
func (*SeekStream) Read ¶
func (s *SeekStream) Read(p []byte) (n int, err error)
Read implements the io.Reader interface.
func (*SeekStream) Seek ¶
func (s *SeekStream) Seek(offset int64, whence int) (int64, error)
Seek implements the io.Seeker interface.
func (*SeekStream) Size ¶
func (s *SeekStream) Size() int64
Size returns the length of the underlying buffer
type TempFileBuffer ¶
TempFileBuffer Buffer implementation using temp file suitable for unknown or large size that does not fit inside memory
func NewTempFileBuffer ¶
func NewTempFileBuffer(dir, pattern string) (*TempFileBuffer, error)
NewTempFileBuffer new temp file buffer. Using os.CreateTemp that creates a new temporary file in the directory dir. The filename is generated by taking pattern and adding a random string to the end.
func (*TempFileBuffer) Clear ¶
func (b *TempFileBuffer) Clear()
Clear performs cleanup on stream close
Source Files