codec.go

/*
Copyright 2019 Vimeo Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package galaxycache

import "time"

// Codec includes both the BinaryMarshaler and BinaryUnmarshaler
// interfaces
type Codec interface {
	MarshalBinary() ([]byte, time.Time, error)
	UnmarshalBinary(data []byte, expire time.Time) error
}

// Note: to ensure that unmarshaling is a read-only operation, bytes
// are always cloned
func cloneBytes(b []byte) []byte {
	tmp := make([]byte, len(b))
	copy(tmp, b)
	return tmp
}

// ByteCodec is a byte slice type that implements Codec
type ByteCodec struct {
	bytes  []byte
	expire time.Time
}

// MarshalBinary on a ByteCodec returns the bytes
func (c *ByteCodec) MarshalBinary() ([]byte, time.Time, error) {
	return c.bytes, c.expire, nil
}

// UnmarshalBinary on a ByteCodec sets the ByteCodec to
// a copy of the provided data
func (c *ByteCodec) UnmarshalBinary(data []byte, expire time.Time) error {
	c.bytes = cloneBytes(data)
	c.expire = expire
	return nil
}

// CopyingByteCodec is a byte slice type that implements Codec
// and returns a copy of the bytes when marshaled
type CopyingByteCodec struct {
	bytes  []byte
	expire time.Time
}

// MarshalBinary on a CopyingByteCodec returns a copy of the bytes
func (c *CopyingByteCodec) MarshalBinary() ([]byte, time.Time, error) {
	return cloneBytes(c.bytes), c.expire, nil
}

// UnmarshalBinary on a CopyingByteCodec sets the ByteCodec to
// a copy of the provided data
func (c *CopyingByteCodec) UnmarshalBinary(data []byte, expire time.Time) error {
	c.bytes = cloneBytes(data)
	c.expire = expire
	return nil
}

// StringCodec is a string type that implements Codec
type StringCodec struct {
	str    string
	expire time.Time
}

// MarshalBinary on a StringCodec returns the bytes underlying
// the string
func (c *StringCodec) MarshalBinary() ([]byte, time.Time, error) {
	return []byte(c.str), c.expire, nil
}

// UnmarshalBinary on a StringCodec sets the StringCodec to
// a stringified copy of the provided data
func (c *StringCodec) UnmarshalBinary(data []byte, expire time.Time) error {
	c.str = string(data)
	c.expire = expire
	return nil
}