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checksum.go
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checksum.go
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// Copyright (c) 2015 Uber Technologies, Inc.
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package tchannel
import (
"hash"
"hash/crc32"
"sync"
)
var checksumPools [checksumCount]sync.Pool
// A ChecksumType is a checksum algorithm supported by TChannel for checksumming call bodies
type ChecksumType byte
const (
// ChecksumTypeNone indicates no checksum is included in the message
ChecksumTypeNone ChecksumType = 0
// ChecksumTypeCrc32 indicates the message checksum is calculated using crc32
ChecksumTypeCrc32 ChecksumType = 1
// ChecksumTypeFarmhash indicates the message checksum is calculated using Farmhash
ChecksumTypeFarmhash ChecksumType = 2
// ChecksumTypeCrc32C indicates the message checksum is calculated using crc32c
ChecksumTypeCrc32C ChecksumType = 3
checksumCount = 4
)
func init() {
crc32CastagnoliTable := crc32.MakeTable(crc32.Castagnoli)
ChecksumTypeNone.pool().New = func() interface{} {
return nullChecksum{}
}
ChecksumTypeCrc32.pool().New = func() interface{} {
return newHashChecksum(ChecksumTypeCrc32, crc32.NewIEEE())
}
ChecksumTypeCrc32C.pool().New = func() interface{} {
return newHashChecksum(ChecksumTypeCrc32C, crc32.New(crc32CastagnoliTable))
}
// TODO: Implement farm hash.
ChecksumTypeFarmhash.pool().New = func() interface{} {
return nullChecksum{}
}
}
// ChecksumSize returns the size in bytes of the checksum calculation
func (t ChecksumType) ChecksumSize() int {
switch t {
case ChecksumTypeNone:
return 0
case ChecksumTypeCrc32, ChecksumTypeCrc32C:
return crc32.Size
case ChecksumTypeFarmhash:
return 4
default:
return 0
}
}
// pool returns the sync.Pool used to pool checksums for this type.
func (t ChecksumType) pool() *sync.Pool {
return &checksumPools[int(t)]
}
// New creates a new Checksum of the given type
func (t ChecksumType) New() Checksum {
s := t.pool().Get().(Checksum)
s.Reset()
return s
}
// Release puts a Checksum back in the pool.
func (t ChecksumType) Release(checksum Checksum) {
t.pool().Put(checksum)
}
// A Checksum calculates a running checksum against a bytestream
type Checksum interface {
// TypeCode returns the type of this checksum
TypeCode() ChecksumType
// Size returns the size of the calculated checksum
Size() int
// Add adds bytes to the checksum calculation
Add(b []byte) []byte
// Sum returns the current checksum value
Sum() []byte
// Release puts a Checksum back in the pool.
Release()
// Reset resets the checksum state to the default 0 value.
Reset()
}
// No checksum
type nullChecksum struct{}
// TypeCode returns the type of the checksum
func (c nullChecksum) TypeCode() ChecksumType { return ChecksumTypeNone }
// Size returns the size of the checksum data, in the case the null checksum this is zero
func (c nullChecksum) Size() int { return 0 }
// Add adds a byteslice to the checksum calculation
func (c nullChecksum) Add(b []byte) []byte { return nil }
// Sum returns the current checksum calculation
func (c nullChecksum) Sum() []byte { return nil }
// Release puts a Checksum back in the pool.
func (c nullChecksum) Release() {
c.TypeCode().Release(c)
}
// Reset resets the checksum state to the default 0 value.
func (c nullChecksum) Reset() {}
// Hash Checksum
type hashChecksum struct {
checksumType ChecksumType
hash hash.Hash
sumCache []byte
}
func newHashChecksum(t ChecksumType, hash hash.Hash) *hashChecksum {
return &hashChecksum{
checksumType: t,
hash: hash,
sumCache: make([]byte, 0, 4),
}
}
// TypeCode returns the type of the checksum
func (h *hashChecksum) TypeCode() ChecksumType { return h.checksumType }
// Size returns the size of the checksum data
func (h *hashChecksum) Size() int { return h.hash.Size() }
// Add adds a byte slice to the checksum calculation
func (h *hashChecksum) Add(b []byte) []byte { h.hash.Write(b); return h.Sum() }
// Sum returns the current value of the checksum calculation
func (h *hashChecksum) Sum() []byte { return h.hash.Sum(h.sumCache) }
// Release puts a Checksum back in the pool.
func (h *hashChecksum) Release() { h.TypeCode().Release(h) }
// Reset resets the checksum state to the default 0 value.
func (h *hashChecksum) Reset() { h.hash.Reset() }
// noReleaseChecksum overrides .Release() with a NOOP so that the checksum won't
// be released by the fragmentingWriter when it is managed externally, e.g. by the
// relayer
type noReleaseChecksum struct {
Checksum
}
func (n *noReleaseChecksum) Release() {}