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// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package mru
import (
"encoding/binary"
"hash"
"github.com/ethereum/go-ethereum/swarm/storage"
)
// LookupParams is used to specify constraints when performing an update lookup
// Limit defines whether or not the lookup should be limited
// If Limit is set to true then Max defines the amount of hops that can be performed
type LookupParams struct {
UpdateLookup
Limit uint32
}
// RootAddr returns the metadata chunk address
func (r *LookupParams) RootAddr() storage.Address {
return r.rootAddr
}
func NewLookupParams(rootAddr storage.Address, period, version uint32, limit uint32) *LookupParams {
return &LookupParams{
UpdateLookup: UpdateLookup{
period: period,
version: version,
rootAddr: rootAddr,
},
Limit: limit,
}
}
// LookupLatest generates lookup parameters that look for the latest version of a resource
func LookupLatest(rootAddr storage.Address) *LookupParams {
return NewLookupParams(rootAddr, 0, 0, 0)
}
// LookupLatestVersionInPeriod generates lookup parameters that look for the latest version of a resource in a given period
func LookupLatestVersionInPeriod(rootAddr storage.Address, period uint32) *LookupParams {
return NewLookupParams(rootAddr, period, 0, 0)
}
// LookupVersion generates lookup parameters that look for a specific version of a resource
func LookupVersion(rootAddr storage.Address, period, version uint32) *LookupParams {
return NewLookupParams(rootAddr, period, version, 0)
}
// UpdateLookup represents the components of a resource update search key
type UpdateLookup struct {
period uint32
version uint32
rootAddr storage.Address
}
// 4 bytes period
// 4 bytes version
// storage.Keylength for rootAddr
const updateLookupLength = 4 + 4 + storage.AddressLength
// UpdateAddr calculates the resource update chunk address corresponding to this lookup key
func (u *UpdateLookup) UpdateAddr() (updateAddr storage.Address) {
serializedData := make([]byte, updateLookupLength)
u.binaryPut(serializedData)
hasher := hashPool.Get().(hash.Hash)
defer hashPool.Put(hasher)
hasher.Reset()
hasher.Write(serializedData)
return hasher.Sum(nil)
}
// binaryPut serializes this UpdateLookup instance into the provided slice
func (u *UpdateLookup) binaryPut(serializedData []byte) error {
if len(serializedData) != updateLookupLength {
return NewErrorf(ErrInvalidValue, "Incorrect slice size to serialize UpdateLookup. Expected %d, got %d", updateLookupLength, len(serializedData))
}
if len(u.rootAddr) != storage.AddressLength {
return NewError(ErrInvalidValue, "UpdateLookup.binaryPut called without rootAddr set")
}
binary.LittleEndian.PutUint32(serializedData[:4], u.period)
binary.LittleEndian.PutUint32(serializedData[4:8], u.version)
copy(serializedData[8:], u.rootAddr[:])
return nil
}
// binaryLength returns the expected size of this structure when serialized
func (u *UpdateLookup) binaryLength() int {
return updateLookupLength
}
// binaryGet restores the current instance from the information contained in the passed slice
func (u *UpdateLookup) binaryGet(serializedData []byte) error {
if len(serializedData) != updateLookupLength {
return NewErrorf(ErrInvalidValue, "Incorrect slice size to read UpdateLookup. Expected %d, got %d", updateLookupLength, len(serializedData))
}
u.period = binary.LittleEndian.Uint32(serializedData[:4])
u.version = binary.LittleEndian.Uint32(serializedData[4:8])
u.rootAddr = storage.Address(make([]byte, storage.AddressLength))
copy(u.rootAddr[:], serializedData[8:])
return nil
}
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