77 lines
2.3 KiB
Go
77 lines
2.3 KiB
Go
// Copyright 2018 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package mru
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import (
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"bytes"
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"context"
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"time"
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"github.com/ethereum/go-ethereum/swarm/storage"
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)
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const (
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defaultStoreTimeout = 4000 * time.Millisecond
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hasherCount = 8
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resourceHashAlgorithm = storage.SHA3Hash
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defaultRetrieveTimeout = 100 * time.Millisecond
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)
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// resource caches resource data and the metadata of its root chunk.
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type resource struct {
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resourceUpdate
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ResourceMetadata
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*bytes.Reader
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lastKey storage.Address
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updated time.Time
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}
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func (r *resource) Context() context.Context {
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return context.TODO()
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}
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// TODO Expire content after a defined period (to force resync)
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func (r *resource) isSynced() bool {
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return !r.updated.IsZero()
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}
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// implements storage.LazySectionReader
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func (r *resource) Size(ctx context.Context, _ chan bool) (int64, error) {
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if !r.isSynced() {
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return 0, NewError(ErrNotSynced, "Not synced")
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}
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return int64(len(r.resourceUpdate.data)), nil
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}
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//returns the resource's human-readable name
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func (r *resource) Name() string {
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return r.ResourceMetadata.Name
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}
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// Helper function to calculate the next update period number from the current time, start time and frequency
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func getNextPeriod(start uint64, current uint64, frequency uint64) (uint32, error) {
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if current < start {
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return 0, NewErrorf(ErrInvalidValue, "given current time value %d < start time %d", current, start)
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}
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if frequency == 0 {
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return 0, NewError(ErrInvalidValue, "frequency is 0")
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}
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timeDiff := current - start
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period := timeDiff / frequency
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return uint32(period + 1), nil
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}
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