/
beaconheadercache.go
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/
beaconheadercache.go
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// Copyright © 2022 Weald Technology Trading.
// 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 util
import (
"context"
"errors"
"fmt"
"net/http"
eth2client "github.com/attestantio/go-eth2-client"
"github.com/attestantio/go-eth2-client/api"
apiv1 "github.com/attestantio/go-eth2-client/api/v1"
"github.com/attestantio/go-eth2-client/spec/phase0"
)
// BeaconBlockHeaderCache is a cache of beacon block headers.
type BeaconBlockHeaderCache struct {
beaconBlockHeadersProvider eth2client.BeaconBlockHeadersProvider
entries map[phase0.Slot]*beaconBlockHeaderEntry
}
// NewBeaconBlockHeaderCache makes a new beacon block header cache.
func NewBeaconBlockHeaderCache(provider eth2client.BeaconBlockHeadersProvider) *BeaconBlockHeaderCache {
return &BeaconBlockHeaderCache{
beaconBlockHeadersProvider: provider,
entries: make(map[phase0.Slot]*beaconBlockHeaderEntry),
}
}
type beaconBlockHeaderEntry struct {
present bool
value *apiv1.BeaconBlockHeader
}
// Fetch the beacon block header for the given slot.
func (b *BeaconBlockHeaderCache) Fetch(ctx context.Context,
slot phase0.Slot,
) (
*apiv1.BeaconBlockHeader,
error,
) {
entry, exists := b.entries[slot]
if !exists {
response, err := b.beaconBlockHeadersProvider.BeaconBlockHeader(ctx, &api.BeaconBlockHeaderOpts{Block: fmt.Sprintf("%d", slot)})
if err != nil {
var apiErr *api.Error
if errors.As(err, &apiErr) && apiErr.StatusCode == http.StatusNotFound {
entry = &beaconBlockHeaderEntry{
present: false,
}
} else {
return nil, err
}
} else {
entry = &beaconBlockHeaderEntry{
present: true,
value: response.Data,
}
}
b.entries[slot] = entry
}
return entry.value, nil
}