mirror of https://github.com/certusone/vouch.git
101 lines
3.5 KiB
Go
101 lines
3.5 KiB
Go
// Copyright © 2020 Attestant Limited.
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package best
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import (
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"context"
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"time"
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eth2client "github.com/attestantio/go-eth2-client"
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spec "github.com/attestantio/go-eth2-client/spec/phase0"
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"github.com/pkg/errors"
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)
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type attestationDataResponse struct {
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provider string
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attestationData *spec.AttestationData
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score float64
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}
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// AttestationData provides the best attestation data from a number of beacon nodes.
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func (s *Service) AttestationData(ctx context.Context, slot spec.Slot, committeeIndex spec.CommitteeIndex) (*spec.AttestationData, error) {
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started := time.Now()
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log := log.With().Uint64("slot", uint64(slot)).Logger()
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// We create a cancelable context with a timeout. If the context times out we take the best to date.
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ctx, cancel := context.WithTimeout(ctx, s.timeout)
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respCh := make(chan *attestationDataResponse, len(s.attestationDataProviders))
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errCh := make(chan error, len(s.attestationDataProviders))
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// Kick off the requests.
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for name, provider := range s.attestationDataProviders {
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go func(ctx context.Context, name string, provider eth2client.AttestationDataProvider, respCh chan *attestationDataResponse, errCh chan error) {
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attestationData, err := provider.AttestationData(ctx, slot, committeeIndex)
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s.clientMonitor.ClientOperation(name, "attestation data", err == nil, time.Since(started))
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if err != nil {
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errCh <- err
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return
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}
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log.Trace().Dur("elapsed", time.Since(started)).Msg("Obtained attestation data")
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if attestationData == nil {
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return
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}
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score := s.scoreAttestationData(ctx, provider, name, attestationData)
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respCh <- &attestationDataResponse{
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provider: name,
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attestationData: attestationData,
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score: score,
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}
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}(ctx, name, provider, respCh, errCh)
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}
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// Wait for all responses (or context done).
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responded := 0
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errored := 0
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bestScore := float64(0)
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var bestAttestationData *spec.AttestationData
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bestProvider := ""
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for responded+errored != len(s.attestationDataProviders) {
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select {
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case <-ctx.Done():
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// Anyone not responded by now is considered errored.
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errored = len(s.attestationDataProviders) - responded
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log.Debug().Dur("elapsed", time.Since(started)).Int("responded", responded).Int("errored", errored).Msg("Timed out waiting for responses")
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case <-errCh:
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errored++
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case resp := <-respCh:
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responded++
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if bestAttestationData == nil || resp.score > bestScore {
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bestAttestationData = resp.attestationData
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bestScore = resp.score
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bestProvider = resp.provider
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}
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}
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}
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cancel()
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log.Trace().Dur("elapsed", time.Since(started)).Int("responded", responded).Int("errored", errored).Msg("Responses")
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if bestAttestationData == nil {
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return nil, errors.New("no attestations received")
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}
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log.Trace().Stringer("attestation_data", bestAttestationData).Float64("score", bestScore).Msg("Selected best attestation")
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if bestProvider != "" {
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s.clientMonitor.StrategyOperation("best", bestProvider, "attestation data", time.Since(started))
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}
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return bestAttestationData, nil
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}
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