package main
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import (
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"context"
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"fmt"
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"math"
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"time"
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e2e "github.com/tendermint/tendermint/test/e2e/pkg"
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"github.com/tendermint/tendermint/types"
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)
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// Benchmark is a simple function for fetching, calculating and printing
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// the following metrics:
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// 1. Average block production time
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// 2. Block interval standard deviation
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// 3. Max block interval (slowest block)
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// 4. Min block interval (fastest block)
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//
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// Metrics are based of the `benchmarkLength`, the amount of consecutive blocks
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// sampled from in the testnet
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func Benchmark(testnet *e2e.Testnet, benchmarkLength int64) error {
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block, _, err := waitForHeight(testnet, 0)
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if err != nil {
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return err
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}
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logger.Info("Beginning benchmark period...", "height", block.Height)
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// wait for the length of the benchmark period in blocks to pass. We allow 5 seconds for each block
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// which should be sufficient.
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waitingTime := time.Duration(benchmarkLength*5) * time.Second
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endHeight, err := waitForAllNodes(testnet, block.Height+benchmarkLength, waitingTime)
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if err != nil {
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return err
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}
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logger.Info("Ending benchmark period", "height", endHeight)
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// fetch a sample of blocks
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blocks, err := fetchBlockChainSample(testnet, benchmarkLength)
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if err != nil {
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return err
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}
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// slice into time intervals and collate data
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timeIntervals := splitIntoBlockIntervals(blocks)
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testnetStats := extractTestnetStats(timeIntervals)
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testnetStats.startHeight = blocks[0].Header.Height
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testnetStats.endHeight = blocks[len(blocks)-1].Header.Height
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// print and return
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logger.Info(testnetStats.String())
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return nil
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}
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type testnetStats struct {
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startHeight int64
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endHeight int64
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// average time to produce a block
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mean time.Duration
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// standard deviation of block production
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std float64
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// longest time to produce a block
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max time.Duration
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// shortest time to produce a block
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min time.Duration
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}
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func (t *testnetStats) String() string {
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return fmt.Sprintf(`Benchmarked from height %v to %v
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Mean Block Interval: %v
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Standard Deviation: %f
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Max Block Interval: %v
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Min Block Interval: %v
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`,
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t.startHeight,
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t.endHeight,
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t.mean,
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t.std,
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t.max,
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t.min,
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)
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}
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// fetchBlockChainSample waits for `benchmarkLength` amount of blocks to pass, fetching
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// all of the headers for these blocks from an archive node and returning it.
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func fetchBlockChainSample(testnet *e2e.Testnet, benchmarkLength int64) ([]*types.BlockMeta, error) {
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var blocks []*types.BlockMeta
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// Find the first archive node
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archiveNode := testnet.ArchiveNodes()[0]
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c, err := archiveNode.Client()
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if err != nil {
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return nil, err
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}
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// find the latest height
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ctx := context.Background()
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s, err := c.Status(ctx)
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if err != nil {
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return nil, err
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}
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to := s.SyncInfo.LatestBlockHeight
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from := to - benchmarkLength + 1
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if from <= testnet.InitialHeight {
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return nil, fmt.Errorf("tesnet was unable to reach required height for benchmarking (latest height %d)", to)
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}
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// Fetch blocks
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for from < to {
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// fetch the blockchain metas. Currently we can only fetch 20 at a time
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resp, err := c.BlockchainInfo(ctx, from, min(from+19, to))
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if err != nil {
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return nil, err
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}
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blockMetas := resp.BlockMetas
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// we receive blocks in descending order so we have to add them in reverse
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for i := len(blockMetas) - 1; i >= 0; i-- {
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if blockMetas[i].Header.Height != from {
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return nil, fmt.Errorf("node gave us another header. Wanted %d, got %d",
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from,
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blockMetas[i].Header.Height,
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)
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}
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from++
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blocks = append(blocks, blockMetas[i])
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}
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}
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return blocks, nil
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}
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func splitIntoBlockIntervals(blocks []*types.BlockMeta) []time.Duration {
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intervals := make([]time.Duration, len(blocks)-1)
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lastTime := blocks[0].Header.Time
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for i, block := range blocks {
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// skip the first block
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if i == 0 {
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continue
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}
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intervals[i-1] = block.Header.Time.Sub(lastTime)
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lastTime = block.Header.Time
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}
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return intervals
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}
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func extractTestnetStats(intervals []time.Duration) testnetStats {
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var (
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sum, mean time.Duration
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std float64
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max = intervals[0]
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min = intervals[0]
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)
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for _, interval := range intervals {
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sum += interval
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if interval > max {
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max = interval
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}
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if interval < min {
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min = interval
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}
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}
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mean = sum / time.Duration(len(intervals))
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for _, interval := range intervals {
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diff := (interval - mean).Seconds()
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std += math.Pow(diff, 2)
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}
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std = math.Sqrt(std / float64(len(intervals)))
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return testnetStats{
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mean: mean,
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std: std,
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max: max,
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min: min,
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}
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}
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func min(a, b int64) int64 {
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if a > b {
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return b
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}
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return a
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}
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