package light_test
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import (
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"context"
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"io/ioutil"
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stdlog "log"
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"os"
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"time"
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dbm "github.com/tendermint/tm-db"
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"github.com/tendermint/tendermint/abci/example/kvstore"
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"github.com/tendermint/tendermint/libs/log"
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"github.com/tendermint/tendermint/light"
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"github.com/tendermint/tendermint/light/provider"
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httpp "github.com/tendermint/tendermint/light/provider/http"
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dbs "github.com/tendermint/tendermint/light/store/db"
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rpctest "github.com/tendermint/tendermint/rpc/test"
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)
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// Manually getting light blocks and verifying them.
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func ExampleClient() {
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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conf := rpctest.CreateConfig("ExampleClient_VerifyLightBlockAtHeight")
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logger := log.TestingLogger()
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// Start a test application
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app := kvstore.NewApplication()
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_, closer, err := rpctest.StartTendermint(ctx, conf, app, rpctest.SuppressStdout)
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if err != nil {
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stdlog.Fatal(err)
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}
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defer func() { _ = closer(ctx) }()
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dbDir, err := ioutil.TempDir("", "light-client-example")
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if err != nil {
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stdlog.Fatal(err)
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}
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defer os.RemoveAll(dbDir)
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chainID := conf.ChainID()
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primary, err := httpp.New(chainID, conf.RPC.ListenAddress)
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if err != nil {
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stdlog.Fatal(err)
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}
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// give Tendermint time to generate some blocks
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time.Sleep(5 * time.Second)
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block, err := primary.LightBlock(ctx, 2)
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if err != nil {
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stdlog.Fatal(err)
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}
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db, err := dbm.NewGoLevelDB("light-client-db", dbDir)
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if err != nil {
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stdlog.Fatal(err)
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}
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c, err := light.NewClient(ctx,
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chainID,
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light.TrustOptions{
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Period: 504 * time.Hour, // 21 days
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Height: 2,
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Hash: block.Hash(),
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},
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primary,
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[]provider.Provider{primary}, // NOTE: primary should not be used here
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dbs.New(db),
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light.Logger(logger),
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)
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if err != nil {
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stdlog.Fatal(err)
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}
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defer func() {
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if err := c.Cleanup(); err != nil {
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stdlog.Fatal(err)
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}
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}()
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// wait for a few more blocks to be produced
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time.Sleep(2 * time.Second)
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// veify the block at height 3
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_, err = c.VerifyLightBlockAtHeight(context.Background(), 3, time.Now())
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if err != nil {
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stdlog.Fatal(err)
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}
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// retrieve light block at height 3
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_, err = c.TrustedLightBlock(3)
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if err != nil {
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stdlog.Fatal(err)
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}
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// update to the latest height
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lb, err := c.Update(ctx, time.Now())
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if err != nil {
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stdlog.Fatal(err)
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}
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logger.Info("verified light block", "light-block", lb)
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}
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