Closes issue #4338
Uses a wrapper function around both the signedHeader and validatorSet calls to the primary provider which attempts to retrieve the information 5 times before deeming the provider unavailable and replacing the primary provider with the first alternative before trying recursively again (until all alternatives are depleted)
Employs a mutex lock for any operations involving the providers of the light client to ensure no operations occurs whilst the new primary is chosen.
Commits:
* created swapProvider function
* eliminates old primary provider after replacement. Uses a mutex when changing providers
* renamed to replaceProvider
* created wrapped functions for signed header and val set
* created test for primary provider replacement
* implemented suggested revisions
* created Witnesses() and Primary()
* modified backoffAndJitterTime
* modified backoffAndJitterTime
* changed backoff base and jitter to functional arguments
* implemented suggested changes
* removed backoff function
* changed exp function to match go version
* halved the backoff time
* removed seeding and added comments
* fixed incorrect test
* extract backoff timeout calc into a function
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>
* lite2: advance to latest header
without any exponential steps
rename autoUpdate to autoUpdateRoutine
* lite2: wait in Cleanup until goroutines finished running
* lite2: move AutoClient into Client
Most of the users will want auto update feature, so it makes sense to
move it into the Client itself, rather than having a separate
abstraction (it makes the code cleaner, but introduces an extra thing
the user will need to learn).
Also, add `FirstTrustedHeight` func to Client to get first trusted height.
* fix db store tests
* separate examples for auto and manual clients
* AutoUpdate tries to update to latest state
NOT 1 header at a time
* fix errors
* lite2: make Logger an option
remove SetLogger func
* fix lite cmd
* lite2: make concurrency assumptions explicit
* fixes after my own review
* no need for nextHeightFn
sequence func will download intermediate headers
* correct comment
Refs #1771
ADR: https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-044-lite-client-with-weak-subjectivity.md
## Commits:
* add Verifier and VerifyCommitTrusting
* add two more checks
make trustLevel an option
* float32 for trustLevel
* check newHeader time
* started writing lite Client
* unify Verify methods
* ensure h2.Header.bfttime < h1.Header.bfttime + tp
* move trust checks into Verify function
* add more comments
* more docs
* started writing tests
* unbonding period failures
* tests are green
* export ErrNewHeaderTooFarIntoFuture
* make golangci happy
* test for non-adjusted headers
* more precision
* providers and stores
* VerifyHeader and VerifyHeaderAtHeight funcs
* fix compile errors
* remove lastVerifiedHeight, persist new trusted header
* sequential verification
* remove TrustedStore option
* started writing tests for light client
* cover basic cases for linear verification
* bisection tests PASS
* rename BisectingVerification to SkippingVerification
* refactor the code
* add TrustedHeader method
* consolidate sequential verification tests
* consolidate skipping verification tests
* rename trustedVals to trustedNextVals
* start writing docs
* ValidateTrustLevel func and ErrOldHeaderExpired error
* AutoClient and example tests
* fix errors
* update doc
* remove ErrNewHeaderTooFarIntoFuture
This check is unnecessary given existing a) ErrOldHeaderExpired b)
h2.Time > now checks.
* return an error if we're at more recent height
* add comments
* add LastSignedHeaderHeight method to Store
I think it's fine if Store tracks last height
* copy over proxy from old lite package
* make TrustedHeader return latest if height=0
* modify LastSignedHeaderHeight to return an error if no headers exist
* copy over proxy impl
* refactor proxy and start http lite client
* Tx and BlockchainInfo methods
* Block method
* commit method
* code compiles again
* lite client compiles
* extract updateLiteClientIfNeededTo func
* move final parts
* add placeholder for tests
* force usage of lite http client in proxy
* comment out query tests for now
* explicitly mention tp: trusting period
* verify nextVals in VerifyHeader
* refactor bisection
* move the NextValidatorsHash check into updateTrustedHeaderAndVals
+ update the comment
* add ConsensusParams method to RPC client
* add ConsensusParams to rpc/mock/client
* change trustLevel type to a new cmn.Fraction type
+ update SkippingVerification comment
* stress out trustLevel is only used for non-adjusted headers
* fixes after Fede's review
Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>
* compare newHeader with a header from an alternative provider
* save pivot header
Refs https://github.com/tendermint/tendermint/pull/3989#discussion_r349122824
* check header can still be trusted in TrustedHeader
Refs https://github.com/tendermint/tendermint/pull/3989#discussion_r349101424
* lite: update Validators and Block endpoints
- Block no longer contains BlockMeta
- Validators now accept two additional params: page and perPage
* make linter happy
