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109 lines
3.7 KiB
109 lines
3.7 KiB
package state
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import (
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"errors"
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"fmt"
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"github.com/tendermint/tendermint/version"
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)
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// Rollback overwrites the current Tendermint state (height n) with the most
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// recent previous state (height n - 1).
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// Note that this function does not affect application state.
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func Rollback(bs BlockStore, ss Store) (int64, []byte, error) {
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invalidState, err := ss.Load()
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if err != nil {
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return -1, nil, err
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}
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if invalidState.IsEmpty() {
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return -1, nil, errors.New("no state found")
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}
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height := bs.Height()
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// NOTE: persistence of state and blocks don't happen atomically. Therefore it is possible that
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// when the user stopped the node the state wasn't updated but the blockstore was. In this situation
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// we don't need to rollback any state and can just return early
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if height == invalidState.LastBlockHeight+1 {
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return invalidState.LastBlockHeight, invalidState.AppHash, nil
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}
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// If the state store isn't one below nor equal to the blockstore height than this violates the
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// invariant
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if height != invalidState.LastBlockHeight {
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return -1, nil, fmt.Errorf("statestore height (%d) is not one below or equal to blockstore height (%d)",
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invalidState.LastBlockHeight, height)
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}
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// state store height is equal to blockstore height. We're good to proceed with rolling back state
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rollbackHeight := invalidState.LastBlockHeight - 1
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rollbackBlock := bs.LoadBlockMeta(rollbackHeight)
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if rollbackBlock == nil {
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return -1, nil, fmt.Errorf("block at height %d not found", rollbackHeight)
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}
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// we also need to retrieve the latest block because the app hash and last results hash is only agreed upon in the following block
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latestBlock := bs.LoadBlockMeta(invalidState.LastBlockHeight)
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if latestBlock == nil {
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return -1, nil, fmt.Errorf("block at height %d not found", invalidState.LastBlockHeight)
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}
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previousLastValidatorSet, err := ss.LoadValidators(rollbackHeight)
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if err != nil {
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return -1, nil, err
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}
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previousParams, err := ss.LoadConsensusParams(rollbackHeight + 1)
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if err != nil {
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return -1, nil, err
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}
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valChangeHeight := invalidState.LastHeightValidatorsChanged
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// this can only happen if the validator set changed since the last block
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if valChangeHeight > rollbackHeight {
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valChangeHeight = rollbackHeight + 1
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}
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paramsChangeHeight := invalidState.LastHeightConsensusParamsChanged
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// this can only happen if params changed from the last block
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if paramsChangeHeight > rollbackHeight {
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paramsChangeHeight = rollbackHeight + 1
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}
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// build the new state from the old state and the prior block
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rolledBackState := State{
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Version: Version{
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Consensus: version.Consensus{
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Block: version.BlockProtocol,
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App: previousParams.Version.AppVersion,
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},
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Software: version.TMVersion,
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},
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// immutable fields
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ChainID: invalidState.ChainID,
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InitialHeight: invalidState.InitialHeight,
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LastBlockHeight: rollbackBlock.Header.Height,
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LastBlockID: rollbackBlock.BlockID,
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LastBlockTime: rollbackBlock.Header.Time,
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NextValidators: invalidState.Validators,
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Validators: invalidState.LastValidators,
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LastValidators: previousLastValidatorSet,
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LastHeightValidatorsChanged: valChangeHeight,
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ConsensusParams: previousParams,
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LastHeightConsensusParamsChanged: paramsChangeHeight,
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LastResultsHash: latestBlock.Header.LastResultsHash,
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AppHash: latestBlock.Header.AppHash,
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}
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// persist the new state. This overrides the invalid one. NOTE: this will also
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// persist the validator set and consensus params over the existing structures,
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// but both should be the same
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if err := ss.Save(rolledBackState); err != nil {
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return -1, nil, fmt.Errorf("failed to save rolled back state: %w", err)
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}
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return rolledBackState.LastBlockHeight, rolledBackState.AppHash, nil
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}
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