105 lines
2.6 KiB
Markdown
105 lines
2.6 KiB
Markdown
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# Tendermint State
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## State
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The state contains information whose cryptographic digest is included in block headers,
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and thus is necessary for validating new blocks.
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For instance, the Merkle root of the results from executing the previous block, or the Merkle root of the current validators.
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While neither the results of transactions now the validators are ever included in the blockchain itself,
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the Merkle roots are, and hence we need a separate data structure to track them.
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```
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type State struct {
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LastResults []Result
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AppHash []byte
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Validators []Validator
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LastValidators []Validator
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ConsensusParams ConsensusParams
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}
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```
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### Result
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```
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type Result struct {
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Code uint32
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Data []byte
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Tags []KVPair
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}
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type KVPair struct {
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Key []byte
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Value []byte
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}
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```
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`Result` is the result of executing a transaction against the application.
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It returns a result code, an arbitrary byte array (ie. a return value),
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and a list of key-value pairs ordered by key. The key-value pairs, or tags,
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can be used to index transactions according to their "effects", which are
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represented in the tags.
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### Validator
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A validator is an active participant in the consensus with a public key and a voting power.
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Validator's also contain an address which is derived from the PubKey:
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```
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type Validator struct {
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Address []byte
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PubKey PubKey
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VotingPower int64
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}
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```
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The `state.Validators` and `state.LastValidators` must always by sorted by validator address,
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so that there is a canonical order for computing the SimpleMerkleRoot.
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We also define a `TotalVotingPower` function, to return the total voting power:
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```
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func TotalVotingPower(vals []Validators) int64{
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sum := 0
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for v := range vals{
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sum += v.VotingPower
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}
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return sum
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}
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```
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### PubKey
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TODO:
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### ConsensusParams
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TODO:
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## Execution
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We define an `Execute` function that takes a state and a block,
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executes the block against the application, and returns an updated state.
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```
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Execute(s State, app ABCIApp, block Block) State {
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abciResponses := app.ApplyBlock(block)
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return State{
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LastResults: abciResponses.DeliverTxResults,
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AppHash: abciResponses.AppHash,
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Validators: UpdateValidators(state.Validators, abciResponses.ValidatorChanges),
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LastValidators: state.Validators,
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ConsensusParams: UpdateConsensusParams(state.ConsensusParams, abci.Responses.ConsensusParamChanges),
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}
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}
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type ABCIResponses struct {
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DeliverTxResults []Result
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ValidatorChanges []Validator
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ConsensusParamChanges ConsensusParams
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AppHash []byte
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}
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```
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