303 lines
13 KiB
Markdown
303 lines
13 KiB
Markdown
<!--
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order: 1
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-->
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# State
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## LastTotalPower
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LastTotalPower tracks the total amounts of bonded tokens recorded during the previous end block.
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- LastTotalPower: `0x12 -> amino(sdk.Int)`
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## Params
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Params is a module-wide configuration structure that stores system parameters
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and defines overall functioning of the staking module.
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- Params: `Paramsspace("staking") -> amino(params)`
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```go
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type Params struct {
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UnbondingTime time.Duration // time duration of unbonding
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MaxValidators uint16 // maximum number of validators
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MaxEntries uint16 // max entries for either unbonding delegation or redelegation (per pair/trio)
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BondDenom string // bondable coin denomination
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}
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```
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## Validator
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Validators can have one of three statuses
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- `Unbonded`: The validator is not in the active set. They cannot sign blocks and do not earn
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rewards. They can receive delegations.
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- `Bonded`": Once the validator receives sufficient bonded tokens they automtically join the
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active set during [`EndBlock`](./05_end_block.md#validator-set-changes) and their status is updated to `Bonded`.
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They are signing blocks and receiving rewards. They can receive further delegations.
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They can be slashed for misbehavior. Delegators to this validator who unbond their delegation
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must wait the duration of the UnbondingTime, a chain-specific param. during which time
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they are still slashable for offences of the source validator if those offences were committed
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during the period of time that the tokens were bonded.
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- `Unbonding`: When a validator leaves the active set, either by choice or due to slashing or
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tombstoning, an unbonding of all their delegations begins. All delegations must then wait the UnbondingTime
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before moving receiving their tokens to their accounts from the `BondedPool`.
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Validators objects should be primarily stored and accessed by the
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`OperatorAddr`, an SDK validator address for the operator of the validator. Two
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additional indices are maintained per validator object in order to fulfill
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required lookups for slashing and validator-set updates. A third special index
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(`LastValidatorPower`) is also maintained which however remains constant
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throughout each block, unlike the first two indices which mirror the validator
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records within a block.
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- Validators: `0x21 | OperatorAddr -> amino(validator)`
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- ValidatorsByConsAddr: `0x22 | ConsAddr -> OperatorAddr`
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- ValidatorsByPower: `0x23 | BigEndian(ConsensusPower) | OperatorAddr -> OperatorAddr`
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- LastValidatorsPower: `0x11 OperatorAddr -> amino(ConsensusPower)`
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`Validators` is the primary index - it ensures that each operator can have only one
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associated validator, where the public key of that validator can change in the
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future. Delegators can refer to the immutable operator of the validator, without
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concern for the changing public key.
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`ValidatorByConsAddr` is an additional index that enables lookups for slashing.
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When Tendermint reports evidence, it provides the validator address, so this
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map is needed to find the operator. Note that the `ConsAddr` corresponds to the
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address which can be derived from the validator's `ConsPubKey`.
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`ValidatorsByPower` is an additional index that provides a sorted list o
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potential validators to quickly determine the current active set. Here
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ConsensusPower is validator.Tokens/10^6. Note that all validators where
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`Jailed` is true are not stored within this index.
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`LastValidatorsPower` is a special index that provides a historical list of the
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last-block's bonded validators. This index remains constant during a block but
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is updated during the validator set update process which takes place in [`EndBlock`](./05_end_block.md).
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Each validator's state is stored in a `Validator` struct:
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```go
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type Validator struct {
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OperatorAddress sdk.ValAddress // address of the validator's operator; bech encoded in JSON
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ConsPubKey crypto.PubKey // the consensus public key of the validator; bech encoded in JSON
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Jailed bool // has the validator been jailed from bonded status?
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Status sdk.BondStatus // validator status (bonded/unbonding/unbonded)
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Tokens sdk.Int // delegated tokens (incl. self-delegation)
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DelegatorShares sdk.Dec // total shares issued to a validator's delegators
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Description Description // description terms for the validator
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UnbondingHeight int64 // if unbonding, height at which this validator has begun unbonding
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UnbondingCompletionTime time.Time // if unbonding, min time for the validator to complete unbonding
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Commission Commission // commission parameters
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MinSelfDelegation sdk.Int // validator's self declared minimum self delegation
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}
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type Commission struct {
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CommissionRates
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UpdateTime time.Time // the last time the commission rate was changed
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}
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CommissionRates struct {
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Rate sdk.Dec // the commission rate charged to delegators, as a fraction
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MaxRate sdk.Dec // maximum commission rate which validator can ever charge, as a fraction
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MaxChangeRate sdk.Dec // maximum daily increase of the validator commission, as a fraction
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}
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type Description struct {
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Moniker string // name
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Identity string // optional identity signature (ex. UPort or Keybase)
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Website string // optional website link
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SecurityContact string // optional email for security contact
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Details string // optional details
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}
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```
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## Delegation
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Delegations are identified by combining `DelegatorAddr` (the address of the delegator)
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with the `ValidatorAddr` Delegators are indexed in the store as follows:
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- Delegation: `0x31 | DelegatorAddr | ValidatorAddr -> amino(delegation)`
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Stake holders may delegate coins to validators; under this circumstance their
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funds are held in a `Delegation` data structure. It is owned by one
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delegator, and is associated with the shares for one validator. The sender of
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the transaction is the owner of the bond.
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```go
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type Delegation struct {
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DelegatorAddr sdk.AccAddress
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ValidatorAddr sdk.ValAddress
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Shares sdk.Dec // delegation shares received
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}
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```
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### Delegator Shares
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When one Delegates tokens to a Validator they are issued a number of delegator shares based on a
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dynamic exchange rate, calculated as follows from the total number of tokens delegated to the
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validator and the number of shares issued so far:
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`Shares per Token = validator.TotalShares() / validator.Tokens()`
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Only the number of shares received is stored on the DelegationEntry. When a delegator then
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Undelegates, the token amount they receive is calculated from the number of shares they currently
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hold and the inverse exchange rate:
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`Tokens per Share = validator.Tokens() / validatorShares()`
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These `Shares` are simply an accounting mechanism. They are not a fungible asset. The reason for
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this mechanism is to simplify the accounting around slashing. Rather than iteratively slashing the
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tokens of every delegation entry, instead the Validators total bonded tokens can be slashed,
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effectively reducing the value of each issued delegator share.
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## UnbondingDelegation
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Shares in a `Delegation` can be unbonded, but they must for some time exist as
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an `UnbondingDelegation`, where shares can be reduced if Byzantine behavior is
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detected.
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`UnbondingDelegation` are indexed in the store as:
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- UnbondingDelegation: `0x32 | DelegatorAddr | ValidatorAddr ->
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amino(unbondingDelegation)`
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- UnbondingDelegationsFromValidator: `0x33 | ValidatorAddr | DelegatorAddr ->
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nil`
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The first map here is used in queries, to lookup all unbonding delegations for
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a given delegator, while the second map is used in slashing, to lookup all
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unbonding delegations associated with a given validator that need to be
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slashed.
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A UnbondingDelegation object is created every time an unbonding is initiated.
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```go
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type UnbondingDelegation struct {
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DelegatorAddr sdk.AccAddress // delegator
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ValidatorAddr sdk.ValAddress // validator unbonding from operator addr
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Entries []UnbondingDelegationEntry // unbonding delegation entries
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}
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type UnbondingDelegationEntry struct {
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CreationHeight int64 // height which the unbonding took place
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CompletionTime time.Time // unix time for unbonding completion
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InitialBalance sdk.Coin // atoms initially scheduled to receive at completion
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Balance sdk.Coin // atoms to receive at completion
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}
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```
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## Redelegation
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The bonded tokens worth of a `Delegation` may be instantly redelegated from a
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source validator to a different validator (destination validator). However when
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this occurs they must be tracked in a `Redelegation` object, whereby their
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shares can be slashed if their tokens have contributed to a Byzantine fault
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committed by the source validator.
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`Redelegation` are indexed in the store as:
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- Redelegations: `0x34 | DelegatorAddr | ValidatorSrcAddr | ValidatorDstAddr -> amino(redelegation)`
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- RedelegationsBySrc: `0x35 | ValidatorSrcAddr | ValidatorDstAddr | DelegatorAddr -> nil`
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- RedelegationsByDst: `0x36 | ValidatorDstAddr | ValidatorSrcAddr | DelegatorAddr -> nil`
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The first map here is used for queries, to lookup all redelegations for a given
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delegator. The second map is used for slashing based on the `ValidatorSrcAddr`,
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while the third map is for slashing based on the `ValidatorDstAddr`.
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A redelegation object is created every time a redelegation occurs. To prevent
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"redelegation hopping" redelegations may not occur under the situation that:
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- the (re)delegator already has another immature redelegation in progress
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with a destination to a validator (let's call it `Validator X`)
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- and, the (re)delegator is attempting to create a _new_ redelegation
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where the source validator for this new redelegation is `Validator-X`.
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```go
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type Redelegation struct {
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DelegatorAddr sdk.AccAddress // delegator
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ValidatorSrcAddr sdk.ValAddress // validator redelegation source operator addr
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ValidatorDstAddr sdk.ValAddress // validator redelegation destination operator addr
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Entries []RedelegationEntry // redelegation entries
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}
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type RedelegationEntry struct {
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CreationHeight int64 // height which the redelegation took place
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CompletionTime time.Time // unix time for redelegation completion
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InitialBalance sdk.Coin // initial balance when redelegation started
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Balance sdk.Coin // current balance (current value held in destination validator)
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SharesDst sdk.Dec // amount of destination-validator shares created by redelegation
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}
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```
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## Queues
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All queues objects are sorted by timestamp. The time used within any queue is
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first rounded to the nearest nanosecond then sorted. The sortable time format
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used is a slight modification of the RFC3339Nano and uses the the format string
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`"2006-01-02T15:04:05.000000000"`. Notably this format:
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- right pads all zeros
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- drops the time zone info (uses UTC)
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In all cases, the stored timestamp represents the maturation time of the queue
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element.
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### UnbondingDelegationQueue
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For the purpose of tracking progress of unbonding delegations the unbonding
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delegations queue is kept.
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- UnbondingDelegation: `0x41 | format(time) -> []DVPair`
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```go
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type DVPair struct {
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DelegatorAddr sdk.AccAddress
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ValidatorAddr sdk.ValAddress
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}
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```
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### RedelegationQueue
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For the purpose of tracking progress of redelegations the redelegation queue is
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kept.
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- UnbondingDelegation: `0x42 | format(time) -> []DVVTriplet`
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```go
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type DVVTriplet struct {
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DelegatorAddr sdk.AccAddress
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ValidatorSrcAddr sdk.ValAddress
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ValidatorDstAddr sdk.ValAddress
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}
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```
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### ValidatorQueue
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For the purpose of tracking progress of unbonding validators the validator
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queue is kept.
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- ValidatorQueueTime: `0x43 | format(time) -> []sdk.ValAddress`
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The stored object as each key is an array of validator operator addresses from
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which the validator object can be accessed. Typically it is expected that only
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a single validator record will be associated with a given timestamp however it is possible
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that multiple validators exist in the queue at the same location.
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## HistoricalInfo
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HistoricalInfo objects are stored and pruned at each block such that the staking keeper persists
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the `n` most recent historical info defined by staking module parameter: `HistoricalEntries`.
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```go
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type HistoricalInfo struct {
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Header abci.Header
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ValSet []types.Validator
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}
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```
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At each BeginBlock, the staking keeper will persist the current Header and the Validators that committed
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the current block in a `HistoricalInfo` object. The Validators are sorted on their address to ensure that
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they are in a determisnistic order.
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The oldest HistoricalEntries will be pruned to ensure that there only exist the parameter-defined number of
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historical entries.
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