Staking

Note

XPLA Chain’s staking module inherits from the Cosmos SDK’s staking module. This document is a stub and covers mainly important XPLA Chain-specific notes about how it is used.

The staking module enables XPLA Chain’s proof-of-stake functionality by requiring validators to bond XPLA, the native staking asset.

State

Pool

Pool is used for tracking bonded and not-bonded token supply of the bond denomination.

LastTotalPower

LastTotalPower tracks the total amounts of bonded tokens recorded during the previous end block. Store entries prefixed with “Last” must remain unchanged until EndBlock.

LastTotalPower: 0x12 -> ProtocolBuffer(sdk.Int)

Params

Params is a module-wide configuration structure that stores system parameters and defines overall functioning of the staking module.

Params: Paramsspace("staking") -> legacy_amino(params)

Validator

Validators can have one of three statuses

Unbonded: The validator is not in the active set. They cannot sign blocks and do not earn rewards. They can receive delegations.
Bonded: Once the validator receives sufficient bonded tokens they automtically join the active set during EndBlock and their status is updated to Bonded. They are signing blocks and receiving rewards. They can receive further delegations. They can be slashed for misbehavior. Delegators to this validator who unbond their delegation must wait the duration of the UnbondingTime, a chain-specific param, during which time they are still slashable for offences of the source validator if those offences were committed during the period of time that the tokens were bonded.
Unbonding: When a validator leaves the active set, either by choice or due to slashing, jailing or tombstoning, an unbonding of all their delegations begins. All delegations must then wait the UnbondingTime before their tokens are moved to their accounts from the BondedPool.

Validators objects should be primarily stored and accessed by the OperatorAddr, an SDK validator address for the operator of the validator. Two additional indices are maintained per validator object in order to fulfill required lookups for slashing and validator-set updates. A third special index (LastValidatorPower) is also maintained which however remains constant throughout each block, unlike the first two indices which mirror the validator records within a block.

Validators: 0x21 | OperatorAddrLen (1 byte) | OperatorAddr -> ProtocolBuffer(validator)
ValidatorsByConsAddr: 0x22 | ConsAddrLen (1 byte) | ConsAddr -> OperatorAddr
ValidatorsByPower: 0x23 | BigEndian(ConsensusPower) | OperatorAddrLen (1 byte) | OperatorAddr -> OperatorAddr
LastValidatorsPower: 0x11 | OperatorAddrLen (1 byte) | OperatorAddr -> ProtocolBuffer(ConsensusPower)

Validators is the primary index - it ensures that each operator can have only one associated validator, where the public key of that validator can change in the future. Delegators can refer to the immutable operator of the validator, without concern for the changing public key.

ValidatorByConsAddr is an additional index that enables lookups for slashing. When Tendermint reports evidence, it provides the validator address, so this map is needed to find the operator. Note that the ConsAddr corresponds to the address which can be derived from the validator’s ConsPubKey.

ValidatorsByPower is an additional index that provides a sorted list of potential validators to quickly determine the current active set. Here ConsensusPower is validator.Tokens/10^18 by default. Note that all validators where Jailed is true are not stored within this index.

LastValidatorsPower is a special index that provides a historical list of the last-block’s bonded validators. This index remains constant during a block but is updated during the validator set update process which takes place in EndBlock.

Each validator’s state is stored in a Validator struct:

// Validator defines a validator, together with the total amount of the
// Validator's bond shares and their exchange rate to coins. Slashing results in
// a decrease in the exchange rate, allowing correct calculation of future
// undelegations without iterating over delegators. When coins are delegated to
// this validator, the validator is credited with a delegation whose number of
// bond shares is based on the amount of coins delegated divided by the current
// exchange rate. Voting power can be calculated as total bonded shares
// multiplied by exchange rate.
type Validator struct {
	// operator_address defines the address of the validator's operator; bech encoded in JSON.
	OperatorAddress string `protobuf:"bytes,1,opt,name=operator_address,json=operatorAddress,proto3" json:"operator_address,omitempty" yaml:"operator_address"`
	// consensus_pubkey is the consensus public key of the validator, as a Protobuf Any.
	ConsensusPubkey *types1.Any `protobuf:"bytes,2,opt,name=consensus_pubkey,json=consensusPubkey,proto3" json:"consensus_pubkey,omitempty" yaml:"consensus_pubkey"`
	// jailed defined whether the validator has been jailed from bonded status or not.
	Jailed bool `protobuf:"varint,3,opt,name=jailed,proto3" json:"jailed,omitempty"`
	// status is the validator status (bonded/unbonding/unbonded).
	Status BondStatus `protobuf:"varint,4,opt,name=status,proto3,enum=cosmos.staking.v1beta1.BondStatus" json:"status,omitempty"`
	// tokens define the delegated tokens (incl. self-delegation).
	Tokens github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,5,opt,name=tokens,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"tokens"`
	// delegator_shares defines total shares issued to a validator's delegators.
	DelegatorShares github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,6,opt,name=delegator_shares,json=delegatorShares,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"delegator_shares" yaml:"delegator_shares"`
	// description defines the description terms for the validator.
	Description Description `protobuf:"bytes,7,opt,name=description,proto3" json:"description"`
	// unbonding_height defines, if unbonding, the height at which this validator has begun unbonding.
	UnbondingHeight int64 `protobuf:"varint,8,opt,name=unbonding_height,json=unbondingHeight,proto3" json:"unbonding_height,omitempty" yaml:"unbonding_height"`
	// unbonding_time defines, if unbonding, the min time for the validator to complete unbonding.
	UnbondingTime time.Time `protobuf:"bytes,9,opt,name=unbonding_time,json=unbondingTime,proto3,stdtime" json:"unbonding_time" yaml:"unbonding_time"`
	// commission defines the commission parameters.
	Commission Commission `protobuf:"bytes,10,opt,name=commission,proto3" json:"commission"`
	// min_self_delegation is the validator's self declared minimum self delegation.
	MinSelfDelegation github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,11,opt,name=min_self_delegation,json=minSelfDelegation,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"min_self_delegation" yaml:"min_self_delegation"`
}

// Commission defines commission parameters for a given validator.
type Commission struct {
	// commission_rates defines the initial commission rates to be used for creating a validator.
	CommissionRates `protobuf:"bytes,1,opt,name=commission_rates,json=commissionRates,proto3,embedded=commission_rates" json:"commission_rates"`
	// update_time is the last time the commission rate was changed.
	UpdateTime time.Time `protobuf:"bytes,2,opt,name=update_time,json=updateTime,proto3,stdtime" json:"update_time" yaml:"update_time"`
}

// CommissionRates defines the initial commission rates to be used for creating
// a validator.
type CommissionRates struct {
	// rate is the commission rate charged to delegators, as a fraction.
	Rate github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,1,opt,name=rate,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"rate"`
	// max_rate defines the maximum commission rate which validator can ever charge, as a fraction.
	MaxRate github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,2,opt,name=max_rate,json=maxRate,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"max_rate" yaml:"max_rate"`
	// max_change_rate defines the maximum daily increase of the validator commission, as a fraction.
	MaxChangeRate github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,3,opt,name=max_change_rate,json=maxChangeRate,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"max_change_rate" yaml:"max_change_rate"`
}

// Description defines a validator description.
type Description struct {
	// moniker defines a human-readable name for the validator.
	Moniker string `protobuf:"bytes,1,opt,name=moniker,proto3" json:"moniker,omitempty"`
	// identity defines an optional identity signature (ex. UPort or Keybase).
	Identity string `protobuf:"bytes,2,opt,name=identity,proto3" json:"identity,omitempty"`
	// website defines an optional website link.
	Website string `protobuf:"bytes,3,opt,name=website,proto3" json:"website,omitempty"`
	// security_contact defines an optional email for security contact.
	SecurityContact string `protobuf:"bytes,4,opt,name=security_contact,json=securityContact,proto3" json:"security_contact,omitempty" yaml:"security_contact"`
	// details define other optional details.
	Details string `protobuf:"bytes,5,opt,name=details,proto3" json:"details,omitempty"`
}

Delegation

Delegations are identified by combining DelegatorAddr (the address of the delegator) with the ValidatorAddr Delegators are indexed in the store as follows:

Delegation: 0x31 | DelegatorAddrLen (1 byte) | DelegatorAddr | ValidatorAddrLen (1 byte) | ValidatorAddr -> ProtocolBuffer(delegation)

Stake holders may delegate coins to validators; under this circumstance their funds are held in a Delegation data structure. It is owned by one delegator, and is associated with the shares for one validator. The sender of the transaction is the owner of the bond.

// Delegation represents the bond with tokens held by an account. It is
// owned by one delegator, and is associated with the voting power of one
// validator.
type Delegation struct {
	// delegator_address is the bech32-encoded address of the delegator.
	DelegatorAddress string `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	// validator_address is the bech32-encoded address of the validator.
	ValidatorAddress string `protobuf:"bytes,2,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"validator_address"`
	// shares define the delegation shares received.
	Shares github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,3,opt,name=shares,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"shares"`
}

Delegator Shares

When one Delegates tokens to a Validator they are issued a number of delegator shares based on a dynamic exchange rate, calculated as follows from the total number of tokens delegated to the validator and the number of shares issued so far:

Shares per Token = validator.TotalShares() / validator.Tokens()

Only the number of shares received is stored on the DelegationEntry. When a delegator then Undelegates, the token amount they receive is calculated from the number of shares they currently hold and the inverse exchange rate:

Tokens per Share = validator.Tokens() / validatorShares()

These Shares are simply an accounting mechanism. They are not a fungible asset. The reason for this mechanism is to simplify the accounting around slashing. Rather than iteratively slashing the tokens of every delegation entry, instead the Validators total bonded tokens can be slashed, effectively reducing the value of each issued delegator share.

UnbondingDelegation

Shares in a Delegation can be unbonded, but they must for some time exist as an UnbondingDelegation, where shares can be reduced if Byzantine behavior is detected.

UnbondingDelegation are indexed in the store as:

UnbondingDelegation: 0x32 | DelegatorAddrLen (1 byte) | DelegatorAddr | ValidatorAddrLen (1 byte) | ValidatorAddr -> ProtocolBuffer(unbondingDelegation)
UnbondingDelegationsFromValidator: 0x33 | ValidatorAddrLen (1 byte) | ValidatorAddr | DelegatorAddrLen (1 byte) | DelegatorAddr -> nil

The first map here is used in queries, to lookup all unbonding delegations for a given delegator, while the second map is used in slashing, to lookup all unbonding delegations associated with a given validator that need to be slashed.

A UnbondingDelegation object is created every time an unbonding is initiated.

// UnbondingDelegation stores all of a single delegator's unbonding bonds
// for a single validator in an time-ordered list.
type UnbondingDelegation struct {
	// delegator_address is the bech32-encoded address of the delegator.
	DelegatorAddress string `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	// validator_address is the bech32-encoded address of the validator.
	ValidatorAddress string `protobuf:"bytes,2,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"validator_address"`
	// entries are the unbonding delegation entries.
	Entries []UnbondingDelegationEntry `protobuf:"bytes,3,rep,name=entries,proto3" json:"entries"`
}

// UnbondingDelegationEntry defines an unbonding object with relevant metadata.
type UnbondingDelegationEntry struct {
	// creation_height is the height which the unbonding took place.
	CreationHeight int64 `protobuf:"varint,1,opt,name=creation_height,json=creationHeight,proto3" json:"creation_height,omitempty" yaml:"creation_height"`
	// completion_time is the unix time for unbonding completion.
	CompletionTime time.Time `protobuf:"bytes,2,opt,name=completion_time,json=completionTime,proto3,stdtime" json:"completion_time" yaml:"completion_time"`
	// initial_balance defines the tokens initially scheduled to receive at completion.
	InitialBalance github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,3,opt,name=initial_balance,json=initialBalance,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"initial_balance" yaml:"initial_balance"`
	// balance defines the tokens to receive at completion.
	Balance github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,4,opt,name=balance,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"balance"`
}

Redelegation

The bonded tokens worth of a Delegation may be instantly redelegated from a source validator to a different validator (destination validator). However when this occurs they must be tracked in a Redelegation object, whereby their shares can be slashed if their tokens have contributed to a Byzantine fault committed by the source validator.

Redelegation are indexed in the store as:

Redelegations: 0x34 | DelegatorAddrLen (1 byte) | DelegatorAddr | ValidatorAddrLen (1 byte) | ValidatorSrcAddr | ValidatorDstAddr -> ProtocolBuffer(redelegation)
RedelegationsBySrc: 0x35 | ValidatorSrcAddrLen (1 byte) | ValidatorSrcAddr | ValidatorDstAddrLen (1 byte) | ValidatorDstAddr | DelegatorAddrLen (1 byte) | DelegatorAddr -> nil
RedelegationsByDst: 0x36 | ValidatorDstAddrLen (1 byte) | ValidatorDstAddr | ValidatorSrcAddrLen (1 byte) | ValidatorSrcAddr | DelegatorAddrLen (1 byte) | DelegatorAddr -> nil

The first map here is used for queries, to lookup all redelegations for a given delegator. The second map is used for slashing based on the ValidatorSrcAddr, while the third map is for slashing based on the ValidatorDstAddr.

A redelegation object is created every time a redelegation occurs. To prevent “redelegation hopping” redelegations may not occur under the situation that:

the (re)delegator already has another immature redelegation in progress with a destination to a validator (let’s call it Validator X)
and, the (re)delegator is attempting to create a new redelegation where the source validator for this new redelegation is Validator X.

// RedelegationEntryResponse is equivalent to a RedelegationEntry except that it
// contains a balance in addition to shares which is more suitable for client
// responses.
type RedelegationEntryResponse struct {
	RedelegationEntry RedelegationEntry                      `protobuf:"bytes,1,opt,name=redelegation_entry,json=redelegationEntry,proto3" json:"redelegation_entry"`
	Balance           github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,4,opt,name=balance,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"balance"`
}

// RedelegationEntry defines a redelegation object with relevant metadata.
type RedelegationEntry struct {
	// creation_height  defines the height which the redelegation took place.
	CreationHeight int64 `protobuf:"varint,1,opt,name=creation_height,json=creationHeight,proto3" json:"creation_height,omitempty" yaml:"creation_height"`
	// completion_time defines the unix time for redelegation completion.
	CompletionTime time.Time `protobuf:"bytes,2,opt,name=completion_time,json=completionTime,proto3,stdtime" json:"completion_time" yaml:"completion_time"`
	// initial_balance defines the initial balance when redelegation started.
	InitialBalance github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,3,opt,name=initial_balance,json=initialBalance,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"initial_balance" yaml:"initial_balance"`
	// shares_dst is the amount of destination-validator shares created by redelegation.
	SharesDst github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,4,opt,name=shares_dst,json=sharesDst,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"shares_dst"`
}

Queues

All queues objects are sorted by timestamp. The time used within any queue is first rounded to the nearest nanosecond then sorted. The sortable time format used is a slight modification of the RFC3339Nano and uses the the format string "2006-01-02T15:04:05.000000000". Notably this format:

right pads all zeros
drops the time zone info (uses UTC)

In all cases, the stored timestamp represents the maturation time of the queue element.

UnbondingDelegationQueue

For the purpose of tracking progress of unbonding delegations the unbonding delegations queue is kept.

UnbondingDelegation: 0x41 | format(time) -> []DVPair

// DVPair is struct that just has a delegator-validator pair with no other data.
// It is intended to be used as a marshalable pointer. For example, a DVPair can
// be used to construct the key to getting an UnbondingDelegation from state.
type DVPair struct {
	DelegatorAddress string `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	ValidatorAddress string `protobuf:"bytes,2,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"validator_address"`
}

RedelegationQueue

For the purpose of tracking progress of redelegations the redelegation queue is kept.

RedelegationQueue: 0x42 | format(time) -> []DVVTriplet

// DVVTriplet is struct that just has a delegator-validator-validator triplet
// with no other data. It is intended to be used as a marshalable pointer. For
// example, a DVVTriplet can be used to construct the key to getting a
// Redelegation from state.
type DVVTriplet struct {
	DelegatorAddress    string `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	ValidatorSrcAddress string `protobuf:"bytes,2,opt,name=validator_src_address,json=validatorSrcAddress,proto3" json:"validator_src_address,omitempty" yaml:"validator_src_address"`
	ValidatorDstAddress string `protobuf:"bytes,3,opt,name=validator_dst_address,json=validatorDstAddress,proto3" json:"validator_dst_address,omitempty" yaml:"validator_dst_address"`
}

ValidatorQueue

For the purpose of tracking progress of unbonding validators the validator queue is kept.

ValidatorQueueTime: 0x43 | format(time) -> []sdk.ValAddress

The stored object as each key is an array of validator operator addresses from which the validator object can be accessed. Typically it is expected that only a single validator record will be associated with a given timestamp however it is possible that multiple validators exist in the queue at the same location.

HistoricalInfo

HistoricalInfo objects are stored and pruned at each block such that the staking keeper persists the n most recent historical info defined by staking module parameter: HistoricalEntries.

// HistoricalInfo contains header and validator information for a given block.
// It is stored as part of staking module's state, which persists the `n` most
// recent HistoricalInfo
// (`n` is set by the staking module's `historical_entries` parameter).
type HistoricalInfo struct {
	Header types.Header `protobuf:"bytes,1,opt,name=header,proto3" json:"header"`
	Valset []Validator  `protobuf:"bytes,2,rep,name=valset,proto3" json:"valset"`
}

At each BeginBlock, the staking keeper will persist the current Header and the Validators that committed the current block in a HistoricalInfo object. The Validators are sorted on their address to ensure that they are in a determisnistic order. The oldest HistoricalEntries will be pruned to ensure that there only exist the parameter-defined number of historical entries.

Message Types

MsgCreateValidator

// MsgCreateValidator defines a SDK message for creating a new validator.
type MsgCreateValidator struct {
	Description       Description                            `protobuf:"bytes,1,opt,name=description,proto3" json:"description"`
	Commission        CommissionRates                        `protobuf:"bytes,2,opt,name=commission,proto3" json:"commission"`
	MinSelfDelegation github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,3,opt,name=min_self_delegation,json=minSelfDelegation,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"min_self_delegation" yaml:"min_self_delegation"`
	DelegatorAddress  string                                 `protobuf:"bytes,4,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	ValidatorAddress  string                                 `protobuf:"bytes,5,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"validator_address"`
	Pubkey            *types.Any                             `protobuf:"bytes,6,opt,name=pubkey,proto3" json:"pubkey,omitempty"`
	Value             types1.Coin                            `protobuf:"bytes,7,opt,name=value,proto3" json:"value"`
}

MsgEditValidator

// MsgEditValidator defines a SDK message for editing an existing validator.
type MsgEditValidator struct {
	Description      Description `protobuf:"bytes,1,opt,name=description,proto3" json:"description"`
	ValidatorAddress string      `protobuf:"bytes,2,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"address"`
	// We pass a reference to the new commission rate and min self delegation as
	// it's not mandatory to update. If not updated, the deserialized rate will be
	// zero with no way to distinguish if an update was intended.
	// REF: #2373
	CommissionRate    *github_com_cosmos_cosmos_sdk_types.Dec `protobuf:"bytes,3,opt,name=commission_rate,json=commissionRate,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Dec" json:"commission_rate,omitempty" yaml:"commission_rate"`
	MinSelfDelegation *github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,4,opt,name=min_self_delegation,json=minSelfDelegation,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"min_self_delegation,omitempty" yaml:"min_self_delegation"`
}

MsgDelegate

// MsgDelegate defines a SDK message for performing a delegation of coins
// from a delegator to a validator.
type MsgDelegate struct {
	DelegatorAddress string      `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	ValidatorAddress string      `protobuf:"bytes,2,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"validator_address"`
	Amount           types1.Coin `protobuf:"bytes,3,opt,name=amount,proto3" json:"amount"`
}

MsgUndelegate

// MsgUndelegate defines a SDK message for performing an undelegation from a
// delegate and a validator.
type MsgUndelegate struct {
	DelegatorAddress string      `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	ValidatorAddress string      `protobuf:"bytes,2,opt,name=validator_address,json=validatorAddress,proto3" json:"validator_address,omitempty" yaml:"validator_address"`
	Amount           types1.Coin `protobuf:"bytes,3,opt,name=amount,proto3" json:"amount"`
}

MsgBeginRedelegate

// MsgBeginRedelegate defines a SDK message for performing a redelegation
// of coins from a delegator and source validator to a destination validator.
type MsgBeginRedelegate struct {
	DelegatorAddress    string      `protobuf:"bytes,1,opt,name=delegator_address,json=delegatorAddress,proto3" json:"delegator_address,omitempty" yaml:"delegator_address"`
	ValidatorSrcAddress string      `protobuf:"bytes,2,opt,name=validator_src_address,json=validatorSrcAddress,proto3" json:"validator_src_address,omitempty" yaml:"validator_src_address"`
	ValidatorDstAddress string      `protobuf:"bytes,3,opt,name=validator_dst_address,json=validatorDstAddress,proto3" json:"validator_dst_address,omitempty" yaml:"validator_dst_address"`
	Amount              types1.Coin `protobuf:"bytes,4,opt,name=amount,proto3" json:"amount"`
}

Transitions

Begin-Block

Each abci begin block call, the historical info will get stored and pruned according to the HistoricalEntries parameter.

Historical Info Tracking

If the HistoricalEntries parameter is 0, then the BeginBlock performs a no-op.

Otherwise, the latest historical info is stored under the key historicalInfoKey|height, while any entries older than height - HistoricalEntries is deleted. In most cases, this results in a single entry being pruned per block. However, if the parameter HistoricalEntries has changed to a lower value there will be multiple entries in the store that must be pruned.

GetLastValidators

This function gets the bonded validators of the previous block. the number of validators in the return value is the same as params.MaxValidators in the cosmos-sdk module, and the XPLA Chain provides as many as the number of Volunteer Validators in addition.

End-Block

Each abci end block call, the operations to update queues and validator set changes are specified to execute.

Validator Set Changes

The staking validator set is updated during this process by state transitions that run at the end of every block. As a part of this process any updated validators are also returned back to Tendermint for inclusion in the Tendermint validator set which is responsible for validating Tendermint messages at the consensus layer. Operations are as following:

the new validator set is taken as the top params.MaxValidators number of validators retrieved from the ValidatorsByPower index
- regardless of power, Volunteer Validators are always included.
the previous validator set is compared with the new validator set:
- missing validators begin unbonding and their Tokens are transferred from the BondedPool to the NotBondedPool ModuleAccount
- new validators are instantly bonded and their Tokens are transferred from the NotBondedPool to the BondedPool ModuleAccount

In all cases, any validators leaving or entering the bonded validator set or changing balances and staying within the bonded validator set incur an update message reporting their new consensus power which is passed back to Tendermint.

The LastTotalPower and LastValidatorsPower hold the state of the total power and validator power from the end of the last block, and are used to check for changes that have occured in ValidatorsByPower and the total new power, which is calculated during EndBlock.

Queues

Within staking, certain state-transitions are not instantaneous but take place over a duration of time (typically the unbonding period). When these transitions are mature certain operations must take place in order to complete the state operation. This is achieved through the use of queues which are checked/processed at the end of each block.

Unbonding Validators

When a validator is kicked out of the bonded validator set (either through being jailed, or not having sufficient bonded tokens) it begins the unbonding process along with all its delegations begin unbonding (while still being delegated to this validator). At this point the validator is said to be an “unbonding validator”, whereby it will mature to become an “unbonded validator” after the unbonding period has passed.

Each block the validator queue is to be checked for mature unbonding validators (namely with a completion time <= current time and completion height <= current block height). At this point any mature validators which do not have any delegations remaining are deleted from state. For all other mature unbonding validators that still have remaining delegations, the validator.Status is switched from types.Unbonding to types.Unbonded.

Unbonding Delegations

Complete the unbonding of all mature UnbondingDelegations.Entries within the UnbondingDelegations queue with the following procedure:

transfer the balance coins to the delegator’s wallet address
remove the mature entry from UnbondingDelegation.Entries
remove the UnbondingDelegation object from the store if there are no remaining entries.

Redelegations

Complete the unbonding of all mature Redelegation.Entries within the Redelegations queue with the following procedure:

remove the mature entry from Redelegation.Entries
remove the Redelegation object from the store if there are no remaining entries.

Hooks

Other modules may register operations to execute when a certain event has occurred within staking. These events can be registered to execute either right Before or After the staking event (as per the hook name). The following hooks can registered with staking:

AfterValidatorCreated(Context, ValAddress)
- called when a validator is created
BeforeValidatorModified(Context, ValAddress)
- called when a validator’s state is changed
AfterValidatorRemoved(Context, ConsAddress, ValAddress)
- called when a validator is deleted
AfterValidatorBonded(Context, ConsAddress, ValAddress)
- called when a validator is bonded
AfterValidatorBeginUnbonding(Context, ConsAddress, ValAddress)
- called when a validator begins unbonding
BeforeDelegationCreated(Context, AccAddress, ValAddress)
- called when a delegation is created
BeforeDelegationSharesModified(Context, AccAddress, ValAddress)
- called when a delegation’s shares are modified
BeforeDelegationRemoved(Context, AccAddress, ValAddress)
- called when a delegation is removed

Parameters

The subspace for the Staking module is staking.

// Params defines the parameters for the staking module.
type Params struct {
	// unbonding_time is the time duration of unbonding.
	UnbondingTime time.Duration `protobuf:"bytes,1,opt,name=unbonding_time,json=unbondingTime,proto3,stdduration" json:"unbonding_time" yaml:"unbonding_time"`
	// max_validators is the maximum number of validators.
	MaxValidators uint32 `protobuf:"varint,2,opt,name=max_validators,json=maxValidators,proto3" json:"max_validators,omitempty" yaml:"max_validators"`
	// max_entries is the max entries for either unbonding delegation or redelegation (per pair/trio).
	MaxEntries uint32 `protobuf:"varint,3,opt,name=max_entries,json=maxEntries,proto3" json:"max_entries,omitempty" yaml:"max_entries"`
	// historical_entries is the number of historical entries to persist.
	HistoricalEntries uint32 `protobuf:"varint,4,opt,name=historical_entries,json=historicalEntries,proto3" json:"historical_entries,omitempty" yaml:"historical_entries"`
	// bond_denom defines the bondable coin denomination.
	BondDenom string `protobuf:"bytes,5,opt,name=bond_denom,json=bondDenom,proto3" json:"bond_denom,omitempty" yaml:"bond_denom"`
}

UnbondingTime

type: time.Duration
default: 3 weeks

Time duration of unbonding.

MaxValidators

type: uint32
default: 40

Maximum number of active validators.

MaxEntries

type: uint32
default: 7

Maximum entries for either unbonding delegation or redelegation per pair or trio. Be aware of potential overflow because this is user-determined.

HistoricalEntries

type: uint32
default: 10000

The number of historical entries to persist.

BondDenom

type: string
default: axpla

Denomination of the asset required for staking.

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Staking

State #

Pool #

LastTotalPower #

Params #

Validator #

Delegation #

Delegator Shares #

UnbondingDelegation #

Redelegation #

Queues #

UnbondingDelegationQueue #

RedelegationQueue #

ValidatorQueue #

HistoricalInfo #

Message Types #

MsgCreateValidator #

MsgEditValidator #

MsgDelegate #

MsgUndelegate #

MsgBeginRedelegate #

Transitions #

Begin-Block #

Historical Info Tracking #

GetLastValidators #

End-Block #

Validator Set Changes #

Queues #

Unbonding Validators #

Unbonding Delegations #

Redelegations #

Hooks #

Parameters #

UnbondingTime #

MaxValidators #

MaxEntries #

HistoricalEntries #

BondDenom #

State

Pool

LastTotalPower

Params

Validator

Delegation

Delegator Shares

UnbondingDelegation

Redelegation

Queues

UnbondingDelegationQueue

RedelegationQueue

ValidatorQueue

HistoricalInfo

Message Types

MsgCreateValidator

MsgEditValidator

MsgDelegate

MsgUndelegate

MsgBeginRedelegate

Transitions

Begin-Block

Historical Info Tracking

GetLastValidators

End-Block

Validator Set Changes

Queues

Unbonding Validators

Unbonding Delegations

Redelegations

Hooks

Parameters

UnbondingTime

MaxValidators

MaxEntries

HistoricalEntries

BondDenom