Grandpa¶

Calls¶

note_stalled¶

Note that the current authority set of the GRANDPA finality gadget has stalled.

This will trigger a forced authority set change at the beginning of the next session, to be enacted delay blocks after that. The delay should be high enough to safely assume that the block signalling the forced change will not be re-orged e.g. 1000 blocks. The block production rate (which may be slowed down because of finality lagging) should be taken into account when choosing the delay. The GRANDPA voters based on the new authority will start voting on top of best_finalized_block_number for new finalized blocks. best_finalized_block_number should be the highest of the latest finalized block of all validators of the new authority set.

Only callable by root.

Attributes¶

Name	Type
delay	`BlockNumberFor<T>`
best_finalized_block_number	`BlockNumberFor<T>`

Python¶

call = substrate.compose_call(
    'Grandpa', 'note_stalled', {
    'best_finalized_block_number': 'u32',
    'delay': 'u32',
}
)

report_equivocation¶

Report voter equivocation/misbehavior. This method will verify the equivocation proof and validate the given key ownership proof against the extracted offender. If both are valid, the offence will be reported.

Attributes¶

Name	Type
equivocation_proof	`Box<EquivocationProof<T::Hash, BlockNumberFor<T>>>`
key_owner_proof	`T::KeyOwnerProof`

Python¶

call = substrate.compose_call(
    'Grandpa', 'report_equivocation', {
    'equivocation_proof': {
        'equivocation': {
            'Precommit': {
                'first': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
                'identity': '[u8; 32]',
                'round_number': 'u64',
                'second': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
            },
            'Prevote': {
                'first': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
                'identity': '[u8; 32]',
                'round_number': 'u64',
                'second': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
            },
        },
        'set_id': 'u64',
    },
    'key_owner_proof': (),
}
)

report_equivocation_unsigned¶

Report voter equivocation/misbehavior. This method will verify the equivocation proof and validate the given key ownership proof against the extracted offender. If both are valid, the offence will be reported.

This extrinsic must be called unsigned and it is expected that only block authors will call it (validated in ValidateUnsigned), as such if the block author is defined it will be defined as the equivocation reporter.

Attributes¶

Name	Type
equivocation_proof	`Box<EquivocationProof<T::Hash, BlockNumberFor<T>>>`
key_owner_proof	`T::KeyOwnerProof`

Python¶

call = substrate.compose_call(
    'Grandpa', 'report_equivocation_unsigned', {
    'equivocation_proof': {
        'equivocation': {
            'Precommit': {
                'first': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
                'identity': '[u8; 32]',
                'round_number': 'u64',
                'second': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
            },
            'Prevote': {
                'first': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
                'identity': '[u8; 32]',
                'round_number': 'u64',
                'second': (
                    {
                        'target_hash': 'scale_info::13',
                        'target_number': 'u32',
                    },
                    '[u8; 64]',
                ),
            },
        },
        'set_id': 'u64',
    },
    'key_owner_proof': (),
}
)

Events¶

NewAuthorities¶

New authority set has been applied.

Attributes¶

Name	Type	Composition
authority_set	`AuthorityList`	`[('[u8; 32]', 'u64')]`

Paused¶

Current authority set has been paused.

Attributes¶

No attributes

Resumed¶

Current authority set has been resumed.

Attributes¶

No attributes

Storage functions¶

Authorities¶

The current list of authorities.

Python¶

result = substrate.query(
    'Grandpa', 'Authorities', []
)

Return value¶

[('[u8; 32]', 'u64')]

CurrentSetId¶

The number of changes (both in terms of keys and underlying economic responsibilities) in the "set" of Grandpa validators from genesis.

Python¶

result = substrate.query(
    'Grandpa', 'CurrentSetId', []
)

Return value¶

'u64'

NextForced¶

next block number where we can force a change.

Python¶

result = substrate.query(
    'Grandpa', 'NextForced', []
)

Return value¶

'u32'

PendingChange¶

Pending change: (signaled at, scheduled change).

Python¶

result = substrate.query(
    'Grandpa', 'PendingChange', []
)

Return value¶

{
    'delay': 'u32',
    'forced': (None, 'u32'),
    'next_authorities': [('[u8; 32]', 'u64')],
    'scheduled_at': 'u32',
}

SetIdSession¶

A mapping from grandpa set ID to the index of the most recent session for which its members were responsible.

This is only used for validating equivocation proofs. An equivocation proof must contains a key-ownership proof for a given session, therefore we need a way to tie together sessions and GRANDPA set ids, i.e. we need to validate that a validator was the owner of a given key on a given session, and what the active set ID was during that session.

TWOX-NOTE: SetId is not under user control.

Python¶

result = substrate.query(
    'Grandpa', 'SetIdSession', ['u64']
)

Return value¶

'u32'

Stalled¶

true if we are currently stalled.

Python¶

result = substrate.query(
    'Grandpa', 'Stalled', []
)

Return value¶

('u32', 'u32')

State¶

State of the current authority set.

Python¶

result = substrate.query(
    'Grandpa', 'State', []
)

Return value¶

{
    'Live': None,
    'Paused': None,
    'PendingPause': {'delay': 'u32', 'scheduled_at': 'u32'},
    'PendingResume': {'delay': 'u32', 'scheduled_at': 'u32'},
}

Constants¶

MaxAuthorities¶

Max Authorities in use

Value¶

Python¶

constant = substrate.get_constant('Grandpa', 'MaxAuthorities')

MaxNominators¶

The maximum number of nominators for each validator.

Value¶

Python¶

constant = substrate.get_constant('Grandpa', 'MaxNominators')

MaxSetIdSessionEntries¶

The maximum number of entries to keep in the set id to session index mapping.

Since the SetIdSession map is only used for validating equivocations this value should relate to the bonding duration of whatever staking system is being used (if any). If equivocation handling is not enabled then this value can be zero.

Value¶

Python¶

constant = substrate.get_constant('Grandpa', 'MaxSetIdSessionEntries')

Errors¶

ChangePending¶

Attempt to signal GRANDPA change with one already pending.

DuplicateOffenceReport¶

A given equivocation report is valid but already previously reported.

InvalidEquivocationProof¶

An equivocation proof provided as part of an equivocation report is invalid.

InvalidKeyOwnershipProof¶

A key ownership proof provided as part of an equivocation report is invalid.

PauseFailed¶

Attempt to signal GRANDPA pause when the authority set isn't live (either paused or already pending pause).

ResumeFailed¶

Attempt to signal GRANDPA resume when the authority set isn't paused (either live or already pending resume).

TooSoon¶

Cannot signal forced change so soon after last.