Closes #2160 First part of [Extrinsic Horizon](https://github.com/paritytech/polkadot-sdk/issues/2415) Introduces a new trait `TransactionExtension` to replace `SignedExtension`. Introduce the idea of transactions which obey the runtime's extensions and have according Extension data (né Extra data) yet do not have hard-coded signatures. Deprecate the terminology of "Unsigned" when used for transactions/extrinsics owing to there now being "proper" unsigned transactions which obey the extension framework and "old-style" unsigned which do not. Instead we have __*General*__ for the former and __*Bare*__ for the latter. (Ultimately, the latter will be phased out as a type of transaction, and Bare will only be used for Inherents.) Types of extrinsic are now therefore: - Bare (no hardcoded signature, no Extra data; used to be known as "Unsigned") - Bare transactions (deprecated): Gossiped, validated with `ValidateUnsigned` (deprecated) and the `_bare_compat` bits of `TransactionExtension` (deprecated). - Inherents: Not gossiped, validated with `ProvideInherent`. - Extended (Extra data): Gossiped, validated via `TransactionExtension`. - Signed transactions (with a hardcoded signature). - General transactions (without a hardcoded signature). `TransactionExtension` differs from `SignedExtension` because: - A signature on the underlying transaction may validly not be present. - It may alter the origin during validation. - `pre_dispatch` is renamed to `prepare` and need not contain the checks present in `validate`. - `validate` and `prepare` is passed an `Origin` rather than a `AccountId`. - `validate` may pass arbitrary information into `prepare` via a new user-specifiable type `Val`. - `AdditionalSigned`/`additional_signed` is renamed to `Implicit`/`implicit`. It is encoded *for the entire transaction* and passed in to each extension as a new argument to `validate`. This facilitates the ability of extensions to acts as underlying crypto. There is a new `DispatchTransaction` trait which contains only default function impls and is impl'ed for any `TransactionExtension` impler. It provides several utility functions which reduce some of the tedium from using `TransactionExtension` (indeed, none of its regular functions should now need to be called directly). Three transaction version discriminator ("versions") are now permissible: - 0b000000100: Bare (used to be called "Unsigned"): contains Signature or Extra (extension data). After bare transactions are no longer supported, this will strictly identify an Inherents only. - 0b100000100: Old-school "Signed" Transaction: contains Signature and Extra (extension data). - 0b010000100: New-school "General" Transaction: contains Extra (extension data), but no Signature. For the New-school General Transaction, it becomes trivial for authors to publish extensions to the mechanism for authorizing an Origin, e.g. through new kinds of key-signing schemes, ZK proofs, pallet state, mutations over pre-authenticated origins or any combination of the above. ## Code Migration ### NOW: Getting it to build Wrap your `SignedExtension`s in `AsTransactionExtension`. This should be accompanied by renaming your aggregate type in line with the new terminology. E.g. Before: ```rust /// The SignedExtension to the basic transaction logic. pub type SignedExtra = ( /* snip */ MySpecialSignedExtension, ); /// Unchecked extrinsic type as expected by this runtime. pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, SignedExtra>; ``` After: ```rust /// The extension to the basic transaction logic. pub type TxExtension = ( /* snip */ AsTransactionExtension<MySpecialSignedExtension>, ); /// Unchecked extrinsic type as expected by this runtime. pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, TxExtension>; ``` You'll also need to alter any transaction building logic to add a `.into()` to make the conversion happen. E.g. Before: ```rust fn construct_extrinsic( /* snip */ ) -> UncheckedExtrinsic { let extra: SignedExtra = ( /* snip */ MySpecialSignedExtension::new(/* snip */), ); let payload = SignedPayload::new(call.clone(), extra.clone()).unwrap(); let signature = payload.using_encoded(|e| sender.sign(e)); UncheckedExtrinsic::new_signed( /* snip */ Signature::Sr25519(signature), extra, ) } ``` After: ```rust fn construct_extrinsic( /* snip */ ) -> UncheckedExtrinsic { let tx_ext: TxExtension = ( /* snip */ MySpecialSignedExtension::new(/* snip */).into(), ); let payload = SignedPayload::new(call.clone(), tx_ext.clone()).unwrap(); let signature = payload.using_encoded(|e| sender.sign(e)); UncheckedExtrinsic::new_signed( /* snip */ Signature::Sr25519(signature), tx_ext, ) } ``` ### SOON: Migrating to `TransactionExtension` Most `SignedExtension`s can be trivially converted to become a `TransactionExtension`. There are a few things to know. - Instead of a single trait like `SignedExtension`, you should now implement two traits individually: `TransactionExtensionBase` and `TransactionExtension`. - Weights are now a thing and must be provided via the new function `fn weight`. #### `TransactionExtensionBase` This trait takes care of anything which is not dependent on types specific to your runtime, most notably `Call`. - `AdditionalSigned`/`additional_signed` is renamed to `Implicit`/`implicit`. - Weight must be returned by implementing the `weight` function. If your extension is associated with a pallet, you'll probably want to do this via the pallet's existing benchmarking infrastructure. #### `TransactionExtension` Generally: - `pre_dispatch` is now `prepare` and you *should not reexecute the `validate` functionality in there*! - You don't get an account ID any more; you get an origin instead. If you need to presume an account ID, then you can use the trait function `AsSystemOriginSigner::as_system_origin_signer`. - You get an additional ticket, similar to `Pre`, called `Val`. This defines data which is passed from `validate` into `prepare`. This is important since you should not be duplicating logic from `validate` to `prepare`, you need a way of passing your working from the former into the latter. This is it. - This trait takes two type parameters: `Call` and `Context`. `Call` is the runtime call type which used to be an associated type; you can just move it to become a type parameter for your trait impl. `Context` is not currently used and you can safely implement over it as an unbounded type. - There's no `AccountId` associated type any more. Just remove it. Regarding `validate`: - You get three new parameters in `validate`; all can be ignored when migrating from `SignedExtension`. - `validate` returns a tuple on success; the second item in the tuple is the new ticket type `Self::Val` which gets passed in to `prepare`. If you use any information extracted during `validate` (off-chain and on-chain, non-mutating) in `prepare` (on-chain, mutating) then you can pass it through with this. For the tuple's last item, just return the `origin` argument. Regarding `prepare`: - This is renamed from `pre_dispatch`, but there is one change: - FUNCTIONALITY TO VALIDATE THE TRANSACTION NEED NOT BE DUPLICATED FROM `validate`!! - (This is different to `SignedExtension` which was required to run the same checks in `pre_dispatch` as in `validate`.) Regarding `post_dispatch`: - Since there are no unsigned transactions handled by `TransactionExtension`, `Pre` is always defined, so the first parameter is `Self::Pre` rather than `Option<Self::Pre>`. If you make use of `SignedExtension::validate_unsigned` or `SignedExtension::pre_dispatch_unsigned`, then: - Just use the regular versions of these functions instead. - Have your logic execute in the case that the `origin` is `None`. - Ensure your transaction creation logic creates a General Transaction rather than a Bare Transaction; this means having to include all `TransactionExtension`s' data. - `ValidateUnsigned` can still be used (for now) if you need to be able to construct transactions which contain none of the extension data, however these will be phased out in stage 2 of the Transactions Horizon, so you should consider moving to an extension-centric design. ## TODO - [x] Introduce `CheckSignature` impl of `TransactionExtension` to ensure it's possible to have crypto be done wholly in a `TransactionExtension`. - [x] Deprecate `SignedExtension` and move all uses in codebase to `TransactionExtension`. - [x] `ChargeTransactionPayment` - [x] `DummyExtension` - [x] `ChargeAssetTxPayment` (asset-tx-payment) - [x] `ChargeAssetTxPayment` (asset-conversion-tx-payment) - [x] `CheckWeight` - [x] `CheckTxVersion` - [x] `CheckSpecVersion` - [x] `CheckNonce` - [x] `CheckNonZeroSender` - [x] `CheckMortality` - [x] `CheckGenesis` - [x] `CheckOnlySudoAccount` - [x] `WatchDummy` - [x] `PrevalidateAttests` - [x] `GenericSignedExtension` - [x] `SignedExtension` (chain-polkadot-bulletin) - [x] `RefundSignedExtensionAdapter` - [x] Implement `fn weight` across the board. - [ ] Go through all pre-existing extensions which assume an account signer and explicitly handle the possibility of another kind of origin. - [x] `CheckNonce` should probably succeed in the case of a non-account origin. - [x] `CheckNonZeroSender` should succeed in the case of a non-account origin. - [x] `ChargeTransactionPayment` and family should fail in the case of a non-account origin. - [ ] - [x] Fix any broken tests. --------- Signed-off-by: georgepisaltu <george.pisaltu@parity.io> 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Democracy Pallet
Overview
The Democracy pallet handles the administration of general stakeholder voting.
There are two different queues that a proposal can be added to before it becomes a referendum, 1) the proposal queue consisting of all public proposals and 2) the external queue consisting of a single proposal that originates from one of the external origins (such as a collective group).
Every launch period - a length defined in the runtime - the Democracy pallet launches a referendum from a proposal that it takes from either the proposal queue or the external queue in turn. Any token holder in the system can vote on referenda. The voting system uses time-lock voting by allowing the token holder to set their conviction behind a vote. The conviction will dictate the length of time the tokens will be locked, as well as the multiplier that scales the vote power.
Terminology
- Enactment Period: The minimum period of locking and the period between a proposal being approved and enacted.
- Lock Period: A period of time after proposal enactment that the tokens of winning voters will be locked.
- Conviction: An indication of a voter's strength of belief in their vote. An increase of one in conviction indicates that a token holder is willing to lock their tokens for twice as many lock periods after enactment.
- Vote: A value that can either be in approval ("Aye") or rejection ("Nay") of a particular referendum.
- Proposal: A submission to the chain that represents an action that a proposer (either an account or an external origin) suggests that the system adopt.
- Referendum: A proposal that is in the process of being voted on for either acceptance or rejection as a change to the system.
- Delegation: The act of granting your voting power to the decisions of another account for up to a certain conviction.
Adaptive Quorum Biasing
A referendum can be either simple majority-carries in which 50%+1 of the votes decide the outcome or adaptive quorum biased. Adaptive quorum biasing makes the threshold for passing or rejecting a referendum higher or lower depending on how the referendum was originally proposed. There are two types of adaptive quorum biasing: 1) positive turnout bias makes a referendum require a super-majority to pass that decreases as turnout increases and 2) negative turnout bias makes a referendum require a super-majority to reject that decreases as turnout increases. Another way to think about the quorum biasing is that positive bias referendums will be rejected by default and negative bias referendums get passed by default.
Interface
Dispatchable Functions
Public
These calls can be made from any externally held account capable of creating a signed extrinsic.
Basic actions:
propose- Submits a sensitive action, represented as a hash. Requires a deposit.second- Signals agreement with a proposal, moves it higher on the proposal queue, and requires a matching deposit to the original.vote- Votes in a referendum, either the vote is "Aye" to enact the proposal or "Nay" to keep the status quo.unvote- Cancel a previous vote, this must be done by the voter before the vote ends.delegate- Delegates the voting power (tokens * conviction) to another account.undelegate- Stops the delegation of voting power to another account.
Administration actions that can be done to any account:
reap_vote- Remove some account's expired votes.unlock- Redetermine the account's balance lock, potentially making tokens available.
Preimage actions:
note_preimage- Registers the preimage for an upcoming proposal, requires a deposit that is returned once the proposal is enacted.note_preimage_operational- same but provided byT::OperationalPreimageOrigin.note_imminent_preimage- Registers the preimage for an upcoming proposal. Does not require a deposit, but the proposal must be in the dispatch queue.note_imminent_preimage_operational- same but provided byT::OperationalPreimageOrigin.reap_preimage- Removes the preimage for an expired proposal. Will only work under the condition that it's the same account that noted it and after the voting period, OR it's a different account after the enactment period.
Cancellation Origin
This call can only be made by the CancellationOrigin.
emergency_cancel- Schedules an emergency cancellation of a referendum. Can only happen once to a specific referendum.
ExternalOrigin
This call can only be made by the ExternalOrigin.
external_propose- Schedules a proposal to become a referendum once it is is legal for an externally proposed referendum.
External Majority Origin
This call can only be made by the ExternalMajorityOrigin.
external_propose_majority- Schedules a proposal to become a majority-carries referendum once it is legal for an externally proposed referendum.
External Default Origin
This call can only be made by the ExternalDefaultOrigin.
external_propose_default- Schedules a proposal to become a negative-turnout-bias referendum once it is legal for an externally proposed referendum.
Fast Track Origin
This call can only be made by the FastTrackOrigin.
fast_track- Schedules the current externally proposed proposal that is "majority-carries" to become a referendum immediately.
Veto Origin
This call can only be made by the VetoOrigin.
veto_external- Vetoes and blacklists the external proposal hash.
Root
cancel_referendum- Removes a referendum.cancel_queued- Cancels a proposal that is queued for enactment.clear_public_proposal- Removes all public proposals.
License: Apache-2.0