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2 changes: 0 additions & 2 deletions frame/aura/src/lib.rs
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Expand Up @@ -33,8 +33,6 @@
//!
//! - [Timestamp](../pallet_timestamp/index.html): The Timestamp module is used in Aura to track
//! consensus rounds (via `slots`).
//! - [Consensus](../frame_consensus/index.html): The Consensus module does not relate directly to Aura,
//! but serves to manage offline reporting by implementing `ProvideInherent` in a similar way.
//!
//! ## References
//!
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78 changes: 29 additions & 49 deletions frame/session/src/lib.rs
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Expand Up @@ -30,92 +30,72 @@
//!
//! - **Session:** A session is a period of time that has a constant set of validators. Validators can only join
//! or exit the validator set at a session change. It is measured in block numbers. The block where a session is
//! ended is determined by the `ShouldSessionEnd` trait. When the session is ending, a new validator set
//! ended is determined by the `ShouldEndSession` trait. When the session is ending, a new validator set
//! can be chosen by `OnSessionEnding` implementations.
//! - **Session key:** A session key is actually several keys kept together that provide the various signing
//! functions required by network authorities/validators in pursuit of their duties.
//! - **Validator ID:** Every account has an associated validator ID. For some simple staking systems, this
//! may just be the same as the account ID. For staking systems using a stash/controller model,
//! the validator ID would be the stash account ID of the controller.
//! - **Session key configuration process:** A session key is set using `set_key` for use in the
//! next session. It is stored in `NextKeyFor`, a mapping between the caller's `ValidatorId` and the session
//! keys provided. `set_key` allows users to set their session key prior to being selected as validator.
//! - **Session key configuration process:** Session keys are set using `set_keys` for use not in
//! the next session, but the session after next. They are stored in `NextKeys`, a mapping between
//! the caller's `ValidatorId` and the session keys provided. `set_keys` allows users to set their
//! session key prior to being selected as validator.
//! It is a public call since it uses `ensure_signed`, which checks that the origin is a signed account.
//! As such, the account ID of the origin stored in in `NextKeyFor` may not necessarily be associated with
//! As such, the account ID of the origin stored in `NextKeys` may not necessarily be associated with
//! a block author or a validator. The session keys of accounts are removed once their account balance is zero.
//! - **Validator set session key configuration process:** Each session we iterate through the current
//! set of validator account IDs to check if a session key was created for it in the previous session
//! using `set_key`. If it was then we call `set_authority` from the [Consensus module](../frame_consensus/index.html)
//! and pass it a set of session keys (each associated with an account ID) as the session keys for the new
//! validator set. Lastly, if the session key of the current authority does not match any session keys stored under
//! its validator index in the `AuthorityStorageVec` mapping, then we update the mapping with its session
//! key and update the saved list of original authorities if necessary
//! (see https://github.com/paritytech/substrate/issues/1290). Note: Authorities are stored in the Consensus module.
//! They are represented by a validator account ID index from the Session module and allocated with a session
//! key for the length of the session.
//! - **Session length change process:** At the start of the next session we allocate a session index and record the
//! timestamp when the session started. If a `NextSessionLength` was recorded in the previous session, we record
//! it as the new session length. Additionally, if the new session length differs from the length of the
//! next session then we record a `LastLengthChange`.
//! - **Session length:** This pallet does not assume anything about the length of each session.
//! Rather, it relies on an implementation of `ShouldEndSession` to dictate a new session's start.
//! This pallet provides the `PeriodicSessions` struct for simple periodic sessions.
//! - **Session rotation configuration:** Configure as either a 'normal' (rewardable session where rewards are
//! applied) or 'exceptional' (slashable) session rotation.
//! - **Session rotation process:** The session is changed at the end of the final block of the current session
//! using the `on_finalize` method. It may be called by either an origin or internally from another runtime
//! module at the end of each block.
//! - **Session rotation process:** At the beginning of each block, the `on_initialize` function
//! queries the provided implementation of `ShouldEndSession`. If the session is to end the newly
//! activated validator IDs and session keys are taken from storage and passed to the
//! `SessionHandler`. The validator set supplied by `SessionManager::new_session` and the corresponding session
//! keys, which may have been registered via `set_keys` during the previous session, are written
//! to storage where they will wait one session before being passed to the `SessionHandler`
//! themselves.
//!
//! ### Goals
//!
//! The Session module in Substrate is designed to make the following possible:
//! The Session pallet is designed to make the following possible:
//!
//! - Set session keys of the validator set for the next session.
//! - Set the length of a session.
//! - Set session keys of the validator set for upcoming sessions.
//! - Control the length of sessions.
//! - Configure and switch between either normal or exceptional session rotations.
//!
//! ## Interface
//!
//! ### Dispatchable Functions
//!
//! - `set_key` - Set a validator's session key for the next session.
//! - `set_length` - Set a new session length to be applied upon the next session change.
//! - `force_new_session` - Force a new session that should be considered either a normal (rewardable)
//! or exceptional rotation.
//! - `on_finalize` - Called when a block is finalized. Will rotate session if it is the last
//! block of the current session.
//! - `set_keys` - Set a validator's session keys for upcoming sessions.
//!
//! ### Public Functions
//!
//! - `validator_count` - Get the current number of validators.
//! - `last_length_change` - Get the block number when the session length last changed.
//! - `apply_force_new_session` - Force a new session. Can be called by other runtime modules.
//! - `set_validators` - Set the current set of validators. Can only be called by the Staking module.
//! - `check_rotate_session` - Rotate the session and apply rewards if necessary. Called after the Staking
//! module updates the authorities to the new validator set.
//! - `rotate_session` - Change to the next session. Register the new authority set. Update session keys.
//! Enact session length change if applicable.
//! - `ideal_session_duration` - Get the time of an ideal session.
//! - `blocks_remaining` - Get the number of blocks remaining in the current session,
//! excluding the current block.
//! - `rotate_session` - Change to the next session. Register the new authority set. Queue changes
//! for next session rotation.
//! - `disable_index` - Disable a validator by index.
//! - `disable` - Disable a validator by Validator ID
//!
//! ## Usage
//!
//! ### Example from the SRML
//!
//! The [Staking module](../pallet_staking/index.html) uses the Session module to get the validator set.
//! The [Staking pallet](../pallet_staking/index.html) uses the Session pallet to get the validator set.
//!
//! ```
//! use pallet_session as session;
//! # fn not_executed<T: session::Trait>() {
//!
//! let validators = <session::Module<T>>::validators();
//! # }
//! fn validators<T: pallet_session::Trait>() -> Vec<<T as pallet_session::Trait>::ValidatorId> {
//! <pallet_session::Module<T>>::validators()
//! }
//! # fn main(){}
//! ```
//!
//! ## Related Modules
//!
//! - [Consensus](../frame_consensus/index.html)
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There are more occurrences in this module. However, the whole description of the module in the docs is not correct anymore.

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(maybe not the whole, but crucial parts)

//! - [Staking](../pallet_staking/index.html)
//! - [Timestamp](../pallet_timestamp/index.html)

#![cfg_attr(not(feature = "std"), no_std)]

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fn deposit_event() = default;

/// Sets the session key(s) of the function caller to `key`.
/// Sets the session key(s) of the function caller to `keys`.
/// Allows an account to set its session key prior to becoming a validator.
/// This doesn't take effect until the next session.
///
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1 change: 0 additions & 1 deletion frame/sudo/src/lib.rs
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//!
//! ## Related Modules
//!
//! * [Consensus](../frame_consensus/index.html)
//! * [Democracy](../pallet_democracy/index.html)
//!
//! [`Call`]: ./enum.Call.html
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