epochs

package
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 Go to latest Published: Feb 10, 2023 License: Apache-2.0 Imports: 15 Imported by: 0

README

Epochs

Abstract

Often in the SDK, we would like to run certain code every-so often. The purpose of epochs module is to allow other modules to set that they would like to be signaled once every period. So another module can specify it wants to execute code once a week, starting at UTC-time = x. epochs creates a generalized epoch interface to other modules so that they can easily be signalled upon such events.

Contents

  1. Concept
  2. State
  3. Events
  4. Keeper
  5. Hooks
  6. Queries

Concepts

The epochs module defines on-chain timers, that execute at fixed time intervals. Other SDK modules can then register logic to be executed at the timer ticks. We refer to the period in between two timer ticks as an "epoch".

Every timer has a unique identifier. Every epoch will have a start time, and an end time, where end time = start time + timer interval. On Merlin mainnet, we only utilize one identifier, with a time interval of one day.

The timer will tick at the first block whose blocktime is greater than the timer end time, and set the start as the prior timer end time. (Notably, its not set to the block time!) This means that if the chain has been down for awhile, you will get one timer tick per block, until the timer has caught up.

State

The Epochs module keeps a single EpochInfo per identifier. This contains the current state of the timer with the corresponding identifier. Its fields are modified at every timer tick. EpochInfos are initialized as part of genesis initialization or upgrade logic, and are only modified on begin blockers.

Events

The epochs module emits the following events:

BeginBlocker
Type Attribute Key Attribute Value
epoch_start epoch_number {epoch_number}
epoch_start start_time {start_time}
EndBlocker
Type Attribute Key Attribute Value
epoch_end epoch_number {epoch_number}

Keepers

Keeper functions

Epochs keeper module provides utility functions to manage epochs.

// Keeper is the interface for lockup module keeper
type Keeper interface {
  // GetEpochInfo returns epoch info by identifier
  GetEpochInfo(ctx sdk.Context, identifier string) types.EpochInfo
  // SetEpochInfo set epoch info
  SetEpochInfo(ctx sdk.Context, epoch types.EpochInfo)
  // DeleteEpochInfo delete epoch info
  DeleteEpochInfo(ctx sdk.Context, identifier string)
  // IterateEpochInfo iterate through epochs
  IterateEpochInfo(ctx sdk.Context, fn func(index int64, epochInfo types.EpochInfo) (stop bool))
  // Get all epoch infos
  AllEpochInfos(ctx sdk.Context) []types.EpochInfo
}

Hooks

  // the first block whose timestamp is after the duration is counted as the end of the epoch
  AfterEpochEnd(ctx sdk.Context, epochIdentifier string, epochNumber int64)
  // new epoch is next block of epoch end block
  BeforeEpochStart(ctx sdk.Context, epochIdentifier string, epochNumber int64)
How modules receive hooks

On hook receiver function of other modules, they need to filter epochIdentifier and only do executions for only specific epochIdentifier. Filtering epochIdentifier could be in Params of other modules so that they can be modified by governance.

This is the standard dev UX of this:

func (k MyModuleKeeper) AfterEpochEnd(ctx sdk.Context, epochIdentifier string, epochNumber int64) {
    params := k.GetParams(ctx)
    if epochIdentifier == params.DistrEpochIdentifier {
    // my logic
  }
}
Panic isolation

If a given epoch hook panics, its state update is reverted, but we keep proceeding through the remaining hooks. This allows more advanced epoch logic to be used, without concern over state machine halting, or halting subsequent modules.

This does mean that if there is behavior you expect from a prior epoch hook, and that epoch hook reverted, your hook may also have an issue. So do keep in mind "what if a prior hook didn't get executed" in the safety checks you consider for a new epoch hook.

Queries

Epochs module is providing below queries to check the module's state.

service Query {
  // EpochInfos provide running epochInfos
  rpc EpochInfos(QueryEpochsInfoRequest) returns (QueryEpochsInfoResponse) {}
  // CurrentEpoch provide current epoch of specified identifier
  rpc CurrentEpoch(QueryCurrentEpochRequest) returns (QueryCurrentEpochResponse) {}
}
Epoch Infos

Query the currently running epochInfos

merlind query epochs epoch-infos

::: details Example

An example output:

epochs:
- current_epoch: "183"
  current_epoch_start_height: "2438409"
  current_epoch_start_time: "2021-12-18T17:16:09.898160996Z"
  duration: 86400s
  epoch_counting_started: true
  identifier: day
  start_time: "2021-06-18T17:00:00Z"
- current_epoch: "26"
  current_epoch_start_height: "2424854"
  current_epoch_start_time: "2021-12-17T17:02:07.229632445Z"
  duration: 604800s
  epoch_counting_started: true
  identifier: week
  start_time: "2021-06-18T17:00:00Z"

:::

Current Epoch

Query the current epoch by the specified identifier

merlind query epochs current-epoch [identifier]

::: details Example

Query the current day epoch:

merlind query epochs current-epoch day

Which in this example outputs:

current_epoch: "183"

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type AppModule 

type AppModule struct {
	AppModuleBasic
	// contains filtered or unexported fields
}

AppModule implements the AppModule interface for the capability module.

func NewAppModule 

func NewAppModule(keeper keeper.Keeper) AppModule

func (AppModule) BeginBlock 

func (am AppModule) BeginBlock(ctx sdk.Context, _ abci.RequestBeginBlock)

BeginBlock executes all ABCI BeginBlock logic respective to the capability module.

func (AppModule) ConsensusVersion 

func (AppModule) ConsensusVersion() uint64

ConsensusVersion implements AppModule/ConsensusVersion.

func (AppModule) EndBlock 

func (am AppModule) EndBlock(ctx sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate

EndBlock executes all ABCI EndBlock logic respective to the capability module. It returns no validator updates.

func (AppModule) ExportGenesis 

func (am AppModule) ExportGenesis(ctx sdk.Context, cdc codec.JSONCodec) json.RawMessage

ExportGenesis returns the capability module's exported genesis state as raw JSON bytes.

func (AppModule) InitGenesis 

func (am AppModule) InitGenesis(ctx sdk.Context, cdc codec.JSONCodec, gs json.RawMessage) []abci.ValidatorUpdate

InitGenesis performs the capability module's genesis initialization It returns no validator updates.

func (AppModule) LegacyQuerierHandler 

func (am AppModule) LegacyQuerierHandler(legacyQuerierCdc *codec.LegacyAmino) sdk.Querier

LegacyQuerierHandler returns the x/epochs module's Querier.

func (AppModule) Name 

func (am AppModule) Name() string

Name returns the capability module's name.

func (AppModule) QuerierRoute 

func (AppModule) QuerierRoute() string

QuerierRoute returns the capability module's query routing key.

func (AppModule) RegisterInvariants 

func (am AppModule) RegisterInvariants(_ sdk.InvariantRegistry)

RegisterInvariants registers the capability module's invariants.

func (AppModule) RegisterServices 

func (am AppModule) RegisterServices(cfg module.Configurator)

RegisterServices registers a GRPC query service to respond to the module-specific GRPC queries.

func (AppModule) Route 

func (am AppModule) Route() sdk.Route

Route returns the capability module's message routing key.

type AppModuleBasic 

type AppModuleBasic struct{}

AppModuleBasic implements the AppModuleBasic interface for the capability module.

func NewAppModuleBasic 

func NewAppModuleBasic() AppModuleBasic

func (AppModuleBasic) DefaultGenesis 

func (AppModuleBasic) DefaultGenesis(cdc codec.JSONCodec) json.RawMessage

DefaultGenesis returns the capability module's default genesis state.

func (AppModuleBasic) GetQueryCmd 

func (AppModuleBasic) GetQueryCmd() *cobra.Command

GetQueryCmd returns the capability module's root query command.

func (AppModuleBasic) GetTxCmd 

func (a AppModuleBasic) GetTxCmd() *cobra.Command

GetTxCmd returns the capability module's root tx command.

func (AppModuleBasic) Name 

func (AppModuleBasic) Name() string

Name returns the capability module's name.

func (AppModuleBasic) RegisterGRPCGatewayRoutes 

func (AppModuleBasic) RegisterGRPCGatewayRoutes(clientCtx client.Context, mux *runtime.ServeMux)

RegisterGRPCGatewayRoutes registers the gRPC Gateway routes for the module.

func (AppModuleBasic) RegisterInterfaces 

func (a AppModuleBasic) RegisterInterfaces(reg cdctypes.InterfaceRegistry)

RegisterInterfaces registers the module's interface types.

func (AppModuleBasic) RegisterLegacyAminoCodec 

func (AppModuleBasic) RegisterLegacyAminoCodec(cdc *codec.LegacyAmino)

RegisterLegacyAminoCodec registers the module's Amino codec that properly handles protobuf types with Any's.

func (AppModuleBasic) RegisterRESTRoutes 

func (AppModuleBasic) RegisterRESTRoutes(clientCtx client.Context, rtr *mux.Router)

RegisterRESTRoutes registers the capability module's REST service handlers.

func (AppModuleBasic) ValidateGenesis 

func (AppModuleBasic) ValidateGenesis(cdc codec.JSONCodec, config client.TxEncodingConfig, bz json.RawMessage) error

ValidateGenesis performs genesis state validation for the capability module.

Source Files

View all Source files

Directories

Path Synopsis
client
cli
Package types translates gRPC into RESTful JSON APIs.
 Package types translates gRPC into RESTful JSON APIs.

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