Interface IActionRenderer

Listens state changes of every step of actions, besides blocks, on a BlockChain<T>. If you need more fine-grained events than IRenderer, implement this interface instead.

The invocation order of methods for each Block are:

1. RenderBlock(Block, Block) (one time)
2. RenderAction(IValue, IActionContext, IAccountStateDelta) & RenderActionError(IValue, IActionContext, Exception) (zero or more times)
3. RenderBlockEnd(Block, Block) (one time)

Inherited Members

IRenderer.RenderBlock(Block, Block)

Namespace: Libplanet.Blockchain.Renderers

Assembly: Libplanet.dll

Syntax

public interface IActionRenderer : IRenderer

Remarks

Although Transactions affect the states in the IStateStore all or nothing at all (i.e., atomically), IActionRenderer receives all action-related events (RenderAction(IValue, IActionContext, IAccountStateDelta)/RenderActionError(IValue, IActionContext, Exception)) immediately without buffering, which means actions are rendered even before whether there are any actions throwing an exception in the same transaction is determined. In other words, for IActionRenderers, it is not guaranteed that actions in a transaction are atomic.

If your action renderer expects to receive only render events about actions belonging successful transactions, wrap your action renderer with AtomicActionRenderer.

Methods

RenderAction(IValue, IActionContext, IAccountStateDelta)

Does things that should be done right after an action is executed and applied to the blockchain.

Declaration

void RenderAction(IValue action, IActionContext context, IAccountStateDelta nextStates)

Parameters

Type	Name	Description
Bencodex.Types.IValue	action	An executed action.
IActionContext	context	The equivalent context object to an object passed to the action's Execute(IActionContext) method. That means PreviousStates are the states right before this action executed. For the states after this action executed, use the nextStates argument instead.
IAccountStateDelta	nextStates	The states right after this action executed, which means it is equivalent to the states action's Execute(IActionContext) method returned.

Remarks

It is guaranteed to be called only once for an action, and only after applied to the blockchain, unless an exception is thrown during executing the action (in that case RenderActionError(IValue, IActionContext, Exception) is called instead) or once the action has been unrendered.

Also note that this method is invoked after RenderBlock(Block, Block) method is called (where its second parameter newTip contains a transaction the action belongs to).

RenderActionError(IValue, IActionContext, Exception)

Does the similar things to RenderAction(IValue, IActionContext, IAccountStateDelta), except that this method is invoked when action has terminated with an exception.

Declaration

void RenderActionError(IValue action, IActionContext context, Exception exception)

Parameters

Type	Name	Description
Bencodex.Types.IValue	action	An action which threw an exception during execution.
IActionContext	context	The equivalent context object to an object passed to the action's Execute(IActionContext) method. That means PreviousStates are the states right before this action executed.
Exception	exception	The exception thrown during executing the action.

Remarks

Also note that this method is invoked after RenderBlock(Block, Block) method is called (where its second parameter newTip contains a transaction the action belongs to).

RenderBlockEnd(Block, Block)

Does things that should be done right all actions in a new Block are rendered.

Declaration

void RenderBlockEnd(Block oldTip, Block newTip)

Parameters

Type	Name	Description
Block	oldTip	The previous Tip.
Block	newTip	The current Tip.

Remarks

It is guaranteed to be called only once for a block.