Make candidate validation timeouts configurable (#4001)

* pvf: make execution timeout configurable

* guide: add timeouts to candidate validation params

* add timeouts to candidate validation messages

* fmt

* port backing to use the backing pvf timeout

* port approval-voting to use the execution timeout

* port dispute participation to use the correct timeout

* fmt

* address grumbles & test failure

polkadot/roadmap/implementers-guide/src/node/approval/approval-voting.md

@@ -281,7 +281,7 @@ On receiving an `ApprovedAncestor(Hash, BlockNumber, response_channel)`:
 * Load the historical validation code of the parachain by dispatching a `RuntimeApiRequest::ValidationCodeByHash(descriptor.validation_code_hash)` against the state of `block_hash`.
 * Spawn a background task with a clone of `background_tx`
   * Wait for the available data
-  * Issue a `CandidateValidationMessage::ValidateFromExhaustive` message
+  * Issue a `CandidateValidationMessage::ValidateFromExhaustive` message with `APPROVAL_EXECUTION_TIMEOUT` as the timeout parameter.
   * Wait for the result of validation
   * Check that the result of validation, if valid, matches the commitments in the receipt.
   * If valid, issue a message on `background_tx` detailing the request.

polkadot/roadmap/implementers-guide/src/node/backing/candidate-backing.md

@@ -123,7 +123,7 @@ Dispatch a [`AvailabilityDistributionMessage`][ADM]`::FetchPoV{ validator_index,
 ### Validate PoV Block
 
 Create a `(sender, receiver)` pair.
-Dispatch a `CandidateValidationMessage::Validate(validation function, candidate, pov, sender)` and listen on the receiver for a response.
+Dispatch a `CandidateValidationMessage::Validate(validation function, candidate, pov, BACKING_EXECUTION_TIMEOUT, sender)` and listen on the receiver for a response.
 
 ### Distribute Signed Statement
 

polkadot/roadmap/implementers-guide/src/node/disputes/dispute-participation.md

@@ -48,7 +48,7 @@ Conclude.
 * If the data is recovered, dispatch a [`RuntimeApiMessage::ValidationCodeByHash`][RuntimeApiMessage] with the parameters `(candidate_receipt.descriptor.validation_code_hash)` at `state.recent_block.hash`.
 * Dispatch a [`AvailabilityStoreMessage::StoreAvailableData`][AvailabilityStoreMessage] with the data.
 * If the code is not fetched from the chain, return. This should be impossible with correct relay chain configuration, at least if chain synchronization is working correctly.
-* Dispatch a [`CandidateValidationMessage::ValidateFromExhaustive`][CandidateValidationMessage] with the available data and the validation code.
+* Dispatch a [`CandidateValidationMessage::ValidateFromExhaustive`][CandidateValidationMessage] with the available data and the validation code and `APPROVAL_EXECUTION_TIMEOUT` as the timeout parameter.
 * If the validation result is `Invalid`, [cast invalid votes](#cast-votes) and return.
 * If the validation fails, [cast invalid votes](#cast-votes) and return.
 * If the validation succeeds, compute the `CandidateCommitments` based on the validation result and compare against the candidate receipt's `commitments_hash`. If they match, [cast valid votes](#cast-votes) and if not, [cast invalid votes](#cast-votes).

polkadot/roadmap/implementers-guide/src/types/overseer-protocol.md

@@ -785,6 +785,9 @@ enum ValidationResult {
     Invalid,
 }
 
+const BACKING_EXECUTION_TIMEOUT: Duration = 2 seconds;
+const APPROVAL_EXECUTION_TIMEOUT: Duration = 6 seconds;
+
 /// Messages received by the Validation subsystem.
 ///
 /// ## Validation Requests
@@ -807,6 +810,7 @@ pub enum CandidateValidationMessage {
     ValidateFromChainState(
         CandidateDescriptor,
         Arc<PoV>,
+        Duration, // Execution timeout.
         oneshot::Sender<Result<ValidationResult, ValidationFailed>>,
     ),
     /// Validate a candidate with provided, exhaustive parameters for validation.
@@ -823,6 +827,7 @@ pub enum CandidateValidationMessage {
         ValidationCode,
         CandidateDescriptor,
         Arc<PoV>,
+        Duration, // Execution timeout.
         oneshot::Sender<Result<ValidationResult, ValidationFailed>>,
     ),
 }