Pvf thiserror (#2958)

resolve #2157 

- [x] fix broken doc links
- [x] fix codec macro typo
https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/node/core/pvf/common/src/error.rs#L81
(see the comment below)
- [x] refactor `ValidationError`, `PrepareError` and related error types
to use `thiserror` crate

## `codec` issue

`codec` macro was mistakenly applied two times to `Kernel` error (so it
was encoded with 10 instead of 11 and the same as `JobDied`). The PR
changes it to 11 because

- it was an initial goal of the code author
- Kernel is less frequent than JobDied so in case of existing error
encoding it is more probable to have 10 as JobDied than Kernel

See https://github.com/paritytech/parity-scale-codec/issues/555

----
polkadot address: 13zCyRG2a1W2ih5SioL8byqmQ6mc8vkgFwQgVzJSdRUUmp46

---------

Co-authored-by: s0me0ne-unkn0wn <48632512+s0me0ne-unkn0wn@users.noreply.github.com>

polkadot/node/core/pvf/common/src/error.rs

@@ -16,7 +16,6 @@
 
 use crate::prepare::{PrepareSuccess, PrepareWorkerSuccess};
 use parity_scale_codec::{Decode, Encode};
-use std::fmt;
 
 /// Result of PVF preparation from a worker, with checksum of the compiled PVF and stats of the
 /// preparation if successful.
@@ -32,35 +31,43 @@ pub type PrecheckResult = Result<(), PrepareError>;
 
 /// An error that occurred during the prepare part of the PVF pipeline.
 // Codec indexes are intended to stabilize pre-encoded payloads (see `OOM_PAYLOAD`)
-#[derive(Debug, Clone, Encode, Decode)]
+#[derive(thiserror::Error, Debug, Clone, Encode, Decode)]
 pub enum PrepareError {
 	/// During the prevalidation stage of preparation an issue was found with the PVF.
 	#[codec(index = 0)]
+	#[error("prepare: prevalidation error: {0}")]
 	Prevalidation(String),
 	/// Compilation failed for the given PVF.
 	#[codec(index = 1)]
+	#[error("prepare: preparation error: {0}")]
 	Preparation(String),
 	/// Instantiation of the WASM module instance failed.
 	#[codec(index = 2)]
+	#[error("prepare: runtime construction: {0}")]
 	RuntimeConstruction(String),
 	/// An unexpected error has occurred in the preparation job.
 	#[codec(index = 3)]
+	#[error("prepare: job error: {0}")]
 	JobError(String),
 	/// Failed to prepare the PVF due to the time limit.
 	#[codec(index = 4)]
+	#[error("prepare: timeout")]
 	TimedOut,
 	/// An IO error occurred. This state is reported by either the validation host or by the
 	/// worker.
 	#[codec(index = 5)]
+	#[error("prepare: io error while receiving response: {0}")]
 	IoErr(String),
 	/// The temporary file for the artifact could not be created at the given cache path. This
 	/// state is reported by the validation host (not by the worker).
 	#[codec(index = 6)]
+	#[error("prepare: error creating tmp file: {0}")]
 	CreateTmpFile(String),
 	/// The response from the worker is received, but the file cannot be renamed (moved) to the
 	/// final destination location. This state is reported by the validation host (not by the
 	/// worker).
 	#[codec(index = 7)]
+	#[error("prepare: error renaming tmp file ({src:?} -> {dest:?}): {err}")]
 	RenameTmpFile {
 		err: String,
 		// Unfortunately `PathBuf` doesn't implement `Encode`/`Decode`, so we do a fallible
@@ -70,17 +77,21 @@ pub enum PrepareError {
 	},
 	/// Memory limit reached
 	#[codec(index = 8)]
+	#[error("prepare: out of memory")]
 	OutOfMemory,
 	/// The response from the worker is received, but the worker cache could not be cleared. The
 	/// worker has to be killed to avoid jobs having access to data from other jobs. This state is
 	/// reported by the validation host (not by the worker).
 	#[codec(index = 9)]
+	#[error("prepare: error clearing worker cache: {0}")]
 	ClearWorkerDir(String),
 	/// The preparation job process died, due to OOM, a seccomp violation, or some other factor.
-	JobDied { err: String, job_pid: i32 },
 	#[codec(index = 10)]
+	#[error("prepare: prepare job with pid {job_pid} died: {err}")]
+	JobDied { err: String, job_pid: i32 },
 	/// Some error occurred when interfacing with the kernel.
 	#[codec(index = 11)]
+	#[error("prepare: error interfacing with the kernel: {0}")]
 	Kernel(String),
 }
 
@@ -109,41 +120,23 @@ impl PrepareError {
 	}
 }
 
-impl fmt::Display for PrepareError {
-	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-		use PrepareError::*;
-		match self {
-			Prevalidation(err) => write!(f, "prevalidation: {}", err),
-			Preparation(err) => write!(f, "preparation: {}", err),
-			RuntimeConstruction(err) => write!(f, "runtime construction: {}", err),
-			JobError(err) => write!(f, "panic: {}", err),
-			TimedOut => write!(f, "prepare: timeout"),
-			IoErr(err) => write!(f, "prepare: io error while receiving response: {}", err),
-			JobDied { err, job_pid } =>
-				write!(f, "prepare: prepare job with pid {job_pid} died: {err}"),
-			CreateTmpFile(err) => write!(f, "prepare: error creating tmp file: {}", err),
-			RenameTmpFile { err, src, dest } =>
-				write!(f, "prepare: error renaming tmp file ({:?} -> {:?}): {}", src, dest, err),
-			OutOfMemory => write!(f, "prepare: out of memory"),
-			ClearWorkerDir(err) => write!(f, "prepare: error clearing worker cache: {}", err),
-			Kernel(err) => write!(f, "prepare: error interfacing with the kernel: {}", err),
-		}
-	}
-}
-
 /// Some internal error occurred.
 ///
 /// Should only ever be used for validation errors independent of the candidate and PVF, or for
 /// errors we ruled out during pre-checking (so preparation errors are fine).
-#[derive(Debug, Clone, Encode, Decode)]
+#[derive(thiserror::Error, Debug, Clone, Encode, Decode)]
 pub enum InternalValidationError {
 	/// Some communication error occurred with the host.
+	#[error("validation: some communication error occurred with the host: {0}")]
 	HostCommunication(String),
 	/// Host could not create a hard link to the artifact path.
+	#[error("validation: host could not create a hard link to the artifact path: {0}")]
 	CouldNotCreateLink(String),
 	/// Could not find or open compiled artifact file.
+	#[error("validation: could not find or open compiled artifact file: {0}")]
 	CouldNotOpenFile(String),
 	/// Host could not clear the worker cache after a job.
+	#[error("validation: host could not clear the worker cache ({path:?}) after a job: {err}")]
 	CouldNotClearWorkerDir {
 		err: String,
 		// Unfortunately `PathBuf` doesn't implement `Encode`/`Decode`, so we do a fallible
@@ -151,32 +144,9 @@ pub enum InternalValidationError {
 		path: Option<String>,
 	},
 	/// Some error occurred when interfacing with the kernel.
+	#[error("validation: error interfacing with the kernel: {0}")]
 	Kernel(String),
-
 	/// Some non-deterministic preparation error occurred.
+	#[error("validation: prepare: {0}")]
 	NonDeterministicPrepareError(PrepareError),
 }
-
-impl fmt::Display for InternalValidationError {
-	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-		use InternalValidationError::*;
-		match self {
-			HostCommunication(err) =>
-				write!(f, "validation: some communication error occurred with the host: {}", err),
-			CouldNotCreateLink(err) => write!(
-				f,
-				"validation: host could not create a hard link to the artifact path: {}",
-				err
-			),
-			CouldNotOpenFile(err) =>
-				write!(f, "validation: could not find or open compiled artifact file: {}", err),
-			CouldNotClearWorkerDir { err, path } => write!(
-				f,
-				"validation: host could not clear the worker cache ({:?}) after a job: {}",
-				path, err
-			),
-			Kernel(err) => write!(f, "validation: error interfacing with the kernel: {}", err),
-			NonDeterministicPrepareError(err) => write!(f, "validation: prepare: {}", err),
-		}
-	}
-}