Preserve artifact cache unless stale (#1918)

Co-authored-by: Marcin S <marcin@realemail.net>

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

@@ -14,16 +14,24 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
-use crate::prepare::PrepareStats;
+use crate::prepare::{PrepareSuccess, PrepareWorkerSuccess};
 use parity_scale_codec::{Decode, Encode};
 use std::fmt;
 
-/// Result of PVF preparation performed by the validation host. Contains stats about the preparation
-/// if successful
-pub type PrepareResult = Result<PrepareStats, PrepareError>;
+/// Result of PVF preparation from a worker, with checksum of the compiled PVF and stats of the
+/// preparation if successful.
+pub type PrepareWorkerResult = Result<PrepareWorkerSuccess, PrepareError>;
+
+/// Result of PVF preparation propagated all the way back to the host, with path to the concluded
+/// artifact and stats of the preparation if successful.
+pub type PrepareResult = Result<PrepareSuccess, PrepareError>;
+
+/// Result of prechecking PVF performed by the validation host. Contains stats about the preparation
+/// if successful.
+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` below)
+// Codec indexes are intended to stabilize pre-encoded payloads (see `OOM_PAYLOAD`)
 #[derive(Debug, Clone, Encode, Decode)]
 pub enum PrepareError {
 	/// During the prevalidation stage of preparation an issue was found with the PVF.

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

@@ -31,6 +31,8 @@ pub use sp_tracing;
 
 const LOG_TARGET: &str = "parachain::pvf-common";
 
+pub const RUNTIME_VERSION: &str = env!("SUBSTRATE_WASMTIME_VERSION");
+
 use std::{
 	io::{self, Read, Write},
 	mem,

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

@@ -15,6 +15,25 @@
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
 use parity_scale_codec::{Decode, Encode};
+use std::path::PathBuf;
+
+/// Result from prepare worker if successful.
+#[derive(Debug, Clone, Default, Encode, Decode)]
+pub struct PrepareWorkerSuccess {
+	/// Checksum of the compiled PVF.
+	pub checksum: String,
+	/// Stats of the current preparation run.
+	pub stats: PrepareStats,
+}
+
+/// Result of PVF preparation if successful.
+#[derive(Debug, Clone, Default)]
+pub struct PrepareSuccess {
+	/// Canonical path to the compiled artifact.
+	pub path: PathBuf,
+	/// Stats of the current preparation run.
+	pub stats: PrepareStats,
+}
 
 /// Preparation statistics, including the CPU time and memory taken.
 #[derive(Debug, Clone, Default, Encode, Decode)]

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

@@ -115,7 +115,7 @@ impl fmt::Debug for PvfPrepData {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		write!(
 			f,
-			"Pvf {{ code, code_hash: {:?}, executor_params: {:?}, prep_timeout: {:?} }}",
+			"Pvf {{ code: [...], code_hash: {:?}, executor_params: {:?}, prep_timeout: {:?} }}",
 			self.code_hash, self.executor_params, self.prep_timeout
 		)
 	}