PVF: Refactor workers into separate crates, remove host dependency (#7253)

* PVF: Refactor workers into separate crates, remove host dependency

* Fix compile error

* Remove some leftover code

* Fix compile errors

* Update Cargo.lock

* Remove worker main.rs files

I accidentally copied these from the other PR. This PR isn't intended to
introduce standalone workers yet.

* Address review comments

* cargo fmt

* Update a couple of comments

* Update log targets

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

@@ -0,0 +1,94 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Various things for testing other crates.
+//!
+//! N.B. This is not guarded with some feature flag. Overexposing items here may affect the final
+//!      artifact even for production builds.
+
+#[doc(hidden)]
+pub use crate::worker_intf::{spawn_with_program_path, SpawnErr};
+
+use polkadot_primitives::ExecutorParams;
+
+/// A function that emulates the stitches together behaviors of the preparation and the execution
+/// worker in a single synchronous function.
+pub fn validate_candidate(
+	code: &[u8],
+	params: &[u8],
+) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
+	use polkadot_node_core_pvf_execute_worker::Executor;
+	use polkadot_node_core_pvf_prepare_worker::{prepare, prevalidate};
+
+	let code = sp_maybe_compressed_blob::decompress(code, 10 * 1024 * 1024)
+		.expect("Decompressing code failed");
+
+	let blob = prevalidate(&code)?;
+	let compiled_artifact_blob = prepare(blob, &ExecutorParams::default())?;
+
+	let executor = Executor::new(ExecutorParams::default())?;
+	let result = unsafe {
+		// SAFETY: This is trivially safe since the artifact is obtained by calling `prepare`
+		//         and is written into a temporary directory in an unmodified state.
+		executor.execute(&compiled_artifact_blob, params)?
+	};
+
+	Ok(result)
+}
+
+/// Use this macro to declare a `fn main() {}` that will check the arguments and dispatch them to
+/// the appropriate worker, making the executable that can be used for spawning workers.
+#[macro_export]
+macro_rules! decl_puppet_worker_main {
+	() => {
+		fn main() {
+			$crate::sp_tracing::try_init_simple();
+
+			let args = std::env::args().collect::<Vec<_>>();
+			if args.len() < 3 {
+				panic!("wrong number of arguments");
+			}
+
+			let mut version = None;
+			let mut socket_path: &str = "";
+
+			for i in 2..args.len() {
+				match args[i].as_ref() {
+					"--socket-path" => socket_path = args[i + 1].as_str(),
+					"--node-version" => version = Some(args[i + 1].as_str()),
+					_ => (),
+				}
+			}
+
+			let subcommand = &args[1];
+			match subcommand.as_ref() {
+				"exit" => {
+					std::process::exit(1);
+				},
+				"sleep" => {
+					std::thread::sleep(std::time::Duration::from_secs(5));
+				},
+				"prepare-worker" => {
+					$crate::prepare_worker_entrypoint(&socket_path, version);
+				},
+				"execute-worker" => {
+					$crate::execute_worker_entrypoint(&socket_path, version);
+				},
+				other => panic!("unknown subcommand: {}", other),
+			}
+		}
+	};
+}