From bb33a59d2668aefbec58a7425ab851b4db2d982a Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 6 Nov 2021 11:51:11 +0100
Subject: driver: return output from spawn_task() for skipped tasks

Preparation for pinned tasks.
---
 crates/driver/src/driver.rs | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/crates/driver/src/driver.rs b/crates/driver/src/driver.rs
index 84262ac..ebbdb36 100644
--- a/crates/driver/src/driver.rs
+++ b/crates/driver/src/driver.rs
@@ -140,6 +140,11 @@ impl<'ctx> CompletionState<'ctx> {
 	}
 }
 
+enum SpawnResult {
+	Spawned(UnixStream),
+	Skipped(TaskOutput),
+}
+
 #[derive(Debug)]
 pub struct Driver<'ctx> {
 	rdeps: HashMap<TaskRef<'ctx>, Vec<TaskRef<'ctx>>>,
@@ -267,10 +272,11 @@ impl<'ctx> Driver<'ctx> {
 		}
 	}
 
-	fn spawn_task(&self, task_ref: &TaskRef<'ctx>, runner: &Runner) -> Result<Option<UnixStream>> {
+	fn spawn_task(&self, task_ref: &TaskRef<'ctx>, runner: &Runner) -> Result<SpawnResult> {
 		let task_def = &self.state.ctx[task_ref];
 		if task_def.action.is_empty() {
-			return Ok(None);
+			println!("Skipping empty task {:#}", task_ref);
+			return Ok(SpawnResult::Skipped(TaskOutput::default()));
 		}
 
 		let task_deps = self.state.task_deps(task_ref)?;
@@ -310,18 +316,20 @@ impl<'ctx> Driver<'ctx> {
 			pins: HashMap::from([rootfs.clone()]),
 		};
 
-		Ok(Some(runner.spawn(&task)))
+		Ok(SpawnResult::Spawned(runner.spawn(&task)))
 	}
 
 	fn run_task(&mut self, task_ref: TaskRef<'ctx>, runner: &Runner) -> Result<()> {
-		if let Some(socket) = self.spawn_task(&task_ref, runner)? {
-			assert!(self
-				.tasks_running
-				.insert(socket.as_raw_fd(), (socket, task_ref))
-				.is_none());
-		} else {
-			println!("Skipping empty task {:#}", task_ref);
-			self.update_runnable(task_ref, TaskOutput::default());
+		match self.spawn_task(&task_ref, runner)? {
+			SpawnResult::Spawned(socket) => {
+				assert!(self
+					.tasks_running
+					.insert(socket.as_raw_fd(), (socket, task_ref))
+					.is_none());
+			}
+			SpawnResult::Skipped(result) => {
+				self.update_runnable(task_ref, result);
+			}
 		}
 		Ok(())
 	}
-- 
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