docs: trim comments and docs from workspace emptying change (#1403)

Follow-up to https://gitea.com/gitea/runner/commit/79faf5e55df7a3b312fb4888b7405a58e01f567c. Reverts the post-task-script doc change, which is too much detail for that page. Also shortens the `DrainGracePeriod` comment and the other comments that commit added, since the code and log messages already say most of it.

Reviewed-on: https://gitea.com/gitea/runner/pulls/1403
Reviewed-by: bircni <[email protected]>
Co-authored-by: silverwind <[email protected]>

act/container/container_types.go

@@ -25,11 +25,7 @@ import (
 
 var hostOS = runtime.GOOS // replaced in tests
 
-// DrainGracePeriod bounds how long we wait for an output-copy goroutine to
-// finish draining a container's output before returning, so that neither a
-// cancellation (waitForCommand) nor a normal container exit (wait) truncates
-// the tail of the log. It is a safety bound: in the common case the stream
-// reaches EOF and the goroutine returns well before this elapses.
+// DrainGracePeriod caps the wait for container output to drain so the log tail is not truncated
 const DrainGracePeriod = 2 * time.Second
 
 // ExitCodeError reports a non-zero process exit code from a container command.

act/runner/run_context.go

@@ -380,7 +380,7 @@ func splitVolumes(specs []string) ([]string, map[string]string, map[string]bool)
 	return binds, mounts, targets
 }
 
-// Returns the binds and mounts for the container, resolving paths as appropriate, and the task workspace the runner binds
+// Returns the container's binds, mounts and bound task workspace, resolving paths as appropriate
 func (rc *RunContext) GetBindsAndMounts(ctx context.Context) ([]string, map[string]string, string) {
 	name := rc.jobContainerName()
 	ext := container.LinuxContainerEnvironmentExtensions{}
@@ -842,7 +842,7 @@ func (rc *RunContext) cleanupJobResources(networkName string, createAndDeleteNet
 	}
 }
 
-// exits 3 unless $1 is a mountpoint in mountinfo $2, at least two levels deep, with no mount below it for rm to cross into
+// exits 3 unless workspace $1 is safe to empty per mountinfo $2
 const emptyTaskWorkspaceScript = `case "$1" in /?*/?*) ;; *) exit 3 ;; esac
 mounted=
 while read -r _ _ _ _ point _; do
@@ -851,9 +851,9 @@ done <"$2"
 [ "$mounted" ] || exit 3
 rm -rf "$1"/* "$1"/.[!.]* "$1"/..?*`
 
-var runnerCanRemoveJobFiles = runtime.GOOS != "linux" || os.Geteuid() == 0 // root, or a desktop VM mapping container files to the user, replaced in tests
+var runnerCanRemoveJobFiles = runtime.GOOS != "linux" || os.Geteuid() == 0 // root, or a desktop VM mapping file ownership, replaced in tests
 
-// empties the workspace as root, on root-owned PATH dirs only, for a runner that may not own what the job wrote, called workflows share it
+// runs as root with root-owned PATH dirs only, skipped for called workflows sharing the workspace
 func (rc *RunContext) emptyTaskWorkspace(ctx context.Context) {
 	if rc.taskWorkspace == "" || rc.caller != nil || runnerCanRemoveJobFiles {
 		return