[SYSINFRA-1419] reflow/flow: Avoid creating copy of Fileset

Summary: Use a pointer instead of value to avoid creating a copy of the resolved fileset.

Test Plan: Unit and Integration tests.

Reviewers: pboyapalli

Reviewed By: pboyapalli

Subscribers: dnicolaou

Differential Revision: https://phabricator.grailbio.com/D72110

fbshipit-source-id: 43f83e8

flow/eval.go

@@ -1714,7 +1714,7 @@ var statusPrinters = [maxOp]struct {
 				fmt.Fprintf(w, "    %s = \n", arg)
 				var fs reflow.Fileset
 				if len(f.resolvedFs) > earg.Index {
-					fs = f.resolvedFs[earg.Index]
+					fs = *f.resolvedFs[earg.Index]
 				}
 				if !fs.Empty() {
 					printFileset(w, "        ", fs)
@@ -1921,13 +1921,13 @@ func (e *Eval) taskWait(ctx context.Context, f *Flow, task *sched.Task) error {
 		// If this is an Exec and f.Argmap is defined, then
 		// update the flow's resolved filesets.
 		n := f.NExecArg()
-		f.resolvedFs = make([]reflow.Fileset, n)
+		f.resolvedFs = make([]*reflow.Fileset, n)
 		for i := 0; i < n; i++ {
 			earg, arg := f.ExecArg(i), task.Config.Args[i]
 			if earg.Out {
 				continue
 			}
-			f.resolvedFs[earg.Index] = *arg.Fileset
+			f.resolvedFs[earg.Index] = arg.Fileset
 		}
 	}
 	e.LogFlow(ctx, f)

flow/flow.go

@@ -250,7 +250,7 @@ type Flow struct {
 	// ArgMap maps exec arguments to dependencies. (OpExec).
 	Argmap []ExecArg
 	// resolvedFs maps exec arguments to resolved filesets. (OpExec).
-	resolvedFs []reflow.Fileset
+	resolvedFs []*reflow.Fileset
 	// OutputIsDir tells whether the output i is a directory.
 	OutputIsDir []bool