From 2b71f8cbe83fb88f1a2de14d54898087181228c8 Mon Sep 17 00:00:00 2001
From: Aaron Jacobs <jacobsa@google.com>
Date: Thu, 21 May 2015 15:19:39 +1000
Subject: [PATCH] PosixTest.MkdirInParallel

---
 samples/memfs/posix_test.go | 59 +++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/samples/memfs/posix_test.go b/samples/memfs/posix_test.go
index 1052814..efb5da2 100644
--- a/samples/memfs/posix_test.go
+++ b/samples/memfs/posix_test.go
@@ -30,6 +30,7 @@ import (
 
 	"golang.org/x/net/context"
 
+	"github.com/jacobsa/fuse/fusetesting"
 	"github.com/jacobsa/gcloud/syncutil"
 	. "github.com/jacobsa/oglematchers"
 	. "github.com/jacobsa/ogletest"
@@ -268,6 +269,60 @@ func runCreateInParallelTest_Exclusive(
 	}
 }
 
+func runMkdirInParallelTest(
+	ctx context.Context,
+	dir string) {
+	// Ensure that we get parallelism for this test.
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(runtime.NumCPU()))
+
+	// Try for awhile to see if anything breaks.
+	const duration = 500 * time.Millisecond
+	startTime := time.Now()
+	for time.Since(startTime) < duration {
+		filename := path.Join(dir, "foo")
+
+		// Set up a function that creates the directory, ignoring EEXIST errors.
+		worker := func(id byte) (err error) {
+			err = os.Mkdir(filename, 0700)
+
+			if os.IsExist(err) {
+				err = nil
+			}
+
+			if err != nil {
+				err = fmt.Errorf("Worker %d: Mkdir: %v", id, err)
+				return
+			}
+
+			return
+		}
+
+		// Run several workers in parallel.
+		const numWorkers = 16
+		b := syncutil.NewBundle(ctx)
+		for i := 0; i < numWorkers; i++ {
+			id := byte(i)
+			b.Add(func(ctx context.Context) (err error) {
+				err = worker(id)
+				return
+			})
+		}
+
+		err := b.Join()
+		AssertEq(nil, err)
+
+		// The directory should have been created, once.
+		entries, err := fusetesting.ReadDirPicky(dir)
+		AssertEq(nil, err)
+		AssertEq(1, len(entries))
+		AssertEq("foo", entries[0].Name())
+
+		// Delete the directory.
+		err = os.Remove(filename)
+		AssertEq(nil, err)
+	}
+}
+
 ////////////////////////////////////////////////////////////////////////
 // Boilerplate
 ////////////////////////////////////////////////////////////////////////
@@ -661,3 +716,7 @@ func (t *PosixTest) CreateInParallel_Truncate() {
 func (t *PosixTest) CreateInParallel_Exclusive() {
 	runCreateInParallelTest_Exclusive(t.ctx, t.dir)
 }
+
+func (t *PosixTest) MkdirInParallel() {
+	runMkdirInParallelTest(t.ctx, t.dir)
+}