File 0001-osutil-honor-SNAPD_UNSAFE_IO-for-testing.p... of Package snapd

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File 0001-osutil-honor-SNAPD_UNSAFE_IO-for-testing.patch of Package snapd (Revision c471c4433a9609a1c92bc1dd75c9c632)

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From 177474195ad05ea1b433f9f1eb3fb82b01e1ecb3 Mon Sep 17 00:00:00 2001
From: Zygmunt Krynicki <me@zygoon.pl>
Date: Mon, 14 Aug 2017 15:06:42 +0200
Subject: [PATCH] osutil: honor SNAPD_UNSAFE_IO for testing

When SNAPD_UNSAFE_IO is set and we are testing (the executable ends with
.test) then skip some sync calls that are very very heavy. Doing this
can easily cut the timy by an order of magnitude.

As a non-scientific but useful measurement, overlord tests go down from
2 minutes 41 seconds to just 15 seconds. This is not representative to
all modules but when it matters, it is noticeable.

zyga@faroe:~/snapd/overlord> time SNAPD_UNSAFE_IO=0 go test
OK: 41 passed
PASS
ok  	github.com/snapcore/snapd/overlord	156.342s

real	2m41,765s
user	0m12,964s
sys	0m7,061s

zyga@faroe:~/snapd/overlord> time SNAPD_UNSAFE_IO=1 go test
OK: 41 passed
PASS
ok  	github.com/snapcore/snapd/overlord	9.963s

real	0m15,380s
user	0m12,217s
sys	0m1,626s

Signed-off-by: Zygmunt Krynicki <me@zygoon.pl>
---
 osutil/io.go | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/osutil/io.go b/osutil/io.go
index eecb8ec62..2aea2227b 100644
--- a/osutil/io.go
+++ b/osutil/io.go
@@ -23,6 +23,7 @@ import (
 	"errors"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/snapcore/snapd/strutil"
 )
@@ -91,13 +92,29 @@ func AtomicWriteFileChown(filename string, data []byte, perm os.FileMode, flags
 		return errors.New("internal error: AtomicWriteFileChown needs none or both of uid and gid set")
 	}
 
-	if err := fd.Sync(); err != nil {
-		return err
+	if shouldReallySync {
+		if err := fd.Sync(); err != nil {
+			return err
+		}
 	}
 
 	if err := os.Rename(tmp, filename); err != nil {
 		return err
 	}
 
-	return dir.Sync()
+	if shouldReallySync {
+		return dir.Sync()
+	}
+	return nil
+}
+
+// Allow disabling sync for testing. This brings massive improvements on
+// certain filesystems (like btrfs) and very much noticeable improvements in
+// all unit tests in genreal.
+var shouldReallySync bool = true
+
+func init() {
+	if len(os.Args) > 0 && strings.HasSuffix(os.Args[0], ".test") && GetenvBool("SNAPD_UNSAFE_IO") {
+		shouldReallySync = false
+	}
 }
-- 
2.14.0

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File 0001-osutil-honor-SNAPD_UNSAFE_IO-for-testing.patch of Package snapd (Revision c471c4433a9609a1c92bc1dd75c9c632)

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