Re: [Tarantool-patches] [PATCH 1/3] wal: sanitize wal_mode

[Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

On Fri, Apr 23, 2021 at 10:57:11PM +0200, Vladislav Shpilevoy wrote:
> Hi! Thanks for the patch!
> 
> > diff --git a/src/box/wal.h b/src/box/wal.h
> > index a8a16ba2e..470aa1cc8 100644
> > --- a/src/box/wal.h
> > +++ b/src/box/wal.h
> > @@ -41,7 +41,29 @@ struct fiber;
> >  struct wal_writer;
> >  struct tt_uuid;
> >  
> > -enum wal_mode { WAL_NONE = 0, WAL_WRITE, WAL_FSYNC, WAL_MODE_MAX };
> > +enum wal_mode {
> > +	/**
> > +	 * Do not write data at all.
> > +	 */
> > +	WAL_NONE,
> > +
> > +	/**
> > +	 * Write without waiting the data to be
> > +	 * flushed to the storage device.
> > +	 */
> > +	WAL_WRITE,
> > +
> > +	/**
> > +	 * Write data and wait the record to be
> > +	 * flushed to the storage device.
> > +	 */
> > +	WAL_FSYNC,
> > +
> > +	WAL_MODE_MAX
> > +};
> > +
> > +/** String constants for the supported modes. */
> > +extern const char *wal_mode_STRS[WAL_MODE_MAX];
> 
> 1. Why do you need to declare in the header the array size?
> The old version with [] was just fine. And less places to change
> if becomes necessary.

If the size is known better to point it explicitly. Thus when you
read this code you will notise the array size (yes, it doesn't
matter from compiler pov if we declare it as a double pointer
but still). But fine I'll leave this declaration untouched.

> 
> 2. Please, keep the global variable where it was. We usually group
> global variable declarations. It was grouped with wal_dir_lock
> below.
---
From: Cyrill Gorcunov <gorcunov@gmail.com>
Date: Fri, 16 Apr 2021 15:54:52 +0300
Subject: [PATCH] wal: sanitize wal_mode

 - there is no need to set WAN_NONE to 0 explicitly
 - add comments about modes
 - there is no need to carry NULL in wal_mode_STRS
 - use designated assignment in wal_mode_STRS

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 src/box/wal.c |  6 +++++-
 src/box/wal.h | 21 ++++++++++++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/box/wal.c b/src/box/wal.c
index 5b6200b81..6468df884 100644
--- a/src/box/wal.c
+++ b/src/box/wal.c
@@ -55,7 +55,11 @@ enum {
 	WAL_FALLOCATE_LEN = 1024 * 1024,
 };
 
-const char *wal_mode_STRS[] = { "none", "write", "fsync", NULL };
+const char *wal_mode_STRS[WAL_MODE_MAX] = {
+	[WAL_NONE]	= "none",
+	[WAL_WRITE]	= "write",
+	[WAL_FSYNC]	= "fsync",
+};
 
 int wal_dir_lock = -1;
 
diff --git a/src/box/wal.h b/src/box/wal.h
index a8a16ba2e..36fcd39bd 100644
--- a/src/box/wal.h
+++ b/src/box/wal.h
@@ -41,7 +41,26 @@ struct fiber;
 struct wal_writer;
 struct tt_uuid;
 
-enum wal_mode { WAL_NONE = 0, WAL_WRITE, WAL_FSYNC, WAL_MODE_MAX };
+enum wal_mode {
+	/**
+	 * Do not write data at all.
+	 */
+	WAL_NONE,
+
+	/**
+	 * Write without waiting the data to be
+	 * flushed to the storage device.
+	 */
+	WAL_WRITE,
+
+	/**
+	 * Write data and wait the record to be
+	 * flushed to the storage device.
+	 */
+	WAL_FSYNC,
+
+	WAL_MODE_MAX
+};
 
 enum {
 	/**
-- 
2.30.2