[ovs-dev] [threads 08/23] dirs: Make thread-safe.

[Alex Wang]

Thanks Ben for the explanation,


On Mon, Jul 22, 2013 at 10:37 AM, Ben Pfaff <blp at nicira.com> wrote:

> Yes.
>
> On Mon, Jul 22, 2013 at 10:25:09AM -0700, Alex Wang wrote:
> > Seems I understand now,
> >
> > Is that for directing all error messages to corresponding lines in
> > "lib/dirs.c.in"?
> >
> >
> > On Mon, Jul 22, 2013 at 10:20 AM, Alex Wang <alexw at nicira.com> wrote:
> >
> > > Looks good to me,
> > >
> > > One question, why do we have the "#line directive" in "lib/dirs.c.in"?
> > > We have already created "dirs.c" in "lib/automake.mk". What is the
> > > use of "#line directive" here?
> > >
> > >
> > > Thanks,
> > >
> > >
> > > On Thu, Jul 18, 2013 at 4:15 PM, Ben Pfaff <blp at nicira.com> wrote:
> > >
> > >> Signed-off-by: Ben Pfaff <blp at nicira.com>
> > >> ---
> > >>  lib/dirs.c.in |   37 +++++++++++++++++++++++++++++--------
> > >>  1 files changed, 29 insertions(+), 8 deletions(-)
> > >>
> > >> diff --git a/lib/dirs.c.in b/lib/dirs.c.in
> > >> index 658a74b..85c49ee 100644
> > >> --- a/lib/dirs.c.in
> > >> +++ b/lib/dirs.c.in
> > >> @@ -1,6 +1,6 @@
> > >>  #line 2 "@srcdir@/lib/dirs.c.in"
> > >>  /*
> > >> - * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
> > >> + * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
> > >>   *
> > >>   * Licensed under the Apache License, Version 2.0 (the "License");
> > >>   * you may not use this file except in compliance with the License.
> > >> @@ -18,22 +18,25 @@
> > >>  #include <config.h>
> > >>  #include "dirs.h"
> > >>  #include <stdlib.h>
> > >> +#include "ovs-thread.h"
> > >>  #include "util.h"
> > >>
> > >>  struct directory {
> > >>      const char *value;          /* Actual value; NULL if not yet
> > >> determined. */
> > >>      const char *default_value;  /* Default value. */
> > >>      const char *var_name;       /* Environment variable to override
> > >> default. */
> > >> +    struct ovsthread_once once; /* Ensures 'value' gets initialized
> > >> once. */
> > >>  };
> > >>
> > >>  static const char *
> > >>  get_dir(struct directory *d)
> > >>  {
> > >> -    if (!d->value) {
> > >> +    if (ovsthread_once_start(&d->once)) {
> > >>          d->value = getenv(d->var_name);
> > >>          if (!d->value || !d->value[0]) {
> > >>              d->value = d->default_value;
> > >>          }
> > >> +        ovsthread_once_done(&d->once);
> > >>      }
> > >>      return d->value;
> > >>  }
> > >> @@ -41,36 +44,50 @@ get_dir(struct directory *d)
> > >>  const char *
> > >>  ovs_sysconfdir(void)
> > >>  {
> > >> -    static struct directory d = { NULL, @sysconfdir@,
> "OVS_SYSCONFDIR"
> > >> };
> > >> +    static struct directory d = {
> > >> +        NULL, @sysconfdir@, "OVS_SYSCONFDIR",
> OVSTHREAD_ONCE_INITIALIZER
> > >> +    };
> > >> +
> > >>      return get_dir(&d);
> > >>  }
> > >>
> > >>  const char *
> > >>  ovs_pkgdatadir(void)
> > >>  {
> > >> -    static struct directory d = { NULL, @pkgdatadir@,
> "OVS_PKGDATADIR"
> > >> };
> > >> +    static struct directory d = {
> > >> +        NULL, @pkgdatadir@, "OVS_PKGDATADIR",
> OVSTHREAD_ONCE_INITIALIZER
> > >> +    };
> > >> +
> > >>      return get_dir(&d);
> > >>  }
> > >>
> > >>  const char *
> > >>  ovs_rundir(void)
> > >>  {
> > >> -    static struct directory d = { NULL, @RUNDIR@, "OVS_RUNDIR" };
> > >> +    static struct directory d = {
> > >> +        NULL, @RUNDIR@, "OVS_RUNDIR", OVSTHREAD_ONCE_INITIALIZER
> > >> +    };
> > >> +
> > >>      return get_dir(&d);
> > >>  }
> > >>
> > >>  const char *
> > >>  ovs_logdir(void)
> > >>  {
> > >> -    static struct directory d = { NULL, @LOGDIR@, "OVS_LOGDIR" };
> > >> +    static struct directory d = {
> > >> +        NULL, @LOGDIR@, "OVS_LOGDIR", OVSTHREAD_ONCE_INITIALIZER
> > >> +    };
> > >> +
> > >>      return get_dir(&d);
> > >>  }
> > >>
> > >>  const char *
> > >>  ovs_dbdir(void)
> > >>  {
> > >> +    static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
> > >>      static const char *dbdir;
> > >> -    if (!dbdir) {
> > >> +
> > >> +    if (ovsthread_once_start(&once)) {
> > >>          dbdir = getenv("OVS_DBDIR");
> > >>          if (!dbdir || !dbdir[0]) {
> > >>              char *sysconfdir = getenv("OVS_SYSCONFDIR");
> > >> @@ -79,6 +96,7 @@ ovs_dbdir(void)
> > >>                       ? xasprintf("%s/openvswitch", sysconfdir)
> > >>                       : @DBDIR@);
> > >>          }
> > >> +        ovsthread_once_done(&once);
> > >>      }
> > >>      return dbdir;
> > >>  }
> > >> @@ -86,6 +104,9 @@ ovs_dbdir(void)
> > >>  const char *
> > >>  ovs_bindir(void)
> > >>  {
> > >> -    static struct directory d = { NULL, @bindir@, "OVS_BINDIR" };
> > >> +    static struct directory d = {
> > >> +        NULL, @bindir@, "OVS_BINDIR", OVSTHREAD_ONCE_INITIALIZER
> > >> +    };
> > >> +
> > >>      return get_dir(&d);
> > >>  }
> > >> --
> > >> 1.7.2.5
> > >>
> > >> _______________________________________________
> > >> dev mailing list
> > >> dev at openvswitch.org
> > >> http://openvswitch.org/mailman/listinfo/dev
> > >>
> > >
> > >
>
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