> On Wed, Feb 05, 2014 at 11:47:17AM +0900, YAMAMOTO Takashi wrote: >> > On Wed, Jan 15, 2014 at 12:41:20PM +0900, YAMAMOTO Takashi wrote: >> >> Add a comment about implicit synchronization which >> >> fat-rwlock seems to rely on. >> >> >> >> Signed-off-by: YAMAMOTO Takashi <yamam...@valinux.co.jp> >> >> --- >> >> lib/ovs-thread.h | 8 ++++++++ >> >> 1 file changed, 8 insertions(+) >> >> >> >> diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h >> >> index 8cf2ecc..dab7510 100644 >> >> --- a/lib/ovs-thread.h >> >> +++ b/lib/ovs-thread.h >> >> @@ -447,6 +447,14 @@ void xpthread_join(pthread_t, void **); >> >> * Compared to pthread_key_t, ovsthread_key_t has the follow limitations: >> >> * >> >> * - Destructors must not access thread-specific data (via >> >> ovsthread_key). >> >> + * >> >> + * Unlike pthread_key_t, this API implicitly serializes key removal >> >> + * (ovsthread_key_delete) and thread exit. (destructor) >> >> + * I.e. >> >> + * - ovsthread_key_delete ensures the completion of destructors for >> >> + * the key. >> >> + * - Once ovsthread_key_delete completed, no destructors for the key >> >> + * will be executed on thread exit. >> >> */ >> >> typedef struct ovsthread_key *ovsthread_key_t; >> > >> > I think I understand what you are saying, but I think that I would >> > phrase it differently. Does the following express what you mean? >> > >> > diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c >> > index a20b2fd..18e524e 100644 >> > --- a/lib/ovs-thread.c >> > +++ b/lib/ovs-thread.c >> > @@ -592,7 +592,8 @@ ovsthread_key_create(ovsthread_key_t *keyp, void >> > (*destructor)(void *)) >> > } >> > >> > /* Frees 'key'. The destructor supplied to ovsthread_key_create(), if >> > any, is >> > - * not called. >> > + * not called. This function returns only after any running destructors >> > for >> > + * 'key' complete execution. >> >> 'running destructors' is not exact. >> i believe pthread api allows for concurrent exiting threads to >> start executing the destructor after pthread_key_delete completed. >> but this ovsthread one doesn't. and fat-rwlock relies on it. >> >> i think it's better to say the difference explicitly as >> it guarantees more than pthread while using similar-looking names. >> i was confused when reading fat-rwlock. > > Do you like the following version?
looks good to me. thanks. YAMAMOTO Takashi > > --8<--------------------------cut here-------------------------->8-- > > From: Ben Pfaff <b...@nicira.com> > Date: Thu, 6 Feb 2014 17:06:00 -0800 > Subject: [PATCH] ovs-thread: Add a comment. > > Reported-by: YAMAMOTO Takashi <yamam...@valinux.co.jp> > Signed-off-by: Ben Pfaff <b...@nicira.com> > --- > lib/ovs-thread.h | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h > index 8cf2ecc..f031894 100644 > --- a/lib/ovs-thread.h > +++ b/lib/ovs-thread.h > @@ -444,9 +444,15 @@ void xpthread_join(pthread_t, void **); > * (by recompiling). Thus, one may more freely use this form of > * thread-specific data. > * > - * Compared to pthread_key_t, ovsthread_key_t has the follow limitations: > + * ovsthread_key_t also differs from pthread_key_t in the following ways: > * > * - Destructors must not access thread-specific data (via ovsthread_key). > + * > + * - The pthread_key_t API allows concurrently exiting threads to start > + * executing the destructor after pthread_key_delete() returns. The > + * ovsthread_key_t API guarantees that, when ovsthread_key_delete() > + * returns, all destructors have returned and no new ones will start > + * execution. > */ > typedef struct ovsthread_key *ovsthread_key_t; > > -- > 1.7.10.4 > > _______________________________________________ > dev mailing list > dev@openvswitch.org > http://openvswitch.org/mailman/listinfo/dev _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
