From: Nadav Har'El <n...@scylladb.com>
Committer: Nadav Har'El <n...@scylladb.com>
Branch: master
pthread: implement pthread_key_delete()
Implement pthread_key_delete().
Currently, it will not mark the key available for re-use.
The danger in allowing re-use is that if we leave data with that key (the
pthread_key_delete(3P) manpage explains why this happens), we can get a new
destructor running on old unrelated data.
The not-as-great side of not re-using keys is that our current
implementation
is limited to 128 keys so we can run out of them. But this patch doesn't
make
this any worse than before.
Signed-off-by: Nadav Har'El <n...@scylladb.com>
Message-Id: <1472389371-13580-1-git-send-email-...@scylladb.com>
Reviewed-by: Benoît Canet <ben...@scylladb.com>
---
diff --git a/libc/pthread.cc b/libc/pthread.cc
--- a/libc/pthread.cc
+++ b/libc/pthread.cc
@@ -261,8 +261,19 @@ extern "C" {
int pthread_key_delete(pthread_key_t key)
{
- WARN_STUBBED();
- return EINVAL;
+ std::lock_guard<mutex> guard(tsd_key_mutex);
+ if (key < 0 || key >= (int)tsd_used_keys.size() |
| !tsd_used_keys[key]) {
+ return EINVAL;
+ }
+ tsd_dtor[key] = nullptr;
+ // TODO: Currently, we keep tsd_used_keys[key] at true so the key will
+ // not be reused. Since pthread_key_delete cannot get rid of existing
+ // data, reusing the key may causes us to later call a new destructor
+ // for old unrelated data. The cost of not reusing keys is that we can
+ // run out of them if many keys are created and deleted (e.g., a shared
+ // object is loaded and unloaded)..
+ //tsd_used_keys[key] = false;
+ return 0;
}
void* pthread_getspecific(pthread_key_t key)
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