[BZ-4214] ACE_File_Lock constructed on already-locked file fails lock forever, even after it's freed #4214
Description
| Field | Value |
|---|---|
| Bugzilla ID | 4214 |
| Reporter | @shuston |
| Assigned to | DOC Center Support List (internal) |
| Product | ACE |
| Component | ACE Core |
| Version | 6.3.0 |
| Platform / OS | x86 / Windows NT |
| Priority | P3 |
| Severity | normal |
| Status | NEW |
| Resolution | |
| Created | 2016-06-07 14:08:18 -0500 |
Originally posted by @shuston on 2016-06-07 14:08:18 -0500
From John Lilley:
On Windows, if a thread attempts to create an ACE_File_Lock while another thread already has the file write-locked, it results in an error. But the error is simply printed to the console:
ACE_File_Lock::ACE_File_Lock: Permission denied E:\DataManagement\RPDM\Server\unit_tests\SystemLockTest.lock
No exception is thrown, but from then on, the TryLock() method will always fail, even after the other thread has released the lock.
The problem is here:
ACE_File_Lock::ACE_File_Lock (ACE_HANDLE h,
bool unlink_in_destructor)
: removed_ (false),
unlink_in_destructor_ (unlink_in_destructor)
{
// ACE_TRACE ("ACE_File_Lock::ACE_File_Lock");
if (ACE_OS::flock_init (&this->lock_) == -1)
ACELIB_ERROR ((LM_ERROR,
ACE_TEXT ("%p\n"),
ACE_TEXT ("ACE_File_Lock::ACE_File_Lock")));
this->set_handle (h);
}
The handle gets set as ACE_INVALID_HANDLE. Fortunately, there is simple workaround. I create the ACE_File_Lock and call TryLock() all at once, and if TryLock fails I destruct the ACE_File_Lock until next attempt.