pthreads handle (opaque) used instead of thread ID on UNIX

[IS2511]

Problematic code:

thread-id/src/lib.rs

Line 57 in b44a6e7

unsafe { libc::pthread_self() as usize }

pthread_self() actually returns a handle to the pthread thread object, not the thread id¹².

Downsides:

• Thread IDs are guaranteed to be unique only within a process.²
• Not portable outside of pthreads calls.²
• Underlying type of pthread_t is not specified in POSIX, assuming is dubious.²³

Suggested solution: syscall(SYS_gettid) or libc::gettid()⁴⁵.

Footnotes

1. https://stackoverflow.com/a/27238113 ↩

2. https://www.man7.org/linux/man-pages/man3/pthread_self.3.html#NOTES ↩ ↩² ↩³ ↩⁴

3. Also, in this case it's libc::pthread_t -> libc::c_ulong -> u64, casting to usize is... ID collision is highly unlikely, but not guaranteed. ↩

4. https://www.gnu.org/software/libc/manual/html_node/Process-Identification.html ↩

5. https://www.man7.org/linux/man-pages/man2/gettid.2.html ↩