[review] [RFC] Don't block on finishing demangling msymbols

[Tom Tromey (Code Review)]

Tom Tromey has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/463
......................................................................


Patch Set 1:

(1 comment)

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/463/1/gdb/minsyms.c 
File gdb/minsyms.c:

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/463/1/gdb/minsyms.c@1390 
PS1, Line 1390: 
1310 | minimal_symbol_reader::install ()
     | ...
1385 |       m_objfile->per_bfd->msymbols = std::move (msym_holder);
1386 | 
1387 |       msymbols = m_objfile->per_bfd->msymbols.get ();
1388 |       objfile_per_bfd_storage* per_bfd = m_objfile->per_bfd;
1389 | 
1390 >       m_objfile->per_bfd->m_minsym_future
1391 > 	= gdb::thread_pool::g_thread_pool->post_task ([msymbols, mcount,
1392 > 						      per_bfd] ()
1393 |         {
1394 | #if CXX_STD_THREAD
1395 | 	  /* Mutex that is used when modifying or accessing the demangled
1396 | 	     hash table.  */
1397 | 	  std::mutex demangled_mutex;

> I didn't look in detail but the main possible danger here is if
> this needs any information from the minimal symbol reader, then
> it will fail since that goes out of scope.

I forgot, there's actually another danger, which is why I haven't
tried to do background psymtab reading yet.

The problem is that an objfile can possibly have a short lifetime.
So, in theory it could be deleted while the worker threads are
still running.

For psymtabs I am thinking I will convert objfiles to be managed
via shared_ptr<>.  However, this patch got a bit bogged down and
so I haven't completed it yet.



-- 
Gerrit-Project: binutils-gdb
Gerrit-Branch: master
Gerrit-Change-Id: I9d871917459ece0b41d31670b3c56600757aea66
Gerrit-Change-Number: 463
Gerrit-PatchSet: 1
Gerrit-Owner: Christian Biesinger <cbiesinger@google.com>
Gerrit-CC: Tom Tromey <tromey@sourceware.org>
Gerrit-Comment-Date: Thu, 31 Oct 2019 22:42:24 +0000
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