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Corinna Vinschen 63b503916d Cygwin: tls_pathbuf: Use Windows heap
Rather than using malloc/free for the buffers, we're now using
HeapAlloc/HeapFree on a HEAP_NO_SERIALIZE heap created for this
thread.

Advantages:
- Less contention. Our malloc/free doesn't scale well in
  multithreaded scenarios
- Even faster heap allocation by using a non serialized heap.
- Internal, local, temporary data not cluttering the user heap.
- Internal, local, temporary data not copied over to child process
  at fork().

Disadvantage:
- A forked process has to start allocating temporary buffers from
  scratch.  However, this should be alleviated by the fact that
  buffer allocation usually reaches its peak very early in process
  runtime, so the longer the proceess runs, the less buffers have
  to allocated, and, only few processes don't exec after fork
  anyway.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2022-08-23 12:09:44 +02:00

159 lines
3.6 KiB
C++

/* cygtls.cc
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#include "winsup.h"
#define USE_SYS_TYPES_FD_SET
#include "cygtls.h"
#include <syslog.h>
#include <stdlib.h>
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "create_posix_thread.h"
#include "cygheap.h"
#include "sigproc.h"
#include "exception.h"
/* Two calls to get the stack right... */
void
_cygtls::call (DWORD (*func) (void *, void *), void *arg)
{
char buf[__CYGTLS_PADSIZE__];
/* Initialize this thread's ability to respond to things like
SIGSEGV or SIGFPE. */
exception protect;
_my_tls.call2 (func, arg, buf);
}
void
_cygtls::call2 (DWORD (*func) (void *, void *), void *arg, void *buf)
{
/* If func is pthread_wrapper, the final stack hasn't been set up yet.
This only happens in pthread_wrapper itself. Thus it doesn't make
sense to call init_thread or perform BLODA detection. pthread_wrapper
eventually calls init_thread by itself. */
if ((void *) func != (void *) pthread_wrapper)
init_thread (buf, func);
DWORD res = func (arg, buf);
remove (INFINITE);
/* Don't call ExitThread on the main thread since we may have been
dynamically loaded. */
if ((void *) func != (void *) dll_crt0_1
&& (void *) func != (void *) dll_dllcrt0_1)
ExitThread (res);
}
void
_cygtls::init_thread (void *x, DWORD (*func) (void *, void *))
{
if (x)
{
memset (this, 0, sizeof (*this));
_REENT_INIT_PTR (&local_clib);
stackptr = stack;
altstack.ss_flags = SS_DISABLE;
if (_REENT_CLEANUP(_GLOBAL_REENT))
local_clib.__cleanup = _cygtls::cleanup_early;
}
thread_id = GetCurrentThreadId ();
initialized = CYGTLS_INITIALIZED;
errno_addr = &(local_clib._errno);
locals.cw_timer = NULL;
locals.pathbufs.clear ();
if ((void *) func == (void *) cygthread::stub
|| (void *) func == (void *) cygthread::simplestub)
return;
cygheap->add_tls (this);
}
void
_cygtls::fixup_after_fork ()
{
if (sig)
{
pop ();
sig = 0;
}
stacklock = spinning = 0;
signal_arrived = NULL;
locals.select.sockevt = NULL;
locals.cw_timer = NULL;
locals.pathbufs.clear ();
wq.thread_ev = NULL;
}
#define free_local(x) \
if (locals.x) \
{ \
free (locals.x); \
locals.x = NULL; \
}
void
_cygtls::remove (DWORD wait)
{
initialized = 0;
if (exit_state >= ES_FINAL)
return;
debug_printf ("wait %u", wait);
HANDLE mutex = cygheap->remove_tls (this);
remove_wq (wait);
/* FIXME: Need some sort of atthreadexit function to allow things like
select to control this themselves. */
remove_pending_sigs ();
if (signal_arrived)
{
HANDLE h = signal_arrived;
signal_arrived = NULL;
CloseHandle (h);
}
/* Close handle and free memory used by select. */
if (locals.select.sockevt)
{
CloseHandle (locals.select.sockevt);
locals.select.sockevt = NULL;
free_local (select.ser_num);
free_local (select.w4);
}
/* Free memory used by network functions. */
free_local (ntoa_buf);
free_local (protoent_buf);
free_local (servent_buf);
free_local (hostent_buf);
/* Free temporary TLS path buffers. */
locals.pathbufs.destroy ();
/* Close timer handle. */
if (locals.cw_timer)
NtClose (locals.cw_timer);
if (mutex)
{
ReleaseMutex (mutex);
CloseHandle (mutex);
}
}
void
_cygtls::cleanup_early (struct _reent *)
{
/* Do nothing */
}
void san::leave ()
{
/* Restore tls_pathbuf counters in case of error. */
_my_tls.locals.pathbufs._counters = _cnt;
_my_tls.andreas = _clemente;
}