newlib-cygwin/winsup/cygwin/cygthread.cc

460 lines
10 KiB
C++

/* cygthread.cc
Copyright 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Red Hat, Inc.
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"
#include <windows.h>
#include <stdlib.h>
#include "exceptions.h"
#include "security.h"
#include "sync.h"
#include "cygerrno.h"
#include "sigproc.h"
#include "thread.h"
#include "cygtls.h"
#undef CloseHandle
static cygthread NO_COPY threads[32];
#define NTHREADS (sizeof (threads) / sizeof (threads[0]))
DWORD NO_COPY cygthread::main_thread_id;
bool NO_COPY cygthread::exiting;
/* Initial stub called by cygthread constructor. Performs initial
per-thread initialization and loops waiting for new thread functions
to execute. */
DWORD WINAPI
cygthread::stub (VOID *arg)
{
cygthread *info = (cygthread *) arg;
_my_tls._ctinfo = info;
if (info->arg == cygself)
{
if (info->ev)
{
CloseHandle (info->ev);
CloseHandle (info->thread_sync);
}
info->ev = info->thread_sync = info->stack_ptr = NULL;
}
else
{
info->stack_ptr = &arg;
debug_printf ("thread '%s', id %p, stack_ptr %p", info->name (), info->id, info->stack_ptr);
if (!info->ev)
{
info->ev = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
info->thread_sync = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
}
}
while (1)
{
if (!info->__name)
#ifdef DEBUGGING
system_printf ("erroneous thread activation, name is NULL prev thread name = '%s'", info->__oldname);
#else
system_printf ("erroneous thread activation, name is NULL");
#endif
else
{
if (exiting)
{
info->inuse = false; // FIXME: Do we need this?
return 0;
}
/* Cygwin threads should not call ExitThread directly */
info->func (info->arg == cygself ? info : info->arg);
/* ...so the above should always return */
/* If func is NULL, the above function has set that to indicate
that it doesn't want to alert anyone with a SetEvent and should
just be marked as no longer inuse. Hopefully the function knows
that it is doing. */
if (!info->func)
info->release (false);
else
{
#ifdef DEBUGGING
info->func = NULL; // catch erroneous activation
info->__oldname = info->__name;
#endif
info->__name = NULL;
SetEvent (info->ev);
}
}
switch (WaitForSingleObject (info->thread_sync, INFINITE))
{
case WAIT_OBJECT_0:
continue;
default:
api_fatal ("WFSO failed, %E");
break;
}
}
}
/* Overflow stub called by cygthread constructor. Calls specified function
and then exits the thread. */
DWORD WINAPI
cygthread::simplestub (VOID *arg)
{
cygthread *info = (cygthread *) arg;
_my_tls._ctinfo = info;
info->stack_ptr = &arg;
info->ev = info->h;
info->func (info->arg == cygself ? info : info->arg);
return 0;
}
/* Start things going. Called from dll_crt0_1. */
void
cygthread::init ()
{
main_thread_id = GetCurrentThreadId ();
}
cygthread *
cygthread::freerange ()
{
cygthread *self = (cygthread *) calloc (1, sizeof (*self));
self->is_freerange = true;
self->inuse = 1;
return self;
}
void * cygthread::operator
new (size_t)
{
cygthread *info;
/* Search the threads array for an empty slot to use */
for (info = threads; info < threads + NTHREADS; info++)
if (!InterlockedExchange (&info->inuse, 1))
{
/* available */
#ifdef DEBUGGING
if (info->__name)
api_fatal ("name not NULL? %s, id %p, i %d", info->__name, info->id, info - threads);
#endif
goto out;
}
#ifdef DEBUGGING
char buf[1024];
if (!GetEnvironmentVariable ("CYGWIN_FREERANGE_NOCHECK", buf, sizeof (buf)))
api_fatal ("Overflowed cygwin thread pool");
else
thread_printf ("Overflowed cygwin thread pool");
#endif
info = freerange (); /* exhausted thread pool */
out:
return info;
}
cygthread::cygthread (LPTHREAD_START_ROUTINE start, LPVOID param,
const char *name): __name (name),
func (start), arg (param)
{
thread_printf ("name %s, id %p", name, id);
if (h)
{
while (!thread_sync)
low_priority_sleep (0);
SetEvent (thread_sync);
thread_printf ("activated name '%s', thread_sync %p for thread %p", name, thread_sync, id);
}
else
{
stack_ptr = NULL;
h = CreateThread (&sec_none_nih, 0, is_freerange ? simplestub : stub,
this, 0, &id);
if (!h)
api_fatal ("thread handle not set - %p<%p>, %E", h, id);
thread_printf ("created name '%s', thread %p, id %p", name, h, id);
#ifdef DEBUGGING
terminated = false;
#endif
}
}
/* Return the symbolic name of the current thread for debugging.
*/
const char *
cygthread::name (DWORD tid)
{
const char *res = NULL;
if (!tid)
tid = GetCurrentThreadId ();
if (tid == main_thread_id)
return "main";
for (DWORD i = 0; i < NTHREADS; i++)
if (threads[i].id == tid)
{
res = threads[i].__name ?: "exiting thread";
break;
}
if (!res)
{
static char buf[30] NO_COPY = {0};
__small_sprintf (buf, "unknown (%p)", tid);
res = buf;
}
return res;
}
cygthread::operator
HANDLE ()
{
while (!ev)
low_priority_sleep (0);
return ev;
}
void
cygthread::release (bool nuke_h)
{
if (nuke_h)
h = NULL;
#ifdef DEBUGGING
__oldname = __name;
debug_printf ("released thread '%s'", __oldname);
#endif
__name = NULL;
func = NULL;
if (ev)
ResetEvent (ev);
if (!InterlockedExchange (&inuse, 0))
#ifdef DEBUGGING
api_fatal ("released a thread that was not inuse");
#else
system_printf ("released a thread that was not inuse");
#endif
}
/* Forcibly terminate a thread. */
bool
cygthread::terminate_thread ()
{
bool terminated = true;
debug_printf ("thread '%s', id %p, inuse %d, stack_ptr %p", name (), id, inuse, stack_ptr);
while (inuse && !stack_ptr)
low_priority_sleep (0);
if (!inuse)
goto force_notterminated;
(void) TerminateThread (h, 0);
(void) WaitForSingleObject (h, INFINITE);
CloseHandle (h);
if (!inuse || exiting)
goto force_notterminated;
if (ev)
terminated = WaitForSingleObject (ev, 0) != WAIT_OBJECT_0;
MEMORY_BASIC_INFORMATION m;
memset (&m, 0, sizeof (m));
(void) VirtualQuery (stack_ptr, &m, sizeof m);
if (!m.RegionSize)
system_printf ("m.RegionSize 0? stack_ptr %p", stack_ptr);
else if (!VirtualFree (m.AllocationBase, 0, MEM_RELEASE))
debug_printf ("VirtualFree of allocation base %p<%p> failed, %E",
stack_ptr, m.AllocationBase);
if (is_freerange)
free (this);
else
{
#ifdef DEBUGGING
terminated = true;
#endif
release (true);
}
goto out;
force_notterminated:
terminated = false;
out:
return terminated;
}
/* Detach the cygthread from the current thread. Note that the
theory is that cygthreads are only associated with one thread.
So, there should be never be multiple threads doing waits
on the same cygthread. */
bool
cygthread::detach (HANDLE sigwait)
{
bool signalled = false;
bool thread_was_reset = false;
if (!inuse)
system_printf ("called detach but inuse %d, thread %p?", inuse, id);
else
{
DWORD res;
if (!sigwait)
res = WaitForSingleObject (*this, INFINITE);
else
{
/* Lower our priority and give priority to the read thread */
HANDLE hth = GetCurrentThread ();
LONG prio = GetThreadPriority (hth);
(void) ::SetThreadPriority (hth, THREAD_PRIORITY_BELOW_NORMAL);
HANDLE w4[2];
unsigned n = 2;
DWORD howlong = INFINITE;
w4[0] = sigwait;
w4[1] = signal_arrived;
/* For a description of the below loop see the end of this file */
for (int i = 0; i < 2; i++)
switch (res = WaitForMultipleObjects (n, w4, FALSE, howlong))
{
case WAIT_OBJECT_0:
if (n == 1)
howlong = 50;
break;
case WAIT_OBJECT_0 + 1:
n = 1;
if (i--)
howlong = 50;
break;
case WAIT_TIMEOUT:
break;
default:
if (!exiting)
api_fatal ("WFMO failed waiting for cygthread '%s'", __name);
break;
}
/* WAIT_OBJECT_0 means that the thread successfully read something,
so wait for the cygthread to "terminate". */
if (res == WAIT_OBJECT_0)
(void) WaitForSingleObject (*this, INFINITE);
else
{
/* Thread didn't terminate on its own, so maybe we have to
do it. */
signalled = terminate_thread ();
/* Possibly the thread completed *just* before it was
terminated. Detect this. If this happened then the
read was not terminated on a signal. */
if (WaitForSingleObject (sigwait, 0) == WAIT_OBJECT_0)
signalled = false;
if (signalled)
set_sig_errno (EINTR);
thread_was_reset = true;
}
(void) ::SetThreadPriority (hth, prio);
}
thread_printf ("%s returns %d, id %p", sigwait ? "WFMO" : "WFSO",
res, id);
if (thread_was_reset)
/* already handled */;
else if (is_freerange)
{
CloseHandle (h);
free (this);
}
else
{
ResetEvent (*this);
/* Mark the thread as available by setting inuse to zero */
(void) InterlockedExchange (&inuse, 0);
}
}
return signalled;
}
void
cygthread::terminate ()
{
exiting = 1;
}
/* The below is an explanation of synchronization loop in cygthread::detach.
The intent is that the loop will always try hard to wait for both
synchronization events from the reader thread but will exit with
res == WAIT_TIMEOUT if a signal occurred and the reader thread is
still blocked.
case 0 - no signal
i == 0 (howlong == INFINITE)
W0 activated
howlong not set because n != 1
just loop
i == 1 (howlong == INFINITE)
W0 activated
howlong not set because n != 1
just loop (to exit loop) - no signal
i == 2 (howlong == INFINITE)
exit loop
case 1 - signal before thread initialized
i == 0 (howlong == INFINITE)
WO + 1 activated
n set to 1
howlong untouched because i-- == 0
loop
i == 0 (howlong == INFINITE)
W0 must be activated
howlong set to 50 because n == 1
i == 1 (howlong == 50)
W0 activated
loop (to exit loop) - no signal
WAIT_TIMEOUT activated
signal potentially detected
loop (to exit loop)
i == 2 (howlong == 50)
exit loop
case 2 - signal after thread initialized
i == 0 (howlong == INFINITE)
W0 activated
howlong not set because n != 1
loop
i == 1 (howlong == INFINITE)
W0 + 1 activated
n set to 1
howlong set to 50 because i-- != 0
loop
i == 1 (howlong == 50)
W0 activated
loop (to exit loop) - no signal
WAIT_TIMEOUT activated
loop (to exit loop) - signal
i == 2 (howlong == 50)
exit loop
*/