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/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file compat_winthreads.c
*
* \brief Implementation for the windows-based multithreading backend
* functions.
*/
#ifdef _WIN32
#include <windows.h>
#include <process.h>
#include "lib/thread/threads.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/log/win32err.h"
/* This value is more or less total cargo-cult */
#define SPIN_COUNT 2000
/** Minimalist interface to run a void function in the background. On
* Unix calls fork, on win32 calls beginthread. Returns -1 on failure.
* func should not return, but rather should call spawn_exit.
*
* NOTE: if <b>data</b> is used, it should not be allocated on the stack,
* since in a multithreaded environment, there is no way to be sure that
* the caller's stack will still be around when the called function is
* running.
*/
int
spawn_func(void (*func)(void *), void *data)
{
int rv;
rv = (int)_beginthread(func, 0, data);
if (rv == (int)-1)
return -1;
return 0;
}
/** End the current thread/process.
*/
void
spawn_exit(void)
{
_endthread();
// LCOV_EXCL_START
//we should never get here. my compiler thinks that _endthread returns, this
//is an attempt to fool it.
tor_assert(0);
_exit(0); // exit ok: unreachable.
// LCOV_EXCL_STOP
}
unsigned long
tor_get_thread_id(void)
{
return (unsigned long)GetCurrentThreadId();
}
int
tor_cond_init(tor_cond_t *cond)
{
memset(cond, 0, sizeof(tor_cond_t));
if (InitializeCriticalSectionAndSpinCount(&cond->lock, SPIN_COUNT)==0) {
return -1;
}
if ((cond->event = CreateEvent(NULL,TRUE,FALSE,NULL)) == NULL) {
DeleteCriticalSection(&cond->lock);
return -1;
}
cond->n_waiting = cond->n_to_wake = cond->generation = 0;
return 0;
}
void
tor_cond_uninit(tor_cond_t *cond)
{
DeleteCriticalSection(&cond->lock);
CloseHandle(cond->event);
}
static void
tor_cond_signal_impl(tor_cond_t *cond, int broadcast)
{
EnterCriticalSection(&cond->lock);
if (broadcast)
cond->n_to_wake = cond->n_waiting;
else
++cond->n_to_wake;
cond->generation++;
SetEvent(cond->event);
LeaveCriticalSection(&cond->lock);
}
void
tor_cond_signal_one(tor_cond_t *cond)
{
tor_cond_signal_impl(cond, 0);
}
void
tor_cond_signal_all(tor_cond_t *cond)
{
tor_cond_signal_impl(cond, 1);
}
int
tor_threadlocal_init(tor_threadlocal_t *threadlocal)
{
threadlocal->index = TlsAlloc();
return (threadlocal->index == TLS_OUT_OF_INDEXES) ? -1 : 0;
}
void
tor_threadlocal_destroy(tor_threadlocal_t *threadlocal)
{
TlsFree(threadlocal->index);
memset(threadlocal, 0, sizeof(tor_threadlocal_t));
}
void *
tor_threadlocal_get(tor_threadlocal_t *threadlocal)
{
void *value = TlsGetValue(threadlocal->index);
if (value == NULL) {
DWORD err = GetLastError();
if (err != ERROR_SUCCESS) {
char *msg = format_win32_error(err);
log_err(LD_GENERAL, "Error retrieving thread-local value: %s", msg);
tor_free(msg);
tor_assert(err == ERROR_SUCCESS);
}
}
return value;
}
void
tor_threadlocal_set(tor_threadlocal_t *threadlocal, void *value)
{
BOOL ok = TlsSetValue(threadlocal->index, value);
if (!ok) {
DWORD err = GetLastError();
char *msg = format_win32_error(err);
log_err(LD_GENERAL, "Error adjusting thread-local value: %s", msg);
tor_free(msg);
tor_assert(ok);
}
}
int
tor_cond_wait(tor_cond_t *cond, tor_mutex_t *lock_, const struct timeval *tv)
{
CRITICAL_SECTION *lock = &lock_->mutex;
int generation_at_start;
int waiting = 1;
int result = -1;
DWORD ms = INFINITE, ms_orig = INFINITE, startTime, endTime;
if (tv)
ms_orig = ms = tv->tv_sec*1000 + (tv->tv_usec+999)/1000;
EnterCriticalSection(&cond->lock);
++cond->n_waiting;
generation_at_start = cond->generation;
LeaveCriticalSection(&cond->lock);
LeaveCriticalSection(lock);
startTime = GetTickCount();
do {
DWORD res;
res = WaitForSingleObject(cond->event, ms);
EnterCriticalSection(&cond->lock);
if (cond->n_to_wake &&
cond->generation != generation_at_start) {
--cond->n_to_wake;
--cond->n_waiting;
result = 0;
waiting = 0;
goto out;
} else if (res != WAIT_OBJECT_0) {
result = (res==WAIT_TIMEOUT) ? 1 : -1;
--cond->n_waiting;
waiting = 0;
goto out;
} else if (ms != INFINITE) {
endTime = GetTickCount();
if (startTime + ms_orig <= endTime) {
result = 1; /* Timeout */
--cond->n_waiting;
waiting = 0;
goto out;
} else {
ms = startTime + ms_orig - endTime;
}
}
/* If we make it here, we are still waiting. */
if (cond->n_to_wake == 0) {
/* There is nobody else who should wake up; reset
* the event. */
ResetEvent(cond->event);
}
out:
LeaveCriticalSection(&cond->lock);
} while (waiting);
EnterCriticalSection(lock);
EnterCriticalSection(&cond->lock);
if (!cond->n_waiting)
ResetEvent(cond->event);
LeaveCriticalSection(&cond->lock);
return result;
}
void
tor_threads_init(void)
{
set_main_thread();
}
#endif /* defined(_WIN32) */
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