/* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
/* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */
/* Eliminated some memory leaks, gsw@agere.com */

#include <windows.h>
#include <limits.h>
#ifdef HAVE_PROCESS_H
#include <process.h>
#endif

/* options */
#ifndef _PY_USE_CV_LOCKS
#define _PY_USE_CV_LOCKS 1 /* use locks based on cond vars */
#endif

/* Now, define a non-recursive mutex using either condition variables
 * and critical sections (fast) or using operating system mutexes
 * (slow)
 */

#if _PY_USE_CV_LOCKS

#include "condvar.h"

typedef struct _NRMUTEX
{
 PyMUTEX_T cs;
 PyCOND_T cv;
 int locked;
} NRMUTEX;
typedef NRMUTEX *PNRMUTEX;

PNRMUTEX
AllocNonRecursiveMutex()
{
 PNRMUTEX m = (PNRMUTEX)PyMem_RawMalloc(sizeof(NRMUTEX));
 if (!m)
 return NULL;
 if (PyCOND_INIT(&m->cv))
 goto fail;
 if (PyMUTEX_INIT(&m->cs)) {
 PyCOND_FINI(&m->cv);
 goto fail;
 }
 m->locked = 0;
 return m;
fail:
 PyMem_RawFree(m);
 return NULL;
}

VOID
FreeNonRecursiveMutex(PNRMUTEX mutex)
{
 if (mutex) {
 PyCOND_FINI(&mutex->cv);
 PyMUTEX_FINI(&mutex->cs);
 PyMem_RawFree(mutex);
 }
}

DWORD
EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
{
 DWORD result = WAIT_OBJECT_0;
 if (PyMUTEX_LOCK(&mutex->cs))
 return WAIT_FAILED;
 if (milliseconds == INFINITE) {
 while (mutex->locked) {
 if (PyCOND_WAIT(&mutex->cv, &mutex->cs)) {
 result = WAIT_FAILED;
 break;
 }
 }
 } else if (milliseconds != 0) {
 /* wait at least until the target */
 ULONGLONG now, target = GetTickCount64() + milliseconds;
 while (mutex->locked) {
 if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, (long long)milliseconds*1000) < 0) {
 result = WAIT_FAILED;
 break;
 }
 now = GetTickCount64();
 if (target <= now)
 break;
 milliseconds = (DWORD)(target-now);
 }
 }
 if (!mutex->locked) {
 mutex->locked = 1;
 result = WAIT_OBJECT_0;
 } else if (result == WAIT_OBJECT_0)
 result = WAIT_TIMEOUT;
 /* else, it is WAIT_FAILED */
 PyMUTEX_UNLOCK(&mutex->cs); /* must ignore result here */
 return result;
}

BOOL
LeaveNonRecursiveMutex(PNRMUTEX mutex)
{
 BOOL result;
 if (PyMUTEX_LOCK(&mutex->cs))
 return FALSE;
 mutex->locked = 0;
 /* condvar APIs return 0 on success. We need to return TRUE on success. */
 result = !PyCOND_SIGNAL(&mutex->cv);
 PyMUTEX_UNLOCK(&mutex->cs);
 return result;
}

#else /* if ! _PY_USE_CV_LOCKS */

/* NR-locks based on a kernel mutex */
#define PNRMUTEX HANDLE

PNRMUTEX
AllocNonRecursiveMutex()
{
 return CreateSemaphore(NULL, 1, 1, NULL);
}

VOID
FreeNonRecursiveMutex(PNRMUTEX mutex)
{
 /* No in-use check */
 CloseHandle(mutex);
}

DWORD
EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
{
 return WaitForSingleObjectEx(mutex, milliseconds, FALSE);
}

BOOL
LeaveNonRecursiveMutex(PNRMUTEX mutex)
{
 return ReleaseSemaphore(mutex, 1, NULL);
}
#endif /* _PY_USE_CV_LOCKS */

unsigned long PyThread_get_thread_ident(void);

#ifdef PY_HAVE_THREAD_NATIVE_ID
unsigned long PyThread_get_thread_native_id(void);
#endif

/*
 * Initialization of the C package, should not be needed.
 */
static void
PyThread__init_thread(void)
{
}

/*
 * Thread support.
 */

typedef struct {
 void (*func)(void*);
 void *arg;
} callobj;

/* thunker to call adapt between the function type used by the system's
thread start function and the internally used one. */
static unsigned __stdcall
bootstrap(void *call)
{
 callobj *obj = (callobj*)call;
 void (*func)(void*) = obj->func;
 void *arg = obj->arg;
 HeapFree(GetProcessHeap(), 0, obj);
 func(arg);
 return 0;
}

unsigned long
PyThread_start_new_thread(void (*func)(void *), void *arg)
{
 HANDLE hThread;
 unsigned threadID;
 callobj *obj;

 dprintf(("%lu: PyThread_start_new_thread called\n",
 PyThread_get_thread_ident()));
 if (!initialized)
 PyThread_init_thread();

 obj = (callobj*)HeapAlloc(GetProcessHeap(), 0, sizeof(*obj));
 if (!obj)
 return PYTHREAD_INVALID_THREAD_ID;
 obj->func = func;
 obj->arg = arg;
 PyThreadState *tstate = _PyThreadState_GET();
 size_t stacksize = tstate ? tstate->interp->pythread_stacksize : 0;
 hThread = (HANDLE)_beginthreadex(0,
 Py_SAFE_DOWNCAST(stacksize, Py_ssize_t, unsigned int),
 bootstrap, obj,
 0, &threadID);
 if (hThread == 0) {
 /* I've seen errno == EAGAIN here, which means "there are
 * too many threads".
 */
 int e = errno;
 dprintf(("%lu: PyThread_start_new_thread failed, errno %d\n",
 PyThread_get_thread_ident(), e));
 threadID = (unsigned)-1;
 HeapFree(GetProcessHeap(), 0, obj);
 }
 else {
 dprintf(("%lu: PyThread_start_new_thread succeeded: %p\n",
 PyThread_get_thread_ident(), (void*)hThread));
 CloseHandle(hThread);
 }
 return threadID;
}

/*
 * Return the thread Id instead of a handle. The Id is said to uniquely identify the
 * thread in the system
 */
unsigned long
PyThread_get_thread_ident(void)
{
 if (!initialized)
 PyThread_init_thread();

 return GetCurrentThreadId();
}

#ifdef PY_HAVE_THREAD_NATIVE_ID
/*
 * Return the native Thread ID (TID) of the calling thread.
 * The native ID of a thread is valid and guaranteed to be unique system-wide
 * from the time the thread is created until the thread has been terminated.
 */
unsigned long
PyThread_get_thread_native_id(void)
{
 if (!initialized) {
 PyThread_init_thread();
 }

 DWORD native_id;
 native_id = GetCurrentThreadId();
 return (unsigned long) native_id;
}
#endif

void _Py_NO_RETURN
PyThread_exit_thread(void)
{
 dprintf(("%lu: PyThread_exit_thread called\n", PyThread_get_thread_ident()));
 if (!initialized)
 exit(0);
 _endthreadex(0);
}

/*
 * Lock support. It has to be implemented as semaphores.
 * I [Dag] tried to implement it with mutex but I could find a way to
 * tell whether a thread already own the lock or not.
 */
PyThread_type_lock
PyThread_allocate_lock(void)
{
 PNRMUTEX aLock;

 dprintf(("PyThread_allocate_lock called\n"));
 if (!initialized)
 PyThread_init_thread();

 aLock = AllocNonRecursiveMutex() ;

 dprintf(("%lu: PyThread_allocate_lock() -> %p\n", PyThread_get_thread_ident(), aLock));

 return (PyThread_type_lock) aLock;
}

void
PyThread_free_lock(PyThread_type_lock aLock)
{
 dprintf(("%lu: PyThread_free_lock(%p) called\n", PyThread_get_thread_ident(),aLock));

 FreeNonRecursiveMutex(aLock) ;
}

/*
 * Return 1 on success if the lock was acquired
 *
 * and 0 if the lock was not acquired. This means a 0 is returned
 * if the lock has already been acquired by this thread!
 */
PyLockStatus
PyThread_acquire_lock_timed(PyThread_type_lock aLock,
 PY_TIMEOUT_T microseconds, int intr_flag)
{
 /* Fow now, intr_flag does nothing on Windows, and lock acquires are
 * uninterruptible. */
 PyLockStatus success;
 PY_TIMEOUT_T milliseconds;

 if (microseconds >= 0) {
 milliseconds = microseconds / 1000;
 if (microseconds % 1000 > 0)
 ++milliseconds;
 if (milliseconds > PY_DWORD_MAX) {
 Py_FatalError("Timeout larger than PY_TIMEOUT_MAX");
 }
 }
 else {
 milliseconds = INFINITE;
 }

 dprintf(("%lu: PyThread_acquire_lock_timed(%p, %lld) called\n",
 PyThread_get_thread_ident(), aLock, microseconds));

 if (aLock && EnterNonRecursiveMutex((PNRMUTEX)aLock,
 (DWORD)milliseconds) == WAIT_OBJECT_0) {
 success = PY_LOCK_ACQUIRED;
 }
 else {
 success = PY_LOCK_FAILURE;
 }

 dprintf(("%lu: PyThread_acquire_lock(%p, %lld) -> %d\n",
 PyThread_get_thread_ident(), aLock, microseconds, success));

 return success;
}
int
PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
{
 return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0, 0);
}

void
PyThread_release_lock(PyThread_type_lock aLock)
{
 dprintf(("%lu: PyThread_release_lock(%p) called\n", PyThread_get_thread_ident(),aLock));

 if (!(aLock && LeaveNonRecursiveMutex((PNRMUTEX) aLock)))
 dprintf(("%lu: Could not PyThread_release_lock(%p) error: %ld\n", PyThread_get_thread_ident(), aLock, GetLastError()));
}

/* minimum/maximum thread stack sizes supported */
#define THREAD_MIN_STACKSIZE 0x8000 /* 32 KiB */
#define THREAD_MAX_STACKSIZE 0x10000000 /* 256 MiB */

/* set the thread stack size.
 * Return 0 if size is valid, -1 otherwise.
 */
static int
_pythread_nt_set_stacksize(size_t size)
{
 /* set to default */
 if (size == 0) {
 _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = 0;
 return 0;
 }

 /* valid range? */
 if (size >= THREAD_MIN_STACKSIZE && size < THREAD_MAX_STACKSIZE) {
 _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = size;
 return 0;
 }

 return -1;
}

#define THREAD_SET_STACKSIZE(x) _pythread_nt_set_stacksize(x)


/* Thread Local Storage (TLS) API

 This API is DEPRECATED since Python 3.7. See PEP 539 for details.
*/

int
PyThread_create_key(void)
{
 DWORD result = TlsAlloc();
 if (result == TLS_OUT_OF_INDEXES)
 return -1;
 return (int)result;
}

void
PyThread_delete_key(int key)
{
 TlsFree(key);
}

int
PyThread_set_key_value(int key, void *value)
{
 BOOL ok = TlsSetValue(key, value);
 return ok ? 0 : -1;
}

void *
PyThread_get_key_value(int key)
{
 /* because TLS is used in the Py_END_ALLOW_THREAD macro,
 * it is necessary to preserve the windows error state, because
 * it is assumed to be preserved across the call to the macro.
 * Ideally, the macro should be fixed, but it is simpler to
 * do it here.
 */
 DWORD error = GetLastError();
 void *result = TlsGetValue(key);
 SetLastError(error);
 return result;
}

void
PyThread_delete_key_value(int key)
{
 /* NULL is used as "key missing", and it is also the default
 * given by TlsGetValue() if nothing has been set yet.
 */
 TlsSetValue(key, NULL);
}


/* reinitialization of TLS is not necessary after fork when using
 * the native TLS functions. And forking isn't supported on Windows either.
 */
void
PyThread_ReInitTLS(void)
{
}


/* Thread Specific Storage (TSS) API

 Platform-specific components of TSS API implementation.
*/

int
PyThread_tss_create(Py_tss_t *key)
{
 assert(key != NULL);
 /* If the key has been created, function is silently skipped. */
 if (key->_is_initialized) {
 return 0;
 }

 DWORD result = TlsAlloc();
 if (result == TLS_OUT_OF_INDEXES) {
 return -1;
 }
 /* In Windows, platform-specific key type is DWORD. */
 key->_key = result;
 key->_is_initialized = 1;
 return 0;
}

void
PyThread_tss_delete(Py_tss_t *key)
{
 assert(key != NULL);
 /* If the key has not been created, function is silently skipped. */
 if (!key->_is_initialized) {
 return;
 }

 TlsFree(key->_key);
 key->_key = TLS_OUT_OF_INDEXES;
 key->_is_initialized = 0;
}

int
PyThread_tss_set(Py_tss_t *key, void *value)
{
 assert(key != NULL);
 BOOL ok = TlsSetValue(key->_key, value);
 return ok ? 0 : -1;
}

void *
PyThread_tss_get(Py_tss_t *key)
{
 assert(key != NULL);
 /* because TSS is used in the Py_END_ALLOW_THREAD macro,
 * it is necessary to preserve the windows error state, because
 * it is assumed to be preserved across the call to the macro.
 * Ideally, the macro should be fixed, but it is simpler to
 * do it here.
 */
 DWORD error = GetLastError();
 void *result = TlsGetValue(key->_key);
 SetLastError(error);
 return result;
}