harvey/sys/src/cmd/gs/src/gp_wsync.c

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  "License") for full details.
  
  Every copy of AFPL Ghostscript must include a copy of the License, normally
  in a plain ASCII text file named PUBLIC.  The License grants you the right
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*/

/*$Id: gp_wsync.c,v 1.2 2000/09/19 19:00:25 lpd Exp $ */
/* MS Windows (Win32) thread / semaphore / monitor implementation */
/* original multi-threading code by John Desrosiers */
#include "malloc_.h"
#include "gserror.h"
#include "gserrors.h"
#include "gpsync.h"
#include "windows_.h"
#include <process.h>

/* ------- Synchronization primitives -------- */

/* Semaphore supports wait/signal semantics */

typedef struct win32_semaphore_s {
    HANDLE handle;		/* returned from CreateSemaphore */
} win32_semaphore;

uint
gp_semaphore_sizeof(void)
{
    return sizeof(win32_semaphore);
}

int	/* if sema <> 0 rets -ve error, 0 ok; if sema == 0, 0 movable, 1 fixed */
gp_semaphore_open(
		  gp_semaphore * sema	/* create semaphore here */
)
{
    win32_semaphore *const winSema = (win32_semaphore *)sema;

    if (winSema) {
	winSema->handle = CreateSemaphore(NULL, 0, max_int, NULL);
	return
	    (winSema->handle != NULL ? 0 :
	     gs_note_error(gs_error_unknownerror));
    } else
	return 0;		/* Win32 semaphores handles may be moved */
}

int
gp_semaphore_close(
		   gp_semaphore * sema	/* semaphore to affect */
)
{
    win32_semaphore *const winSema = (win32_semaphore *)sema;

    if (winSema->handle != NULL)
	CloseHandle(winSema->handle);
    winSema->handle = NULL;
    return 0;
}

int				/* rets 0 ok, -ve error */
gp_semaphore_wait(
		  gp_semaphore * sema	/* semaphore to affect */
)
{
    win32_semaphore *const winSema = (win32_semaphore *)sema;

    return
	(WaitForSingleObject(winSema->handle, INFINITE) == WAIT_OBJECT_0
	 ? 0 : gs_error_unknownerror);
}

int				/* rets 0 ok, -ve error */
gp_semaphore_signal(
		    gp_semaphore * sema	/* semaphore to affect */
)
{
    win32_semaphore *const winSema = (win32_semaphore *)sema;

    return
	(ReleaseSemaphore(winSema->handle, 1, NULL) ? 0 :
	 gs_error_unknownerror);
}


/* Monitor supports enter/leave semantics */

typedef struct win32_monitor_s {
    CRITICAL_SECTION lock;	/* critical section lock */
} win32_monitor;

uint
gp_monitor_sizeof(void)
{
    return sizeof(win32_monitor);
}

int	/* if sema <> 0 rets -ve error, 0 ok; if sema == 0, 0 movable, 1 fixed */
gp_monitor_open(
		gp_monitor * mon	/* create monitor here */
)
{
    win32_monitor *const winMon = (win32_monitor *)mon;

    if (mon) {
	InitializeCriticalSection(&winMon->lock);	/* returns no status */
	return 0;
    } else
	return 1;		/* Win32 critical sections mutsn't be moved */
}

int
gp_monitor_close(
		 gp_monitor * mon	/* monitor to affect */
)
{
    win32_monitor *const winMon = (win32_monitor *)mon;

    DeleteCriticalSection(&winMon->lock);	/* rets no status */
    return 0;
}

int				/* rets 0 ok, -ve error */
gp_monitor_enter(
		 gp_monitor * mon	/* monitor to affect */
)
{
    win32_monitor *const winMon = (win32_monitor *)mon;

    EnterCriticalSection(&winMon->lock);	/* rets no status */
    return 0;
}

int				/* rets 0 ok, -ve error */
gp_monitor_leave(
		 gp_monitor * mon	/* monitor to affect */
)
{
    win32_monitor *const winMon = (win32_monitor *)mon;

    LeaveCriticalSection(&winMon->lock);	/* rets no status */
    return 0;
}

/* --------- Thread primitives ---------- */

typedef struct gp_thread_creation_closure_s {
    gp_thread_creation_callback_t function;	/* function to start */
    void *data;			/* magic data to pass to thread */
} gp_thread_creation_closure;

/* Origin of new threads started by gp_create_thread */
private void
gp_thread_begin_wrapper(
			void *thread_data	/* gp_thread_creation_closure passed as magic data */
)
{
    gp_thread_creation_closure closure;

    closure = *(gp_thread_creation_closure *)thread_data;
    free(thread_data);
    (*closure.function)(closure.data);
    _endthread();
}

/* Call a function on a brand new thread */
int				/* 0 ok, -ve error */
gp_create_thread(
		 gp_thread_creation_callback_t function,	/* function to start */
		 void *data	/* magic data to pass to thread fn */
)
{
    /* Create the magic closure that thread_wrapper gets passed */
    gp_thread_creation_closure *closure =
	(gp_thread_creation_closure *)malloc(sizeof(*closure));

    if (!closure)
	return gs_error_VMerror;
    closure->function = function;
    closure->data = data;

    /*
     * Start thread_wrapper.  The Watcom _beginthread returns (int)(-1) if
     * the call fails.  The Microsoft _beginthread returns -1 (according to
     * the doc, even though the return type is "unsigned long" !!!) if the
     * call fails; we aren't sure what the Borland _beginthread returns.
     * The hack with ~ avoids a source code commitment as to whether the
     * return type is [u]int or [u]long.
     *
     * BEGIN_THREAD is a macro (defined in windows_.h) because _beginthread
     * takes different arguments in Watcom C.
     */
    if (~BEGIN_THREAD(gp_thread_begin_wrapper, 0, closure) != 0)
	return 0;
    return_error(gs_error_unknownerror);
}