path: root/src/Threads.c

/************************************************************
Copyright (c) 1993, Oracle and/or its affiliates. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice (including the next
paragraph) shall be included in all copies or substantial portions of the
Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

********************************************************/

/*

Copyright 1994, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of The Open Group shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from The Open Group.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "IntrinsicI.h"

#ifdef XTHREADS

#define xmalloc __XtMalloc
#define xfree XtFree
#include <X11/Xthreads.h>

#ifndef NDEBUG
#define NDEBUG
#endif
#include <assert.h>
#include <stdio.h>

typedef struct _ThreadStack {
    unsigned int size;
    int sp;
    struct _Tstack {
        xthread_t t;
        xcondition_t c;
    } *st;
} ThreadStack;

typedef struct _LockRec {
    xmutex_t mutex;
    int level;
    ThreadStack stack;
#ifndef _XMUTEX_NESTS
    xthread_t holder;
    xcondition_t cond;
#endif
} LockRec;

#define STACK_INCR 16

static LockPtr process_lock = NULL;

static void
InitProcessLock(void)
{
    if (!process_lock) {
        process_lock = XtNew(LockRec);
        process_lock->mutex = xmutex_malloc();
        xmutex_init(process_lock->mutex);
        process_lock->level = 0;
#ifndef _XMUTEX_NESTS
        process_lock->cond = xcondition_malloc();
        xcondition_init(process_lock->cond);
        xthread_clear_id(process_lock->holder);
#endif
    }
}

static void
ProcessLock(void)
{
#ifdef _XMUTEX_NESTS
    xmutex_lock(process_lock->mutex);
    process_lock->level++;
#else
    xthread_t this_thread = xthread_self();

    xmutex_lock(process_lock->mutex);

    if (!xthread_have_id(process_lock->holder)) {
        process_lock->holder = this_thread;
        xmutex_unlock(process_lock->mutex);
        return;
    }

    if (xthread_equal(process_lock->holder, this_thread)) {
        process_lock->level++;
        xmutex_unlock(process_lock->mutex);
        return;
    }

    while (xthread_have_id(process_lock->holder))
        xcondition_wait(process_lock->cond, process_lock->mutex);

    process_lock->holder = this_thread;
    assert(xthread_equal(process_lock->holder, this_thread));
    xmutex_unlock(process_lock->mutex);
#endif
}

static void
ProcessUnlock(void)
{
#ifdef _XMUTEX_NESTS
    process_lock->level--;
    xmutex_unlock(process_lock->mutex);
#else
    xmutex_lock(process_lock->mutex);
    assert(xthread_equal(process_lock->holder, xthread_self()));
    if (process_lock->level != 0) {
        process_lock->level--;
        xmutex_unlock(process_lock->mutex);
        return;
    }

    xthread_clear_id(process_lock->holder);
    xcondition_signal(process_lock->cond);

    xmutex_unlock(process_lock->mutex);
#endif
}

static void
AppLock(XtAppContext app)
{
    LockPtr app_lock = app->lock_info;

#ifdef _XMUTEX_NESTS
    xmutex_lock(app_lock->mutex);
    app_lock->level++;
#else
    xthread_t self = xthread_self();

    xmutex_lock(app_lock->mutex);
    if (!xthread_have_id(app_lock->holder)) {
        app_lock->holder = self;
        assert(xthread_equal(app_lock->holder, self));
        xmutex_unlock(app_lock->mutex);
        return;
    }
    if (xthread_equal(app_lock->holder, self)) {
        app_lock->level++;
        xmutex_unlock(app_lock->mutex);
        return;
    }
    while (xthread_have_id(app_lock->holder)) {
        xcondition_wait(app_lock->cond, app_lock->mutex);
    }
    app_lock->holder = self;
    assert(xthread_equal(app_lock->holder, self));
    xmutex_unlock(app_lock->mutex);
#endif
}

static void
AppUnlock(XtAppContext app)
{
    LockPtr app_lock = app->lock_info;

#ifdef _XMUTEX_NESTS
    app_lock->level--;
    xmutex_unlock(app_lock->mutex);
#else
    xthread_t self;

    self = xthread_self();
    (void) self;

    xmutex_lock(app_lock->mutex);
    assert(xthread_equal(app_lock->holder, self));
    if (app_lock->level != 0) {
        app_lock->level--;
        xmutex_unlock(app_lock->mutex);
        return;
    }
    xthread_clear_id(app_lock->holder);
    xcondition_signal(app_lock->cond);
    xmutex_unlock(app_lock->mutex);
#endif
}

static void
YieldAppLock(XtAppContext app,
             Boolean *push_thread,
             Boolean *pushed_thread,
             int *level)
{
    LockPtr app_lock = app->lock_info;
    xthread_t self = xthread_self();

#ifndef _XMUTEX_NESTS
    xmutex_lock(app_lock->mutex);
    assert(xthread_equal(app_lock->holder, self));
#endif
    *level = app_lock->level;
    if (*push_thread) {
        *push_thread = FALSE;
        *pushed_thread = TRUE;

        if (app_lock->stack.sp == (int) app_lock->stack.size - 1) {
            unsigned ii;

            app_lock->stack.st = (struct _Tstack *)
                XtRealloc((char *) app_lock->stack.st,
                          (Cardinal) ((app_lock->stack.size +
                                       STACK_INCR) * sizeof(struct _Tstack)));
            ii = app_lock->stack.size;
            app_lock->stack.size += STACK_INCR;
            for (; ii < app_lock->stack.size; ii++) {
                app_lock->stack.st[ii].c = xcondition_malloc();
                xcondition_init(app_lock->stack.st[ii].c);
            }
        }
        app_lock->stack.st[++(app_lock->stack.sp)].t = self;
    }
#ifdef _XMUTEX_NESTS
    while (app_lock->level > 0) {
        app_lock->level--;
        xmutex_unlock(app_lock->mutex);
    }
#else
    xcondition_signal(app_lock->cond);
    app_lock->level = 0;
    xthread_clear_id(app_lock->holder);
    xmutex_unlock(app_lock->mutex);
#endif
}

static void
RestoreAppLock(XtAppContext app, int level, Boolean *pushed_thread)
{
    LockPtr app_lock = app->lock_info;
    xthread_t self = xthread_self();

    xmutex_lock(app_lock->mutex);
#ifdef _XMUTEX_NESTS
    app_lock->level++;
#else
    while (xthread_have_id(app_lock->holder)) {
        xcondition_wait(app_lock->cond, app_lock->mutex);
    }
#endif
    if (!xthread_equal(app_lock->stack.st[app_lock->stack.sp].t, self)) {
        int ii;

        for (ii = app_lock->stack.sp - 1; ii >= 0; ii--) {
            if (xthread_equal(app_lock->stack.st[ii].t, self)) {
                xcondition_wait(app_lock->stack.st[ii].c, app_lock->mutex);
                break;
            }
        }
#ifndef _XMUTEX_NESTS
        while (xthread_have_id(app_lock->holder)) {
            xcondition_wait(app_lock->cond, app_lock->mutex);
        }
#endif
    }
#ifdef _XMUTEX_NESTS
    while (app_lock->level < level) {
        xmutex_lock(app_lock->mutex);
        app_lock->level++;
    }
#else
    app_lock->holder = self;
    app_lock->level = level;
    assert(xthread_equal(app_lock->holder, self));
#endif
    if (*pushed_thread) {
        *pushed_thread = FALSE;
        (app_lock->stack.sp)--;
        if (app_lock->stack.sp >= 0) {
            xcondition_signal(app_lock->stack.st[app_lock->stack.sp].c);
        }
    }
#ifndef _XMUTEX_NESTS
    xmutex_unlock(app_lock->mutex);
#endif
}

static void
FreeAppLock(XtAppContext app)
{
    unsigned ii;
    LockPtr app_lock = app->lock_info;

    if (app_lock) {
        xmutex_clear(app_lock->mutex);
        xmutex_free(app_lock->mutex);
#ifndef _XMUTEX_NESTS
        xcondition_clear(app_lock->cond);
        xcondition_free(app_lock->cond);
#endif
        if (app_lock->stack.st != (struct _Tstack *) NULL) {
            for (ii = 0; ii < app_lock->stack.size; ii++) {
                xcondition_clear(app_lock->stack.st[ii].c);
                xcondition_free(app_lock->stack.st[ii].c);
            }
            XtFree((char *) app_lock->stack.st);
        }
        XtFree((char *) app_lock);
        app->lock_info = NULL;
    }
}

static void
InitAppLock(XtAppContext app)
{
    int ii;
    LockPtr app_lock;

    app->lock = AppLock;
    app->unlock = AppUnlock;
    app->yield_lock = YieldAppLock;
    app->restore_lock = RestoreAppLock;
    app->free_lock = FreeAppLock;

    app_lock = app->lock_info = XtNew(LockRec);
    app_lock->mutex = xmutex_malloc();
    xmutex_init(app_lock->mutex);
    app_lock->level = 0;
#ifndef _XMUTEX_NESTS
    app_lock->cond = xcondition_malloc();
    xcondition_init(app_lock->cond);
    xthread_clear_id(app_lock->holder);
#endif
    app_lock->stack.size = STACK_INCR;
    app_lock->stack.sp = -1;
    app_lock->stack.st =
        (struct _Tstack *) __XtMalloc(sizeof(struct _Tstack) * STACK_INCR);
    for (ii = 0; ii < STACK_INCR; ii++) {
        app_lock->stack.st[ii].c = xcondition_malloc();
        xcondition_init(app_lock->stack.st[ii].c);
    }
}

#endif                          /* defined(XTHREADS) */

void
XtAppLock(XtAppContext app)
{
#ifdef XTHREADS
    if (app->lock)
        (*app->lock) (app);
#endif
}

void
XtAppUnlock(XtAppContext app)
{
#ifdef XTHREADS
    if (app->unlock)
        (*app->unlock) (app);
#endif
}

void
XtProcessLock(void)
{
#ifdef XTHREADS
    if (_XtProcessLock)
        (*_XtProcessLock) ();
#endif
}

void
XtProcessUnlock(void)
{
#ifdef XTHREADS
    if (_XtProcessUnlock)
        (*_XtProcessUnlock) ();
#endif
}

Boolean
XtToolkitThreadInitialize(void)
{
#ifdef XTHREADS
    if (_XtProcessLock == NULL) {
#ifdef xthread_init
        xthread_init();
#endif
        InitProcessLock();
        _XtProcessLock = ProcessLock;
        _XtProcessUnlock = ProcessUnlock;
        _XtInitAppLock = InitAppLock;
    }
    return True;
#else
    return False;
#endif
}