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/* $Id: Helper.cpp $ */
/** @file
*
* VBox frontends: VBoxSDL (simple frontend based on SDL):
* Miscellaneous helpers
*/
/*
* Copyright (C) 2006-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#define LOG_GROUP LOG_GROUP_GUI
#include <iprt/errcore.h>
#include <VBox/log.h>
#include <iprt/asm.h>
#include <iprt/assert.h>
#include <iprt/thread.h>
#include <iprt/semaphore.h>
#include "VBoxSDL.h"
#include "Helper.h"
/**
* Globals
*/
#ifdef USE_XPCOM_QUEUE_THREAD
/** global flag indicating that the event queue thread should terminate */
static bool volatile g_fTerminateXPCOMQueueThread = false;
/** How many XPCOM user events are on air. Only allow one pending event to
* prevent an overflow of the SDL event queue. */
static volatile int32_t g_s32XPCOMEventsPending;
/** Semaphore the XPCOM event thread will sleep on while it waits for the main thread to process pending requests. */
RTSEMEVENT g_EventSemXPCOMQueueThread = NULL;
/**
* Thread method to wait for XPCOM events and notify the SDL thread.
*
* @returns Error code
* @param thread Thread ID
* @param pvUser User specific parameter, the file descriptor
* of the event queue socket
*/
DECLCALLBACK(int) xpcomEventThread(RTTHREAD hThreadSelf, void *pvUser)
{
RT_NOREF(hThreadSelf);
int eqFD = (intptr_t)pvUser;
unsigned cErrors = 0;
int rc;
/* Wait with the processing till the main thread needs it. */
RTSemEventWait(g_EventSemXPCOMQueueThread, 2500);
do
{
fd_set fdset;
FD_ZERO(&fdset);
FD_SET(eqFD, &fdset);
int n = select(eqFD + 1, &fdset, NULL, NULL, NULL);
/* are there any events to process? */
if ((n > 0) && !g_fTerminateXPCOMQueueThread)
{
/*
* Wait until all XPCOM events are processed. 1s just for sanity.
*/
int iWait = 1000;
/*
* Don't post an event if there is a pending XPCOM event to prevent an
* overflow of the SDL event queue.
*/
if (g_s32XPCOMEventsPending < 1)
{
/*
* Post the event and wait for it to be processed. If we don't wait,
* we'll flood the queue on SMP systems and when the main thread is busy.
* In the event of a push error, we'll yield the timeslice and retry.
*/
SDL_Event event = {0};
event.type = SDL_USEREVENT;
event.user.type = SDL_USER_EVENT_XPCOM_EVENTQUEUE;
rc = SDL_PushEvent(&event);
if (!rc)
{
/* success */
ASMAtomicIncS32(&g_s32XPCOMEventsPending);
cErrors = 0;
}
else
{
/* failure */
cErrors++;
if (!RTThreadYield())
RTThreadSleep(2);
iWait = (cErrors >= 10) ? RT_MIN(cErrors - 8, 50) : 0;
}
}
else
Log2(("not enqueueing SDL XPCOM event (%d)\n", g_s32XPCOMEventsPending));
if (iWait)
RTSemEventWait(g_EventSemXPCOMQueueThread, iWait);
}
} while (!g_fTerminateXPCOMQueueThread);
return VINF_SUCCESS;
}
/**
* Creates the XPCOM event thread
*
* @returns VBOX status code
* @param eqFD XPCOM event queue file descriptor
*/
int startXPCOMEventQueueThread(int eqFD)
{
int rc = RTSemEventCreate(&g_EventSemXPCOMQueueThread);
if (RT_SUCCESS(rc))
{
RTTHREAD Thread;
rc = RTThreadCreate(&Thread, xpcomEventThread, (void *)(intptr_t)eqFD,
0, RTTHREADTYPE_MSG_PUMP, 0, "XPCOMEvent");
}
AssertRC(rc);
return rc;
}
/**
* Notify the XPCOM thread that we consumed an XPCOM event.
*/
void consumedXPCOMUserEvent(void)
{
ASMAtomicDecS32(&g_s32XPCOMEventsPending);
}
/**
* Signal to the XPCOM even queue thread that it should select for more events.
*/
void signalXPCOMEventQueueThread(void)
{
int rc = RTSemEventSignal(g_EventSemXPCOMQueueThread);
AssertRC(rc);
}
/**
* Indicates to the XPCOM thread that it should terminate now.
*/
void terminateXPCOMQueueThread(void)
{
g_fTerminateXPCOMQueueThread = true;
if (g_EventSemXPCOMQueueThread)
{
RTSemEventSignal(g_EventSemXPCOMQueueThread);
RTThreadYield();
}
}
#endif /* USE_XPCOM_QUEUE_THREAD */
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