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/*
 * QEMU System Emulator
 *
 * Copyright (c) 2003-2008 Fabrice Bellard
 *
 * 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 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.
 */

#ifndef QEMU_MAIN_LOOP_H
#define QEMU_MAIN_LOOP_H 1

#include "block/aio.h"

#define SIG_IPI SIGUSR1

/**
 * qemu_init_main_loop: Set up the process so that it can run the main loop.
 *
 * This includes setting up signal handlers.  It should be called before
 * any other threads are created.  In addition, threads other than the
 * main one should block signals that are trapped by the main loop.
 * For simplicity, you can consider these signals to be safe: SIGUSR1,
 * SIGUSR2, thread signals (SIGFPE, SIGILL, SIGSEGV, SIGBUS) and real-time
 * signals if available.  Remember that Windows in practice does not have
 * signals, though.
 *
 * In the case of QEMU tools, this will also start/initialize timers.
 */
int qemu_init_main_loop(void);

/**
 * main_loop_wait: Run one iteration of the main loop.
 *
 * If @nonblocking is true, poll for events, otherwise suspend until
 * one actually occurs.  The main loop usually consists of a loop that
 * repeatedly calls main_loop_wait(false).
 *
 * Main loop services include file descriptor callbacks, bottom halves
 * and timers (defined in qemu-timer.h).  Bottom halves are similar to timers
 * that execute immediately, but have a lower overhead and scheduling them
 * is wait-free, thread-safe and signal-safe.
 *
 * It is sometimes useful to put a whole program in a coroutine.  In this
 * case, the coroutine actually should be started from within the main loop,
 * so that the main loop can run whenever the coroutine yields.  To do this,
 * you can use a bottom half to enter the coroutine as soon as the main loop
 * starts:
 *
 *     void enter_co_bh(void *opaque) {
 *         QEMUCoroutine *co = opaque;
 *         qemu_coroutine_enter(co, NULL);
 *     }
 *
 *     ...
 *     QEMUCoroutine *co = qemu_coroutine_create(coroutine_entry);
 *     QEMUBH *start_bh = qemu_bh_new(enter_co_bh, co);
 *     qemu_bh_schedule(start_bh);
 *     while (...) {
 *         main_loop_wait(false);
 *     }
 *
 * (In the future we may provide a wrapper for this).
 *
 * @nonblocking: Whether the caller should block until an event occurs.
 */
int main_loop_wait(int nonblocking);

/**
 * qemu_get_aio_context: Return the main loop's AioContext
 */
AioContext *qemu_get_aio_context(void);

/**
 * qemu_notify_event: Force processing of pending events.
 *
 * Similar to signaling a condition variable, qemu_notify_event forces
 * main_loop_wait to look at pending events and exit.  The caller of
 * main_loop_wait will usually call it again very soon, so qemu_notify_event
 * also has the side effect of recalculating the sets of file descriptors
 * that the main loop waits for.
 *
 * Calling qemu_notify_event is rarely necessary, because main loop
 * services (bottom halves and timers) call it themselves.  One notable
 * exception occurs when using qemu_set_fd_handler2 (see below).
 */
void qemu_notify_event(void);

#ifdef _WIN32
/* return TRUE if no sleep should be done afterwards */
typedef int PollingFunc(void *opaque);

/**
 * qemu_add_polling_cb: Register a Windows-specific polling callback
 *
 * Currently, under Windows some events are polled rather than waited for.
 * Polling callbacks do not ensure that @func is called timely, because
 * the main loop might wait for an arbitrarily long time.  If possible,
 * you should instead create a separate thread that does a blocking poll
 * and set a Win32 event object.  The event can then be passed to
 * qemu_add_wait_object.
 *
 * Polling callbacks really have nothing Windows specific in them, but
 * as they are a hack and are currently not necessary under POSIX systems,
 * they are only available when QEMU is running under Windows.
 *
 * @func: The function that does the polling, and returns 1 to force
 * immediate completion of main_loop_wait.
 * @opaque: A pointer-size value that is passed to @func.
 */
int qemu_add_polling_cb(PollingFunc *func, void *opaque);

/**
 * qemu_del_polling_cb: Unregister a Windows-specific polling callback
 *
 * This function removes a callback that was registered with