| /* |
| * 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(Error **errp); |
| |
| /** |
| * 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 |
| * qemu_add_polling_cb. |
| * |
| * @func: The function that was passed to qemu_add_polling_cb. |
| * @opaque: A pointer-size value that was passed to qemu_add_polling_cb. |
| */ |
| void qemu_del_polling_cb(PollingFunc *func, void *opaque); |
| |
| /* Wait objects handling */ |
| typedef void WaitObjectFunc(void *opaque); |
| |
| /** |
| * qemu_add_wait_object: Register a callback for a Windows handle |
| * |
| * Under Windows, the iohandler mechanism can only be used with sockets. |
| * QEMU must use the WaitForMultipleObjects API to wait on other handles. |
| * This function registers a #HANDLE with QEMU, so that it will be included |
| * in the main loop's calls to WaitForMultipleObjects. When the handle |
| * is in a signaled state, QEMU will call @func. |
| * |
| * @handle: The Windows handle to be observed. |
| * @func: A function to be called when @handle is in a signaled state. |
| * @opaque: A pointer-size value that is passed to @func. |
| */ |
| int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque); |
| |
| /** |
| * qemu_del_wait_object: Unregister a callback for a Windows handle |
| * |
| * This function removes a callback that was registered with |
| * qemu_add_wait_object. |
| * |
| * @func: The function that was passed to qemu_add_wait_object. |
| * @opaque: A pointer-size value that was passed to qemu_add_wait_object. |
| */ |
| void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque); |
| #endif |
| |
| /* async I/O support */ |
| |
| typedef void IOReadHandler(void *opaque, const uint8_t *buf, int size); |
| typedef int IOCanReadHandler(void *opaque); |
| |
| /** |
| * qemu_set_fd_handler2: Register a file descriptor with the main loop |
| * |
| * This function tells the main loop to wake up whenever one of the |
| * following conditions is true: |
| * |
| * 1) if @fd_write is not %NULL, when the file descriptor is writable; |
| * |
| * 2) if @fd_read is not %NULL, when the file descriptor is readable. |
| * |
| * @fd_read_poll can be used to disable the @fd_read callback temporarily. |
| * This is useful to avoid calling qemu_set_fd_handler2 every time the |
| * client becomes interested in reading (or dually, stops being interested). |
| * A typical example is when @fd is a listening socket and you want to bound |
| * the number of active clients. Remember to call qemu_notify_event whenever |
| * the condition may change from %false to %true. |
| * |
| * The callbacks that are set up by qemu_set_fd_handler2 are level-triggered. |
| * If @fd_read does not read from @fd, or @fd_write does not write to @fd |
| * until its buffers are full, they will be called again on the next |
| * iteration. |
| * |
| * @fd: The file descriptor to be observed. Under Windows it must be |
| * a #SOCKET. |
| * |
| * @fd_read_poll: A function that returns 1 if the @fd_read callback |
| * should be fired. If the function returns 0, the main loop will not |
| * end its iteration even if @fd becomes readable. |
| * |
| * @fd_read: A level-triggered callback that is fired if @fd is readable |
| * at the beginning of a main loop iteration, or if it becomes readable |
| * during one. |
| * |
| * @fd_write: A level-triggered callback that is fired when @fd is writable |
| * at the beginning of a main loop iteration, or if it becomes writable |
| * during one. |
| * |
| * @opaque: A pointer-sized value that is passed to @fd_read_poll, |
| * @fd_read and @fd_write. |
| */ |
| int qemu_set_fd_handler2(int fd, |
| IOCanReadHandler *fd_read_poll, |
| IOHandler *fd_read, |
| IOHandler *fd_write, |
| void *opaque); |
| |
| /** |
| * qemu_set_fd_handler: Register a file descriptor with the main loop |
| * |
| * This function tells the main loop to wake up whenever one of the |
| * following conditions is true: |
| * |
| * 1) if @fd_write is not %NULL, when the file descriptor is writable; |
| * |
| * 2) if @fd_read is not %NULL, when the file descriptor is readable. |
| * |
| * The callbacks that are set up by qemu_set_fd_handler are level-triggered. |
| * If @fd_read does not read from @fd, or @fd_write does not write to @fd |
| * until its buffers are full, they will be called again on the next |
| * iteration. |
| * |
| * @fd: The file descriptor to be observed. Under Windows it must be |
| * a #SOCKET. |
| * |
| * @fd_read: A level-triggered callback that is fired if @fd is readable |
| * at the beginning of a main loop iteration, or if it becomes readable |
| * during one. |
| * |
| * @fd_write: A level-triggered callback that is fired when @fd is writable |
| * at the beginning of a main loop iteration, or if it becomes writable |
| * during one. |
| * |
| * @opaque: A pointer-sized value that is passed to @fd_read and @fd_write. |
| */ |
| int qemu_set_fd_handler(int fd, |
| IOHandler *fd_read, |
| IOHandler *fd_write, |
| void *opaque); |
| |
| #ifdef CONFIG_POSIX |
| /** |
| * qemu_add_child_watch: Register a child process for reaping. |
| * |
| * Under POSIX systems, a parent process must read the exit status of |
| * its child processes using waitpid, or the operating system will not |
| * free some of the resources attached to that process. |
| * |
| * This function directs the QEMU main loop to observe a child process |
| * and call waitpid as soon as it exits; the watch is then removed |
| * automatically. It is useful whenever QEMU forks a child process |
| * but will find out about its termination by other means such as a |
| * "broken pipe". |
| * |
| * @pid: The pid that QEMU should observe. |
| */ |
| int qemu_add_child_watch(pid_t pid); |
| #endif |
| |
| /** |
| * qemu_mutex_lock_iothread: Lock the main loop mutex. |
| * |
| * This function locks the main loop mutex. The mutex is taken by |
| * qemu_init_main_loop and always taken except while waiting on |
| * external events (such as with select). The mutex should be taken |
| * by threads other than the main loop thread when calling |
| * qemu_bh_new(), qemu_set_fd_handler() and basically all other |
| * functions documented in this file. |
| * |
| * NOTE: tools currently are single-threaded and qemu_mutex_lock_iothread |
| * is a no-op there. |
| */ |
| void qemu_mutex_lock_iothread(void); |
| |
| /** |
| * qemu_mutex_unlock_iothread: Unlock the main loop mutex. |
| * |
| * This function unlocks the main loop mutex. The mutex is taken by |
| * qemu_init_main_loop and always taken except while waiting on |
| * external events (such as with select). The mutex should be unlocked |
| * as soon as possible by threads other than the main loop thread, |
| * because it prevents the main loop from processing callbacks, |
| * including timers and bottom halves. |
| * |
| * NOTE: tools currently are single-threaded and qemu_mutex_unlock_iothread |
| * is a no-op there. |
| */ |
| void qemu_mutex_unlock_iothread(void); |
| |
| /* internal interfaces */ |
| |
| void qemu_fd_register(int fd); |
| void qemu_iohandler_fill(GArray *pollfds); |
| void qemu_iohandler_poll(GArray *pollfds, int rc); |
| |
| QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque); |
| void qemu_bh_schedule_idle(QEMUBH *bh); |
| |
| #endif |