02ffb50448
qemu_co_queue_next(&queue) arranges that the next queued coroutine is run at a later point in time. This deferred restart is useful because the caller may not want to transfer control yet. This behavior was implemented using QEMUBH in the past, which meant that CoQueue (and hence CoMutex and CoRwlock) had a dependency on the AioContext event loop. This hidden dependency causes trouble when we move to a world with multiple event loops - now qemu_co_queue_next() needs to know which event loop to schedule the QEMUBH in. After pondering how to stash AioContext I realized the best solution is to not use AioContext at all. This patch implements the deferred restart behavior purely in terms of coroutines and no longer uses QEMUBH. Here is how it works: Each Coroutine has a wakeup queue that starts out empty. When qemu_co_queue_next() is called, the next coroutine is added to our wakeup queue. The wakeup queue is processed when we yield or terminate. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
54 lines
1.9 KiB
C
54 lines
1.9 KiB
C
/*
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* Coroutine internals
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*
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* Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef QEMU_COROUTINE_INT_H
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#define QEMU_COROUTINE_INT_H
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#include "qemu/queue.h"
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#include "block/coroutine.h"
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typedef enum {
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COROUTINE_YIELD = 1,
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COROUTINE_TERMINATE = 2,
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} CoroutineAction;
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struct Coroutine {
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CoroutineEntry *entry;
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void *entry_arg;
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Coroutine *caller;
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QSLIST_ENTRY(Coroutine) pool_next;
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/* Coroutines that should be woken up when we yield or terminate */
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QTAILQ_HEAD(, Coroutine) co_queue_wakeup;
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QTAILQ_ENTRY(Coroutine) co_queue_next;
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};
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Coroutine *qemu_coroutine_new(void);
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void qemu_coroutine_delete(Coroutine *co);
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CoroutineAction qemu_coroutine_switch(Coroutine *from, Coroutine *to,
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CoroutineAction action);
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void coroutine_fn qemu_co_queue_run_restart(Coroutine *co);
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#endif
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