96 lines
2.6 KiB
C
96 lines
2.6 KiB
C
/*
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* QEMU coroutine implementation
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#ifndef QEMU_COROUTINE_H
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#define QEMU_COROUTINE_H
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#include <stdbool.h>
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/**
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* Coroutines are a mechanism for stack switching and can be used for
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* cooperative userspace threading. These functions provide a simple but
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* useful flavor of coroutines that is suitable for writing sequential code,
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* rather than callbacks, for operations that need to give up control while
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* waiting for events to complete.
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*
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* These functions are re-entrant and may be used outside the global mutex.
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*/
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/**
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* Mark a function that executes in coroutine context
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*
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* Functions that execute in coroutine context cannot be called directly from
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* normal functions. In the future it would be nice to enable compiler or
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* static checker support for catching such errors. This annotation might make
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* it possible and in the meantime it serves as documentation.
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*
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* For example:
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*
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* static void coroutine_fn foo(void) {
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* ....
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* }
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*/
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#define coroutine_fn
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typedef struct Coroutine Coroutine;
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/**
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* Coroutine entry point
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*
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* When the coroutine is entered for the first time, opaque is passed in as an
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* argument.
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*
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* When this function returns, the coroutine is destroyed automatically and
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* execution continues in the caller who last entered the coroutine.
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*/
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typedef void coroutine_fn CoroutineEntry(void *opaque);
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/**
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* Create a new coroutine
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*
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* Use qemu_coroutine_enter() to actually transfer control to the coroutine.
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*/
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Coroutine *qemu_coroutine_create(CoroutineEntry *entry);
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/**
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* Transfer control to a coroutine
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*
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* The opaque argument is passed as the argument to the entry point when
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* entering the coroutine for the first time. It is subsequently ignored.
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*/
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void qemu_coroutine_enter(Coroutine *coroutine, void *opaque);
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/**
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* Transfer control back to a coroutine's caller
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*
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* This function does not return until the coroutine is re-entered using
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* qemu_coroutine_enter().
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*/
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void coroutine_fn qemu_coroutine_yield(void);
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/**
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* Get the currently executing coroutine
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*/
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Coroutine *coroutine_fn qemu_coroutine_self(void);
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/**
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* Return whether or not currently inside a coroutine
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*
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* This can be used to write functions that work both when in coroutine context
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* and when not in coroutine context. Note that such functions cannot use the
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* coroutine_fn annotation since they work outside coroutine context.
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*/
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bool qemu_in_coroutine(void);
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#endif /* QEMU_COROUTINE_H */
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