qemu-coroutine.h

   1 /*
   2  * QEMU coroutine implementation
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  *
  12  */
  13
  14 #ifndef QEMU_COROUTINE_H
  15 #define QEMU_COROUTINE_H
  16
  17 #include <stdbool.h>
  18
  19 /**
  20  * Mark a function that executes in coroutine context
  21  *
  22  * Functions that execute in coroutine context cannot be called directly from
  23  * normal functions.  In the future it would be nice to enable compiler or
  24  * static checker support for catching such errors.  This annotation might make
  25  * it possible and in the meantime it serves as documentation.
  26  *
  27  * For example:
  28  *
  29  *   static void coroutine_fn foo(void) {
  30  *       ....
  31  *   }
  32  */
  33 #define coroutine_fn
  34
  35 typedef struct Coroutine Coroutine;
  36
  37 /**
  38  * Coroutine entry point
  39  *
  40  * When the coroutine is entered for the first time, opaque is passed in as an
  41  * argument.
  42  *
  43  * When this function returns, the coroutine is destroyed automatically and the
  44  * return value is passed back to the caller who last entered the coroutine.
  45  */
  46 typedef void * coroutine_fn CoroutineEntry(void *opaque);
  47
  48 /**
  49  * Create a new coroutine
  50  *
  51  * Use qemu_coroutine_enter() to actually transfer control to the coroutine.
  52  */
  53 Coroutine *qemu_coroutine_create(CoroutineEntry *entry);
  54
  55 /**
  56  * Transfer control to a coroutine
  57  *
  58  * The opaque argument is made available to the coroutine either as the entry
  59  * function argument if this is the first time a new coroutine is entered, or
  60  * as the return value from qemu_coroutine_yield().
  61  *
  62  * The return value from this function is either an opaque value yielded by the
  63  * coroutine or the coroutine entry function return value when the coroutine
  64  * terminates.
  65  */
  66 void *qemu_coroutine_enter(Coroutine *coroutine, void *opaque);
  67
  68 /**
  69  * Transfer control back to a coroutine's caller
  70  *
  71  * The opaque argument is returned from the calling qemu_coroutine_enter().
  72  *
  73  * The return value is the argument passed back in from the next
  74  * qemu_coroutine_enter().
  75  */
  76 void * coroutine_fn qemu_coroutine_yield(void *opaque);
  77
  78 /**
  79  * Get the currently executing coroutine
  80  */
  81 Coroutine * coroutine_fn qemu_coroutine_self(void);
  82
  83 /**
  84  * Return whether or not currently inside a coroutine
  85  */
  86 bool qemu_in_coroutine(void);
  87
  88 #endif /* QEMU_COROUTINE_H */