path: root/trace-events
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authorKevin Wolf <kwolf@redhat.com>2011-01-17 16:08:14 +0000
committerKevin Wolf <kwolf@redhat.com>2011-08-01 12:14:09 +0200
commit00dccaf1f848290d979a4b1e6248281ce1b32aaa (patch)
treeacc1d17a272a1a3494125d96ff22bb638566f076 /trace-events
parentf6e8ffc22fe153ba981f2747e4c52ea7e55f6ecc (diff)
coroutine: introduce coroutines
Asynchronous code is becoming very complex. At the same time synchronous code is growing because it is convenient to write. Sometimes duplicate code paths are even added, one synchronous and the other asynchronous. This patch introduces coroutines which allow code that looks synchronous but is asynchronous under the covers. A coroutine has its own stack and is therefore able to preserve state across blocking operations, which traditionally require callback functions and manual marshalling of parameters. Creating and starting a coroutine is easy: coroutine = qemu_coroutine_create(my_coroutine); qemu_coroutine_enter(coroutine, my_data); The coroutine then executes until it returns or yields: void coroutine_fn my_coroutine(void *opaque) { MyData *my_data = opaque; /* do some work */ qemu_coroutine_yield(); /* do some more work */ } Yielding switches control back to the caller of qemu_coroutine_enter(). This is typically used to switch back to the main thread's event loop after issuing an asynchronous I/O request. The request callback will then invoke qemu_coroutine_enter() once more to switch back to the coroutine. Note that if coroutines are used only from threads which hold the global mutex they will never execute concurrently. This makes programming with coroutines easier than with threads. Race conditions cannot occur since only one coroutine may be active at any time. Other coroutines can only run across yield. This coroutines implementation is based on the gtk-vnc implementation written by Anthony Liguori <anthony@codemonkey.ws> but it has been significantly rewritten by Kevin Wolf <kwolf@redhat.com> to use setjmp()/longjmp() instead of the more expensive swapcontext() and by Paolo Bonzini <pbonzini@redhat.com> for Windows Fibers support. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Diffstat (limited to 'trace-events')
1 files changed, 5 insertions, 0 deletions
diff --git a/trace-events b/trace-events
index 713f04208..136f7759f 100644
--- a/trace-events
+++ b/trace-events
@@ -425,3 +425,8 @@ disable qemu_put_ram_ptr(void* addr) "%p"
# hw/xen_platform.c
disable xen_platform_log(char *s) "xen platform: %s"
+# qemu-coroutine.c
+disable qemu_coroutine_enter(void *from, void *to, void *opaque) "from %p to %p opaque %p"
+disable qemu_coroutine_yield(void *from, void *to) "from %p to %p"
+disable qemu_coroutine_terminate(void *co) "self %p"