coroutine: add co_sleep_ns() coroutine sleep function

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Makefile.objs

@@ -13,6 +13,7 @@ oslib-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
 #######################################################################
 # coroutines
 coroutine-obj-y = qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o
+coroutine-obj-y += qemu-coroutine-sleep.o
 ifeq ($(CONFIG_UCONTEXT_COROUTINE),y)
 coroutine-obj-$(CONFIG_POSIX) += coroutine-ucontext.o
 else

qemu-coroutine-sleep.c

@@ -0,0 +1,38 @@
+/*
+ * QEMU coroutine sleep
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "qemu-coroutine.h"
+#include "qemu-timer.h"
+
+typedef struct CoSleepCB {
+    QEMUTimer *ts;
+    Coroutine *co;
+} CoSleepCB;
+
+static void co_sleep_cb(void *opaque)
+{
+    CoSleepCB *sleep_cb = opaque;
+
+    qemu_free_timer(sleep_cb->ts);
+    qemu_coroutine_enter(sleep_cb->co, NULL);
+}
+
+void coroutine_fn co_sleep_ns(QEMUClock *clock, int64_t ns)
+{
+    CoSleepCB sleep_cb = {
+        .co = qemu_coroutine_self(),
+    };
+    sleep_cb.ts = qemu_new_timer(clock, SCALE_NS, co_sleep_cb, &sleep_cb);
+    qemu_mod_timer(sleep_cb.ts, qemu_get_clock_ns(clock) + ns);
+    qemu_coroutine_yield();
+}

qemu-coroutine.h

@@ -17,6 +17,7 @@
 
 #include <stdbool.h>
 #include "qemu-queue.h"
+#include "qemu-timer.h"
 
 /**
  * Coroutines are a mechanism for stack switching and can be used for
@@ -199,4 +200,12 @@ void qemu_co_rwlock_wrlock(CoRwlock *lock);
  */
 void qemu_co_rwlock_unlock(CoRwlock *lock);
 
+/**
+ * Yield the coroutine for a given duration
+ *
+ * Note this function uses timers and hence only works when a main loop is in
+ * use.  See main-loop.h and do not use from qemu-tool programs.
+ */
+void coroutine_fn co_sleep_ns(QEMUClock *clock, int64_t ns);
+
 #endif /* QEMU_COROUTINE_H */