util: add qemu-co-timeout

Add new API, to make a time limited call of the coroutine.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

include/qemu/coroutine.h

@@ -331,6 +331,19 @@ static inline void coroutine_fn qemu_co_sleep_ns(QEMUClockType type, int64_t ns)
     qemu_co_sleep_ns_wakeable(&w, type, ns);
 }
 
+typedef void CleanupFunc(void *opaque);
+/**
+ * Run entry in a coroutine and start timer. Wait for entry to finish or for
+ * timer to elapse, what happen first. If entry finished, return 0, if timer
+ * elapsed earlier, return -ETIMEDOUT.
+ *
+ * Be careful, entry execution is not canceled, user should handle it somehow.
+ * If @clean is provided, it's called after coroutine finish if timeout
+ * happened.
+ */
+int coroutine_fn qemu_co_timeout(CoroutineEntry *entry, void *opaque,
+                                 uint64_t timeout_ns, CleanupFunc clean);
+
 /**
  * Wake a coroutine if it is sleeping in qemu_co_sleep_ns. The timer will be
  * deleted. @sleep_state must be the variable whose address was given to

util/meson.build

@@ -85,6 +85,7 @@ if have_block
   util_ss.add(files('block-helpers.c'))
   util_ss.add(files('qemu-coroutine-sleep.c'))
   util_ss.add(files('qemu-co-shared-resource.c'))
+  util_ss.add(files('qemu-co-timeout.c'))
   util_ss.add(files('thread-pool.c', 'qemu-timer.c'))
   util_ss.add(files('readline.c'))
   util_ss.add(files('throttle.c'))

util/qemu-co-timeout.c

@@ -0,0 +1,89 @@
+/*
+ * Helper functionality for distributing a fixed total amount of
+ * an abstract resource among multiple coroutines.
+ *
+ * Copyright (c) 2022 Virtuozzo International GmbH
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/coroutine.h"
+#include "block/aio.h"
+
+typedef struct QemuCoTimeoutState {
+    CoroutineEntry *entry;
+    void *opaque;
+    QemuCoSleep sleep_state;
+    bool marker;
+    CleanupFunc *clean;
+} QemuCoTimeoutState;
+
+static void coroutine_fn qemu_co_timeout_entry(void *opaque)
+{
+    QemuCoTimeoutState *s = opaque;
+
+    s->entry(s->opaque);
+
+    if (s->marker) {
+        assert(!s->sleep_state.to_wake);
+        /* .marker set by qemu_co_timeout, it have been failed */
+        if (s->clean) {
+            s->clean(s->opaque);
+        }
+        g_free(s);
+    } else {
+        s->marker = true;
+        qemu_co_sleep_wake(&s->sleep_state);
+    }
+}
+
+int coroutine_fn qemu_co_timeout(CoroutineEntry *entry, void *opaque,
+                                 uint64_t timeout_ns, CleanupFunc clean)
+{
+    QemuCoTimeoutState *s;
+    Coroutine *co;
+
+    if (timeout_ns == 0) {
+        entry(opaque);
+        return 0;
+    }
+
+    s = g_new(QemuCoTimeoutState, 1);
+    *s = (QemuCoTimeoutState) {
+        .entry = entry,
+        .opaque = opaque,
+        .clean = clean
+    };
+
+    co = qemu_coroutine_create(qemu_co_timeout_entry, s);
+
+    aio_co_enter(qemu_get_current_aio_context(), co);
+    qemu_co_sleep_ns_wakeable(&s->sleep_state, QEMU_CLOCK_REALTIME, timeout_ns);
+
+    if (s->marker) {
+        /* .marker set by qemu_co_timeout_entry, success */
+        g_free(s);
+        return 0;
+    }
+
+    /* Don't free s, as we can't cancel qemu_co_timeout_entry execution */
+    s->marker = true;
+    return -ETIMEDOUT;
+}