io: add QIOTask class for async operations

A number of I/O operations need to be performed asynchronously
to avoid blocking the main loop. The caller of such APIs need
to provide a callback to be invoked on completion/error and
need access to the error, if any. The small QIOTask provides
a simple framework for dealing with such probes. The API
docs inline provide an outline of how this is to be used.

Some functions don't have the ability to run asynchronously
(eg getaddrinfo always blocks), so to facilitate their use,
the task class provides a mechanism to run a blocking
function in a thread, while triggering the completion
callback in the main event loop thread. This easily allows
any synchronous function to be made asynchronous, albeit
at the cost of spawning a thread.

In this series, the QIOTask class will be used for things like
the TLS handshake, the websockets handshake and TCP connect()
progress.

The concept of QIOTask is inspired by the GAsyncResult
interface / GTask class in the GIO libraries. The min
version requirements on glib don't allow those to be
used from QEMU, so QIOTask provides a facsimilie which
can be easily switched to GTask in the future if the
min version is increased.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

3 files changed, 272 insertions, 0 deletions

diff --git a/tests/.gitignore b/tests/.gitignore
index 1e55722b6a..eec12cc2db 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -24,6 +24,7 @@ test-cutils
 test-hbitmap
 test-int128
 test-iov
+test-io-task
 test-mul64
 test-opts-visitor
 test-qapi-event.[ch]
diff --git a/tests/Makefile b/tests/Makefile
index 053c1ae481..515a7c7c30 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -84,6 +84,7 @@ check-unit-$(CONFIG_GNUTLS) += tests/test-crypto-tlscredsx509$(EXESUF)
 check-unit-$(CONFIG_GNUTLS) += tests/test-crypto-tlssession$(EXESUF)
 check-unit-$(CONFIG_LINUX) += tests/test-qga$(EXESUF)
 check-unit-y += tests/test-timed-average$(EXESUF)
+check-unit-y += tests/test-io-task$(EXESUF)
 
 check-block-$(CONFIG_POSIX) += tests/qemu-iotests-quick.sh
 
@@ -381,6 +382,7 @@ test-qapi-obj-y = tests/test-qapi-visit.o tests/test-qapi-types.o \
 	$(test-qom-obj-y)
 test-crypto-obj-y = $(crypto-obj-y) $(test-qom-obj-y)
 test-block-obj-y = $(block-obj-y) $(test-crypto-obj-y)
+test-io-obj-y = $(io-obj-y) $(test-crypto-obj-y)
 
 tests/check-qint$(EXESUF): tests/check-qint.o $(test-util-obj-y)
 tests/check-qstring$(EXESUF): tests/check-qstring.o $(test-util-obj-y)
@@ -469,6 +471,7 @@ tests/test-crypto-tlscredsx509$(EXESUF): tests/test-crypto-tlscredsx509.o \
 tests/test-crypto-tlssession.o-cflags := $(TASN1_CFLAGS)
 tests/test-crypto-tlssession$(EXESUF): tests/test-crypto-tlssession.o \
 	tests/crypto-tls-x509-helpers.o tests/pkix_asn1_tab.o $(test-crypto-obj-y)
+tests/test-io-task$(EXESUF): tests/test-io-task.o $(test-io-obj-y)
 
 libqos-obj-y = tests/libqos/pci.o tests/libqos/fw_cfg.o tests/libqos/malloc.o
 libqos-obj-y += tests/libqos/i2c.o tests/libqos/libqos.o
diff --git a/tests/test-io-task.c b/tests/test-io-task.c
new file mode 100644
index 0000000000..3344382c7f
--- /dev/null
+++ b/tests/test-io-task.c
@@ -0,0 +1,268 @@
+/*
+ * QEMU I/O task tests
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <glib.h>
+
+#include "io/task.h"
+
+#define TYPE_DUMMY "qemu:dummy"
+
+typedef struct DummyObject DummyObject;
+typedef struct DummyObjectClass DummyObjectClass;
+
+struct DummyObject {
+    Object parent;
+};
+
+struct DummyObjectClass {
+    ObjectClass parent;
+};
+
+static const TypeInfo dummy_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_DUMMY,
+    .instance_size = sizeof(DummyObject),
+    .class_size = sizeof(DummyObjectClass),
+};
+
+struct TestTaskData {
+    Object *source;
+    Error *err;
+    bool freed;
+};
+
+
+static void task_callback(Object *source,
+                          Error *err,
+                          gpointer opaque)
+{
+    struct TestTaskData *data = opaque;
+
+    data->source = source;
+    data->err = err;
+}
+
+
+static void test_task_complete(void)
+{
+    QIOTask *task;
+    Object *obj = object_new(TYPE_DUMMY);
+    Object *src;
+    struct TestTaskData data = { NULL, NULL, false };
+
+    task = qio_task_new(obj, task_callback, &data, NULL);
+    src = qio_task_get_source(task);
+
+    qio_task_complete(task);
+
+    g_assert(obj == src);
+
+    object_unref(obj);
+    object_unref(src);
+
+    g_assert(data.source == obj);
+    g_assert(data.err == NULL);
+    g_assert(data.freed == false);
+}
+
+
+static void task_data_free(gpointer opaque)
+{
+    struct TestTaskData *data = opaque;
+
+    data->freed = true;
+}
+
+
+static void test_task_data_free(void)
+{
+    QIOTask *task;
+    Object *obj = object_new(TYPE_DUMMY);
+    struct TestTaskData data = { NULL, NULL, false };
+
+    task = qio_task_new(obj, task_callback, &data, task_data_free);
+
+    qio_task_complete(task);
+
+    object_unref(obj);
+
+    g_assert(data.source == obj);
+    g_assert(data.err == NULL);
+    g_assert(data.freed == true);
+}
+
+
+static void test_task_error(void)
+{
+    QIOTask *task;
+    Object *obj = object_new(TYPE_DUMMY);
+    struct TestTaskData data = { NULL, NULL, false };
+    Error *err = NULL;
+
+    task = qio_task_new(obj, task_callback, &data, NULL);
+
+    error_setg(&err, "Some error");
+
+    qio_task_abort(task, err);
+
+    error_free(err);
+    object_unref(obj);
+
+    g_assert(data.source == obj);
+    g_assert(data.err == err);
+    g_assert(data.freed == false);
+
+}
+
+
+struct TestThreadWorkerData {
+    Object *source;
+    Error *err;
+    bool fail;
+    GThread *worker;
+    GThread *complete;
+    GMainLoop *loop;
+};
+
+static int test_task_thread_worker(QIOTask *task,
+                                   Error **errp,
+                                   gpointer opaque)
+{
+    struct TestThreadWorkerData *data = opaque;
+
+    data->worker = g_thread_self();
+
+    if (data->fail) {
+        error_setg(errp, "Testing fail");
+        return -1;
+    }
+
+    return 0;
+}
+
+
+static void test_task_thread_callback(Object *source,
+                                      Error *err,
+                                      gpointer opaque)
+{
+    struct TestThreadWorkerData *data = opaque;
+
+    data->source = source;
+    data->err = err;
+
+    data->complete = g_thread_self();
+
+    g_main_loop_quit(data->loop);
+}
+
+
+static void test_task_thread_complete(void)
+{
+    QIOTask *task;
+    Object *obj = object_new(TYPE_DUMMY);
+    struct TestThreadWorkerData data = { 0 };
+    GThread *self;
+
+    data.loop = g_main_loop_new(g_main_context_default(),
+                                TRUE);
+
+    task = qio_task_new(obj,
+                        test_task_thread_callback,
+                        &data,
+                        NULL);
+
+    qio_task_run_in_thread(task,
+                           test_task_thread_worker,
+                           &data,
+                           NULL);
+
+    g_main_loop_run(data.loop);
+
+    g_main_loop_unref(data.loop);
+    object_unref(obj);
+
+    g_assert(data.source == obj);
+    g_assert(data.err == NULL);
+
+    self = g_thread_self();
+
+    /* Make sure the test_task_thread_worker actually got
+     * run in a different thread */
+    g_assert(data.worker != self);
+
+    /* And that the test_task_thread_callback got rnu in
+     * the main loop thread (ie this one) */
+    g_assert(data.complete == self);
+}
+
+
+static void test_task_thread_error(void)
+{
+    QIOTask *task;
+    Object *obj = object_new(TYPE_DUMMY);
+    struct TestThreadWorkerData data = { 0 };
+    GThread *self;
+
+    data.loop = g_main_loop_new(g_main_context_default(),
+                                TRUE);
+    data.fail = true;
+
+    task = qio_task_new(obj,
+                        test_task_thread_callback,
+                        &data,
+                        NULL);
+
+    qio_task_run_in_thread(task,
+                           test_task_thread_worker,
+                           &data,
+                           NULL);
+
+    g_main_loop_run(data.loop);
+
+    g_main_loop_unref(data.loop);
+    object_unref(obj);
+
+    g_assert(data.source == obj);
+    g_assert(data.err != NULL);
+
+    self = g_thread_self();
+
+    /* Make sure the test_task_thread_worker actually got
+     * run in a different thread */
+    g_assert(data.worker != self);
+
+    /* And that the test_task_thread_callback got rnu in
+     * the main loop thread (ie this one) */
+    g_assert(data.complete == self);
+}
+
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+    module_call_init(MODULE_INIT_QOM);
+    type_register_static(&dummy_info);
+    g_test_add_func("/crypto/task/complete", test_task_complete);
+    g_test_add_func("/crypto/task/datafree", test_task_data_free);
+    g_test_add_func("/crypto/task/error", test_task_error);
+    g_test_add_func("/crypto/task/thread_complete", test_task_thread_complete);
+    g_test_add_func("/crypto/task/thread_error", test_task_thread_error);
+    return g_test_run();
+}