[Qemu-devel] [PATCH 5/8] io: add ability to associate an error with a task

["Daniel P. Berrange" <berrange@redhat.com>]

Currently when a task fails, the error is never explicitly
associated with the task object, it is just passed along
through the completion callback. This adds ability to
explicitly associate an error with the task.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 include/io/task.h | 29 +++++++++++++++++++++++++++++
 io/task.c         | 23 +++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/include/io/task.h b/include/io/task.h
index ece1372..244c1a1 100644
--- a/include/io/task.h
+++ b/include/io/task.h
@@ -240,6 +240,35 @@ void qio_task_abort(QIOTask *task,
 
 
 /**
+ * qio_task_set_error:
+ * @task: the task struct
+ * @err: pointer to the error
+ *
+ * Associate an error with the task, which can later
+ * be retrieved with the qio_task_propagate_error()
+ * method. This method takes ownership of @err, so
+ * it is not valid to access it after this call
+ * completes.
+ */
+void qio_task_set_error(QIOTask *task,
+                        Error *err);
+
+
+/**
+ * qio_task_propagate_error:
+ * @task: the task struct
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Propagate the error associated with @task
+ * into @errp.
+ *
+ * Returns: true if an error was propagated, false otherwise
+ */
+gboolean qio_task_propagate_error(QIOTask *task,
+                                  Error **errp);
+
+
+/**
  * qio_task_set_result_pointer:
  * @task: the task struct
  * @result: pointer to the result data
diff --git a/io/task.c b/io/task.c
index 675e196..1136c75 100644
--- a/io/task.c
+++ b/io/task.c
@@ -29,6 +29,7 @@ struct QIOTask {
     QIOTaskFunc func;
     gpointer opaque;
     GDestroyNotify destroy;
+    Error *err;
     gpointer result;
     GDestroyNotify destroyResult;
 };
@@ -62,6 +63,9 @@ static void qio_task_free(QIOTask *task)
     if (task->destroyResult) {
         task->destroyResult(task->result);
     }
+    if (task->err) {
+        error_free(task->err);
+    }
     object_unref(task->source);
 
     g_free(task);
@@ -159,6 +163,25 @@ void qio_task_abort(QIOTask *task,
 }
 
 
+void qio_task_set_error(QIOTask *task,
+                        Error *err)
+{
+    error_propagate(&task->err, err);
+}
+
+
+gboolean qio_task_propagate_error(QIOTask *task,
+                                  Error **errp)
+{
+    if (task->err) {
+        error_propagate(errp, task->err);
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+
 void qio_task_set_result_pointer(QIOTask *task,
                                  gpointer result,
                                  GDestroyNotify destroy)
-- 
2.9.3