[Qemu-devel] [PATCH] qapi: change QmpOutputVisitor to QSLIST

[Paolo Bonzini <pbonzini@redhat.com>]

This saves a little memory compared to the doubly-linked QTAILQ.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 qapi/qmp-output-visitor.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 4d3cf78..676df1f 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -22,15 +22,13 @@
 typedef struct QStackEntry
 {
     QObject *value;
-    QTAILQ_ENTRY(QStackEntry) node;
+    QSLIST_ENTRY(QStackEntry) node;
 } QStackEntry;
 
-typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
-
 struct QmpOutputVisitor
 {
     Visitor visitor;
-    QStack stack; /* Stack of containers that haven't yet been finished */
+    QSLIST_HEAD(, QStackEntry) stack; /* Stack of containers that haven't yet been finished */
     QObject *root; /* Root of the output visit */
 };
 
@@ -51,17 +49,17 @@ static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
     assert(qov->root);
     assert(value);
     e->value = value;
-    QTAILQ_INSERT_HEAD(&qov->stack, e, node);
+    QSLIST_INSERT_HEAD(&qov->stack, e, node);
 }
 
 /* Pop a value off the stack of QObjects being built, and return it. */
 static QObject *qmp_output_pop(QmpOutputVisitor *qov)
 {
-    QStackEntry *e = QTAILQ_FIRST(&qov->stack);
+    QStackEntry *e = QSLIST_FIRST(&qov->stack);
     QObject *value;
 
     assert(e);
-    QTAILQ_REMOVE(&qov->stack, e, node);
+    QSLIST_REMOVE_HEAD(&qov->stack, node);
     value = e->value;
     assert(value);
     g_free(e);
@@ -74,7 +72,7 @@ static QObject *qmp_output_pop(QmpOutputVisitor *qov)
 static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
                                QObject *value)
 {
-    QStackEntry *e = QTAILQ_FIRST(&qov->stack);
+    QStackEntry *e = QSLIST_FIRST(&qov->stack);
     QObject *cur = e ? e->value : NULL;
 
     if (!cur) {
@@ -198,7 +196,7 @@ static void qmp_output_type_null(Visitor *v, const char *name, Error **errp)
 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 {
     /* A visit must have occurred, with each start paired with end.  */
-    assert(qov->root && QTAILQ_EMPTY(&qov->stack));
+    assert(qov->root && QSLIST_EMPTY(&qov->stack));
 
     qobject_incref(qov->root);
     return qov->root;
@@ -211,11 +209,8 @@ Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
 
 void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
 {
-    QStackEntry *e, *tmp;
-
-    QTAILQ_FOREACH_SAFE(e, &v->stack, node, tmp) {
-        QTAILQ_REMOVE(&v->stack, e, node);
-        g_free(e);
+    while (!QSLIST_EMPTY(&v->stack)) {
+        qmp_output_pop(v);
     }
 
     qobject_decref(v->root);
@@ -242,7 +237,5 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
     v->visitor.type_any = qmp_output_type_any;
     v->visitor.type_null = qmp_output_type_null;
 
-    QTAILQ_INIT(&v->stack);
-
     return v;
 }
-- 
2.7.4