[Qemu-block] [PATCH 1/2] qdict: add qdict_steal()

[Marc-André Lureau]

Add a new function qdict_steal(), that deletes a key from a dict, and
returns the associated value, if any. Simplify related code.

Signed-off-by: Marc-André Lureau <address@hidden>
---
 include/qapi/qmp/qdict.h |  1 +
 monitor.c                |  3 +--
 qobject/block-qdict.c    |  7 ++-----
 qobject/qdict.c          | 22 ++++++++++++++++++++++
 4 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h
index 7f3ec10a10..84644bfba6 100644
--- a/include/qapi/qmp/qdict.h
+++ b/include/qapi/qmp/qdict.h
@@ -37,6 +37,7 @@ QObject *qdict_entry_value(const QDictEntry *entry);
 size_t qdict_size(const QDict *qdict);
 void qdict_put_obj(QDict *qdict, const char *key, QObject *value);
 void qdict_del(QDict *qdict, const char *key);
+QObject *qdict_steal(QDict *qdict, const char *key);
 int qdict_haskey(const QDict *qdict, const char *key);
 QObject *qdict_get(const QDict *qdict, const char *key);
 bool qdict_is_equal(const QObject *x, const QObject *y);
diff --git a/monitor.c b/monitor.c
index a1999e396c..eab2dc7b7b 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4262,8 +4262,7 @@ static void handle_qmp_command(JSONMessageParser *parser, 
GQueue *tokens)
 
     qdict = qobject_to(QDict, req);
     if (qdict) {
-        id = qobject_ref(qdict_get(qdict, "id"));
-        qdict_del(qdict, "id");
+        id = qdict_steal(qdict, "id");
     } /* else will fail qmp_dispatch() */
 
     if (req && trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) {
diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
index 42054cc274..a07664ee6a 100644
--- a/qobject/block-qdict.c
+++ b/qobject/block-qdict.c
@@ -692,8 +692,6 @@ void qdict_join(QDict *dest, QDict *src, bool overwrite)
  */
 bool qdict_rename_keys(QDict *qdict, const QDictRenames *renames, Error **errp)
 {
-    QObject *qobj;
-
     while (renames->from) {
         if (qdict_haskey(qdict, renames->from)) {
             if (qdict_haskey(qdict, renames->to)) {
@@ -702,9 +700,8 @@ bool qdict_rename_keys(QDict *qdict, const QDictRenames 
*renames, Error **errp)
                 return false;
             }
 
-            qobj = qdict_get(qdict, renames->from);
-            qdict_put_obj(qdict, renames->to, qobject_ref(qobj));
-            qdict_del(qdict, renames->from);
+            qdict_put_obj(qdict, renames->to,
+                          qdict_steal(qdict, renames->from));
         }
 
         renames++;
diff --git a/qobject/qdict.c b/qobject/qdict.c
index 3d8c2f7bbc..322f23f094 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -406,6 +406,28 @@ void qdict_del(QDict *qdict, const char *key)
     }
 }
 
+/**
+ * qdict_steal(): Steal a 'key:value' pair from the dictionary
+ *
+ * Return the associated entry value and remove it, or NULL.
+ */
+QObject *qdict_steal(QDict *qdict, const char *key)
+{
+    QDictEntry *entry;
+    QObject *val = NULL;
+
+    entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_BUCKET_MAX);
+    if (entry) {
+        QLIST_REMOVE(entry, next);
+        val = qobject_ref(entry->value);
+        qentry_destroy(entry);
+        qdict->size--;
+    }
+
+    return val;
+}
+
+
 /**
  * qdict_is_equal(): Test whether the two QDicts are equal
  *
-- 
2.18.0.547.g1d89318c48