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[libvirt] [PATCH v3 14/16] util: Introduce virObjectLookupHashClone



A convenience API that will utilize the virHashForEach API for a specified
LookupHash in order to create a clone/copy. Primary consumer is the interface
driver which has a desire to save off a copy of it's @Name LookupHash table
in order to possible restore it if something goes wrong during processing.
The callback function's primary purpose is to copy anything within the
local LookupKeys into the target.

Signed-off-by: John Ferlan <jferlan redhat com>
---
 src/libvirt_private.syms |  1 +
 src/util/virobject.c     | 79 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/util/virobject.h     | 10 ++++++
 3 files changed, 90 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 2c4296a..41638f6 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2287,6 +2287,7 @@ virObjectListFreeCount;
 virObjectLock;
 virObjectLockableNew;
 virObjectLookupHashAdd;
+virObjectLookupHashClone;
 virObjectLookupHashFind;
 virObjectLookupHashForEach;
 virObjectLookupHashGetName;
diff --git a/src/util/virobject.c b/src/util/virobject.c
index 60bc5b5..9182a2e 100644
--- a/src/util/virobject.c
+++ b/src/util/virobject.c
@@ -992,3 +992,82 @@ virObjectLookupHashSearch(void *tableobj,
 
     return obj;
 }
+
+
+struct cloneData {
+    virObjectLookupHashCloneCallback callback;
+    virObjectLookupHashPtr dst;
+    bool error;
+};
+
+/*
+ * Take the provided virHashForEach element and call the driver @cb function
+ * with the input @dstTable and the source element from the @srcTable in order
+ * to perform the copy - tracking success/failure using the error boolean.
+ * Once there's a failure, no future copy/clone will occur.
+ *
+ * The @cb function can expect the @srcTable object to be locked upon entry.
+ *
+ * Returns 0 to the virHashForEach on success, -1 on failure.
+ */
+static int
+cloneCallback(void *payload,
+              const void *name ATTRIBUTE_UNUSED,
+              void *opaque)
+{
+    virObjectLookupKeysPtr obj = payload;
+    struct cloneData *data = opaque;
+
+    if (data->error)
+        return 0;
+
+    virObjectLock(obj);
+
+    if (data->callback(data->dst, obj) < 0)
+        data->error = true;
+
+    virObjectUnlock(obj);
+
+    if (data->error)
+        return -1;
+
+    return 0;
+}
+
+/**
+ * virObjectLookupHashClone
+ * @srcTable: source poolable hash table pointer to clone from
+ * @dstTable: destination poolable hash table pointer to clone to
+ * @useUUID: Use the objsUUID for clone (or objsName)
+ * @cb: callback function from driver code to handle the clone
+ *
+ * The clone function is designed to traverse each @srcTable hash element
+ * and call the driver specific @cb function with the element from the
+ * @srcTable in order to clone into the @dstTable. If @useUUID is true,
+ * then clone the objsUUID table; otherwise, clone the objsName table.
+ *
+ * Return 0 on success, -1 on failure
+ */
+int
+virObjectLookupHashClone(void *srcTable,
+                         void *dstTable,
+                         bool useUUID,
+                         virObjectLookupHashCloneCallback cb)
+{
+    virObjectLookupHashPtr src = virObjectGetLookupHashObj(srcTable);
+    virObjectLookupHashPtr dst = virObjectGetLookupHashObj(dstTable);
+    struct cloneData data = { .callback = cb, .dst = dst, .error = false };
+
+    if (!src || !dst)
+        return -1;
+
+    virObjectLock(src);
+    virHashForEach(useUUID ? src->objsUUID : src->objsName,
+                   cloneCallback, &data);
+    virObjectUnlock(src);
+
+    if (data.error)
+        return -1;
+
+    return 0;
+}
diff --git a/src/util/virobject.h b/src/util/virobject.h
index 7e58e34..350929d 100644
--- a/src/util/virobject.h
+++ b/src/util/virobject.h
@@ -224,4 +224,14 @@ virObjectLookupHashSearch(void *tableobj,
                           virHashSearcher callback,
                           void *opaque);
 
+typedef int (*virObjectLookupHashCloneCallback)(void *dstTable,
+                                                       void *srcElem);
+int
+virObjectLookupHashClone(void *srcTable,
+                         void *dstTable,
+                         bool useUUID,
+                         virObjectLookupHashCloneCallback cb)
+    ATTRIBUTE_NONNULL(4);
+
+
 #endif /* __VIR_OBJECT_H */
-- 
2.9.4


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