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[libvirt] [PATCH v5 02/15] util: Introduce virObjectLookupHash



Define an object meant to combine/manage the aspects of the various
_vir*ObjList structs into one common purpose list management system
that will store and manage _vir*Obj virObjectLockable objects rather
than having multiple structs and API's to do that.

The object will use the virObjectRWLockable class as the base and may
have one or two hash tables that will be keyed by UUID or Name based
on the needs of the consumer stored in:

    objsUUID -> Hash table for storing objects for lookup by UUID
    objsName -> Hash table for storing objects for lookup by Name

The virObjectLookupHashNew will require the consumer to provide which
hash tables are to be used via virObjectLookupHashNewFlags.

A secondary benefit of self locking hash tables is each driver then
does not have to keep a higher level driver lock for interactions with
the object storage since the object itself can manage locking as needed.

Signed-off-by: John Ferlan <jferlan redhat com>
---
 src/libvirt_private.syms |  2 ++
 src/util/virobject.c     | 93 +++++++++++++++++++++++++++++++++++++++++++++++-
 src/util/virobject.h     | 34 ++++++++++++++++++
 3 files changed, 128 insertions(+), 1 deletion(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 2149b11..33dbd92 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2318,6 +2318,7 @@ virNumaSetupMemoryPolicy;
 # util/virobject.h
 virClassForObject;
 virClassForObjectLockable;
+virClassForObjectLookupHash;
 virClassForObjectRWLockable;
 virClassIsDerivedFrom;
 virClassName;
@@ -2329,6 +2330,7 @@ virObjectListFree;
 virObjectListFreeCount;
 virObjectLock;
 virObjectLockableNew;
+virObjectLookupHashNew;
 virObjectNew;
 virObjectRef;
 virObjectRWLockableNew;
diff --git a/src/util/virobject.c b/src/util/virobject.c
index 38db692..edd8097 100644
--- a/src/util/virobject.c
+++ b/src/util/virobject.c
@@ -68,9 +68,11 @@ struct _virClass {
 static virClassPtr virObjectClass;
 static virClassPtr virObjectLockableClass;
 static virClassPtr virObjectRWLockableClass;
+static virClassPtr virObjectLookupHashClass;
 
 static void virObjectLockableDispose(void *anyobj);
 static void virObjectRWLockableDispose(void *anyobj);
+static void virObjectLookupHashDispose(void *anyobj);
 
 static int
 virObjectOnceInit(void)
@@ -93,6 +95,12 @@ virObjectOnceInit(void)
                                                  virObjectRWLockableDispose)))
         return -1;
 
+    if (!(virObjectLookupHashClass = virClassNew(virObjectRWLockableClass,
+                                                 "virObjectLookupHash",
+                                                 sizeof(virObjectLookupHash),
+                                                 virObjectLookupHashDispose)))
+        return -1;
+
     return 0;
 }
 
@@ -145,6 +153,21 @@ virClassForObjectRWLockable(void)
 
 
 /**
+ * virClassForObjectLookupHash:
+ *
+ * Returns the class instance for the virObjectLookupHash type
+ */
+virClassPtr
+virClassForObjectLookupHash(void)
+{
+    if (virObjectInitialize() < 0)
+        return NULL;
+
+    return virObjectLookupHashClass;
+}
+
+
+/**
  * virClassNew:
  * @parent: the parent class
  * @name: the class name
@@ -328,6 +351,73 @@ virObjectRWLockableDispose(void *anyobj)
 
 
 /**
+ * virObjectLookupHashNew:
+ * @klass: the klass to check
+ * @tableElemsStart: initial size of each hash table
+ * @flags: virObjectLookupHashNewFlags to indicate which tables to create
+ *
+ * Create a new poolable hash table object for storing either 1 or 2 hash
+ * tables capable of storing virObjectLockable objects by UUID or Name. This
+ * object will use the RWLockable objects in order to allow for concurrent
+ * table reads by multiple threads looking to return lists of data.
+ *
+ * Returns: New object on success, NULL on failure w/ error message set
+ */
+void *
+virObjectLookupHashNew(virClassPtr klass,
+                       int tableElemsStart,
+                       virObjectLookupHashNewFlags flags)
+{
+    virObjectLookupHashPtr obj;
+
+    if (!flags || !(flags & (VIR_OBJECT_LOOKUP_HASH_UUID |
+                             VIR_OBJECT_LOOKUP_HASH_NAME))) {
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("flags=%x must be non zero or properly set"), flags);
+        return NULL;
+    }
+
+    if (!virClassIsDerivedFrom(klass, virClassForObjectLookupHash())) {
+        virReportInvalidArg(klass,
+                            _("Class %s must derive from virObjectLookupHash"),
+                            virClassName(klass));
+        return NULL;
+    }
+
+    if (!(obj = virObjectRWLockableNew(klass)))
+        return NULL;
+
+    if (flags & VIR_OBJECT_LOOKUP_HASH_UUID) {
+        if (!(obj->objsUUID = virHashCreate(tableElemsStart,
+                                            virObjectFreeHashData)))
+            goto error;
+    }
+
+    if (flags & VIR_OBJECT_LOOKUP_HASH_NAME) {
+        if (!(obj->objsName = virHashCreate(tableElemsStart,
+                                            virObjectFreeHashData)))
+        goto error;
+    }
+
+    return obj;
+
+ error:
+    virObjectUnref(obj);
+    return NULL;
+}
+
+
+static void
+virObjectLookupHashDispose(void *anyobj)
+{
+    virObjectLookupHashPtr obj = anyobj;
+
+    virHashFree(obj->objsUUID);
+    virHashFree(obj->objsName);
+}
+
+
+/**
  * virObjectUnref:
  * @anyobj: any instance of virObjectPtr
  *
@@ -404,7 +494,8 @@ virObjectGetLockableObj(void *anyobj)
 static virObjectRWLockablePtr
 virObjectGetRWLockableObj(void *anyobj)
 {
-    if (virObjectIsClass(anyobj, virObjectRWLockableClass))
+    if (virObjectIsClass(anyobj, virObjectRWLockableClass) ||
+        virObjectIsClass(anyobj, virObjectLookupHashClass))
         return anyobj;
 
     VIR_OBJECT_USAGE_PRINT_ERROR(anyobj, virObjectRWLockable);
diff --git a/src/util/virobject.h b/src/util/virobject.h
index ac6cf22..75efa90 100644
--- a/src/util/virobject.h
+++ b/src/util/virobject.h
@@ -23,6 +23,7 @@
 # define __VIR_OBJECT_H__
 
 # include "internal.h"
+# include "virhash.h"
 # include "virthread.h"
 
 typedef struct _virClass virClass;
@@ -37,6 +38,9 @@ typedef virObjectLockable *virObjectLockablePtr;
 typedef struct _virObjectRWLockable virObjectRWLockable;
 typedef virObjectRWLockable *virObjectRWLockablePtr;
 
+typedef struct _virObjectLookupHash virObjectLookupHash;
+typedef virObjectLookupHash *virObjectLookupHashPtr;
+
 typedef void (*virObjectDisposeCallback)(void *obj);
 
 /* Most code should not play with the contents of this struct; however,
@@ -71,6 +75,24 @@ virClassPtr virClassForObject(void);
 virClassPtr virClassForObjectLockable(void);
 virClassPtr virClassForObjectRWLockable(void);
 
+struct _virObjectLookupHash {
+    virObjectRWLockable parent;
+
+    /* key1 string -> object mapping for O(1),
+     * lockless lookup-by-uuid */
+    virHashTable *objsUUID;
+
+    /* key2 string -> object mapping for O(1),
+     * lockless lookup-by-name */
+    virHashTable *objsName;
+};
+
+
+virClassPtr virClassForObject(void);
+virClassPtr virClassForObjectLockable(void);
+virClassPtr virClassForObjectRWLockable(void);
+virClassPtr virClassForObjectLookupHash(void);
+
 # ifndef VIR_PARENT_REQUIRED
 #  define VIR_PARENT_REQUIRED ATTRIBUTE_NONNULL(1)
 # endif
@@ -120,6 +142,18 @@ void *
 virObjectRWLockableNew(virClassPtr klass)
     ATTRIBUTE_NONNULL(1);
 
+typedef enum {
+    VIR_OBJECT_LOOKUP_HASH_UUID = (1 << 0),
+    VIR_OBJECT_LOOKUP_HASH_NAME = (1 << 1),
+} virObjectLookupHashNewFlags;
+
+void *
+virObjectLookupHashNew(virClassPtr klass,
+                       int tableElemsStart,
+                       virObjectLookupHashNewFlags flags)
+
+    ATTRIBUTE_NONNULL(1);
+
 void
 virObjectLock(void *lockableobj)
     ATTRIBUTE_NONNULL(1);
-- 
2.9.5


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