c# - 正确的处理方式 : object not disposed along all exception paths

Question

我收到第 84 行和第 85 行的消息(这两行使用堆叠):

CA2000 : Microsoft.Reliability : In method 'RavenDataAccess.GetRavenDatabase()', object '<>g_initLocal9' is not disposed along all exception paths. Call System.IDisposable.Dispose on object '<>g_initLocal9' before all references to it are out of scope.

DocumentStore 实现了 IDisposable。

为什么？我还能如何处理 DocumentStore 对象？它们是在 using block 中创建的，我在 catch block 中处理它们。这应该如何解决？

private static IDocumentStore GetRavenDatabase()
{
    Shards shards = new Shards();

    try
    {
        using (DocumentStore docStore1 = new DocumentStore { Url = ConfigurationManager.AppSettings["RavenShard1"] })  // Line 84
        using (DocumentStore docStore2 = new DocumentStore { Url = ConfigurationManager.AppSettings["RavenShard2"] })  // Line 85
        {
            shards.Add(docStore1);
            shards.Add(docStore2);
        }

        using (ShardedDocumentStore documentStore = new ShardedDocumentStore(new ShardStrategy(), shards))
        {
            documentStore.Initialize();

            IndexCreation.CreateIndexes(typeof(RavenDataAccess).Assembly, documentStore);

            return documentStore;
        }
    }
    catch
    {
        shards.ForEach(docStore => docStore.Dispose());

        throw;
    }
}

Answer 1

您必须确保沿着任何可能的异常路径处置所有新创建的 Disposable 对象。见下文:

private static IDocumentStore GetRavenDatabase()
{
    Shards shards = new Shards();
    DocumentStore docStore1 = null;
    DocumentStore docStore2 = null;

    ShardedDocumentStore shardedDocumentStore = null;
    ShardedDocumentStore tempShardedDocumentStore = null;

    try
    {
        docStore1 = new DocumentStore();
        docStore1.Url = ConfigurationManager.AppSettings["RavenShard1"];
        docStore2 = new DocumentStore();
        docStore2.Url = ConfigurationManager.AppSettings["RavenShard2"];

        shards.Add(docStore1);
        shards.Add(docStore2);

        tempShardedDocumentStore = new ShardedDocumentStore(new ShardStrategy(), shards);
        tempShardedDocumentStore.Initialize();

        IndexCreation.CreateIndexes(typeof(RavenDataAccess).Assembly, tempShardedDocumentStore);

        docStore1 = null;
        docStore2 = null;

        shardedDocumentStore = tempShardedDocumentStore;
        tempShardedDocumentStore = null;

        return shardedDocumentStore;
    }
    finally
    {
        if (tempShardedDocumentStore != null) { tempShardedDocumentStore.Dispose(); }
        if (docStore1 != null) { docStore1.Dispose(); }
        if (docStore2 != null) { docStore2.Dispose(); }
    }
}

CA 似乎对内联属性初始值设定项有问题，但如果您将它们排除在外，这应该会起作用。关键是要确保无论在 try block 中的哪个位置抛出异常，都可以清除所有可以处理的新对象。

通过设置临时引用，您不再需要null(docStore1、docStore2 和tempShardedDocumentStore)在返回之前，您可以检查 finally block 以查看它们是否实际上被设置为 null，如果不是，则某处发生异常，您可以在执行离开此方法之前处理它们。

注意 docStore1 和 docStore2 是临时引用，因为它们被添加到 Shards集合。