c# - 使用 .NET 客户端的 RavenDB 并发更新

Question

我想知道在使用 .net 客户端的以下场景中会发生什么。

using (IDocumentSession session = documentStore.OpenSession())
{
    thingToUpdate = session.Load<TUpdateThing>(id);

    // Modify thingToUpdate here

    // ** Someplace else the object is updated and saved. **

    session.SaveChanges();  // What happens here?
}

这会根据 etag 的更改自动抛出错误，还是会自动覆盖其他人所做的更改？

我已经看到了一些与 http api 相关的东西：http: //ravendb.net/docs/http-api/http-api-comcurrency

Answer 1

你说的是乐观并发。如果你想使用它，你设置

session.Advanced.UseOptimisticConcurrency = true;

默认情况下，未设置。

这是一个通过测试来证明这一点：

public class ConcurrentUpdates : LocalClientTest
{
    [Fact]
    public void ConcurrentUpdatesWillThrowAConcurrencyException()
    {
        using (var store = NewDocumentStore())
        {
            var originalPost = new Post { Text = "Nothing yet" };
            using (var s = store.OpenSession())
            {
                s.Store(originalPost);
                s.SaveChanges();
            }

            using (var session1 = store.OpenSession())
            using (var session2 = store.OpenSession())
            {
                session1.Advanced.UseOptimisticConcurrency = true;
                session2.Advanced.UseOptimisticConcurrency = true;

                var post1 = session1.Load<Post>(originalPost.Id);
                var post2 = session2.Load<Post>(originalPost.Id);

                post1.Text = "First change";
                post2.Text = "Second change";

                session1.SaveChanges();

                // Saving the second text will throw a concurrency exception
                Assert.Throws<ConcurrencyException>(() => session2.SaveChanges());
            }

            using (var s = store.OpenSession())
            {
                Assert.Equal("First change", s.Load<Post>(originalPost.Id).Text);
            }
        }
    }

    public class Post
    {
        public string Id { get; set; }
        public string Text { get; set; }
    }
}