From 4f1fe5404c954c85f3bc2379c7ae130b57ea5e73 Mon Sep 17 00:00:00 2001
From: Vika <vika@fireburn.ru>
Date: Wed, 28 Aug 2024 15:01:57 +0300
Subject: Introduce `Storage::update_with`

This function takes a closure that modifies the post. This could be
useful in maintenance utilities that scan and fixup posts. For now
this isn't used anywhere within Kittybox, but once all backends
implement this correctly, this could replace `Storage::update_post`
calls. For supporting backends, `Storage::update_post` is implemented
in terms of `Storage::update_with`.
---
 src/database/mod.rs | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

(limited to 'src/database/mod.rs')

diff --git a/src/database/mod.rs b/src/database/mod.rs
index 058fc0c..0993715 100644
--- a/src/database/mod.rs
+++ b/src/database/mod.rs
@@ -251,7 +251,31 @@ pub trait Storage: std::fmt::Debug + Clone + Send + Sync {
     /// each other's changes or simply corrupting something. Rejecting
     /// is allowed in case of concurrent updates if waiting for a lock
     /// cannot be done.
-    fn update_post(&self, url: &str, update: MicropubUpdate) -> impl Future<Output = Result<()>> + Send;
+    ///
+    /// Default implementation calls [`Storage::update_with`] and uses
+    /// [`update.apply`][MicropubUpdate::apply] to update the post.
+    fn update_post(&self, url: &str, update: MicropubUpdate) -> impl Future<Output = Result<()>> + Send {
+        let fut = self.update_with(url, |post| {
+            update.apply(post);
+        });
+
+        // The old interface didn't return anything, the new interface
+        // returns the old and new post. Adapt accordingly.
+        futures::TryFutureExt::map_ok(fut, |(_old, _new)| ())
+    }
+
+    /// Modify a post using an arbitrary closure.
+    ///
+    /// Note to implementors: the update operation MUST be atomic and
+    /// SHOULD lock the database to prevent two clients overwriting
+    /// each other's changes or simply corrupting something. Rejecting
+    /// is allowed in case of concurrent updates if waiting for a lock
+    /// cannot be done.
+    ///
+    /// Returns old post and the new post after editing.
+    fn update_with<F: FnOnce(&mut serde_json::Value) + Send>(
+        &self, url: &str, f: F
+    ) -> impl Future<Output = Result<(serde_json::Value, serde_json::Value)>> + Send;
 
     /// Get a list of channels available for the user represented by
     /// the `user` domain to write to.
-- 
cgit 1.4.1