database: add downcast methods for dyn NostrDatabase

Implement downcasting methods to the `NostrDatabase` trait, allowing easy conversion to concrete database types.

Pull-Request: #845
Signed-off-by: Yuki Kishimoto <[email protected]>

Author: yukibtc

Cargo.lock

@@ -33,6 +33,7 @@ nostr-relay-builder = { version = "0.42", path = "./crates/nostr-relay-builder",
 nostr-relay-pool = { version = "0.42", path = "./crates/nostr-relay-pool", default-features = false }
 nostr-sdk = { version = "0.42", path = "./crates/nostr-sdk", default-features = false }
 reqwest = { version = "0.12", default-features = false }
+rustversion = "1.0"
 serde = { version = "1.0", default-features = false }
 serde_json = { version = "1.0", default-features = false }
 tempfile = "3.19"

Cargo.toml

@@ -19,6 +19,7 @@ flatbuf = ["dep:flatbuffers"]
 flatbuffers = { version = "23.5", optional = true }
 lru.workspace = true
 nostr = { workspace = true, features = ["std"] }
+rustversion.workspace = true
 tokio = { workspace = true, features = ["sync"] }
 
 [dev-dependencies]

crates/nostr-database/Cargo.toml

@@ -193,6 +193,43 @@ pub trait NostrDatabase: Any + Debug + Send + Sync {
     fn wipe(&self) -> BoxedFuture<Result<(), DatabaseError>>;
 }
 
+#[rustversion::since(1.86)]
+impl dyn NostrDatabase {
+    /// Upcast to [`Any`].
+    #[inline]
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    /// Upcast to [`Any`].
+    #[inline]
+    fn as_any_arc(self: Arc<Self>) -> Arc<dyn Any + Send + Sync> {
+        self
+    }
+
+    /// Downcast [`NostrDatabase`] to a concrete type reference.
+    ///
+    /// **Requires rustc >= 1.86!**
+    #[inline]
+    pub fn downcast_ref<T>(&self) -> Option<&T>
+    where
+        T: NostrDatabase,
+    {
+        self.as_any().downcast_ref()
+    }
+
+    /// Downcast [`NostrDatabase`] to a concrete type.
+    ///
+    /// **Requires rustc >= 1.86!**
+    #[inline]
+    pub fn downcast<T>(self: Arc<Self>) -> Option<Arc<T>>
+    where
+        T: NostrDatabase,
+    {
+        self.as_any_arc().downcast().ok()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/nostr-database/src/lib.rs

@@ -16,47 +16,58 @@ async fn main() -> Result<()> {
         .database(database)
         .build();
 
-    client.add_relay("wss://relay.damus.io").await?;
-    client.add_relay("wss://nostr.wine").await?;
-    client.add_relay("wss://nostr.oxtr.dev").await?;
-
-    client.connect().await;
-
-    // Publish a text note
-    let builder = EventBuilder::text_note("Hello world");
-    client.send_event_builder(builder).await?;
-
-    // Negentropy sync
-    let filter = Filter::new().author(keys.public_key());
-    let (tx, mut rx) = SyncProgress::channel();
-    let opts = SyncOptions::default().progress(tx);
-
-    tokio::spawn(async move {
-        while rx.changed().await.is_ok() {
-            let progress = *rx.borrow_and_update();
-            if progress.total > 0 {
-                println!("{:.2}%", progress.percentage() * 100.0);
-            }
-        }
-    });
-    let output = client.sync(filter, &opts).await?;
-
-    println!("Local: {}", output.local.len());
-    println!("Remote: {}", output.remote.len());
-    println!("Sent: {}", output.sent.len());
-    println!("Received: {}", output.received.len());
-    println!("Failures:");
-    for (url, map) in output.send_failures.iter() {
-        println!("* '{url}':");
-        for (id, e) in map.iter() {
-            println!("  - {id}: {e}");
-        }
-    }
+    // client.add_relay("wss://relay.damus.io").await?;
+    // client.add_relay("wss://nostr.wine").await?;
+    // client.add_relay("wss://nostr.oxtr.dev").await?;
+    //
+    // client.connect().await;
+
+    // // Publish a text note
+    // let builder = EventBuilder::text_note("Hello world");
+    // client.send_event_builder(builder).await?;
+
+    // // Negentropy sync
+    // let filter = Filter::new().author(keys.public_key());
+    // let (tx, mut rx) = SyncProgress::channel();
+    // let opts = SyncOptions::default().progress(tx);
+    //
+    // tokio::spawn(async move {
+    //     while rx.changed().await.is_ok() {
+    //         let progress = *rx.borrow_and_update();
+    //         if progress.total > 0 {
+    //             println!("{:.2}%", progress.percentage() * 100.0);
+    //         }
+    //     }
+    // });
+    // let output = client.sync(filter, &opts).await?;
+    //
+    // println!("Local: {}", output.local.len());
+    // println!("Remote: {}", output.remote.len());
+    // println!("Sent: {}", output.sent.len());
+    // println!("Received: {}", output.received.len());
+    // println!("Failures:");
+    // for (url, map) in output.send_failures.iter() {
+    //     println!("* '{url}':");
+    //     for (id, e) in map.iter() {
+    //         println!("  - {id}: {e}");
+    //     }
+    // }
+    //
+    // // Query events from database
+    // let filter = Filter::new().author(keys.public_key()).limit(10);
+    // let events = client.database().query(filter).await?;
+    // println!("Events: {events:?}");
 
-    // Query events from database
-    let filter = Filter::new().author(keys.public_key()).limit(10);
-    let events = client.database().query(filter).await?;
-    println!("Events: {events:?}");
+    // Database downcasting
+    // let database = client.database().clone();
+    // let upcast = database as Arc<dyn Any + Send + Sync>;
+    // let lmdb: &NostrLMDB = upcast.downcast_ref().unwrap();
+    //let lmdb: &NostrLMDB = (database as &dyn Any).downcast_ref::<NostrLMDB>().unwrap();
+
+    // Database downcasting to access to specific APIs
+    if let Some(_lmdb) = client.database().downcast_ref::<NostrLMDB>() {
+        // Access specific APIs here
+    }
 
     Ok(())
 }

crates/nostr-sdk/examples/lmdb.rs

@@ -18,22 +18,27 @@ async fn main() -> Result<()> {
         .database(database)
         .build();
 
-    client.add_relay("wss://relay.damus.io").await?;
-    client.add_relay("wss://atl.purplerelay.com").await?;
-    client.connect().await;
-
-    // Publish a text note
-    let builder = EventBuilder::text_note("Hello world");
-    client.send_event_builder(builder).await?;
-
-    // Negentropy reconcile
-    let filter = Filter::new().author(keys.public_key());
-    client.sync(filter, &SyncOptions::default()).await?;
-
-    // Query events from database
-    let filter = Filter::new().author(keys.public_key()).limit(10);
-    let events = client.database().query(filter).await?;
-    println!("Events: {events:?}");
+    // client.add_relay("wss://relay.damus.io").await?;
+    // client.add_relay("wss://atl.purplerelay.com").await?;
+    // client.connect().await;
+    //
+    // // Publish a text note
+    // let builder = EventBuilder::text_note("Hello world");
+    // client.send_event_builder(builder).await?;
+    //
+    // // Negentropy reconcile
+    // let filter = Filter::new().author(keys.public_key());
+    // client.sync(filter, &SyncOptions::default()).await?;
+    //
+    // // Query events from database
+    // let filter = Filter::new().author(keys.public_key()).limit(10);
+    // let events = client.database().query(filter).await?;
+    // println!("Events: {events:?}");
+
+    // Database downcasting to access to specific APIs
+    if let Some(ndb) = client.database().downcast_ref::<NdbDatabase>() {
+        println!("Subscription counts: {}", ndb.subscription_count());
+    }
 
     Ok(())
 }