Database basics

flake.lock

@@ -15,6 +15,21 @@
         "type": "github"
       }
     },
+    "flake-utils_2": {
+      "locked": {
+        "lastModified": 1637014545,
+        "narHash": "sha256-26IZAc5yzlD9FlDT54io1oqG/bBoyka+FJk5guaX4x4=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "bba5dcc8e0b20ab664967ad83d24d64cb64ec4f4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "naersk": {
       "inputs": {
         "nixpkgs": "nixpkgs"
@@ -61,11 +76,47 @@
         "type": "indirect"
       }
     },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1637453606,
+        "narHash": "sha256-Gy6cwUswft9xqsjWxFYEnx/63/qzaFUwatcbV5GF/GQ=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "8afc4e543663ca0a6a4f496262cd05233737e732",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "oxalica": {
+      "inputs": {
+        "flake-utils": "flake-utils_2",
+        "nixpkgs": "nixpkgs_3"
+      },
+      "locked": {
+        "lastModified": 1655606998,
+        "narHash": "sha256-6XIQEwmoldCE3lzI54VQxD2tFJoeRsjRMYWkthtGRRw=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "4b600525be94c23b44c42441f33460343fafe7a1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
         "naersk": "naersk",
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": "nixpkgs_2",
+        "oxalica": "oxalica"
       }
     }
   },

flake.nix

@@ -1,32 +1,37 @@
 {
     inputs = {
         flake-utils.url = "github:numtide/flake-utils";
+        oxalica.url     = "github:oxalica/rust-overlay";
         naersk.url      = "github:nix-community/naersk";
     };
 
-  outputs = { self, nixpkgs, flake-utils, naersk }:
+    outputs = { self, nixpkgs, flake-utils, naersk, oxalica }:
-    flake-utils.lib.eachDefaultSystem (
+    	flake-utils.lib.eachDefaultSystem (system:
-      system: let
+            let pkgs = import nixpkgs { inherit system; overlays = [ oxalica.overlay ]; };
-        pkgs = nixpkgs.legacyPackages."${system}";
                 naersk-lib = naersk.lib."${system}";
-      in
+            in rec {
-        rec {
                 # `nix build`
                 packages."hermit" = naersk-lib.buildPackage {
                     pname = "hermit";
                     root = ./.;
                 };
+                
                 defaultPackage = packages."hermit";
 
                 # `nix run`
                 apps."hermit"= flake-utils.lib.mkApp {
                     drv = packages."hermit";
                 };
+
                 defaultApp = apps."hermit";
 
                 # `nix develop`
                 devShell = pkgs.mkShell {
-            nativeBuildInputs = with pkgs; [ rustc cargo openssl pkgconfig ];
+                    nativeBuildInputs = with pkgs; [
+                        (rust-bin.selectLatestNightlyWith (t: t.default))
+                        openssl
+                        pkgconfig
+                    ];
                 };
             }
         );

src/ap/mod.rs

@@ -1,24 +1,25 @@
 //! ActivityPub implementation code and related abstractions.
 
 use futures::prelude::*;
+use serde::Serialize;
 
 use crate::{ Id, Activity, err, Result, Error, sign, ctx::Context };
 
-#[derive(Clone)]
+#[derive(Clone, Serialize)]
 pub enum Create {
     Note { object: Note }
 }
 
 impl From<Create> for Activity { fn from (a: Create) -> Activity { Activity::Create (a) } }
 
-#[derive(Clone)]
+#[derive(Clone, Serialize)]
 pub enum Follow {
 	Actor { object: Actor }
 }
 
 impl From<Follow> for Activity { fn from (a: Follow) -> Activity { Activity::Follow (a) } }
 
-#[derive(Clone)]
+#[derive(Clone, Serialize)]
 pub enum Accept {
 	Follow { object: Follow }
 }
@@ -26,12 +27,12 @@ pub enum Accept {
 impl From<Accept> for Activity { fn from (a: Accept) -> Activity { Activity::Accept (a) } }
 
 /// An entity that publishes activities.
-#[derive(Clone)]
+#[derive(Clone, Serialize, sqlx::FromRow)]
 pub struct Actor {
 	id: Id,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Serialize)]
 pub struct Note {
 	id: Id,
 }

src/db/mod.rs

@@ -1,13 +1,17 @@
 //! Database abstraction layer used by Hermit.
 
-use crate::{ Id, Result };
+use std::borrow::Borrow;
+use std::{marker::PhantomData, pin::Pin};
+
+use crate::{ Id, Result, ap::Actor, err };
 use futures::prelude::*;
-use sqlx::{Executor, pool::PoolConnection};
+use sqlx::{Executor, pool::PoolConnection, database::HasArguments};
+use sqlx::{ FromRow, Either::Right };
 
 /// `const ()` but in Rust
 fn void <T> (_: T) -> () { () }
 
-type Database = sqlx::Postgres;
+pub(crate) type Database = sqlx::Postgres;
 
 /// Specifies how to connect to the database.
 pub struct Config {}
@@ -28,32 +32,27 @@ impl Client {
 		todo!()
 	}
 
-	/// Fetch the data mapped to the given `key` from the database.
+	pub async fn query <'e, T: 'e> (&self, query: Query<'e, T>) -> Pin<Box<dyn Stream<Item = Result<T>> + Send + 'e>> {
-	pub async fn get <T> (&self, key: T::Key) -> Result<Option<T>>
+    	let Query (q, f) = query;
-	where
+    	let stream = q
-    	T: Get,
+        	.fetch_many(&self.pool)
-	{
+        	.filter_map(async move |r| {
-		self.with_conn(|c| T::get(key, c))
+            	match r.map_err(err) {
-			.await
+                	Ok (Right (row)) => Some (f(row)),
+                	Err (error) => Some (Err (error)),
+            		_ => None,
+            	}
+        	});
+
+       	Box::pin (stream)
 	}
 
-    /// Perfom an insertion on the database.
+	pub async fn get <'q, T: 'q> (&self, query: Query<'q, T>) -> Result<Option<T>> {
-	pub async fn insert <T> (&mut self, data: T) -> Result<()>
+		self.query(query)
-	where
-		T: Insert,
-	{
-		self.with_conn(|c| data.set(c))
     		.await
-			.map(void)
+    		.next()
-	}
-
-    /// Delete something from the database.
-	pub async fn delete <T> (&mut self, key: T::Key) -> Result<()>
-	where
-		T: Delete,
-	{
-		self.with_conn(|c| T::del(key, c))
     		.await
+    		.transpose()
 	}
 
 	/// Handles the getting-a-connection logic.
@@ -62,8 +61,6 @@ impl Client {
     	F: FnOnce (&mut PoolConnection<Database>) -> O,
     	O: Future<Output = Result<T>>,
 	{
-    	use crate::err;
-
 		self.pool
     		.acquire()
     		.map_err(err)
@@ -75,52 +72,24 @@ impl Client {
 	
 }
 
-pub trait Object: Sized {
+type Q<'a> = sqlx::query::Query<'a, Database, <Database as HasArguments<'a>>::Arguments>;
-	type Key: Eq;
+type Row = <Database as sqlx::Database>::Row;
-	fn key (&self) -> &Self::Key;
-}
 
-pub trait Insert: Object {
+pub struct Query <'a, T> (Q<'a>, fn (Row) -> Result<T>);
-	type Future: Future<Output = Result<Self::Key>>;
-	fn set <'e, E> (self, exec: E) -> Self::Future
-	where
-		E: Executor<'e>;
-}
 
-pub trait Delete: Object {
+/// Generate a query that gets an [`Actor`] by its [`Id`].
-	type Future: Future<Output = Result<()>>;
+pub fn get_actor <'a> (id: &'a Id) -> Query<'a, Actor> {
-	fn del <'e, E> (key: Self::Key, exec: E) -> Self::Future where E: Executor<'e>;
-}
 
-pub trait Get: Object {
+    // Prepare a query
-	type Future: Future<Output = Result<Option<Self>>>;
+    let query = sqlx::query("select * from actors where id = $1")
-	fn get <'e, E> (key: Self::Key, exec: E) -> Self::Future where E: Executor<'e>;
+        .bind(id);
-}
 
-pub mod ops {
+    // Return an sql query which will result in a series of rows,
+    // and a decoder function that will translate each row to a
+    // value of type `Actor`.
+    Query (query, |row: Row| {
+        let data = Actor::from_row(&row)?;
+        Ok (data)
+    })
 
-	//! Database operations (queries and updates).
-
-	use super::*;
-
-	pub struct Following {
-    	pub from: Id,
-		pub to: Id,
-		pub id: Id,
-	}
-
-	impl Object for Following {
-		type Key = Id;
-		fn key (&self) -> &Self::Key { &self.id }
-	}
-
-	impl Insert for Following {
-		type Future = future::BoxFuture<'static, Result<Id>>;
-		fn set <'e, E> (self, exec: E) -> Self::Future
-		where
-    		E: Executor<'e>
-		{
-			todo!()
-		}
-	}
 }

src/lib.rs

@@ -1,7 +1,11 @@
+#![feature(async_closure)]
 //! # The Hermit ActivityPub server
 //!
 //! This library contains the types and trait impls that make up the ActivityPub
 //! support and database interaction for the Hermit ActivityPub server.
+#![feature(generic_associated_types)]
+
+use serde::Serialize;
 
 // Expose the `Id` type in the crate root
 pub use id::Id;
@@ -14,7 +18,7 @@ pub mod db;
 pub mod ap;
 
 /// The Activity supertype used in abstractions over any kind of activity.
-#[derive(Clone)]
+#[derive(Clone, Serialize)]
 pub enum Activity {
     /// Create a post.
 	Create (ap::Create),
@@ -62,18 +66,19 @@ pub (crate) fn err (e: impl Into<Error>) -> Error { e.into() }
 
 mod id {
 
-    use std::str::FromStr;
+    use std::{str::FromStr, error::Error};
 
     use serde::{ Deserialize, Serialize };
+    use sqlx::database::{HasArguments, HasValueRef};
+    use url::ParseError;
+
+    use crate::db;
 
 	/// An ActivityPub identifier.
     #[derive(PartialEq, Eq, Clone, Serialize, Deserialize)]
+    #[serde(transparent)]
     pub struct Id (reqwest::Url);
 
-    impl crate::IntoUrl for Id {
-    	fn into_url (self) -> Option<url::Url> { Some (self.0) }
-    }
-
     impl FromStr for Id {
         type Err = url::ParseError;
 
@@ -82,6 +87,31 @@ mod id {
         }
     }
 
+    impl std::fmt::Display for Id {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            write!(f, "{}", self.0.to_string())
+        }
+    }
+
+    impl sqlx::Type<db::Database> for Id {
+        fn type_info () -> <db::Database as sqlx::Database>::TypeInfo {
+            String::type_info()
+        }
+    }
+
+    impl<'q> sqlx::Encode<'q, db::Database> for Id {
+        fn encode_by_ref(&self, buf: &mut <db::Database as HasArguments<'q>>::ArgumentBuffer) -> sqlx::encode::IsNull {
+            self.0.to_string().encode_by_ref(buf)
+        }
+    }
+
+    impl<'r> sqlx::Decode<'r, db::Database> for Id {
+        fn decode(value: <db::Database as HasValueRef<'r>>::ValueRef) -> Result<Self, sqlx::error::BoxDynError> {
+            <String as sqlx::Decode<db::Database>>::decode(value)
+           		.map(|s| s.parse().expect("Failed to parse ID as URL"))
+           		.map(Id)
+        }
+    }
 }
 
 mod ctx {
@@ -89,9 +119,9 @@ mod ctx {
     use std::sync::Arc;
 
     use futures::prelude::*;
-    use serde_json::Value;
+    use serde_json::{Value, to_value};
 
-    use crate::{ conf::Config, db, Result, sign::Sign, ap, Activity };
+    use crate::{ conf::Config, db, Result, sign::Sign, ap::{self, Actor}, Activity, Id, err };
 
 	/// The context of a thread/task.
 	///
@@ -224,6 +254,20 @@ mod ctx {
 
     		Ok (value)
         		
+    	}
+
+		/// Fetch a value from the database by trying all the ActivityPub
+		/// records.
+    	async fn db_fetch (&self, id: Id) -> Result<Option<Value>> {
+
+			if let Some (data) = self.db.get(db::get_actor(&id)).await? {
+				return to_value(data)
+    				.map_err(err)
+    				.map(Some)
+			}
+
+			todo!()
+
     	}
 
     	/// Attempt to dereference to a [`Create`](ap::Create) activity.

src/main.rs

@@ -1,11 +1,11 @@
+
 use std::sync::Arc;
 
-use futures::stream;
 use hermit::{ Context, Error, db, sign, Activity, };
 use hermit::conf::Config;
 use tokio::sync::{mpsc, broadcast};
 use task::Executor;
-use tokio_stream::wrappers::{ReceiverStream, BroadcastStream};
+use tokio_stream::wrappers::ReceiverStream;
 
 /// Module that contains all the API endpoints and frontend pages
 /// used by Hermit.
@@ -68,6 +68,8 @@ async fn main () {
         ctrl_tx,
     });
 
+	// Redefine `ctrl_tx`: it is now the transmitter that transmits
+	// *from* `Ctrl`.
     let (ctrl_tx, _rx) = broadcast::channel(256);
 
     ctx.run (task::Auto {
@@ -93,32 +95,28 @@ fn mk_channel <T> (size: usize) -> (mpsc::Sender<T>, ReceiverStream<T>) {
 	(tx, rx)
 }
 
-fn err (e: impl Into<Error>) -> Error { e.into() }
-
 mod task {
 
     //! Async tasks, communicating with each other across threads through generic
     //! streams and sinks.
 
 	use std::pin::Pin;
-    use tokio::sync::{mpsc, broadcast};
+    use tokio::sync::{
+        broadcast,
+        mpsc,
+    };
 	use futures::prelude::*;
     use serde_json::Value;
-    use crate::web;
+	use crate::{
-    use crate::sign::Sign;
+    	flow::Flow,
-	use crate::{flow::Flow, Activity, ctrl::Message, Context};
+        ctrl::Message,
+        sign::Sign,
+    	Activity,
+        Context,
+    	web,
+	};
 
-	impl<S> Executor for Context<S>
+	/// Something that can execute a [`Task`].
-    where
-        S: Sign + Send + Sync + 'static
-    {
-        fn run (&self, task: impl Task) {
-            let ctx: Context<S> = self.clone();
-            tokio::spawn(task.run(ctx));
-        }
-    }
-
-	/// Something that can execute a task.
     pub trait Executor {
 
         /// Perform a [`Task`].
@@ -137,6 +135,16 @@ mod task {
 		where
     		S: Sign + Send + Sync + 'static;
 
+    }
+
+	impl<S> Executor for Context<S>
+    where
+        S: Sign + Send + Sync + 'static
+    {
+        fn run (&self, task: impl Task) {
+            let ctx: Context<S> = self.clone();
+            tokio::spawn(task.run(ctx));
+        }
     }
 
 	/// The main web server.