more main cleanup

Cargo.toml

@@ -11,10 +11,12 @@ edition = "2018"
 #tokio = { version = "0.2", features = ["full"] }
 
 async-std = "1.5"
-futures = "0.3"
+futures = { version = "0.3", features = ["thread-pool", "compat"] }
 futures-util = "0.3"
 futures-signals = "0.3"
 
+signal-hook = { version = "0.1", features = ["tokio-support"] }
+
 slog = { version = "2.5", features = ["max_level_trace"] }
 slog-term = "2.5"
 slog-async = "2.4"
@@ -29,5 +31,7 @@ casbin = "0.2"
 
 uuid = { version = "0.8", features = ["serde", "v4"] }
 
+clap = "2.33"
+
 [build-dependencies]
 capnpc = "0.12"

src/main.rs

@@ -24,7 +24,9 @@ use session::Session;
 
 use futures::prelude::*;
 use futures::executor::{LocalPool, ThreadPool};
+use futures::compat::Stream01CompatExt;
 use futures::join;
+use futures::task::SpawnExt;
 
 use capnp_rpc::twoparty::{VatNetwork, VatId};
 use capnp_rpc::rpc_twoparty_capnp::Side;
@@ -110,19 +112,21 @@ fn main() -> Result<(), Error> {
 
     // Bind to each address in config.listen.
     // This is a Stream over Futures so it will do absolutely nothing unless polled to completion
-    let listeners_s: futures::stream::Collect<_, Vec<TcpListener>> = stream::iter((&config).listen.iter())
+    let listeners_s: futures::stream::Collect<_, Vec<TcpListener>> 
+        = stream::iter((&config).listen.iter())
         .map(|l| {
             let addr = l.address.clone();
-            TcpListener::bind((l.address.as_str(), l.port.unwrap_or(config::DEFAULT_PORT)))
+            let port = l.port.unwrap_or(config::DEFAULT_PORT);
+            TcpListener::bind((l.address.as_str(), port))
                 // If the bind errors, include the address so we can log it
                 // Since this closure is lazy we need to have a cloned addr
-                .map_err(|e| { (addr, e) })
+                .map_err(move |e| { (addr, port, e) })
         })
         .filter_map(|f| async {
             match f.await {
                 Ok(l) => Some(l),
-                Err((addr, e)) => {
-                    error!(&log, "Could not connect to {}: {}", addr, e);
+                Err((addr, port, e)) => {
+                    error!(&log, "Could not setup socket on {} port {}: {}", addr, port, e);
                     None
                 }
             }
@@ -130,7 +134,7 @@ fn main() -> Result<(), Error> {
 
     let (mdb, pdb, auth) = exec.run_until(async {
         // Rull all futures to completion in parallel.
-        // This will "block" until all three are done starting up.
+        // This will block until all three are done starting up.
         join!(machinedb_f, permission_f, authentication_f)
     });
 
@@ -141,29 +145,122 @@ fn main() -> Result<(), Error> {
 
     // Since the below closures will happen at a much later time we need to make sure all pointers
     // are still valid. Thus, Arc.
-    let l2 = log.clone();
-    let l3 = log.clone();
+    let start_log = log.clone();
+    let stop_log = log.clone();
 
     // Create a thread pool to run tasks on
-    let mut pool = ThreadPool::builder()
-        .after_start(move |i| { info!(l2.new(o!("system" => "threadpool")), "Starting Thread <{}>", i)})
-        .before_stop(move |i| { info!(l3.new(o!("system" => "threadpool")), "Stopping Thread <{}>", i)})
+    let pool = ThreadPool::builder()
+        .after_start(move |i| {
+            info!(start_log.new(o!("system" => "threadpool")), "Starting Thread <{}>", i)
+        })
+        .before_stop(move |i| {
+            info!(stop_log.new(o!("system" => "threadpool")), "Stopping Thread <{}>", i)
+        })
         .create()?;
 
-    // Spawner is a handle to the shared ThreadPool forwarded into each connection
-    let spawner = pool.clone();
+    // Closure inefficiencies. Lucky cloning an Arc is pretty cheap.
+    let inner_log = log.clone();
+    let loop_log = log.clone();
 
-    let result: Result<(), Box<dyn std::error::Error>> = exec.run_until(async move {
+    exec.run_until(async move {
         // Generate a stream of TcpStreams appearing on any of the interfaces we listen to
         let listeners = listeners_s.await;
-        let mut incoming = stream::select_all(listeners.iter().map(|l| l.incoming()));
+        let incoming = stream::select_all(listeners.iter().map(|l| l.incoming()));
 
-        // Runn
-        while let Some(socket) = incoming.next().await {
+        // Spawner is a handle to the shared ThreadPool forwarded into each connection
+        let spawner = pool.clone();
+
+        // For each incoming connection start a new task to handle it and throw it on the thread
+        // pool
+        let handle_sockets = incoming.map(|socket| {
+            // incoming.next() is an error when the underlying `accept` call yielded an error
+            // In POSIX those are protocol errors we can't really handle, so we just log the error
+            // and the move on
+            match socket {
+                Ok(socket) => {
+                    // If we have it available add the peer's address to all log messages
+                    let log =
+                        if let Ok(addr) = socket.peer_addr() {
+                            inner_log.new(o!("address" => addr))
+                        } else {
+                            inner_log.new(o!())
+                        };
+
+                    // Clone a log for potential error handling
+                    let elog = log.clone();
+
+                    // We handle the error using map_err, `let _` is used to quiet the compiler
+                    // warning
+                    let f = api::handle_connection(log.clone(), socket, spawner.clone())
+                        .map_err(move |e| {
+                            error!(log, "Error occured during protocol handling: {}", e);
+                        })
+                        // Void any and all results since pool.spawn allows no return value.
+                        .map(|_| ());
+
+                    // In this case only the error is relevant since the Value is always ()
+                    if let Err(e) = pool.spawn(f) {
+                        error!(elog, "Failed to spawn connection handler: {}", e);
+                        // Failing to spawn a handler means we are most likely overloaded
+                        return LoopResult::Overloaded;
+                    }
+                },
+                Err(e) => {
+                    error!(inner_log, "Socket `accept` error: {}", e);
+                }
+            }
+
+            // Unless we are overloaded we just want to keep going.
+            return LoopResult::Continue;
+        });
+
+        // Check each signal as it arrives
+        // signals is a futures-0.1 stream, compat() makes it a futures-0.3 (which we use) stream
+        let handle_signals = signals.compat().map(|_signal| {
+            // _signal is the signal c_int.
+            // But since we only listen for SIGINT at the moment we don't really need to look at
+            // it.
+            return LoopResult::Stop;
+        });
+
+        // Now actually check if a connection was opened or a signal recv'd
+        let mut combined = stream::select(handle_signals, handle_sockets);
+        loop {
+            match combined.next().await {
+                // When the result says to continue, do exactly that
+                Some(LoopResult::Continue) => {}
+                Some(LoopResult::Overloaded) => {
+                    // In case over server overload we should install a replacement handler that
+                    // would instead just return `overloaded` for all connections until the
+                    // situation is remedied.
+                    //
+                    // For now, just log the overload and keep going.
+                    error!(loop_log, "Server overloaded");
+                }
+                // None should never be returned because it would mean all sockets were closed and
+                // we can not receive any further signals. Still, in that case shut down cleanly
+                // anyway, the only reason this could happen are some heavy bugs in the runtime
+                Some(LoopResult::Stop) | None => {
+                    warn!(loop_log, "Stopping server");
+                    break;
+                }
+            }
         }
-
-        Ok(())
     });
 
+    // TODO: Run actual shut down code here
+    info!(log, "Shutting down...");
+
+    // Returning () is an implicit success so this will properly set the exit code as well
     Ok(())
 }
+
+/// The result of one iteration of the core loop
+enum LoopResult {
+    /// Everything was fine, keep going
+    Continue,
+    /// Something happened that means we should shut down
+    Stop,
+    /// The Server is currently overloaded
+    Overloaded,
+}