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// Copyright (c) 2013-2017 Sandstorm Development Group, Inc. and contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//! An implementation of the [Cap'n Proto remote procedure call](https://capnproto.org/rpc.html)
//! protocol. Includes all [Level 1](https://capnproto.org/rpc.html#protocol-features) features.
//!
//! # Example
//!
//! ```capnp
//! # Cap'n Proto schema
//! interface Foo {
//! identity @0 (x: UInt32) -> (y: UInt32);
//! }
//! ```
//!
//! ```ignore
//! // Rust server defining an implementation of Foo.
//! struct FooImpl;
//! impl foo::Server for FooImpl {
//! fn identity(&mut self,
//! params: foo::IdentityParams,
//! mut results: foo::IdentityResults)
//! -> Promise<(), ::capnp::Error>
//! {
//! let x = pry!(params.get()).get_x();
//! results.get().set_y(x);
//! Promise::ok(())
//! }
//! }
//! ```
//!
//! ```ignore
//! // Rust client calling a remote implementation of Foo.
//! let mut request = foo_client.identity_request();
//! request.get().set_x(123);
//! let promise = request.send().promise.and_then(|response| {
//! println!("results = {}", response.get()?.get_y());
//! Ok(())
//! });
//! ```
//!
//! For a more complete example, see <https://github.com/capnproto/capnproto-rust/tree/master/capnp-rpc/examples/calculator>
use capnp::capability::Promise;
use capnp::private::capability::ClientHook;
use capnp::Error;
use futures::channel::oneshot;
use futures::{Future, FutureExt, TryFutureExt};
use std::cell::RefCell;
use std::pin::Pin;
use std::rc::{Rc, Weak};
use std::task::{Context, Poll};
pub use crate::rpc::Disconnector;
use crate::task_set::TaskSet;
pub use crate::reconnect::{auto_reconnect, lazy_auto_reconnect, SetTarget};
/// Code generated from
/// [rpc.capnp](https://github.com/sandstorm-io/capnproto/blob/master/c%2B%2B/src/capnp/rpc.capnp).
pub mod rpc_capnp;
/// Code generated from
/// [rpc-twoparty.capnp](https://github.com/sandstorm-io/capnproto/blob/master/c%2B%2B/src/capnp/rpc-twoparty.capnp).
pub mod rpc_twoparty_capnp;
/// Like `try!()`, but for functions that return a `Promise<T, E>` rather than a `Result<T, E>`.
///
/// Unwraps a `Result<T, E>`. In the case of an error `Err(e)`, immediately returns from the
/// enclosing function with `Promise::err(e)`.
#[macro_export]
macro_rules! pry {
($expr:expr) => {
match $expr {
::std::result::Result::Ok(val) => val,
::std::result::Result::Err(err) => {
return ::capnp::capability::Promise::err(::std::convert::From::from(err))
}
}
};
}
mod attach;
mod broken;
mod local;
mod queued;
mod reconnect;
mod rpc;
mod sender_queue;
mod split;
mod task_set;
pub mod twoparty;
use capnp::message;
pub trait OutgoingMessage {
fn get_body(&mut self) -> ::capnp::Result<::capnp::any_pointer::Builder>;
fn get_body_as_reader(&self) -> ::capnp::Result<::capnp::any_pointer::Reader>;
/// Sends the message. Returns a promise for the message that resolves once the send has completed.
/// Dropping the returned promise does *not* cancel the send.
fn send(
self: Box<Self>,
) -> (
Promise<Rc<message::Builder<message::HeapAllocator>>, Error>,
Rc<message::Builder<message::HeapAllocator>>,
);
fn take(self: Box<Self>) -> ::capnp::message::Builder<::capnp::message::HeapAllocator>;
}
pub trait IncomingMessage {
fn get_body(&self) -> ::capnp::Result<::capnp::any_pointer::Reader>;
}
pub trait Connection<VatId> {
fn get_peer_vat_id(&self) -> VatId;
fn new_outgoing_message(&mut self, first_segment_word_size: u32) -> Box<dyn OutgoingMessage>;
/// Waits for a message to be received and returns it. If the read stream cleanly terminates,
/// returns None. If any other problem occurs, returns an Error.
fn receive_incoming_message(&mut self) -> Promise<Option<Box<dyn IncomingMessage>>, Error>;
// Waits until all outgoing messages have been sent, then shuts down the outgoing stream. The
// returned promise resolves after shutdown is complete.
fn shutdown(&mut self, result: ::capnp::Result<()>) -> Promise<(), Error>;
}
pub trait VatNetwork<VatId> {
/// Returns None if `hostId` refers to the local vat.
fn connect(&mut self, host_id: VatId) -> Option<Box<dyn Connection<VatId>>>;
/// Waits for the next incoming connection and return it.
fn accept(&mut self) -> Promise<Box<dyn Connection<VatId>>, ::capnp::Error>;
fn drive_until_shutdown(&mut self) -> Promise<(), Error>;
}
/// A portal to objects available on the network.
///
/// The RPC implemententation sits on top of an implementation of `VatNetwork`, which
/// determines how to form connections between vats. The RPC implementation determines
/// how to use such connections to manage object references and make method calls.
///
/// At the moment, this is all rather more general than it needs to be, because the only
/// implementation of `VatNetwork` is `twoparty::VatNetwork`. However, eventually we
/// will need to have more sophisticated `VatNetwork` implementations, in order to support
/// [level 3](https://capnproto.org/rpc.html#protocol-features) features.
///
/// An `RpcSystem` is a `Future` and needs to be driven by a task executor. A common way
/// accomplish that is to pass the `RpcSystem` to `tokio_core::reactor::Handle::spawn()`.
#[must_use = "futures do nothing unless polled"]
pub struct RpcSystem<VatId>
where
VatId: 'static,
{
network: Box<dyn crate::VatNetwork<VatId>>,
bootstrap_cap: Box<dyn ClientHook>,
// XXX To handle three or more party networks, this should be a map from connection pointers
// to connection states.
connection_state: Rc<RefCell<Option<Rc<rpc::ConnectionState<VatId>>>>>,
tasks: TaskSet<Error>,
handle: crate::task_set::TaskSetHandle<Error>,
}
impl<VatId> RpcSystem<VatId> {
/// Constructs a new `RpcSystem` with the given network and bootstrap capability.
pub fn new(
mut network: Box<dyn crate::VatNetwork<VatId>>,
bootstrap: Option<::capnp::capability::Client>,
) -> Self {
let bootstrap_cap = match bootstrap {
Some(cap) => cap.hook,
None => broken::new_cap(Error::failed("no bootstrap capability".to_string())),
};
let (mut handle, tasks) = TaskSet::new(Box::new(SystemTaskReaper));
let mut handle1 = handle.clone();
handle.add(network.drive_until_shutdown().then(move |r| {
let r = match r {
Ok(()) => Ok(()),
Err(e) => {
if e.kind != ::capnp::ErrorKind::Disconnected {
// Don't report disconnects as an error.
Err(e)
} else {
Ok(())
}
}
};
handle1.terminate(r);
Promise::ok(())
}));
let mut result = Self {
network,
bootstrap_cap,
connection_state: Rc::new(RefCell::new(None)),
tasks,
handle: handle.clone(),
};
let accept_loop = result.accept_loop();
handle.add(accept_loop);
result
}
/// Connects to the given vat and returns its bootstrap interface.
pub fn bootstrap<T>(&mut self, vat_id: VatId) -> T
where
T: ::capnp::capability::FromClientHook,
{
let Some(connection) = self.network.connect(vat_id) else {
return T::new(self.bootstrap_cap.clone());
};
let connection_state = Self::get_connection_state(
&self.connection_state,
self.bootstrap_cap.clone(),
connection,
self.handle.clone(),
);
let hook = rpc::ConnectionState::bootstrap(&connection_state);
T::new(hook)
}
// not really a loop, because it doesn't need to be for the two party case
fn accept_loop(&mut self) -> Promise<(), Error> {
let connection_state_ref = self.connection_state.clone();
let bootstrap_cap = self.bootstrap_cap.clone();
let handle = self.handle.clone();
Promise::from_future(self.network.accept().map_ok(move |connection| {
Self::get_connection_state(&connection_state_ref, bootstrap_cap, connection, handle);
}))
}
// If `connection_state_ref` is not already populated, populates it with a new
// `ConnectionState` built from a local bootstrap capability and `connection`,
// spawning any background tasks onto `handle`. Returns the resulting value
// held in `connection_state_ref`.
fn get_connection_state(
connection_state_ref: &Rc<RefCell<Option<Rc<rpc::ConnectionState<VatId>>>>>,
bootstrap_cap: Box<dyn ClientHook>,
connection: Box<dyn crate::Connection<VatId>>,
mut handle: crate::task_set::TaskSetHandle<Error>,
) -> Rc<rpc::ConnectionState<VatId>> {
// TODO this needs to be updated once we allow more general VatNetworks.
let (tasks, result) = match *connection_state_ref.borrow() {
Some(ref connection_state) => {
// return early.
return connection_state.clone();
}
None => {
let (on_disconnect_fulfiller, on_disconnect_promise) =
oneshot::channel::<Promise<(), Error>>();
let connection_state_ref1 = connection_state_ref.clone();
handle.add(on_disconnect_promise.then(move |shutdown_promise| {
*connection_state_ref1.borrow_mut() = None;
match shutdown_promise {
Ok(s) => s,
Err(e) => Promise::err(Error::failed(format!("{e}"))),
}
}));
rpc::ConnectionState::new(bootstrap_cap, connection, on_disconnect_fulfiller)
}
};
*connection_state_ref.borrow_mut() = Some(result.clone());
handle.add(tasks);
result
}
/// Returns a `Disconnector` future that can be run to cleanly close the connection to this `RpcSystem`'s network.
/// You should get the `Disconnector` before you spawn the `RpcSystem`.
pub fn get_disconnector(&self) -> rpc::Disconnector<VatId> {
rpc::Disconnector::new(self.connection_state.clone())
}
}
impl<VatId> Future for RpcSystem<VatId>
where
VatId: 'static,
{
type Output = Result<(), Error>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
Pin::new(&mut self.tasks).poll(cx)
}
}
/// Creates a new local RPC client of type `C` out of an object that implements a server trait `S`.
pub fn new_client<C, S>(s: S) -> C
where
C: capnp::capability::FromServer<S>,
{
capnp::capability::FromClientHook::new(Box::new(local::Client::new(
<C as capnp::capability::FromServer<S>>::from_server(s),
)))
}
/// Allows a server to recognize its own capabilities when passed back to it, and obtain the
/// underlying Server objects associated with them. Holds only weak references to Server objects
/// allowing Server objects to be dropped when dropped by the remote client. Call the `gc` method
/// to reclaim memory used for Server objects that have been dropped.
pub struct CapabilityServerSet<S, C>
where
C: capnp::capability::FromServer<S>,
{
caps: std::collections::HashMap<usize, Weak<RefCell<C::Dispatch>>>,
}
impl<S, C> Default for CapabilityServerSet<S, C>
where
C: capnp::capability::FromServer<S>,
{
fn default() -> Self {
Self {
caps: std::default::Default::default(),
}
}
}
impl<S, C> CapabilityServerSet<S, C>
where
C: capnp::capability::FromServer<S>,
{
pub fn new() -> Self {
Self::default()
}
/// Adds a new capability to the set and returns a client backed by it.
pub fn new_client(&mut self, s: S) -> C {
let dispatch = <C as capnp::capability::FromServer<S>>::from_server(s);
let wrapped = Rc::new(RefCell::new(dispatch));
let ptr = wrapped.as_ptr() as usize;
self.caps.insert(ptr, Rc::downgrade(&wrapped));
capnp::capability::FromClientHook::new(Box::new(local::Client::from_rc(wrapped)))
}
/// Looks up a capability and returns its underlying server object, if found.
/// Fully resolves the capability before looking it up.
pub async fn get_local_server(&self, client: &C) -> Option<Rc<RefCell<C::Dispatch>>>
where
C: capnp::capability::FromClientHook,
{
let resolved: C = capnp::capability::get_resolved_cap(
capnp::capability::FromClientHook::new(client.as_client_hook().add_ref()),
)
.await;
let hook = resolved.into_client_hook();
let ptr = hook.get_ptr();
self.caps.get(&ptr).and_then(|c| c.upgrade())
}
/// Looks up a capability and returns its underlying server object, if found.
/// Does *not* attempt to resolve the capability first, so you will usually want
/// to call `get_resolved_cap()` before calling this. The advantage of this method
/// over `get_local_server()` is that this one is synchronous and borrows `self`
/// over a shorter span (which can be very important if `self` is inside a `RefCell`).
pub fn get_local_server_of_resolved(&self, client: &C) -> Option<Rc<RefCell<C::Dispatch>>>
where
C: capnp::capability::FromClientHook,
{
let hook = client.as_client_hook();
let ptr = hook.get_ptr();
self.caps.get(&ptr).and_then(|c| c.upgrade())
}
/// Reclaim memory used for Server objects that no longer exist.
pub fn gc(&mut self) {
self.caps.retain(|_, c| c.strong_count() > 0);
}
}
/// Converts a promise for a client into a client that queues up any calls that arrive
/// before the promise resolves.
// TODO: figure out a better way to allow construction of promise clients.
pub fn new_promise_client<T, F>(client_promise: F) -> T
where
T: ::capnp::capability::FromClientHook,
F: ::futures::Future<Output = Result<capnp::capability::Client, Error>>,
F: 'static + Unpin,
{
let mut queued_client = crate::queued::Client::new(None);
let weak_client = Rc::downgrade(&queued_client.inner);
queued_client.drive(client_promise.then(move |r| {
if let Some(queued_inner) = weak_client.upgrade() {
crate::queued::ClientInner::resolve(&queued_inner, r.map(|c| c.hook));
}
Promise::ok(())
}));
T::new(Box::new(queued_client))
}
struct SystemTaskReaper;
impl crate::task_set::TaskReaper<Error> for SystemTaskReaper {
fn task_failed(&mut self, error: Error) {
println!("ERROR: {error}");
}
}
pub struct ImbuedMessageBuilder<A>
where
A: ::capnp::message::Allocator,
{
builder: ::capnp::message::Builder<A>,
cap_table: Vec<Option<Box<dyn (::capnp::private::capability::ClientHook)>>>,
}
impl<A> ImbuedMessageBuilder<A>
where
A: ::capnp::message::Allocator,
{
pub fn new(allocator: A) -> Self {
Self {
builder: ::capnp::message::Builder::new(allocator),
cap_table: Vec::new(),
}
}
pub fn get_root<'a, T>(&'a mut self) -> ::capnp::Result<T>
where
T: ::capnp::traits::FromPointerBuilder<'a>,
{
use capnp::traits::ImbueMut;
let mut root: ::capnp::any_pointer::Builder = self.builder.get_root()?;
root.imbue_mut(&mut self.cap_table);
root.get_as()
}
pub fn set_root<T: ::capnp::traits::Owned>(
&mut self,
value: impl ::capnp::traits::SetterInput<T>,
) -> ::capnp::Result<()> {
use capnp::traits::ImbueMut;
let mut root: ::capnp::any_pointer::Builder = self.builder.get_root()?;
root.imbue_mut(&mut self.cap_table);
root.set_as(value)
}
}
fn canceled_to_error(_e: futures::channel::oneshot::Canceled) -> Error {
Error::failed("oneshot was canceled".to_string())
}