core: Add ResourceTable (#3150)

5 files changed, 156 insertions, 84 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 2f9fe4518..4fbd10fce 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -255,6 +255,7 @@ dependencies = [
 name = "deno"
 version = "0.21.0"
 dependencies = [
+ "downcast-rs 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -342,6 +343,11 @@ dependencies = [
 ]
 
 [[package]]
+name = "downcast-rs"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "dtoa"
 version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1990,6 +1996,7 @@ dependencies = [
 "checksum ct-logs 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4d3686f5fa27dbc1d76c751300376e167c5a43387f44bb451fd1c24776e49113"
 "checksum dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "13aea89a5c93364a98e9b37b2fa237effbb694d5cfe01c5b70941f7eb087d5e3"
 "checksum dirs-sys 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "afa0b23de8fd801745c471deffa6e12d248f962c9fd4b4c33787b055599bde7b"
+"checksum downcast-rs 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5fe414cc2fd4447b7da94b27ddfb6831a8a06f35f6d077ab5613ec703866c49a"
 "checksum dtoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)" = "ea57b42383d091c85abcc2706240b94ab2a8fa1fc81c10ff23c4de06e2a90b5e"
 "checksum either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
 "checksum encoding_rs 0.8.19 (registry+https://github.com/rust-lang/crates.io-index)" = "79906e1ad1f7f8bc48864fcc6ffd58336fb5992e627bf61928099cb25fdf4314"
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 241e8a2ac..cbc19edbc 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -14,6 +14,7 @@ repository = "https://github.com/denoland/deno"
 path = "lib.rs"
 
 [dependencies]
+downcast-rs = "1.1.0"
 futures = "0.1.29"
 lazy_static = "1.4.0"
 libc = "0.2.62"
diff --git a/core/examples/http_bench.rs b/core/examples/http_bench.rs
index c019d8a11..a6cc6d548 100644
--- a/core/examples/http_bench.rs
+++ b/core/examples/http_bench.rs
@@ -14,12 +14,10 @@ extern crate lazy_static;
 
 use deno::*;
 use futures::future::lazy;
-use std::collections::HashMap;
 use std::env;
 use std::net::SocketAddr;
-use std::sync::atomic::AtomicUsize;
-use std::sync::atomic::Ordering;
 use std::sync::Mutex;
+use std::sync::MutexGuard;
 use tokio::prelude::*;
 
 static LOGGER: Logger = Logger;
@@ -184,44 +182,38 @@ fn main() {
   }
 }
 
-enum Repr {
-  TcpListener(tokio::net::TcpListener),
-  TcpStream(tokio::net::TcpStream),
-}
+struct TcpListener(tokio::net::TcpListener);
+
+impl Resource for TcpListener {}
+
+struct TcpStream(tokio::net::TcpStream);
+
+impl Resource for TcpStream {}
 
-type ResourceTable = HashMap<i32, Repr>;
 lazy_static! {
-  static ref RESOURCE_TABLE: Mutex<ResourceTable> = Mutex::new(HashMap::new());
-  static ref NEXT_RID: AtomicUsize = AtomicUsize::new(3);
+  static ref RESOURCE_TABLE: Mutex<ResourceTable> =
+    Mutex::new(ResourceTable::default());
 }
 
-fn new_rid() -> i32 {
-  let rid = NEXT_RID.fetch_add(1, Ordering::SeqCst);
-  rid as i32
+fn lock_resource_table<'a>() -> MutexGuard<'a, ResourceTable> {
+  RESOURCE_TABLE.lock().unwrap()
 }
 
 fn op_accept(record: Record, _zero_copy_buf: Option<PinnedBuf>) -> Box<HttpOp> {
-  let listener_rid = record.arg;
-  debug!("accept {}", listener_rid);
-  Box::new(
-    futures::future::poll_fn(move || {
-      let mut table = RESOURCE_TABLE.lock().unwrap();
-      let maybe_repr = table.get_mut(&listener_rid);
-      match maybe_repr {
-        Some(Repr::TcpListener(ref mut listener)) => listener.poll_accept(),
-        _ => panic!("bad rid {}", listener_rid),
-      }
-    })
-    .and_then(move |(stream, addr)| {
-      debug!("accept success {}", addr);
-      let rid = new_rid();
-
-      let mut guard = RESOURCE_TABLE.lock().unwrap();
-      guard.insert(rid, Repr::TcpStream(stream));
-
-      Ok(rid as i32)
-    }),
-  )
+  let rid = record.arg as u32;
+  debug!("accept {}", rid);
+  let fut = futures::future::poll_fn(move || {
+    let mut table = lock_resource_table();
+    let listener = table.get_mut::<TcpListener>(rid)?;
+    listener.0.poll_accept()
+  })
+  .and_then(move |(stream, addr)| {
+    debug!("accept success {}", addr);
+    let mut table = lock_resource_table();
+    let rid = table.add(Box::new(TcpStream(stream)));
+    Ok(rid as i32)
+  });
+  Box::new(fut)
 }
 
 fn op_listen(
@@ -229,70 +221,54 @@ fn op_listen(
   _zero_copy_buf: Option<PinnedBuf>,
 ) -> Box<HttpOp> {
   debug!("listen");
-  Box::new(lazy(move || {
-    let addr = "127.0.0.1:4544".parse::<SocketAddr>().unwrap();
-    let listener = tokio::net::TcpListener::bind(&addr).unwrap();
-    let rid = new_rid();
-
-    let mut guard = RESOURCE_TABLE.lock().unwrap();
-    guard.insert(rid, Repr::TcpListener(listener));
-    futures::future::ok(rid)
-  }))
+  let addr = "127.0.0.1:4544".parse::<SocketAddr>().unwrap();
+  let listener = tokio::net::TcpListener::bind(&addr).unwrap();
+  let mut table = lock_resource_table();
+  let rid = table.add(Box::new(TcpListener(listener)));
+  Box::new(futures::future::ok(rid as i32))
 }
 
 fn op_close(record: Record, _zero_copy_buf: Option<PinnedBuf>) -> Box<HttpOp> {
   debug!("close");
-  let rid = record.arg;
-  Box::new(lazy(move || {
-    let mut table = RESOURCE_TABLE.lock().unwrap();
-    let r = table.remove(&rid);
-    let result = if r.is_some() { 0 } else { -1 };
-    futures::future::ok(result)
-  }))
+  let rid = record.arg as u32;
+  let mut table = lock_resource_table();
+  let fut = match table.close(rid) {
+    Ok(_) => futures::future::ok(0),
+    Err(e) => futures::future::err(e),
+  };
+  Box::new(fut)
 }
 
 fn op_read(record: Record, zero_copy_buf: Option<PinnedBuf>) -> Box<HttpOp> {
-  let rid = record.arg;
+  let rid = record.arg as u32;
   debug!("read rid={}", rid);
   let mut zero_copy_buf = zero_copy_buf.unwrap();
-  Box::new(
-    futures::future::poll_fn(move || {
-      let mut table = RESOURCE_TABLE.lock().unwrap();
-      let maybe_repr = table.get_mut(&rid);
-      match maybe_repr {
-        Some(Repr::TcpStream(ref mut stream)) => {
-          stream.poll_read(&mut zero_copy_buf)
-        }
-        _ => panic!("bad rid"),
-      }
-    })
-    .and_then(move |nread| {
-      debug!("read success {}", nread);
-      Ok(nread as i32)
-    }),
-  )
+  let fut = futures::future::poll_fn(move || {
+    let mut table = lock_resource_table();
+    let stream = table.get_mut::<TcpStream>(rid)?;
+    stream.0.poll_read(&mut zero_copy_buf)
+  })
+  .and_then(move |nread| {
+    debug!("read success {}", nread);
+    Ok(nread as i32)
+  });
+  Box::new(fut)
 }
 
 fn op_write(record: Record, zero_copy_buf: Option<PinnedBuf>) -> Box<HttpOp> {
-  let rid = record.arg;
+  let rid = record.arg as u32;
   debug!("write rid={}", rid);
   let zero_copy_buf = zero_copy_buf.unwrap();
-  Box::new(
-    futures::future::poll_fn(move || {
-      let mut table = RESOURCE_TABLE.lock().unwrap();
-      let maybe_repr = table.get_mut(&rid);
-      match maybe_repr {
-        Some(Repr::TcpStream(ref mut stream)) => {
-          stream.poll_write(&zero_copy_buf)
-        }
-        _ => panic!("bad rid"),
-      }
-    })
-    .and_then(move |nwritten| {
-      debug!("write success {}", nwritten);
-      Ok(nwritten as i32)
-    }),
-  )
+  let fut = futures::future::poll_fn(move || {
+    let mut table = lock_resource_table();
+    let stream = table.get_mut::<TcpStream>(rid)?;
+    stream.0.poll_write(&zero_copy_buf)
+  })
+  .and_then(move |nwritten| {
+    debug!("write success {}", nwritten);
+    Ok(nwritten as i32)
+  });
+  Box::new(fut)
 }
 
 fn js_check(r: Result<(), ErrBox>) {
diff --git a/core/lib.rs b/core/lib.rs
index 42a692f1a..31f717769 100644
--- a/core/lib.rs
+++ b/core/lib.rs
@@ -3,6 +3,8 @@
 extern crate log;
 extern crate futures;
 extern crate libc;
+#[macro_use]
+extern crate downcast_rs;
 
 mod any_error;
 mod flags;
@@ -12,6 +14,7 @@ mod libdeno;
 mod module_specifier;
 mod modules;
 mod ops;
+mod resources;
 mod shared_queue;
 
 pub use crate::any_error::*;
@@ -24,6 +27,7 @@ pub use crate::libdeno::PinnedBuf;
 pub use crate::module_specifier::*;
 pub use crate::modules::*;
 pub use crate::ops::*;
+pub use crate::resources::*;
 
 pub fn v8_version() -> &'static str {
   use std::ffi::CStr;
diff --git a/core/resources.rs b/core/resources.rs
new file mode 100644
index 000000000..c3d8b7107
--- /dev/null
+++ b/core/resources.rs
@@ -0,0 +1,84 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+// Think of Resources as File Descriptors. They are integers that are allocated by
+// the privileged side of Deno to refer to various rust objects that need to be
+// referenced between multiple ops. For example, network sockets are resources.
+// Resources may or may not correspond to a real operating system file
+// descriptor (hence the different name).
+
+use downcast_rs::Downcast;
+use std;
+use std::any::Any;
+use std::collections::HashMap;
+use std::io::Error;
+use std::io::ErrorKind;
+
+/// ResourceId is Deno's version of a file descriptor. ResourceId is also referred
+/// to as rid in the code base.
+pub type ResourceId = u32;
+
+/// These store Deno's file descriptors. These are not necessarily the operating
+/// system ones.
+type ResourceMap = HashMap<ResourceId, Box<dyn Resource>>;
+
+#[derive(Default)]
+pub struct ResourceTable {
+  map: ResourceMap,
+  next_id: u32,
+}
+
+impl ResourceTable {
+  pub fn get<T: Resource>(&self, rid: ResourceId) -> Result<&T, Error> {
+    let resource = self.map.get(&rid).ok_or_else(bad_resource)?;
+    let resource = &resource.downcast_ref::<T>().ok_or_else(bad_resource)?;
+    Ok(resource)
+  }
+
+  pub fn get_mut<T: Resource>(
+    &mut self,
+    rid: ResourceId,
+  ) -> Result<&mut T, Error> {
+    let resource = self.map.get_mut(&rid).ok_or_else(bad_resource)?;
+    let resource = resource.downcast_mut::<T>().ok_or_else(bad_resource)?;
+    Ok(resource)
+  }
+
+  // TODO: resource id allocation should probably be randomized for security.
+  fn next_rid(&mut self) -> ResourceId {
+    let next_rid = self.next_id;
+    self.next_id += 1;
+    next_rid as ResourceId
+  }
+
+  pub fn add(&mut self, resource: Box<dyn Resource>) -> ResourceId {
+    let rid = self.next_rid();
+    let r = self.map.insert(rid, resource);
+    assert!(r.is_none());
+    rid
+  }
+
+  // close(2) is done by dropping the value. Therefore we just need to remove
+  // the resource from the RESOURCE_TABLE.
+  pub fn close(&mut self, rid: ResourceId) -> Result<(), Error> {
+    let repr = self.map.remove(&rid).ok_or_else(bad_resource)?;
+    // Give resource a chance to cleanup (notify tasks, etc.)
+    repr.close();
+    Ok(())
+  }
+}
+
+/// Abstract type representing resource in Deno.
+pub trait Resource: Downcast + Any + Send {
+  /// Method that allows to cleanup resource.
+  fn close(&self) {}
+
+  fn inspect_repr(&self) -> &str {
+    unimplemented!();
+  }
+}
+impl_downcast!(Resource);
+
+// TODO: probably bad error kind
+pub fn bad_resource() -> Error {
+  Error::new(ErrorKind::NotFound, "bad resource id")
+}