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// Copyright 2018 the Deno authors. All rights reserved. MIT license.
// Think of Resources as File Descriptors. They are integers that are allocated
// by the privlaged side of Deno to refer to various resources. The simplest
// example are standard file system files and stdio - but there will be other
// resources added in the future that might not correspond to operating system
// level File Descriptors. To avoid confusion we call them "resources" not "file
// descriptors". This module implements a global resource table. Ops (AKA
// handlers) look up resources by their integer id here.
use futures;
use futures::Poll;
use std;
use std::collections::HashMap;
use std::io::Error;
use std::io::{Read, Write};
use std::sync::atomic::AtomicIsize;
use std::sync::atomic::Ordering;
use std::sync::Mutex;
use tokio;
use tokio::io::{AsyncRead, AsyncWrite};
pub type ResourceId = i32; // Sometimes referred to RID.
// These store Deno's file descriptors. These are not necessarily the operating
// system ones.
type ResourceTable = HashMap<ResourceId, Repr>;
lazy_static! {
// Starts at 3 because stdio is [0-2].
static ref NEXT_RID: AtomicIsize = AtomicIsize::new(3);
static ref RESOURCE_TABLE: Mutex<ResourceTable> = Mutex::new({
let mut m = HashMap::new();
// TODO Load these lazily during lookup?
m.insert(0, Repr::Stdin(tokio::io::stdin()));
m.insert(1, Repr::Stdout(tokio::io::stdout()));
m.insert(2, Repr::Stderr(tokio::io::stderr()));
m
});
}
// Internal representation of Resource.
enum Repr {
Stdin(tokio::io::Stdin),
Stdout(tokio::io::Stdout),
Stderr(tokio::io::Stderr),
FsFile(tokio::fs::File),
}
// Abstract async file interface.
// Ideally in unix, if Resource represents an OS rid, it will be the same.
pub struct Resource {
pub rid: ResourceId,
}
impl Read for Resource {
fn read(&mut self, _buf: &mut [u8]) -> std::io::Result<usize> {
unimplemented!();
}
}
impl AsyncRead for Resource {
fn poll_read(&mut self, buf: &mut [u8]) -> Poll<usize, Error> {
let mut table = RESOURCE_TABLE.lock().unwrap();
let maybe_repr = table.get_mut(&self.rid);
match maybe_repr {
None => panic!("bad rid"),
Some(repr) => match repr {
Repr::FsFile(ref mut f) => f.poll_read(buf),
Repr::Stdin(ref mut f) => f.poll_read(buf),
Repr::Stdout(_) | Repr::Stderr(_) => {
panic!("Cannot read from stdout/stderr")
}
},
}
}
}
impl Write for Resource {
fn write(&mut self, _buf: &[u8]) -> std::io::Result<usize> {
unimplemented!()
}
fn flush(&mut self) -> std::io::Result<()> {
unimplemented!()
}
}
impl AsyncWrite for Resource {
fn poll_write(&mut self, buf: &[u8]) -> Poll<usize, Error> {
let mut table = RESOURCE_TABLE.lock().unwrap();
let maybe_repr = table.get_mut(&self.rid);
match maybe_repr {
None => panic!("bad rid"),
Some(repr) => match repr {
Repr::FsFile(ref mut f) => f.poll_write(buf),
Repr::Stdout(ref mut f) => f.poll_write(buf),
Repr::Stderr(ref mut f) => f.poll_write(buf),
Repr::Stdin(_) => panic!("Cannot write to stdin"),
},
}
}
fn shutdown(&mut self) -> futures::Poll<(), std::io::Error> {
unimplemented!()
}
}
fn new_rid() -> ResourceId {
let next_rid = NEXT_RID.fetch_add(1, Ordering::SeqCst);
next_rid as ResourceId
}
pub fn add_fs_file(fs_file: tokio::fs::File) -> Resource {
let rid = new_rid();
let mut tg = RESOURCE_TABLE.lock().unwrap();
match tg.insert(rid, Repr::FsFile(fs_file)) {
Some(_) => panic!("There is already a file with that rid"),
None => Resource { rid },
}
}
pub fn lookup(rid: ResourceId) -> Option<Resource> {
let table = RESOURCE_TABLE.lock().unwrap();
table.get(&rid).map(|_| Resource { rid })
}
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