From 375ce63c6390cf7710210ce22f14a2b5a02cbfc3 Mon Sep 17 00:00:00 2001
From: Aaron O'Mullan <aaron.omullan@gmail.com>
Date: Tue, 9 Nov 2021 19:26:17 +0100
Subject: feat(core): streams (#12596)

This allows resources to be "streams" by implementing read/write/shutdown. These streams are implicit since their nature (read/write/duplex) isn't known until called, but we could easily add another method to explicitly tag resources as streams.

`op_read/op_write/op_shutdown` are now builtin ops provided by `deno_core`

Note: this current implementation is simple & straightforward but it results in an additional alloc per read/write call

Closes #12556
---
 core/ops_builtin.rs | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

(limited to 'core/ops_builtin.rs')

diff --git a/core/ops_builtin.rs b/core/ops_builtin.rs
index d33565caf..a6cf82fe9 100644
--- a/core/ops_builtin.rs
+++ b/core/ops_builtin.rs
@@ -1,6 +1,7 @@
 use crate::error::type_error;
 use crate::error::AnyError;
 use crate::include_js_files;
+use crate::op_async;
 use crate::op_sync;
 use crate::ops_metrics::OpMetrics;
 use crate::resources::ResourceId;
@@ -36,6 +37,10 @@ pub(crate) fn init_builtins() -> Extension {
       ("op_metrics", op_sync(op_metrics)),
       ("op_void_sync", void_op_sync()),
       ("op_void_async", void_op_async()),
+      // TODO(@AaronO): track IO metrics for builtin streams
+      ("op_read", op_async(op_read)),
+      ("op_write", op_async(op_write)),
+      ("op_shutdown", op_async(op_shutdown)),
     ])
     .build()
 }
@@ -170,3 +175,30 @@ pub fn op_metrics(
   let per_op = state.tracker.per_op();
   Ok((aggregate, per_op))
 }
+
+async fn op_read(
+  state: Rc<RefCell<OpState>>,
+  rid: ResourceId,
+  buf: ZeroCopyBuf,
+) -> Result<u32, AnyError> {
+  let resource = state.borrow().resource_table.get_any(rid)?;
+  resource.read(buf).await.map(|n| n as u32)
+}
+
+async fn op_write(
+  state: Rc<RefCell<OpState>>,
+  rid: ResourceId,
+  buf: ZeroCopyBuf,
+) -> Result<u32, AnyError> {
+  let resource = state.borrow().resource_table.get_any(rid)?;
+  resource.write(buf).await.map(|n| n as u32)
+}
+
+async fn op_shutdown(
+  state: Rc<RefCell<OpState>>,
+  rid: ResourceId,
+  _: (),
+) -> Result<(), AnyError> {
+  let resource = state.borrow().resource_table.get_any(rid)?;
+  resource.shutdown().await
+}
-- 
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