feat: blob URL support (#10045)

This commit adds blob URL support. Blob URLs are stored in a process
global storage, that can be accessed from all workers, and the module
loader. Blob URLs can be created using `URL.createObjectURL` and revoked
using `URL.revokeObjectURL`.

This commit does not add support for `fetch`ing blob URLs. This will be
added in a follow up commit.

op_crates/file/lib.rs

@@ -1,7 +1,85 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
+use deno_core::error::null_opbuf;
+use deno_core::error::AnyError;
+use deno_core::url::Url;
 use deno_core::JsRuntime;
+use deno_core::ModuleSpecifier;
+use deno_core::ZeroCopyBuf;
+use std::collections::HashMap;
 use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::Mutex;
+use uuid::Uuid;
+
+#[derive(Clone)]
+pub struct Blob {
+  pub data: Vec<u8>,
+  pub media_type: String,
+}
+
+pub struct Location(pub Url);
+
+#[derive(Default, Clone)]
+pub struct BlobUrlStore(Arc<Mutex<HashMap<Url, Blob>>>);
+
+impl BlobUrlStore {
+  pub fn get(&self, url: &ModuleSpecifier) -> Result<Option<Blob>, AnyError> {
+    let blob_store = self.0.lock().unwrap();
+    Ok(blob_store.get(url).cloned())
+  }
+
+  pub fn insert(&self, blob: Blob, maybe_location: Option<Url>) -> Url {
+    let origin = if let Some(location) = maybe_location {
+      location.origin().ascii_serialization()
+    } else {
+      "null".to_string()
+    };
+    let id = Uuid::new_v4();
+    let url = Url::parse(&format!("blob:{}/{}", origin, id)).unwrap();
+
+    let mut blob_store = self.0.lock().unwrap();
+    blob_store.insert(url.clone(), blob);
+
+    url
+  }
+
+  pub fn remove(&self, url: &ModuleSpecifier) {
+    let mut blob_store = self.0.lock().unwrap();
+    blob_store.remove(&url);
+  }
+}
+
+pub fn op_file_create_object_url(
+  state: &mut deno_core::OpState,
+  media_type: String,
+  zero_copy: Option<ZeroCopyBuf>,
+) -> Result<String, AnyError> {
+  let data = zero_copy.ok_or_else(null_opbuf)?;
+  let blob = Blob {
+    data: data.to_vec(),
+    media_type,
+  };
+
+  let maybe_location = state.try_borrow::<Location>();
+  let blob_store = state.borrow::<BlobUrlStore>();
+
+  let url =
+    blob_store.insert(blob, maybe_location.map(|location| location.0.clone()));
+
+  Ok(url.to_string())
+}
+
+pub fn op_file_revoke_object_url(
+  state: &mut deno_core::OpState,
+  url: String,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<(), AnyError> {
+  let url = Url::parse(&url)?;
+  let blob_store = state.borrow::<BlobUrlStore>();
+  blob_store.remove(&url);
+  Ok(())
+}
 
 /// Load and execute the javascript code.
 pub fn init(isolate: &mut JsRuntime) {
@@ -11,6 +89,10 @@ pub fn init(isolate: &mut JsRuntime) {
       "deno:op_crates/file/02_filereader.js",
       include_str!("02_filereader.js"),
     ),
+    (
+      "deno:op_crates/file/03_blob_url.js",
+      include_str!("03_blob_url.js"),
+    ),
   ];
   for (url, source_code) in files {
     isolate.execute(url, source_code).unwrap();