build: add "include_js_files_for_snapshotting" Cargo feature (#17826)

This allows to not include source code into the binary (because
it will already be included in the V8 snapshot).

Nothing changes for the embedders - everything should still build the
same.

This commit brings the binary size from 87Mb to 82Mb on M1.

Alternative to https://github.com/denoland/deno/pull/17820 and
https://github.com/denoland/deno/pull/17653

---------

Co-authored-by: Leo Kettmeir <crowlkats@toaxl.com>

5 files changed, 61 insertions, 31 deletions

diff --git a/runtime/Cargo.toml b/runtime/Cargo.toml
index 2d93f9dff..b2ef0637a 100644
--- a/runtime/Cargo.toml
+++ b/runtime/Cargo.toml
@@ -12,8 +12,17 @@ description = "Provides the deno runtime library"
 [features]
 # "fake" feature that allows to generate docs on docs.rs
 docsrs = []
-# feature that modifies the snapshot to allow extending it
+# A feature that disables creation of startup snapshot during in the build script.
+dont_create_runtime_snapshot = []
+# A feature that changes how startup snapshot is generated, that allows
+# extending it in embedder crates.
 snapshot_from_snapshot = []
+# A feature that disables embedding of the JavaScript source files in the binary.
+# With this feature enabled, the sources must be consumed during build time,
+# by creating a startup snapshot.
+include_js_files_for_snapshotting = [
+  "deno_core/include_js_files_for_snapshotting",
+]
 
 [lib]
 name = "deno_runtime"
diff --git a/runtime/build.rs b/runtime/build.rs
index a813d63cb..4678eab99 100644
--- a/runtime/build.rs
+++ b/runtime/build.rs
@@ -1,24 +1,25 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
-use deno_core::include_js_files;
 use std::env;
 use std::path::PathBuf;
 
-// This is a shim that allows to generate documentation on docs.rs
-mod not_docs {
+#[cfg(all(
+  not(feature = "docsrs"),
+  not(feature = "dont_create_runtime_snapshot")
+))]
+mod startup_snapshot {
   use std::path::Path;
 
   use super::*;
-  use deno_cache::SqliteBackedCache;
-  use deno_core::snapshot_util::*;
-  use deno_core::Extension;
-
   use deno_ast::MediaType;
   use deno_ast::ParseParams;
   use deno_ast::SourceTextInfo;
+  use deno_cache::SqliteBackedCache;
   use deno_core::error::AnyError;
+  use deno_core::include_js_files;
+  use deno_core::snapshot_util::*;
+  use deno_core::Extension;
   use deno_core::ExtensionFileSource;
-  use deno_core::ExtensionFileSourceCode;
 
   fn transpile_ts_for_snapshotting(
     file_source: &ExtensionFileSource,
@@ -34,16 +35,15 @@ mod not_docs {
         file_source.specifier
       ),
     };
-
-    let ExtensionFileSourceCode::IncludedInBinary(code) = file_source.code;
+    let code = file_source.code.load()?;
 
     if !should_transpile {
-      return Ok(code.to_string());
+      return Ok(code);
     }
 
     let parsed = deno_ast::parse_module(ParseParams {
       specifier: file_source.specifier.to_string(),
-      text_info: SourceTextInfo::from_string(code.to_string()),
+      text_info: SourceTextInfo::from_string(code),
       media_type,
       capture_tokens: false,
       scope_analysis: false,
@@ -281,6 +281,7 @@ mod not_docs {
 
     #[cfg(not(feature = "snapshot_from_snapshot"))]
     {
+      use deno_core::ExtensionFileSourceCode;
       maybe_additional_extension = Some(
         Extension::builder("runtime_main")
           .dependencies(vec!["runtime"])
@@ -314,9 +315,13 @@ fn main() {
   // doesn't actually compile on docs.rs
   if env::var_os("DOCS_RS").is_some() {
     let snapshot_slice = &[];
+    #[allow(clippy::needless_borrow)]
     std::fs::write(&runtime_snapshot_path, snapshot_slice).unwrap();
   }
 
-  #[cfg(not(feature = "docsrs"))]
-  not_docs::build_snapshot(runtime_snapshot_path)
+  #[cfg(all(
+    not(feature = "docsrs"),
+    not(feature = "dont_create_runtime_snapshot")
+  ))]
+  startup_snapshot::build_snapshot(runtime_snapshot_path)
 }
diff --git a/runtime/js.rs b/runtime/js.rs
index 82e58a09c..57b1e7be4 100644
--- a/runtime/js.rs
+++ b/runtime/js.rs
@@ -1,16 +1,21 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+#[cfg(not(feature = "dont_create_runtime_snapshot"))]
 use deno_core::Snapshot;
+#[cfg(not(feature = "dont_create_runtime_snapshot"))]
 use log::debug;
+#[cfg(not(feature = "dont_create_runtime_snapshot"))]
 use once_cell::sync::Lazy;
 
+#[cfg(not(feature = "dont_create_runtime_snapshot"))]
+static COMPRESSED_RUNTIME_SNAPSHOT: &[u8] =
+  include_bytes!(concat!(env!("OUT_DIR"), "/RUNTIME_SNAPSHOT.bin"));
+
+#[cfg(not(feature = "dont_create_runtime_snapshot"))]
 pub static RUNTIME_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
   #[allow(clippy::uninit_vec)]
   #[cold]
   #[inline(never)]
   || {
-    static COMPRESSED_RUNTIME_SNAPSHOT: &[u8] =
-      include_bytes!(concat!(env!("OUT_DIR"), "/RUNTIME_SNAPSHOT.bin"));
-
     let size =
       u32::from_le_bytes(COMPRESSED_RUNTIME_SNAPSHOT[0..4].try_into().unwrap())
         as usize;
@@ -29,10 +34,15 @@ pub static RUNTIME_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
   },
 );
 
+#[cfg(not(feature = "dont_create_runtime_snapshot"))]
 pub fn deno_isolate_init() -> Snapshot {
   debug!("Deno isolate init with snapshots.");
   Snapshot::Static(&RUNTIME_SNAPSHOT)
 }
 
-#[cfg(feature = "snapshot_from_snapshot")]
+#[cfg(not(feature = "include_js_files_for_snapshotting"))]
 pub static SOURCE_CODE_FOR_99_MAIN_JS: &str = include_str!("js/99_main.js");
+
+#[cfg(feature = "include_js_files_for_snapshotting")]
+pub static PATH_FOR_99_MAIN_JS: &str =
+  concat!(env!("CARGO_MANIFEST_DIR"), "/js/99_main.js");
diff --git a/runtime/web_worker.rs b/runtime/web_worker.rs
index df75d79c1..bcf999b3b 100644
--- a/runtime/web_worker.rs
+++ b/runtime/web_worker.rs
@@ -1,7 +1,6 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 use crate::colors;
 use crate::inspector_server::InspectorServer;
-use crate::js;
 use crate::ops;
 use crate::ops::io::Stdio;
 use crate::permissions::PermissionsContainer;
@@ -453,13 +452,17 @@ impl WebWorker {
     // Append exts
     extensions.extend(std::mem::take(&mut options.extensions));
 
+    #[cfg(not(feature = "dont_create_runtime_snapshot"))]
+    let startup_snapshot = options
+      .startup_snapshot
+      .unwrap_or_else(crate::js::deno_isolate_init);
+    #[cfg(feature = "dont_create_runtime_snapshot")]
+    let startup_snapshot = options.startup_snapshot
+      .expect("deno_runtime startup snapshot is not available with 'create_runtime_snapshot' Cargo feature.");
+
     let mut js_runtime = JsRuntime::new(RuntimeOptions {
       module_loader: Some(options.module_loader.clone()),
-      startup_snapshot: Some(
-        options
-          .startup_snapshot
-          .unwrap_or_else(js::deno_isolate_init),
-      ),
+      startup_snapshot: Some(startup_snapshot),
       source_map_getter: options.source_map_getter,
       get_error_class_fn: options.get_error_class_fn,
       shared_array_buffer_store: options.shared_array_buffer_store.clone(),
diff --git a/runtime/worker.rs b/runtime/worker.rs
index 141b5a650..d1998cd88 100644
--- a/runtime/worker.rs
+++ b/runtime/worker.rs
@@ -35,7 +35,6 @@ use deno_web::BlobStore;
 use log::debug;
 
 use crate::inspector_server::InspectorServer;
-use crate::js;
 use crate::ops;
 use crate::ops::io::Stdio;
 use crate::permissions::PermissionsContainer;
@@ -282,13 +281,17 @@ impl MainWorker {
     ];
     extensions.extend(std::mem::take(&mut options.extensions));
 
+    #[cfg(not(feature = "dont_create_runtime_snapshot"))]
+    let startup_snapshot = options
+      .startup_snapshot
+      .unwrap_or_else(crate::js::deno_isolate_init);
+    #[cfg(feature = "dont_create_runtime_snapshot")]
+    let startup_snapshot = options.startup_snapshot
+      .expect("deno_runtime startup snapshot is not available with 'create_runtime_snapshot' Cargo feature.");
+
     let mut js_runtime = JsRuntime::new(RuntimeOptions {
       module_loader: Some(options.module_loader.clone()),
-      startup_snapshot: Some(
-        options
-          .startup_snapshot
-          .unwrap_or_else(js::deno_isolate_init),
-      ),
+      startup_snapshot: Some(startup_snapshot),
       source_map_getter: options.source_map_getter,
       get_error_class_fn: options.get_error_class_fn,
       shared_array_buffer_store: options.shared_array_buffer_store.clone(),