feat(cli, runtime): compress snapshots (#13320)

1 files changed, 25 insertions, 4 deletions

diff --git a/runtime/js.rs b/runtime/js.rs
index 58053ac02..c259ff5ee 100644
--- a/runtime/js.rs
+++ b/runtime/js.rs
@@ -1,14 +1,35 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
 use deno_core::Snapshot;
 use log::debug;
+use once_cell::sync::Lazy;
 
-pub static CLI_SNAPSHOT: &[u8] =
-  include_bytes!(concat!(env!("OUT_DIR"), "/CLI_SNAPSHOT.bin"));
+pub static CLI_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
+  #[cold]
+  #[inline(never)]
+  || {
+    static COMPRESSED_CLI_SNAPSHOT: &[u8] =
+      include_bytes!(concat!(env!("OUT_DIR"), "/CLI_SNAPSHOT.bin"));
+
+    let size =
+      u32::from_le_bytes(COMPRESSED_CLI_SNAPSHOT[0..4].try_into().unwrap())
+        as usize;
+    let mut vec = Vec::with_capacity(size);
+
+    // SAFETY: vec is allocated with exact snapshot size (+ alignment)
+    // SAFETY: non zeroed bytes are overwritten with decompressed snapshot
+    unsafe {
+      vec.set_len(size);
+    }
+
+    lzzzz::lz4::decompress(&COMPRESSED_CLI_SNAPSHOT[4..], &mut vec).unwrap();
+
+    vec.into_boxed_slice()
+  },
+);
 
 pub fn deno_isolate_init() -> Snapshot {
   debug!("Deno isolate init with snapshots.");
-  let data = CLI_SNAPSHOT;
-  Snapshot::Static(data)
+  Snapshot::Static(&*CLI_SNAPSHOT)
 }
 
 #[cfg(test)]