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

3 files changed, 54 insertions, 5 deletions

diff --git a/runtime/Cargo.toml b/runtime/Cargo.toml
index 67fc6a82d..8c88ce2e3 100644
--- a/runtime/Cargo.toml
+++ b/runtime/Cargo.toml
@@ -39,6 +39,8 @@ deno_webidl = { version = "0.31.0", path = "../ext/webidl" }
 deno_websocket = { version = "0.36.0", path = "../ext/websocket" }
 deno_webstorage = { version = "0.26.0", path = "../ext/webstorage" }
 
+lzzzz = '=0.8.0'
+
 [target.'cfg(windows)'.build-dependencies]
 winres = "0.1.11"
 winapi = "0.3.9"
@@ -70,6 +72,7 @@ http = "0.2.4"
 hyper = { version = "0.14.12", features = ["server", "stream", "http1", "http2", "runtime"] }
 libc = "0.2.106"
 log = "0.4.14"
+lzzzz = '=0.8.0'
 netif = "0.1.0"
 notify = "=5.0.0-pre.12"
 once_cell = "=1.9.0"
diff --git a/runtime/build.rs b/runtime/build.rs
index d1e8517b8..e2fe21b9e 100644
--- a/runtime/build.rs
+++ b/runtime/build.rs
@@ -37,7 +37,32 @@ mod not_docs {
     let snapshot = js_runtime.snapshot();
     let snapshot_slice: &[u8] = &*snapshot;
     println!("Snapshot size: {}", snapshot_slice.len());
-    std::fs::write(&snapshot_path, snapshot_slice).unwrap();
+
+    let compressed_snapshot_with_size = {
+      let mut vec = vec![];
+
+      vec.extend_from_slice(
+        &u32::try_from(snapshot.len())
+          .expect("snapshot larger than 4gb")
+          .to_le_bytes(),
+      );
+
+      lzzzz::lz4_hc::compress_to_vec(
+        snapshot_slice,
+        &mut vec,
+        lzzzz::lz4_hc::CLEVEL_MAX,
+      )
+      .expect("snapshot compression failed");
+
+      vec
+    };
+
+    println!(
+      "Snapshot compressed size: {}",
+      compressed_snapshot_with_size.len()
+    );
+
+    std::fs::write(&snapshot_path, compressed_snapshot_with_size).unwrap();
     println!("Snapshot written to: {} ", snapshot_path.display());
   }
 
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)]