From 8f9becee76f26db7893caabb9f3a1a7980791e0e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bartek=20Iwa=C5=84czuk?= <biwanczuk@gmail.com>
Date: Thu, 16 Mar 2023 23:19:46 -0400
Subject: perf: disable runtime snapshot compression (#18239)

This commit removes compression for the runtime JS code.

It means that we will have a bigger binary, but faster startup. After
several discussion in the CLI team we decided it's worth to trade
about 3Mb of binary size for 2ms faster startup time. With WebGPU
removed in 35196eab279340376929dd75ed717ef4830e2fa9
it shouldn't have such a big impact on the binary size.
---
 runtime/Cargo.toml |  3 ---
 runtime/build.rs   |  9 +--------
 runtime/js.rs      | 30 ++----------------------------
 3 files changed, 3 insertions(+), 39 deletions(-)

(limited to 'runtime')

diff --git a/runtime/Cargo.toml b/runtime/Cargo.toml
index eeee6dad6..50fedcaa1 100644
--- a/runtime/Cargo.toml
+++ b/runtime/Cargo.toml
@@ -55,8 +55,6 @@ deno_websocket.workspace = true
 deno_webstorage.workspace = true
 deno_napi.workspace = true
 
-lzzzz.workspace = true
-
 [target.'cfg(windows)'.build-dependencies]
 winres.workspace = true
 winapi.workspace = true
@@ -93,7 +91,6 @@ http.workspace = true
 hyper = { workspace = true, features = ["server", "stream", "http1", "http2", "runtime"] }
 libc.workspace = true
 log.workspace = true
-lzzzz.workspace = true
 netif = "0.1.6"
 notify.workspace = true
 once_cell.workspace = true
diff --git a/runtime/build.rs b/runtime/build.rs
index 1e79eaf8a..63bc3439e 100644
--- a/runtime/build.rs
+++ b/runtime/build.rs
@@ -299,14 +299,7 @@ mod startup_snapshot {
       snapshot_path,
       startup_snapshot: None,
       extensions,
-      compression_cb: Some(Box::new(|vec, snapshot_slice| {
-        lzzzz::lz4_hc::compress_to_vec(
-          snapshot_slice,
-          vec,
-          lzzzz::lz4_hc::CLEVEL_MAX,
-        )
-        .expect("snapshot compression failed");
-      })),
+      compression_cb: None,
       snapshot_module_load_cb: Some(Box::new(transpile_ts_for_snapshotting)),
     });
   }
diff --git a/runtime/js.rs b/runtime/js.rs
index 57b1e7be4..def2724ce 100644
--- a/runtime/js.rs
+++ b/runtime/js.rs
@@ -3,41 +3,15 @@
 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] =
+static 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)]
-  || {
-    let size =
-      u32::from_le_bytes(COMPRESSED_RUNTIME_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_RUNTIME_SNAPSHOT[4..], &mut vec)
-      .unwrap();
-
-    vec.into_boxed_slice()
-  },
-);
-
 #[cfg(not(feature = "dont_create_runtime_snapshot"))]
 pub fn deno_isolate_init() -> Snapshot {
   debug!("Deno isolate init with snapshots.");
-  Snapshot::Static(&RUNTIME_SNAPSHOT)
+  Snapshot::Static(RUNTIME_SNAPSHOT)
 }
 
 #[cfg(not(feature = "include_js_files_for_snapshotting"))]
-- 
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