Add custom zstd compression level (#2199)

* Add custom zstd compression level

* docs for SCCACHE_CACHE_ZSTD_LEVEL

* add zstd level test

* docs for zstd level that warns new cache required

* fix integration-test of zstd-compression-level

Author: nyanrus

.github/workflows/integration-tests.yml

@@ -523,7 +523,6 @@ jobs:
         shell: bash
         run: cat "$SCCACHE_ERROR_LOG"
 
-
   clang:
     runs-on: ubuntu-latest
     needs: build
@@ -576,7 +575,7 @@ jobs:
           ${SCCACHE_PATH} --show-stats | grep -e "Cache hits\s*[1-9]"
 
   hip:
-    # Probably wouldn't matter anyway since we run in a container, but staying 
+    # Probably wouldn't matter anyway since we run in a container, but staying
     # close to the version is better than not.
     runs-on: ubuntu-22.04
     needs: build
@@ -646,7 +645,6 @@ jobs:
 
           ${SCCACHE_PATH} --show-stats | grep -e "Cache hits\s*[1-9]"
 
-
   gcc:
     runs-on: ubuntu-latest
     needs: build
@@ -691,7 +689,6 @@ jobs:
 
           ${SCCACHE_PATH} --show-stats | grep -e "Cache hits\s*[1-9]"
 
-
   autotools:
     runs-on: ubuntu-latest
     needs: build
@@ -846,3 +843,54 @@ jobs:
         run: |
           ${SCCACHE_PATH} --show-stats
           ${SCCACHE_PATH} --show-stats | grep -e "Cache hits\s*[1-9]"
+
+  zstd-compression-level:
+    runs-on: ubuntu-latest
+    needs: build
+
+    env:
+      RUSTC_WRAPPER: /home/runner/.cargo/bin/sccache
+      SCCACHE_DIR:
+      CARGO_INCREMENTAL: "0"
+
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          name: integration-tests
+          path: /home/runner/.cargo/bin/
+      - name: Chmod for binary
+        run: chmod +x ${SCCACHE_PATH}
+
+      - name: Clone repository
+        uses: actions/checkout@v4
+
+      - name: Install rust
+        uses: ./.github/actions/rust-toolchain
+        with:
+          toolchain: "stable"
+
+      - name: default-test-save
+        run: |
+          export SCCACHE_DIR=${PWD}/temp-test/zstd-level/default
+          cargo build
+      - name: default-stats-save
+        run: ${SCCACHE_PATH} --show-stats
+      - name: default-test-use
+        run: |
+          cargo clean && cargo build
+      - name: default-stats-use
+        run: ${SCCACHE_PATH} --show-stats
+      - name: lv10-test-save
+        run: |
+          export SCCACHE_DIR=${PWD}/temp-test/zstd-level/10
+          export SCCACHE_CACHE_ZSTD_LEVEL=10
+          ${SCCACHE_PATH} --stop-server > /dev/null
+          cargo clean
+          cargo build
+      - name: lv10-stats-save
+        run: ${SCCACHE_PATH} --show-stats
+      - name: lv10-test-use
+        run: |
+          cargo clean && cargo build
+      - name: lv10-stats-use
+        run: ${SCCACHE_PATH} --show-stats

docs/Configuration.md

@@ -133,6 +133,10 @@ configuration variables
 * `SCCACHE_MAX_FRAME_LENGTH` how much data can be transferred between client and server
 * `SCCACHE_NO_DAEMON` set to `1` to disable putting the server to the background
 * `SCCACHE_CACHE_MULTIARCH` to disable caching of multi architecture builds.
+* `SCCACHE_CACHE_ZSTD_LEVEL` to set zstd compression level of cache. the range is `1-22` and default is `3`.
+  - For example, in `10`, it have about 0.9x size with about 1.6x time than default `3` (tested with compiling sccache code)
+  - This option will only applied to newly compressed cache and don't affect existing cache.
+  - If you want to be apply to all cache, you should reset cache and make new cache.
 
 ### cache configs
 

src/cache/cache.rs

@@ -290,7 +290,12 @@ impl CacheWrite {
         self.zip
             .start_file(name, opts)
             .context("Failed to start cache entry object")?;
-        zstd::stream::copy_encode(from, &mut self.zip, 3)?;
+
+        let compression_level = std::env::var("SCCACHE_CACHE_ZSTD_LEVEL")
+            .ok()
+            .and_then(|value| value.parse::<i32>().ok())
+            .unwrap_or(3);
+        zstd::stream::copy_encode(from, &mut self.zip, compression_level)?;
         Ok(())
     }