From b92cca253430396ec1148c534ae5832b1c3d6c14 Mon Sep 17 00:00:00 2001
From: Peder Bergebakken Sundt <pbsds@hotmail.com>
Date: Sun, 4 May 2025 03:36:12 +0200
Subject: [PATCH] ccache

---
 overlays.nix | 85 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 81 insertions(+), 4 deletions(-)

diff --git a/overlays.nix b/overlays.nix
index 885747d..be2c3a1 100755
--- a/overlays.nix
+++ b/overlays.nix
@@ -1,6 +1,7 @@
 #!/usr/bin/env -S nix-instantiate --parse
 let
   lib = import ./master/lib;
+  forBuildHost = p: p.__spliced.buildHost or p;
   # merge = sets: lib.foldl' lib.recursiveUpdate {} sets;
   appendIfMissing = list: val: if builtins.elem val list then list else list ++ [ val ];
 
@@ -43,7 +44,7 @@ let
         #   extendDrvArgs = f final prev stdenv;
         # };
         mkDerivationFromStdenv = extendMkDerivationArgs stdenv (
-          finalAttrs: prevAttrs: # TODO: drop finalAttrs?
+          finalAttrs: prevAttrs:
           lib.optionalAttrs (!(lib.strings.hasInfix "bootstrap" stdenv.name)) (
             let
               stdenv' = stdenv // {
@@ -274,6 +275,82 @@ let
     );
   };
 
+  # usage: nix-build ./dev.nix -A <package>.withCcache
+  overlays.withCcache =
+    let
+      ccacheConfig = ''
+        export CCACHE_DIR=/var/cache/ccache
+        export CCACHE_UMASK=007
+        export CCACHE_COMPRESS=1
+
+        # may break reproducibility or cause cache poisoning
+        # https://wiki.nixos.org/wiki/CCache#Sloppiness
+        # https://github.com/NixOS/nixpkgs/issues/109033
+        export CCACHE_SLOPPINESS=random_seed
+
+        if [[ ! -d "$CCACHE_DIR" ]]; then
+          echo "ERROR: \$CCACHE_DIR=$CCACHE_DIR not found!"
+          exit 1
+        elif [[ ! -w "$CCACHE_DIR" ]]; then
+          echo "ERROR: \$CCACHE_DIR=$CCACHE_DIR not writeable!"
+          exit 1
+        fi
+      '';
+    in
+    final: prev:
+    {
+      ccacheWrapper = prev.ccacheWrapper.override {
+        extraConfig = ccacheConfig;
+      };
+
+      # TODO: swap to this scope if in cudaPackages withCcache
+      # cudaPackages' = final.cudaPackages.overrideScope (
+      #   cudaFinal: cudaPrev: {
+      #     cuda_nvcc = cudaPrev.cuda_nvcc.overrideAttrs (oldAttrs: {
+      #       nativeBuildInputs = oldAttrs.nativeBuildInputs or [ ] ++ [ final.makeWrapper ];
+      #       postFixup =
+      #         oldAttrs.postFixup or ""
+      #         + ''
+      #           mv "$out/bin/nvcc" "$out/bin/.nvcc-no-ccache"
+      #           args=(
+      #             "${prev.lib.getExe (forBuildHost final.ccache)}"
+      #             "$out/bin/nvcc"
+      #             --run ${prev.lib.escapeShellArg ccacheConfig}
+      #             --add-flags "$out/bin/.nvcc-no-ccache"
+      #           )
+      #           makeWrapper "''${args[@]}"
+      #         '';
+      #     });
+      #   }
+      # );
+
+      # pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [
+      #   (pythonFinal: pythonPrev: {
+      #   })
+      # ];
+    }
+    // (mkDerivationOverlay (final: prev: prevStdenv: finalAttrs: prevAttrs: {
+      passthru = {
+        # withCcache = prevStdenv.mkDerivation (
+        withCcache = prev.ccacheStdenv.mkDerivation (
+          {
+            requiredSystemFeatures = prevAttrs.requiredSystemFeatures or [ ] ++ [
+              "ccache"
+              # "sccache"
+            ];
+            # RUSTC_WRAPPER = lib.getExe final.sccache;
+            # SCCACHE_DIR = "/var/cache/sccache";
+            # # SCCACHE_REDIS_ENDPOINT = "redis+unix://run/redis-nix-sccache/redis.sock";
+            # # SCCACHE_IDLE_TIMEOUT = 0;
+            # SCCACHE_CACHE_ZSTD_LEVEL = 19;
+            # # SCCACHE_LOG = "debug";
+            # # SCCACHE_NO_DAEMON = true;
+          }
+          // prevAttrs
+        );
+      } // prevAttrs.passthru or { };
+    }) final prev);
+
   # very hacky, not guaranteed to work, but may save a lot of .whl rebuilds
   # usage: nix-build ./dev.nix -A python3Packages.<package>.twostage
   # usage: nix-build ./dev.nix -A python3Packages.<package>.twostage.first
@@ -439,14 +516,14 @@ let
 
 in
 [
-  overlays.withShellCheck
   overlays.withDebug
   overlays.srcOnly
   overlays.withInvalidateFetcherByDrvHash
   overlays.withUnpacked
+  overlays.withShellCheck
+  # overlays.withCudaOrRocm # WIP
+  overlays.withCcache # WIP
   overlays.withTwostagePythonBuildPassthru
   overlays.withPytestCheckHooks
   overlays.toplevelCudaRocmPkgs
-  # WIP:
-  # overlays.withCudaOrRocm
 ]