attic: try prefetching 16 chunks

.github/workflows/build-machines-and-homes.yml

@@ -63,13 +63,17 @@ jobs:
         run: |
           nix profile install github:zhaofengli/attic
           attic login cy7 https://cache.cy7.sh "$ATTIC_TOKEN"
-      - name: build and cache
+      - name: build
         run: |
           package=".#nixosConfigurations."${{ matrix.machine }}".config.system.build.toplevel"
           nix build -L "$package"
+      - name: cache
+        if: always()
+        run: |
+          package=".#nixosConfigurations."${{ matrix.machine }}".config.system.build.toplevel"
           derivation="$(nix path-info --derivation "$package")"
           cache="$(nix-store --query --requisites --include-outputs "$derivation")"
-          attic push main --stdin <<< "$cache"
+          xargs attic push main <<< "$cache"
   build-homes:
     strategy:
       fail-fast: false
@@ -119,10 +123,14 @@ jobs:
         run: |
           nix profile install github:zhaofengli/attic
           attic login cy7 https://cache.cy7.sh "$ATTIC_TOKEN"
-      - name: build and cache
+      - name: build
         run: |
           package=".#homeConfigurations."${{ matrix.home }}".activationPackage"
           nix build -L "$package"
+      - name: cache
+        if: always()
+        run: |
+          package=".#homeConfigurations."${{ matrix.home }}".activationPackage"
           derivation="$(nix path-info --derivation "$package")"
           cache="$(nix-store --query --requisites --include-outputs "$derivation")"
           attic push main --stdin <<< "$cache"

.github/workflows/build-packages.yml

@@ -42,10 +42,11 @@ jobs:
           attic login cy7 https://cache.cy7.sh "$ATTIC_TOKEN"
       - run: nix build -L ${{ matrix.package }}
       - name: cache result
+        if: always()
         run: |
           derivation="$(nix path-info --derivation "${{ matrix.package }}")"
           cache="$(nix-store --query --requisites --include-outputs "$derivation")"
-          attic push main --stdin <<< "$cache"
+          xargs attic push main <<< "$cache"
       - name: prepare tarball to upload
         run: nix run github:nixos/nixpkgs#gnutar hcvf result.tar result
       - name: upload result

overlay/attic/prefetch-N-chunks.patch

@@ -7,7 +7,7 @@ index 02e4857..71eeee8 100644
          // TODO: Make num_prefetch configurable
          // The ideal size depends on the average chunk size
 -        let merged = merge_chunks(chunks, streamer, storage, 2).map_err(|e| {
-+        let merged = merge_chunks(chunks, streamer, storage, 32).map_err(|e| {
++        let merged = merge_chunks(chunks, streamer, storage, 16).map_err(|e| {
              tracing::error!(%e, "Stream error");
              e
          });