Add chunk plan cache configuration and storage

internal/core/workspace/chunk_plan.go

@@ -0,0 +1,22 @@
+package workspace
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+)
+
+func DefaultChunkPlanRoot(userCacheDir func() (string, error)) (string, error) {
+	if userCacheDir == nil {
+		return "", fmt.Errorf("user cache directory resolver must not be nil")
+	}
+	root, err := userCacheDir()
+	if err != nil {
+		return "", fmt.Errorf("resolve user cache directory: %w", err)
+	}
+	root = strings.TrimSpace(root)
+	if root == "" {
+		return "", fmt.Errorf("user cache directory must not be empty")
+	}
+	return filepath.Join(filepath.Clean(root), "notarius", "chunk-plans"), nil
+}

internal/core/workspace/chunk_plan_test.go

@@ -0,0 +1,57 @@
+package workspace
+
+import (
+	"errors"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/config"
+)
+
+func TestDefaultChunkPlanRoot(t *testing.T) {
+	got, err := DefaultChunkPlanRoot(func() (string, error) { return "/cache/user", nil })
+	if err != nil {
+		t.Fatalf("DefaultChunkPlanRoot() error = %v", err)
+	}
+	if want := filepath.Join("/cache/user", "notarius", "chunk-plans"); got != want {
+		t.Fatalf("root = %q, want %q", got, want)
+	}
+}
+
+func TestDefaultChunkPlanRootRejectsResolverFailures(t *testing.T) {
+	boom := errors.New("resolver failed")
+	if _, err := DefaultChunkPlanRoot(func() (string, error) { return "", boom }); !errors.Is(err, boom) {
+		t.Fatalf("resolver error = %v", err)
+	}
+	if _, err := DefaultChunkPlanRoot(func() (string, error) { return " \t ", nil }); err == nil || !strings.Contains(err.Error(), "empty") {
+		t.Fatalf("empty result error = %v", err)
+	}
+	if _, err := DefaultChunkPlanRoot(nil); err == nil {
+		t.Fatal("nil resolver error = nil")
+	}
+}
+
+func TestChunkPlanDirectoryIsIndependentFromWorkspaceSettings(t *testing.T) {
+	base := config.Default()
+	base.Workspace.Directory = "/workspace/one"
+	base.Workspace.ChunkCache.Directory = "/cache/plans"
+	first := FromConfig(base)
+
+	changedWorkspace := base
+	changedWorkspace.Workspace.Directory = "/workspace/two"
+	second := FromConfig(changedWorkspace)
+	if base.Workspace.ChunkCache.Directory != changedWorkspace.Workspace.ChunkCache.Directory {
+		t.Fatal("workspace directory changed chunk plan directory")
+	}
+	if first.RootDir == second.RootDir || first.CheckpointsRoot == second.CheckpointsRoot || first.DebugRoot == second.DebugRoot {
+		t.Fatalf("workspace settings did not follow workspace directory: %#v %#v", first, second)
+	}
+
+	changedCache := base
+	changedCache.Workspace.ChunkCache.Directory = "/cache/other"
+	third := FromConfig(changedCache)
+	if first != third {
+		t.Fatalf("chunk plan directory changed workspace settings: %#v %#v", first, third)
+	}
+}