Add systemd resource budgets with TOML profiles

internal/budget/units.go

@@ -0,0 +1,142 @@
+package budget
+
+import (
+	"fmt"
+	"slices"
+	"strings"
+)
+
+const serviceText = "[Unit]\nDescription=Terminal workload resource profiles\n\n[Service]\nExecStart=%h/.local/bin/budget watch\n\n[Install]\nWantedBy=default.target\n"
+
+func escape(name string) string {
+	var result strings.Builder
+	for i := range len(name) {
+		b := name[i]
+		switch {
+		case b == '/':
+			result.WriteByte('-')
+		case b >= 'a' && b <= 'z', b >= 'A' && b <= 'Z', b >= '0' && b <= '9', b == ':', b == '_', b == '.' && i != 0:
+			result.WriteByte(b)
+		default:
+			fmt.Fprintf(&result, `\x%02x`, b)
+		}
+	}
+	return result.String()
+}
+
+func appDirs(app string) []string {
+	app = escape(app)
+	return []string{"app-" + app + ".service.d", "app-" + app + "@.service.d", "app-" + app + "-.scope.d", "app-flatpak-" + app + "-.scope.d"}
+}
+
+func appMatches(app, unit string) bool {
+	app = escape(app)
+	return unit == "app-"+app+".service" || strings.HasPrefix(unit, "app-"+app+"@") || strings.HasPrefix(unit, "app-"+app+"-") || strings.HasPrefix(unit, "app-flatpak-"+app+"-")
+}
+
+func (c config) sharedSlice() string {
+	apps := keys(c.Shared)
+	if len(apps) == 0 {
+		return ""
+	}
+	return "app-" + escape(apps[0]) + ".slice"
+}
+
+func (c config) unitProfile(unit string) string {
+	for _, name := range keys(c.Units) {
+		if slices.Contains(c.Units[name], unit) {
+			return name
+		}
+	}
+	for _, name := range keys(c.Apps) {
+		for _, app := range c.Apps[name] {
+			if appMatches(app, unit) {
+				return name
+			}
+		}
+	}
+	for _, name := range keys(c.Prefixes) {
+		for _, prefix := range c.Prefixes[name] {
+			parts := strings.Split(prefix, ".")
+			stem := strings.Join(parts[:len(parts)-2], ".")
+			kind := "." + parts[len(parts)-2]
+			if strings.HasPrefix(unit, stem) && strings.HasSuffix(unit, kind) {
+				return name
+			}
+		}
+	}
+	if unit == "search.slice" {
+		return "search"
+	}
+	if slice := c.sharedSlice(); slice != "" && unit == slice {
+		return "default"
+	}
+	if strings.HasPrefix(unit, "app-") && (strings.HasSuffix(unit, ".scope") || strings.HasSuffix(unit, ".service")) {
+		return "default"
+	}
+	return ""
+}
+
+func (c config) render() (map[string]string, error) {
+	files := map[string]string{}
+	add := func(directory, name, extra string) error {
+		values, err := c.assignments(name)
+		if err != nil {
+			return err
+		}
+		section := "Service"
+		if strings.Contains(directory, ".scope.") {
+			section = "Scope"
+		}
+		files[directory+"/50-budget.conf"] = "[" + section + "]\n" + strings.Join(values, "\n") + "\n" + extra
+		return nil
+	}
+	for _, directory := range []string{"app-.service.d", "app-.scope.d"} {
+		if err := add(directory, "default", ""); err != nil {
+			return nil, err
+		}
+	}
+	for _, name := range keys(c.Apps) {
+		for _, app := range c.Apps[name] {
+			for _, directory := range appDirs(app) {
+				if err := add(directory, name, ""); err != nil {
+					return nil, err
+				}
+			}
+		}
+	}
+	for _, name := range keys(c.Units) {
+		for _, unit := range c.Units[name] {
+			if err := add(unit+".d", name, ""); err != nil {
+				return nil, err
+			}
+		}
+	}
+	for _, name := range keys(c.Prefixes) {
+		for _, directory := range c.Prefixes[name] {
+			if err := add(directory, name, ""); err != nil {
+				return nil, err
+			}
+		}
+	}
+	for _, app := range keys(c.Shared) {
+		for _, directory := range appDirs(app) {
+			if err := add(directory, c.Shared[app], "Slice="+c.sharedSlice()+"\n"); err != nil {
+				return nil, err
+			}
+		}
+	}
+	groups := map[string]string{"search.slice": "search"}
+	if len(c.Shared) > 0 {
+		groups[c.sharedSlice()] = "default"
+	}
+	for unit, name := range groups {
+		values, err := c.assignments(name)
+		if err != nil {
+			return nil, err
+		}
+		files[unit] = "[Slice]\n" + strings.Join(values, "\n") + "\n"
+	}
+	files["budget.service"] = serviceText
+	return files, nil
+}