Add systemd resource budgets with TOML profiles

internal/budget/app.go

@@ -0,0 +1,119 @@
+package budget
+
+import (
+	"fmt"
+	"io"
+	"strings"
+)
+
+type application struct {
+	config config
+	paths  paths
+	ctl    unitCtl
+	run    func(...string) error
+	out    io.Writer
+}
+
+func (a application) apply() error {
+	files, err := a.config.render()
+	if err != nil {
+		return err
+	}
+	if err := writeFiles(a.paths, files); err != nil {
+		return err
+	}
+	if err := a.run("daemon-reload"); err != nil {
+		return err
+	}
+	units, err := a.ctl.Units()
+	if err != nil {
+		return err
+	}
+	for _, unit := range units {
+		name := a.config.unitProfile(unit.Name)
+		if name == "" || unit.Active != "active" {
+			continue
+		}
+		values, err := a.config.properties(name)
+		if err != nil {
+			return err
+		}
+		if err := a.ctl.Set(unit.Name, values); err != nil {
+			return err
+		}
+	}
+	if err := a.run("enable", "budget.service"); err != nil {
+		return err
+	}
+	if err := a.run("restart", "budget.service"); err != nil {
+		return err
+	}
+	_, err = fmt.Fprintf(a.out, "Applied %d resource configuration files\n", len(files))
+	return err
+}
+
+func selectUnits(c config, units []unit, target string) []string {
+	selected := map[string]bool{}
+	if strings.HasSuffix(target, ".slice") || strings.HasSuffix(target, ".scope") || strings.HasSuffix(target, ".service") {
+		selected[target] = true
+	} else {
+		for _, unit := range units {
+			if unit.Active == "active" && appMatches(target, unit.Name) {
+				selected[unit.Name] = true
+			}
+		}
+		if _, shared := c.Shared[target]; shared {
+			selected[c.sharedSlice()] = true
+		}
+	}
+	return keys(selected)
+}
+
+func (a application) override(name, target string) error {
+	values, err := a.config.properties(name)
+	if err != nil {
+		return err
+	}
+	units, err := a.ctl.Units()
+	if err != nil {
+		return err
+	}
+	selected := selectUnits(a.config, units, target)
+	if len(selected) == 0 {
+		return fmt.Errorf("no running unit matches %s", target)
+	}
+	all := map[string]bool{}
+	for _, name := range selected {
+		all[name] = true
+	}
+	for _, unit := range selected {
+		if !strings.HasSuffix(unit, ".slice") {
+			continue
+		}
+		group, err := a.ctl.Group(unit)
+		if err != nil {
+			return err
+		}
+		for _, child := range units {
+			if child.Active != "active" || all[child.Name] || (!strings.HasSuffix(child.Name, ".scope") && !strings.HasSuffix(child.Name, ".service")) {
+				continue
+			}
+			childGroup, err := a.ctl.Group(child.Name)
+			if err != nil {
+				return err
+			}
+			if strings.HasPrefix(childGroup, group+"/") {
+				all[child.Name] = true
+			}
+		}
+	}
+	for _, unit := range keys(all) {
+		if err := a.ctl.Set(unit, values); err != nil {
+			return err
+		}
+		if _, err := fmt.Fprintf(a.out, "%s: %s\n", unit, name); err != nil {
+			return err
+		}
+	}
+	return nil
+}