Support cache (#25)

See [Caching dependencies to speed up workflows](https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows).

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/25
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: Zettat123 <zettat123@noreply.gitea.io>
Co-authored-by: Jason Song <i@wolfogre.com>
Co-committed-by: Jason Song <i@wolfogre.com>

artifactcache/util.go

@@ -0,0 +1,72 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package artifactcache
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/go-chi/render"
+	"xorm.io/xorm"
+)
+
+func responseJson(w http.ResponseWriter, r *http.Request, code int, v ...any) {
+	render.Status(r, code)
+	if len(v) == 0 || v[0] == nil {
+		render.JSON(w, r, struct{}{})
+	} else if err, ok := v[0].(error); ok {
+		logger.Errorf("%v %v: %v", r.Method, r.RequestURI, err)
+		render.JSON(w, r, map[string]any{
+			"error": err.Error(),
+		})
+	} else {
+		render.JSON(w, r, v[0])
+	}
+}
+
+func parseContentRange(s string) (int64, int64, error) {
+	// support the format like "bytes 11-22/*" only
+	s, _, _ = strings.Cut(strings.TrimPrefix(s, "bytes "), "/")
+	s1, s2, _ := strings.Cut(s, "-")
+
+	start, err := strconv.ParseInt(s1, 10, 64)
+	if err != nil {
+		return 0, 0, fmt.Errorf("parse %q: %w", s, err)
+	}
+	stop, err := strconv.ParseInt(s2, 10, 64)
+	if err != nil {
+		return 0, 0, fmt.Errorf("parse %q: %w", s, err)
+	}
+	return start, stop, nil
+}
+
+// engine is a wrapper of *xorm.Engine, with a lock.
+// To avoid racing of sqlite, we don't careperformance here.
+type engine struct {
+	e *xorm.Engine
+	m sync.Mutex
+}
+
+func (e *engine) Exec(f func(*xorm.Session) error) error {
+	e.m.Lock()
+	defer e.m.Unlock()
+
+	sess := e.e.NewSession()
+	defer sess.Close()
+
+	return f(sess)
+}
+
+func (e *engine) ExecBool(f func(*xorm.Session) (bool, error)) (bool, error) {
+	e.m.Lock()
+	defer e.m.Unlock()
+
+	sess := e.e.NewSession()
+	defer sess.Close()
+
+	return f(sess)
+}