implement graceful shutdown to webhook mode

ensures all pending tasks are finished before quit.

lib/git.go

@@ -0,0 +1,159 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package lib
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"os"
+	"os/exec"
+	"path"
+	"path/filepath"
+	"sync"
+)
+
+type repoSpec struct {
+	user string
+	name string
+}
+
+type GitRunner struct {
+	ch  <-chan repoSpec
+	cfg *WebhookCFG
+}
+
+func (g *GitRunner) Run(ctx context.Context) error {
+	// graceful: exit only if all tasks are done
+	for {
+		select {
+		case repo := <-g.ch:
+			err := g.cfg.download(repo.user, repo.name)
+			if err != nil {
+				fmt.Println("Failed to download repo: ", err)
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+}
+
+func (c *WebhookCFG) pageDir(user, repo string) string {
+	return filepath.Join(c.PageDir, user, repo)
+}
+
+func (c *WebhookCFG) gitDir(user, repo string) string {
+	return filepath.Join(c.GitDir, user, repo)
+}
+
+func (c *WebhookCFG) checkout(user, repo string) (err error) {
+	pageDir := c.pageDir(user, repo)
+	gitDir := c.gitDir(user, repo)
+
+	git := exec.Command(
+		"git",
+		"--git-dir", gitDir,
+		"--work-tree", pageDir,
+		"checkout", "origin/"+c.Branch,
+	)
+	output, err := git.CombinedOutput()
+	if err != nil {
+		fmt.Println("git checkout failed: ", err)
+		fmt.Println("=========== Dump output: ============")
+		fmt.Println(string(output))
+		fmt.Println("=====================================")
+	}
+
+	return
+}
+
+func (c *WebhookCFG) fetch(user, repo string) (err error) {
+	gitDir := c.gitDir(user, repo)
+	git := exec.Command(
+		"git",
+		"--git-dir", gitDir,
+		"fetch", "origin", c.Branch,
+	)
+	output, err := git.CombinedOutput()
+	if err != nil {
+		fmt.Println("git fetch failed: ", err)
+		fmt.Println("=========== Dump output: ============")
+		fmt.Println(string(output))
+		fmt.Println("=====================================")
+	}
+
+	return
+}
+
+func (c *WebhookCFG) clone(user, repo string) (err error) {
+	pageDir := c.pageDir(user, repo)
+	err = os.MkdirAll(filepath.Dir(pageDir), 0755)
+	if err != nil {
+		return
+	}
+
+	gitDir := c.gitDir(user, repo)
+	err = os.MkdirAll(filepath.Dir(gitDir), 0700)
+	if err != nil {
+		return
+	}
+
+	uri := c.Server
+	uri.Path = "/" + path.Join(user, repo) + ".git"
+	uri.User = url.UserPassword(c.GitUser, c.GitPass)
+
+	git := exec.Command(
+		"git",
+		"clone",
+		"-b", c.Branch,
+		"--single-branch",
+		"--no-tags",
+		"--separate-git-dir", gitDir,
+		uri.String(),
+		pageDir,
+	)
+	output, err := git.CombinedOutput()
+	if err != nil {
+		fmt.Println("git clone failed: ", err)
+		fmt.Println("=========== Dump output: ============")
+		fmt.Println(string(output))
+		fmt.Println("=====================================")
+	}
+
+	os.Remove(filepath.Join(pageDir, ".git"))
+
+	return
+}
+
+var repoLock = &sync.Map{}
+
+func (c *WebhookCFG) lock(user, repo string) func() {
+	key := user + "/" + repo
+
+	lock, _ := repoLock.LoadOrStore(key, &sync.Mutex{})
+	m := lock.(*sync.Mutex)
+	m.Lock()
+	return m.Unlock
+}
+
+func (c *WebhookCFG) download(user, repo string) (err error) {
+	unlock := c.lock(user, repo)
+	defer unlock()
+	fmt.Println("Pulling ", user, repo)
+
+	gitDir := c.gitDir(user, repo)
+	if _, err = os.Stat(gitDir); os.IsNotExist(err) {
+		err = c.clone(user, repo)
+	} else {
+		err = c.fetch(user, repo)
+	}
+
+	if err != nil {
+		return
+	}
+
+	err = c.checkout(user, repo)
+	return
+}