Add deadlines to git network ops and lock merges per project

internal/git/git.go

@@ -1,6 +1,7 @@
 package git
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -10,6 +11,8 @@ import (
 	"slices"
 	"strconv"
 	"strings"
+	"syscall"
+	"time"
 )
 
 type RepoInfo struct {
@@ -228,10 +231,17 @@ func SquashCommit(repo, worktree, target, message string, env []string) (string,
 
 const Remote = "origin"
 
+const networkTimeout = 2 * time.Minute
+
+var networkEnv = []string{
+	"GIT_TERMINAL_PROMPT=0",
+	"GIT_SSH_COMMAND=ssh -o BatchMode=yes -o ConnectTimeout=30",
+}
+
 var ErrRemoteMoved = errors.New("the remote's branch has moved")
 
-func Push(repo, commit, branch, notes string) error {
-	out, stderr, code, err := runCode(repo, nil, "push", "--atomic", "--porcelain", Remote, commit+":refs/heads/"+branch, notes+":"+NotesRef)
+func Push(ctx context.Context, repo, commit, branch, notes string) error {
+	out, stderr, code, err := runNetwork(ctx, repo, "push", "--atomic", "--porcelain", Remote, commit+":refs/heads/"+branch, notes+":"+NotesRef)
 	if err != nil {
 		return err
 	}
@@ -251,13 +261,19 @@ func FastForward(repo, rev string) error {
 	return err
 }
 
-func Fetch(repo string) error {
-	_, err := run(repo, "fetch", Remote)
-	return err
+func Fetch(ctx context.Context, repo string) error {
+	_, stderr, code, err := runNetwork(ctx, repo, "fetch", Remote)
+	if err != nil {
+		return err
+	}
+	if code != 0 {
+		return fmt.Errorf("git fetch %s: exit status %d: %s", Remote, code, stderr)
+	}
+	return nil
 }
 
-func FetchFastForward(repo, branch string) error {
-	err := Fetch(repo)
+func FetchFastForward(ctx context.Context, repo, branch string) error {
+	err := Fetch(ctx, repo)
 	if err != nil {
 		return err
 	}
@@ -336,7 +352,7 @@ func runEnv(dir string, env []string, args ...string) (string, error) {
 }
 
 func runInput(dir string, env []string, input string, args ...string) (string, error) {
-	out, stderr, code, err := runCodeInput(dir, env, strings.NewReader(input), args...)
+	out, stderr, code, err := runCodeInput(context.Background(), dir, env, strings.NewReader(input), args...)
 	if err != nil {
 		return "", err
 	}
@@ -347,17 +363,31 @@ func runInput(dir string, env []string, input string, args ...string) (string, e
 }
 
 func runCode(dir string, env []string, args ...string) (string, string, int, error) {
-	return runCodeInput(dir, env, nil, args...)
+	return runCodeInput(context.Background(), dir, env, nil, args...)
 }
 
-func runCodeInput(dir string, env []string, stdin io.Reader, args ...string) (string, string, int, error) {
-	cmd := exec.Command("git", args...)
+func runNetwork(ctx context.Context, dir string, args ...string) (string, string, int, error) {
+	ctx, cancel := context.WithTimeout(ctx, networkTimeout)
+	defer cancel()
+	return runCodeInput(ctx, dir, networkEnv, nil, args...)
+}
+
+func runCodeInput(ctx context.Context, dir string, env []string, stdin io.Reader, args ...string) (string, string, int, error) {
+	cmd := exec.CommandContext(ctx, "git", args...)
 	cmd.Dir = dir
 	cmd.Env = append(os.Environ(), env...)
 	cmd.Stdin = stdin
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	cmd.Cancel = func() error {
+		return syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+	}
+	cmd.WaitDelay = 5 * time.Second
 	stderr := &strings.Builder{}
 	cmd.Stderr = stderr
 	out, err := cmd.Output()
+	if ctx.Err() != nil {
+		return "", "", 0, fmt.Errorf("git %s: %w: %s", strings.Join(args, " "), context.Cause(ctx), strings.TrimSpace(stderr.String()))
+	}
 	exit := &exec.ExitError{}
 	if errors.As(err, &exit) {
 		return strings.TrimSpace(string(out)), strings.TrimSpace(stderr.String()), exit.ExitCode(), nil