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0cd0e52a24
Starting two runner daemons with the same `.runner` file makes both present an identical UUID+token, so Gitea treats them as one runner and they cancel each other's jobs. This adds a non-blocking advisory lock on a sibling `<runner-file>.lock`: the daemon (and `register`) acquire it at startup, and a second process on the same host fails fast with a clear error instead of silently interfering. The OS releases the lock when the process exits — including a hard kill — so no stale lock is left behind. Legitimate multi-runner setups are unaffected since each already uses its own `runner.file`. Note: this covers the common single-host case; two hosts sharing a copied `.runner` (e.g. over NFS) would still need server-side detection in Gitea. --------- Co-authored-by: Zettat123 <zettat123@gmail.com> Reviewed-on: https://gitea.com/gitea/runner/pulls/1099 Reviewed-by: Zettat123 <39446+zettat123@noreply.gitea.com>
36 lines
931 B
Go
36 lines
931 B
Go
// Copyright 2026 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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//go:build !windows && !plan9
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package lock
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import (
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"errors"
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"os"
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"golang.org/x/sys/unix"
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)
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// tryLock opens (creating if needed) the lock file and takes a non-blocking
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// exclusive flock on it. The returned release closes the file, which drops the
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// lock; the kernel also drops it when the process exits.
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func tryLock(path string) (func() error, error) {
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f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
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if err != nil {
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return nil, err
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}
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if err := unix.Flock(int(f.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
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_ = f.Close()
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if errors.Is(err, unix.EWOULDBLOCK) || errors.Is(err, unix.EAGAIN) {
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return nil, ErrLocked
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}
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return nil, err
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}
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return func() error {
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// Best-effort unlock; closing the fd releases the lock regardless.
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_ = unix.Flock(int(f.Fd()), unix.LOCK_UN)
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return f.Close()
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}, nil
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}
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