mirror of
https://github.com/charmbracelet/crush.git
synced 2026-05-30 18:47:33 +00:00
Christian RochaandCharm Crush
d41c118511
When two clients started up at the same time they would both try to spawn a server and one would lose the bind race, leaving a confusing log behind. Take an exclusive file lock around the spawn-and-wait sequence, re-check health after acquiring the lock, and skip the spawn entirely if a peer client has already brought the server up. The lock is released as soon as the new server is ready. Co-Authored-By: Charm Crush <crush@charm.land>
33 lines
933 B
Go
33 lines
933 B
Go
//go:build windows
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package cmd
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import (
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"fmt"
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"math"
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"os"
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"golang.org/x/sys/windows"
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)
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// acquireSpawnLock takes an exclusive lock on the given file (creating
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// it if necessary) using LockFileEx, and returns a release function
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// that unlocks and closes the file. Blocks until the lock is acquired.
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func acquireSpawnLock(path string) (func(), error) {
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f, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE, 0o600)
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if err != nil {
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return nil, fmt.Errorf("open spawn lock %q: %v", path, err)
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}
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h := windows.Handle(f.Fd())
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ol := new(windows.Overlapped)
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if err := windows.LockFileEx(h, windows.LOCKFILE_EXCLUSIVE_LOCK, 0, math.MaxUint32, math.MaxUint32, ol); err != nil {
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_ = f.Close()
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return nil, fmt.Errorf("LockFileEx spawn lock %q: %v", path, err)
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}
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return func() {
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ol := new(windows.Overlapped)
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_ = windows.UnlockFileEx(windows.Handle(f.Fd()), 0, math.MaxUint32, math.MaxUint32, ol)
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_ = f.Close()
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}, nil
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}
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