83 lines
1.3 KiB
V
83 lines
1.3 KiB
V
module filelock
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import time
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#include <sys/file.h>
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fn C.unlink(&char) int
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fn C.open(&char, int, int) int
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fn C.flock(int, int) int
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[unsafe]
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pub fn (mut l FileLock) unlink() {
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if l.fd != -1 {
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C.close(l.fd)
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l.fd = -1
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}
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C.unlink(&char(l.name.str))
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}
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pub fn (mut l FileLock) acquire() ?bool {
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if l.fd != -1 {
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// lock already acquired by this instance
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return false
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}
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fd := open_lockfile(l.name)
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if fd == -1 {
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return error('cannot create lock file $l.name')
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}
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if C.flock(fd, C.LOCK_EX) == -1 {
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C.close(fd)
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return error('cannot lock')
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}
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l.fd = fd
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return true
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}
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pub fn (mut l FileLock) release() bool {
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if l.fd != -1 {
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unsafe {
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l.unlink()
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}
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return true
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}
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return false
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}
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pub fn (mut l FileLock) wait_acquire(s int) ?bool {
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fin := time.now().add(s)
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for time.now() < fin {
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if l.try_acquire() {
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return true
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}
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C.usleep(1000)
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}
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return false
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}
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fn open_lockfile(f string) int {
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mut fd := C.open(&char(f.str), C.O_CREAT, 0o644)
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if fd == -1 {
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// if stat is too old delete lockfile
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fd = C.open(&char(f.str), C.O_RDONLY, 0)
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}
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return fd
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}
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pub fn (mut l FileLock) try_acquire() bool {
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if l.fd != -1 {
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return true
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}
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fd := open_lockfile('$l.name')
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if fd != -1 {
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err := C.flock(fd, C.LOCK_EX | C.LOCK_NB)
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if err == -1 {
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C.close(fd)
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return false
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}
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l.fd = fd
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return true
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}
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return false
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}
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