lua-file-lock

simple file lock for lua by posix fcntl

sample

sample dir shows one process set a write lock and anthor process try to get lock failed after write lock unlocked, the trying process can successfully get lock.

[lua-file-lock]$ lua sample/set_lock.lua 
1539930102   : locked
1539930107   : unlocked

[lua-file-lock]$ lua sample/try_lock.lua 
1539930103  : locked, retry after 1s
1539930105  : locked, retry after 1s
1539930107  : lockable

new(opts)

syntax

local flock = require('file_lock')
local lock = flock:new{
    name = 'file.lock'
}

new a file_lock object with the given file name.

return table holds the lock and fd.

in case of error, nil and error message returned.

• opts.name filename of file lock
• opts.flags (optional) flags of open file set open api in fcntl.h
• opts.mode (optional) mode of open file set open api in fcntl.h

**

read_lock()

syntax

local status, errmsg, errno = flock:read_lock()

try to get a read lock(F_RDLCK) by fnctl with cmd F_SETLK

return 0 if set lock success, otherwise nil returned with errmsg and errno

write_lock()

syntax

local status, errmsg, errno = flock:write_lock()

try to get a write lock(F_WRLCK) by fnctl with cmd F_SETLK

return 0 if set lock success, otherwise nil returned with errmsg and errno

try_read_lock()

syntax

local status, errmsg, errno = flock:try_read_lock()

test if read lock(L_RDLCK) could be set, return true if success or false and errmsg and errno will be returned

try_write_lock()

syntax

local status, errmsg, errno = flock:try_write_lock()

test if write lock(L_WRLCK) could be set, return true if success or false and errmsg and errno will be returned

unlock()

syntax

local status, errmsg, errno = flock:unlock()

try to unlock(F_UNLCK) by fnctl with cmd F_SETLK

return 0 if set success, otherwise nil returned with errmsg and errno

delete()

syntax

flock:delete()

unlock and free fd.