ecairn / posixlock

SYNOPSIS:

methods to add posix (fcntl based and nfs safe) locking to the builtin File class

URLS:

• http://raa.ruby-lang.org/project/posixlock/

• http://www.codeforpeople.com/lib/ruby/posixlock/

EXAMPLES:

File.open('even_an_nfs_mounted_file','r+').posixlock File::LOCK_EX

File.open('even_an_nfs_mounted_file','r+').lockf File::F_LOCK, 0

open('even_an_nfs_mounted_file','r') do |f|
  f.lockf File::F_LOCKR, 42
end

f = open 'foo', 'r+'

if((pid = f.lockf File::F_TEST, 0))
  STDERR.puts "process <#{ pid }> prevents write lock"
end

f = open 'foo', 'r'

if((pid = f.lockf File::F_TESTR, 0))
  STDERR.puts "process <#{ pid }> prevents read lock"
end

DOCS:

• posixlock.c

• File#posixlock has an identical interface to the builtin File#flock

• for File#lockf see man (3) lockf

  the additional flags

  File::F_LOCKR

  File::F_LOCKW

  File::F_TLOCKR

  File::F_TLOCKW

  File::F_TESTR

  File::F_TESTW

  have the obvious meaning

AUTHOR:

[email protected]

BUGS:

HISTORY:

0.0.1: changed behaviour so that, instead of replacing flock, two new methods are added: File#posixlock gives access to read/write locks with an interface identical to File#flock, and File#lockf gives access to a lockf impl similar to the one posix specifies with added functionality for read locks. the biggest difference between the two methods is that lockf will throw errors for errno's like EAGAIN, EACCESS, etc.

0.0.0: initial version