Module: Bricolage::VacuumLock

Included in:
EmbeddedCodeAPI, PSQLDataSource, PSQLTask
Defined in:
lib/bricolage/vacuumlock.rb

Constant Summary collapse

DEFAULT_VACUUM_LOCK_FILE = 
'/tmp/bricolage.vacuum.lock'
DEFAULT_VACUUM_LOCK_TIMEOUT =

60min

3600

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.cleanup_vacuum_lock ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 89

def VacuumLock.cleanup_vacuum_lock
  return unless enable_vacuum_lock?
  path, timeout = vacuum_lock_parameters
  if locking?(path)
    $stderr.puts "remove VACUUM lock by #{Process.pid}"
    FileUtils.rm_f path
  end
end

.create_lockfile_cmd ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 43

def create_lockfile_cmd
  Pathname(__FILE__).parent.parent.parent + 'libexec/create-lockfile'
end

.create_vacuum_lock_file(path, timeout) ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 60

def create_vacuum_lock_file(path, timeout)
  start_time = Time.now
  begin
    File.open(path, File::WRONLY | File::CREAT | File::EXCL) {|f|
      f.puts "#{Time.now}: created by bricolage [#{Process.pid}]"
    }
  rescue Errno::EEXIST
    if Time.now - start_time > timeout
      raise LockTimeout, "could not create lock file: #{path} (timeout #{timeout} seconds)"
    end
    sleep 1
    retry
  end
end

.enable_vacuum_lock? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/bricolage/vacuumlock.rb', line 7

def enable_vacuum_lock?
  !!ENV['BRICOLAGE_VACUUM_LOCK']
end

.locking?(path) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/bricolage/vacuumlock.rb', line 98

def VacuumLock.locking?(path)
  # do not check file existance, just read to avoid race condition
  locker_pid = File.read(path).slice(/\[(\d+)\]/, 1).to_i
  $stderr.puts "bricolage_pid: #{$$}, vacuum_locked_by: #{locker_pid}"
  locker_pid == Process.pid
rescue
  $stderr.puts "bricolage_pid: #{$$}, vacuum_locked_by: (none)"
  false
end

.psql_serialize_vacuum_begin ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 23

def psql_serialize_vacuum_begin
  if enable_vacuum_lock?
    path, timeout = vacuum_lock_parameters
    "\\! #{create_lockfile_cmd} #{path} #{timeout}"
  else
    ';'
  end
end

.psql_serialize_vacuum_end ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 33

def psql_serialize_vacuum_end
  if enable_vacuum_lock?
    path, timeout = vacuum_lock_parameters
    "\\! rm -f #{path}"
  else
    ';'
  end
end

.serialize_vacuum ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 48

def serialize_vacuum
  return yield unless enable_vacuum_lock?
  path, timeout = vacuum_lock_parameters
  create_vacuum_lock_file path, timeout
  begin
    yield
  ensure
    FileUtils.rm_f path
  end
end

.using ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 76

def VacuumLock.using
  return yield unless enable_vacuum_lock?
  begin
    yield
  ensure
    cleanup_vacuum_lock
  end
end

.vacuum_lock_parameters ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 15

def vacuum_lock_parameters
  return nil unless enable_vacuum_lock?
  path, tm = ENV['BRICOLAGE_VACUUM_LOCK'].split(':', 2)
  timeout = tm ? [tm.to_i, 1].max : DEFAULT_VACUUM_LOCK_TIMEOUT
  return path, timeout
end

Instance Method Details

#using_vacuum_lock(&block) ⇒ Object 



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# File 'lib/bricolage/vacuumlock.rb', line 85

def using_vacuum_lock(&block)
  VacuumLock.using(&block)
end