Class: Distem::Lib::Semaphore

Inherits:

Object

• Object
• Distem::Lib::Semaphore

show all

Defined in:

lib/distem/distemlib/semaphore.rb

Overview

Instance Attribute Summary (collapse)

• - (Object) size readonly

  The size of the semaphore.

Instance Method Summary (collapse)

• - (Object) acquire

  Try to acquire a a resource.

• - (Semaphore) initialize(size) constructor

  Create a new Semaphore object ==== Attributes * size The size of the semaphore.

• - (Object) release

  Leave a resource.

• - (Object) synchronize

  Acquire then release a resource.

14
15
16
17
18
19
20

# File 'lib/distem/distemlib/semaphore.rb', line 14

def initialize(size)
  raise InvalidParameterError unless size >= 0
  @size = size
  @val = @size
  @lock = Mutex.new
  @positive = ConditionVariable.new
end

9
10
11

# File 'lib/distem/distemlib/semaphore.rb', line 9

def size
  @size
end

23
24
25
26
27
28
29
30
31

# File 'lib/distem/distemlib/semaphore.rb', line 23

def acquire
  @lock.synchronize do
    if @val == 0
      @positive.wait(@lock)
    end

    @val -= 1
  end
end

34
35
36
37
38
39

# File 'lib/distem/distemlib/semaphore.rb', line 34

def release
  @lock.synchronize do
    @val += 1
    @positive.signal
  end
end

42
43
44
45
46
47
48
49

# File 'lib/distem/distemlib/semaphore.rb', line 42

def synchronize
  acquire
  begin
    yield
  ensure
    release
  end
end