Moved semaphore classes into own files.

Author: jdantonio

lib/concurrent/atomic/mutex_semaphore.rb

@@ -0,0 +1,115 @@
+require 'concurrent/synchronization'
+
+module Concurrent
+
+  # @!macro semaphore
+  # @!visibility private
+  # @!macro internal_implementation_note
+  class MutexSemaphore < Synchronization::Object
+
+    # @!macro semaphore_method_initialize
+    def initialize(count)
+      unless count.is_a?(Fixnum) && count >= 0
+        fail ArgumentError, 'count must be an non-negative integer'
+      end
+      super()
+      synchronize { ns_initialize count }
+    end
+
+    # @!macro semaphore_method_acquire
+    def acquire(permits = 1)
+      unless permits.is_a?(Fixnum) && permits > 0
+        fail ArgumentError, 'permits must be an integer greater than zero'
+      end
+      synchronize do
+        try_acquire_timed(permits, nil)
+        nil
+      end
+    end
+
+    # @!macro semaphore_method_available_permits
+    def available_permits
+      synchronize { @free }
+    end
+
+    # @!macro semaphore_method_drain_permits
+    #
+    #   Acquires and returns all permits that are immediately available.
+    #
+    #   @return [Integer]
+    def drain_permits
+      synchronize do
+        @free.tap { |_| @free = 0 }
+      end
+    end
+
+    # @!macro semaphore_method_try_acquire
+    def try_acquire(permits = 1, timeout = nil)
+      unless permits.is_a?(Fixnum) && permits > 0
+        fail ArgumentError, 'permits must be an integer greater than zero'
+      end
+      synchronize do
+        if timeout.nil?
+          try_acquire_now(permits)
+        else
+          try_acquire_timed(permits, timeout)
+        end
+      end
+    end
+
+    # @!macro semaphore_method_release
+    def release(permits = 1)
+      unless permits.is_a?(Fixnum) && permits > 0
+        fail ArgumentError, 'permits must be an integer greater than zero'
+      end
+      synchronize do
+        @free += permits
+        permits.times { ns_signal }
+      end
+      nil
+    end
+
+    # Shrinks the number of available permits by the indicated reduction.
+    #
+    # @param [Fixnum] reduction Number of permits to remove.
+    #
+    # @raise [ArgumentError] if `reduction` is not an integer or is negative
+    #
+    # @raise [ArgumentError] if `@free` - `@reduction` is less than zero
+    #
+    # @return [nil]
+    # 
+    # @!visibility private
+    def reduce_permits(reduction)
+      unless reduction.is_a?(Fixnum) && reduction >= 0
+        fail ArgumentError, 'reduction must be an non-negative integer'
+      end
+      synchronize { @free -= reduction }
+      nil
+    end
+
+    protected
+
+    # @!visibility private
+    def ns_initialize(count)
+      @free = count
+    end
+
+    private
+
+    # @!visibility private
+    def try_acquire_now(permits)
+      if @free >= permits
+        @free -= permits
+        true
+      else
+        false
+      end
+    end
+
+    # @!visibility private
+    def try_acquire_timed(permits, timeout)
+      ns_wait_until(timeout) { try_acquire_now(permits) }
+    end
+  end
+end