Optimized MutexAtomicBoolean

Author: mighe

lib/concurrent/atomic/atomic_boolean.rb

@@ -16,7 +16,7 @@ class MutexAtomicBoolean
     #
     # @param [Boolean] init the initial value
     def initialize(initial = false)
-      @value = !! initial
+      @value = !!initial
       @mutex = Mutex.new
     end
 
@@ -26,7 +26,10 @@ def initialize(initial = false)
     #
     #   @return [Boolean] the current value
     def value
-      @mutex.synchronize{ @value }
+      @mutex.lock
+      result = @value
+      @mutex.unlock
+      result
     end
 
     # @!macro [attach] atomic_boolean_method_value_eq
@@ -37,7 +40,11 @@ def value
     #
     #   @return [Boolean] the current value
     def value=(value)
-      @mutex.synchronize{ @value = !! value }
+      @mutex.lock
+      @value = !!value
+      result = @value
+      @mutex.unlock
+      result
     end
 
     # @!macro [attach] atomic_boolean_method_is_true
@@ -46,7 +53,10 @@ def value=(value)
     #
     #   @return [Boolean] true if the current value is `true`, else false
     def true?
-      @mutex.synchronize{ @value == true }
+      @mutex.lock
+      result = @value
+      @mutex.unlock
+      result
     end
 
     # @!macro [attach] atomic_boolean_method_is_false
@@ -55,27 +65,36 @@ def true?
     #
     #   @return [Boolean] true if the current value is `false`, else false
     def false?
-      @mutex.synchronize{ @value != true }
+      @mutex.lock
+      result = !@value
+      @mutex.unlock
+      result
     end
 
     # @!macro [attach] atomic_boolean_method_make_true
     #
     #   Explicitly sets the value to true.
     #
-    #   @return [Boolean] the current value
+    #   @return [Boolean] true if the value changed
     def make_true
-      @mutex.synchronize{ @value = true }
-      nil
+      @mutex.lock
+      old = @value
+      @value = true
+      @mutex.unlock
+      !old
     end
 
     # @!macro [attach] atomic_boolean_method_make_false
     #
     #   Explicitly sets the value to false.
     #
-    #   @return [Boolean] the current value
+    #   @return [Boolean] true if the value changed
     def make_false
-      @mutex.synchronize{ @value = false }
-      nil
+      @mutex.lock
+      old = @value
+      @value = false
+      @mutex.unlock
+      old
     end
   end
 
@@ -87,7 +106,7 @@ class JavaAtomicBoolean
       # @!macro atomic_boolean_method_initialize
       #
       def initialize(initial = false)
-        @atomic = java.util.concurrent.atomic.AtomicBoolean.new(!! initial)
+        @atomic = java.util.concurrent.atomic.AtomicBoolean.new(!!initial)
       end
 
       # @!macro atomic_boolean_method_value
@@ -99,7 +118,7 @@ def value
       # @!macro atomic_boolean_method_value_eq
       #
       def value=(value)
-        @atomic.set(!! value)
+        @atomic.set(!!value)
       end
 
       # @!macro [attach] atomic_boolean_method_is_true

spec/concurrent/atomic/atomic_boolean_spec.rb

@@ -2,7 +2,7 @@
 
 share_examples_for :atomic_boolean do
 
-  context 'construction' do
+  describe 'construction' do
 
     it 'sets the initial value' do
       described_class.new(true).value.should be_true
@@ -21,7 +21,7 @@
     end
   end
 
-  context '#value' do
+  describe '#value' do
 
     it 'returns the current value' do
       counter = described_class.new(true)
@@ -33,7 +33,7 @@
     end
   end
 
-  context '#value=' do
+  describe '#value=' do
 
     it 'sets the #value to the given `Boolean`' do
       atomic = described_class.new(true)
@@ -59,46 +59,46 @@
     end
   end
 
-  context 'true?' do
+  describe '#true?' do
 
     specify { described_class.new(true).true?.should be_true }
 
     specify { described_class.new(false).true?.should be_false }
   end
 
-  context 'false?' do
+  describe '#false?' do
 
     specify { described_class.new(true).false?.should be_false }
 
     specify { described_class.new(false).false?.should be_true }
   end
 
-  context 'make_true' do
+  describe '#make_true' do
 
-    it 'makes a false value true and returns nil' do
+    it 'makes a false value true and returns true' do
       subject = described_class.new(false)
-      subject.make_true.should be_nil
+      subject.make_true.should be_true
       subject.value.should be_true
     end
 
-    it 'keeps a true value true and returns nil' do
+    it 'keeps a true value true and returns false' do
       subject = described_class.new(true)
-      subject.make_true.should be_nil
+      subject.make_true.should be_false
       subject.value.should be_true
     end
   end
 
-  context 'make_false' do
+  describe '#make_false' do
 
-    it 'makes a true value false and returns nil' do
+    it 'makes a true value false and returns true' do
       subject = described_class.new(true)
-      subject.make_false.should be_nil
+      subject.make_false.should be_true
       subject.value.should be_false
     end
 
-    it 'keeps a false value false and returns nil' do
+    it 'keeps a false value false and returns false' do
       subject = described_class.new(false)
-      subject.make_false.should be_nil
+      subject.make_false.should be_false
       subject.value.should be_false
     end
   end
@@ -116,46 +116,38 @@ module Concurrent
       described_class.new
     end
 
-    specify 'value is synchronized' do
-      mutex = double('mutex')
-      Mutex.stub(:new).with(no_args).and_return(mutex)
-      mutex.should_receive(:synchronize)
-      described_class.new.value
-    end
+    context 'instance methods' do
 
-    specify 'value= is synchronized' do
-      mutex = double('mutex')
-      Mutex.stub(:new).with(no_args).and_return(mutex)
-      mutex.should_receive(:synchronize)
-      described_class.new.value = 10
-    end
+      before(:each) do
+        mutex = double('mutex')
+        Mutex.stub(:new).with(no_args).and_return(mutex)
+        mutex.should_receive(:lock)
+        mutex.should_receive(:unlock)
+      end
 
-    specify 'true? is synchronized' do
-      mutex = double('mutex')
-      Mutex.stub(:new).with(no_args).and_return(mutex)
-      mutex.should_receive(:synchronize)
-      described_class.new.true?
-    end
+      specify 'value is synchronized' do
+        described_class.new.value
+      end
 
-    specify 'false? is synchronized' do
-      mutex = double('mutex')
-      Mutex.stub(:new).with(no_args).and_return(mutex)
-      mutex.should_receive(:synchronize)
-      described_class.new.false?
-    end
+      specify 'value= is synchronized' do
+        described_class.new.value = 10
+      end
 
-    specify 'make_true is synchronized' do
-      mutex = double('mutex')
-      Mutex.stub(:new).with(no_args).and_return(mutex)
-      mutex.should_receive(:synchronize)
-      described_class.new.make_true
-    end
+      specify 'true? is synchronized' do
+        described_class.new.true?
+      end
 
-    specify 'make_false is synchronized' do
-      mutex = double('mutex')
-      Mutex.stub(:new).with(no_args).and_return(mutex)
-      mutex.should_receive(:synchronize)
-      described_class.new.make_false
+      specify 'false? is synchronized' do
+        described_class.new.false?
+      end
+
+      specify 'make_true is synchronized' do
+        described_class.new.make_true
+      end
+
+      specify 'make_false is synchronized' do
+        described_class.new.make_false
+      end
     end
   end