From 15fe2e50570212c7b15bb2a037b3e16c2aee42a6 Mon Sep 17 00:00:00 2001
From: Patrick Mahoney <pat@polycrystal.org>
Date: Tue, 7 Feb 2012 23:06:17 -0600
Subject: [PATCH] Refactor class hierarchy, implementation selection details.

---
 lib/process_shared.rb                         | 32 +++++--------
 lib/process_shared/binary_semaphore.rb        |  9 +---
 lib/process_shared/condition_variable.rb      |  2 +-
 lib/process_shared/mach/semaphore.rb          |  5 +-
 lib/process_shared/mutex.rb                   | 11 ++---
 .../{shared_memory.rb => object_buffer.rb}    | 20 ++------
 lib/process_shared/open_with_self.rb          | 20 ++++++++
 lib/process_shared/posix/semaphore.rb         |  6 ++-
 lib/process_shared/posix/shared_memory.rb     |  7 +--
 lib/process_shared/semaphore.rb               | 37 --------------
 lib/process_shared/shared_array.rb            |  2 +-
 .../synchronizable_semaphore.rb               | 16 +++++++
 lib/process_shared/with_self.rb               | 20 --------
 spec/mach/semaphore_spec.rb                   | 48 ++++++++++---------
 spec/process_shared/mutex_spec.rb             |  9 ++--
 spec/process_shared/semaphore_spec.rb         |  3 +-
 16 files changed, 100 insertions(+), 147 deletions(-)
 rename lib/process_shared/{shared_memory.rb => object_buffer.rb} (82%)
 create mode 100644 lib/process_shared/open_with_self.rb
 delete mode 100644 lib/process_shared/semaphore.rb
 create mode 100644 lib/process_shared/synchronizable_semaphore.rb
 delete mode 100644 lib/process_shared/with_self.rb

diff --git a/lib/process_shared.rb b/lib/process_shared.rb
index e93c4b3..1d625d6 100644
--- a/lib/process_shared.rb
+++ b/lib/process_shared.rb
@@ -3,39 +3,29 @@ require 'ffi'
 if RUBY_VERSION =~ /^1.8/
   require 'process_shared/define_singleton_method'
   
-  module ProcessShared
-    module PSem
-      extend DefineSingletonMethod
-    end
-
-    module RT
-      extend DefineSingletonMethod
-    end
-
-    module LibC
-      extend DefineSingletonMethod
-    end
+  class Module
+    include ProcessShared::DefineSingletonMethod
   end
 end
 
-require 'process_shared/semaphore'
-require 'process_shared/binary_semaphore'
-require 'process_shared/mutex'
-require 'process_shared/shared_memory'
-
 module ProcessShared
   case FFI::Platform::OS
   when 'linux'
     require 'process_shared/posix/shared_memory'
     require 'process_shared/posix/semaphore'
 
-    SharedMemory.impl = Posix::SharedMemory
-    Semaphore.impl = Posix::Semaphore
+    SharedMemory = Posix::SharedMemory
+    Semaphore = Posix::Semaphore
   when 'darwin'
     require 'process_shared/posix/shared_memory'
     require 'process_shared/mach/semaphore'
 
-    SharedMemory.impl = Posix::SharedMemory
-    Semaphore.impl = Mach::Semaphore
+    SharedMemory = Posix::SharedMemory
+    Semaphore = Mach::Semaphore
   end
 end
+
+require 'process_shared/binary_semaphore'
+require 'process_shared/mutex'
+require 'process_shared/condition_variable'
+
diff --git a/lib/process_shared/binary_semaphore.rb b/lib/process_shared/binary_semaphore.rb
index 73b11ac..f716a0d 100644
--- a/lib/process_shared/binary_semaphore.rb
+++ b/lib/process_shared/binary_semaphore.rb
@@ -1,8 +1,7 @@
 require 'forwardable'
 
 require 'process_shared'
-require 'process_shared/with_self'
-require 'process_shared/semaphore'
+require 'process_shared/open_with_self'
 require 'process_shared/process_error'
 
 module ProcessShared
@@ -14,14 +13,10 @@ module ProcessShared
   # This is identical to a Semaphore but with extra error checking.
   class BinarySemaphore
     extend Forwardable
-    include ProcessShared::WithSelf
+    extend ProcessShared::OpenWithSelf
 
     def_delegators :@sem, :wait, :try_wait, :synchronize, :value, :close
 
-    def self.open(value = 1, &block)
-      new(value).with_self(&block)
-    end
-
     # Create a new semaphore with initial value +value+.  After
     # {Kernel#fork}, the semaphore will be shared across two (or more)
     # processes. The semaphore must be closed with {#close} in each
diff --git a/lib/process_shared/condition_variable.rb b/lib/process_shared/condition_variable.rb
index 3079aa6..0fd42b4 100644
--- a/lib/process_shared/condition_variable.rb
+++ b/lib/process_shared/condition_variable.rb
@@ -1,4 +1,4 @@
-require 'process_shared/semaphore'
+require 'process_shared'
 
 module ProcessShared
   class ConditionVariable
diff --git a/lib/process_shared/mach/semaphore.rb b/lib/process_shared/mach/semaphore.rb
index a0fce59..1a87488 100644
--- a/lib/process_shared/mach/semaphore.rb
+++ b/lib/process_shared/mach/semaphore.rb
@@ -2,12 +2,15 @@ require 'mach'
 require 'mach/error'
 
 require 'process_shared/mach'
+require 'process_shared/open_with_self'
+require 'process_shared/synchronizable_semaphore'
 
 module ProcessShared
   module Mach
     # Extends ::Mach::Semaphore to be compatible with ProcessShared::Semaphore
     class Semaphore < ::Mach::Semaphore
-      include ProcessShared::Semaphore
+      extend ProcessShared::OpenWithSelf
+      include ProcessShared::SynchronizableSemaphore
 
       def initialize(value = 1)
         super(:value => value)
diff --git a/lib/process_shared/mutex.rb b/lib/process_shared/mutex.rb
index 8505f40..6de5d12 100644
--- a/lib/process_shared/mutex.rb
+++ b/lib/process_shared/mutex.rb
@@ -1,6 +1,5 @@
-require 'process_shared/semaphore'
-require 'process_shared/with_self'
-require 'process_shared/shared_memory'
+require 'process_shared'
+require 'process_shared/open_with_self'
 require 'process_shared/process_error'
 
 module ProcessShared
@@ -20,11 +19,7 @@ module ProcessShared
   # release its {Semaphore} and {SharedMemory} resources.  For now,
   # rely on the object finalizers of those objects...
   class Mutex
-    # include WithSelf
-
-    # def self.open(&block)
-    #   new.with_self(&block)
-    # end
+    extend OpenWithSelf
 
     def initialize
       @internal_sem = Semaphore.new
diff --git a/lib/process_shared/shared_memory.rb b/lib/process_shared/object_buffer.rb
similarity index 82%
rename from lib/process_shared/shared_memory.rb
rename to lib/process_shared/object_buffer.rb
index 192cc39..6bf72b5 100644
--- a/lib/process_shared/shared_memory.rb
+++ b/lib/process_shared/object_buffer.rb
@@ -1,23 +1,9 @@
-require 'process_shared/with_self'
 require 'process_shared/shared_memory_io'
 
 module ProcessShared
-  # Memory block shared across processes.
-  module SharedMemory
-    include ProcessShared::WithSelf
-
-    class << self
-      attr_accessor :impl
-
-      def new(*args)
-        impl.new(*args)
-      end
-
-      def open(size, &block)
-        new(size).with_self(&block)
-      end
-    end
-
+  # Provides reading and writing of serialized objects from a memory
+  # buffer.
+  module ObjectBuffer
     # Write the serialization of +obj+ (using Marshal.dump) to this
     # shared memory object at +offset+ (in bytes).
     #
diff --git a/lib/process_shared/open_with_self.rb b/lib/process_shared/open_with_self.rb
new file mode 100644
index 0000000..a5c5ae8
--- /dev/null
+++ b/lib/process_shared/open_with_self.rb
@@ -0,0 +1,20 @@
+module ProcessShared
+  module OpenWithSelf
+    # Like #new but if the optional code block is given, it will be
+    # passed the new object as an argument, and the object will
+    # automatically be closed (by invoking +close+) when the block
+    # terminates. In this instance, value of the block is returned.
+    def open(*args, &block)
+      obj = new(*args)
+      if block_given?
+        begin
+          yield obj
+        ensure
+          obj.close
+        end
+      else
+        obj
+      end
+    end
+  end
+end
diff --git a/lib/process_shared/posix/semaphore.rb b/lib/process_shared/posix/semaphore.rb
index e72d1a6..e75028f 100644
--- a/lib/process_shared/posix/semaphore.rb
+++ b/lib/process_shared/posix/semaphore.rb
@@ -1,4 +1,5 @@
-require 'process_shared/semaphore'
+require 'process_shared/synchronizable_semaphore'
+require 'process_shared/open_with_self'
 
 require 'process_shared/posix/errno'
 require 'process_shared/posix/libc'
@@ -34,8 +35,9 @@ module ProcessShared
                     :sem_timedwait)
       end
 
+      extend ProcessShared::OpenWithSelf
       include Foreign
-      include ProcessShared::Semaphore
+      include ProcessShared::SynchronizableSemaphore
 
       # Make a Proc suitable for use as a finalizer that will call
       # +shm_unlink+ on +sem+.
diff --git a/lib/process_shared/posix/shared_memory.rb b/lib/process_shared/posix/shared_memory.rb
index d612eb3..351dbab 100644
--- a/lib/process_shared/posix/shared_memory.rb
+++ b/lib/process_shared/posix/shared_memory.rb
@@ -2,7 +2,8 @@ require 'ffi'
 
 require 'process_shared/posix/errno'
 require 'process_shared/posix/libc'
-require 'process_shared/shared_memory'
+require 'process_shared/object_buffer'
+require 'process_shared/open_with_self'
 
 module ProcessShared
   module Posix
@@ -25,10 +26,10 @@ module ProcessShared
         error_check :shm_open, :shm_unlink
       end
 
+      extend ProcessShared::OpenWithSelf
       include SharedMemory::Foreign
       include LibC
-      
-      include ProcessShared::SharedMemory
+      include ProcessShared::ObjectBuffer
 
       attr_reader :size, :type, :type_size, :count, :fd
 
diff --git a/lib/process_shared/semaphore.rb b/lib/process_shared/semaphore.rb
deleted file mode 100644
index b1766e3..0000000
--- a/lib/process_shared/semaphore.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require 'process_shared/with_self'
-
-module ProcessShared
-  module Semaphore
-    include ProcessShared::WithSelf
-
-    class << self
-      # the implementation to use to create semaphores.  impl is set
-      # based on the platform in 'process_shared'
-      attr_accessor :impl
-      
-      def new(*args)
-        impl.new(*args)
-      end
-
-      # With no associated block, open is a synonym for
-      # Semaphore.new. If the optional code block is given, it will be
-      # passed +sem+ as an argument, and the Semaphore object will
-      # automatically be closed when the block terminates. In this
-      # instance, Semaphore.open returns the value of the block.
-      #
-      # @param [Integer] value the initial semaphore value
-      def open(value = 1, &block)
-        new(value).with_self(&block)
-      end
-    end
-
-    def synchronize
-      wait
-      begin
-        yield
-      ensure
-        post
-      end
-    end
-  end
-end
diff --git a/lib/process_shared/shared_array.rb b/lib/process_shared/shared_array.rb
index a4409e8..a4e65c8 100644
--- a/lib/process_shared/shared_array.rb
+++ b/lib/process_shared/shared_array.rb
@@ -1,7 +1,7 @@
 require 'process_shared'
 
 module ProcessShared
-  class SharedArray < SharedMemory.impl
+  class SharedArray < SharedMemory
     include Enumerable
 
     # A fixed-size array in shared memory.  Processes forked from this
diff --git a/lib/process_shared/synchronizable_semaphore.rb b/lib/process_shared/synchronizable_semaphore.rb
new file mode 100644
index 0000000..38529c8
--- /dev/null
+++ b/lib/process_shared/synchronizable_semaphore.rb
@@ -0,0 +1,16 @@
+module ProcessShared
+  module SynchronizableSemaphore
+    # Yield the block after decrementing the semaphore, ensuring that
+    # the semaphore is incremented.
+    #
+    # @return [Object] the value of the block
+    def synchronize
+      wait
+      begin
+        yield
+      ensure
+        post
+      end
+    end
+  end
+end
diff --git a/lib/process_shared/with_self.rb b/lib/process_shared/with_self.rb
deleted file mode 100644
index 3e20b05..0000000
--- a/lib/process_shared/with_self.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-module ProcessShared
-  module WithSelf
-    # With no associated block, return self.  If the optional code
-    # block is given, it will be passed `self` as an argument, and the
-    # self object will automatically be closed (by invoking +close+ on
-    # +self+) when the block terminates. In this instance, value of
-    # the block is returned.
-    def with_self
-      if block_given?
-        begin
-          yield self
-        ensure
-          self.close
-        end
-      else
-        self
-      end
-    end
-  end
-end
diff --git a/spec/mach/semaphore_spec.rb b/spec/mach/semaphore_spec.rb
index b1eef36..f3bd076 100644
--- a/spec/mach/semaphore_spec.rb
+++ b/spec/mach/semaphore_spec.rb
@@ -30,31 +30,35 @@ module Mach
     end
 
     it 'coordinates access to shared resource between two tasks' do
-      sem = Semaphore.new(:value => 0)
+      begin
+        sem = Semaphore.new(:value => 0)
 
-      port = Port.new
-      port.insert_right(:make_send)
-      Task.self.set_bootstrap_port(port)
+        port = Port.new
+        port.insert_right(:make_send)
+        Task.self.set_bootstrap_port(port)
 
-      child = fork do
-        parent_port = Task.self.get_bootstrap_port
-        Task.self.copy_send(parent_port)
-        # parent will copy send rights to sem into child task
-        sleep 0.5
-        sem.signal
-        Kernel.exit!
+        child = fork do
+          parent_port = Task.self.get_bootstrap_port
+          Task.self.copy_send(parent_port)
+          # parent will copy send rights to sem into child task
+          sleep 0.5
+          sem.signal
+          Kernel.exit!
+        end
+
+        child_task_port = port.receive_right
+
+        start = Time.now.to_f
+        sem.insert_right(:copy_send, :ipc_space => child_task_port)
+        sem.wait
+        elapsed = Time.now.to_f - start
+
+        Process.wait child
+
+        elapsed.must be_gt(0.4)
+      ensure
+        Task.self.set_bootstrap_port(Mach::Functions.bootstrap_port)
       end
-
-      child_task_port = port.receive_right
-
-      start = Time.now.to_f
-      sem.insert_right(:copy_send, :ipc_space => child_task_port)
-      sem.wait
-      elapsed = Time.now.to_f - start
-
-      Process.wait child
-
-      elapsed.must be_gt(0.4)
     end
   end
 end
diff --git a/spec/process_shared/mutex_spec.rb b/spec/process_shared/mutex_spec.rb
index f9a08bb..e790ab0 100644
--- a/spec/process_shared/mutex_spec.rb
+++ b/spec/process_shared/mutex_spec.rb
@@ -1,6 +1,5 @@
 require 'spec_helper'
-require 'process_shared/mutex'
-require 'process_shared/shared_memory'
+require 'process_shared'
 
 module ProcessShared
   describe Mutex do
@@ -60,9 +59,9 @@ module ProcessShared
 
       pid = Kernel.fork do
         mutex.lock
-        sleep 0.2
-        mutex.unlock
-        Kernel.exit!
+        # sleep 0.2
+        # mutex.unlock
+        # Kernel.exit!
       end
 
       sleep 0.1
diff --git a/spec/process_shared/semaphore_spec.rb b/spec/process_shared/semaphore_spec.rb
index 2cf50ec..75b9236 100644
--- a/spec/process_shared/semaphore_spec.rb
+++ b/spec/process_shared/semaphore_spec.rb
@@ -1,8 +1,7 @@
 require 'spec_helper'
 
 require 'ffi'
-require 'process_shared/semaphore'
-require 'process_shared/shared_memory'
+require 'process_shared'
 
 module ProcessShared
   describe Semaphore do