Merge pull request #1092 from opscode/runlock-windows-access

Check before creating a new system mutex on windows.

1 files changed, 50 insertions, 27 deletions

diff --git a/lib/chef/win32/mutex.rb b/lib/chef/win32/mutex.rb
index b0a9ba210e..0b7d99f111 100644
--- a/lib/chef/win32/mutex.rb
+++ b/lib/chef/win32/mutex.rb
@@ -22,25 +22,10 @@ class Chef
   module ReservedNames::Win32
     class Mutex
       include Chef::ReservedNames::Win32::API::Synchronization
-      extend Chef::ReservedNames::Win32::API::Synchronization
 
       def initialize(name)
         @name = name
-        # First check if there exists a mutex in the system with the
-        # given name.
-
-        # In the initial creation of the mutex initial_owner is set to
-        # false so that mutex will not be acquired until someone calls
-        # acquire.
-        # In order to call "*W" windows apis, strings needs to be
-        # encoded as wide strings.
-        @handle = CreateMutexW(nil, false, name.to_wstring)
-
-        # Fail early if we can't get a handle to the named mutex
-        if @handle == 0
-          Chef::Log.error("Failed to create system mutex with name'#{name}'")
-          Chef::ReservedNames::Win32::Error.raise!
-        end
+        create_system_mutex
       end
 
       attr_reader :handle
@@ -57,17 +42,27 @@ class Chef
       #####################################################
       # Attempts to grab the mutex and waits until it is acquired.
       def wait
-        wait_result = WaitForSingleObject(handle, INFINITE)
-        case wait_result
-        when WAIT_ABANDONED
-          # Previous owner of the mutex died before it can release the
-          # mutex. Log a warning and continue.
-          Chef::Log.debug "Existing owner of the mutex exited prematurely."
-        when WAIT_OBJECT_0
-          # Mutex is successfully acquired.
-        else
-          Chef::Log.error("Failed to acquire system mutex '#{name}'. Return code: #{wait_result}")
-          Chef::ReservedNames::Win32::Error.raise!
+        loop do
+          wait_result = WaitForSingleObject(handle, 1000)
+          case wait_result
+          when WAIT_TIMEOUT
+            # We are periodically waking up in order to give ruby a
+            # chance to process any signal it got while we were
+            # sleeping. This condition shouldn't contain any logic
+            # other than sleeping.
+            sleep 0.1
+          when WAIT_ABANDONED
+            # Previous owner of the mutex died before it can release the
+            # mutex. Log a warning and continue.
+            Chef::Log.debug "Existing owner of the mutex exited prematurely."
+            break
+          when WAIT_OBJECT_0
+            # Mutex is successfully acquired.
+            break
+          else
+            Chef::Log.error("Failed to acquire system mutex '#{name}'. Return code: #{wait_result}")
+            Chef::ReservedNames::Win32::Error.raise!
+          end
         end
       end
 
@@ -87,6 +82,34 @@ if the mutex is attempted to be acquired by other threads.")
           Chef::ReservedNames::Win32::Error.raise!
         end
       end
+
+      private
+
+      def create_system_mutex
+        # First check if there exists a mutex in the system with the
+        # given name. We need only synchronize rights if a mutex is
+        # already created.
+        # InheritHandle is set to true so that subprocesses can
+        # inherit the ownership of the mutex.
+        @handle = OpenMutexW(SYNCHRONIZE, true, name.to_wstring)
+
+        if @handle == 0
+          # Mutext doesn't exist so create one.
+          # In the initial creation of the mutex initial_owner is set to
+          # false so that mutex will not be acquired until someone calls
+          # acquire.
+          # In order to call "*W" windows apis, strings needs to be
+          # encoded as wide strings.
+          @handle = CreateMutexW(nil, false, name.to_wstring)
+
+          # Looks like we can't create the mutex for some reason.
+          # Fail early.
+          if @handle == 0
+            Chef::Log.error("Failed to create system mutex with name'#{name}'")
+            Chef::ReservedNames::Win32::Error.raise!
+          end
+        end
+      end
     end
   end
 end