lib/sync-defer.rb in sync-defer-0.9.4 vs lib/sync-defer.rb in sync-defer-0.9.5

@@ -1,6 +1,8 @@
 
+require 'fiber'
+
 begin
   require 'eventmachine/sync-defer'
 rescue LoadError
 end
 
@@ -8,25 +10,42 @@
   require 'cool.io/sync-defer'
 rescue LoadError
 end
 
 module SyncDefer
+  # assume we would always require 'rest-core' in root fiber
+  RootFiber = Fiber.current
+
   module_function
   def defer *args, &block
-    if Object.const_defined?(:EventMachine) && EventMachine.reactor_running?
+    if root_fiber?
+      fallback("Not called inside a fiber.", *args, &block)
+
+    elsif Object.const_defined?(:EventMachine) &&
+          EventMachine.reactor_running?
       EventMachine::SyncDefer.defer(*args, &block)
+
     elsif Object.const_defined?(:Coolio) &&
           Coolio::Loop.default.has_active_watchers?
       Coolio::SyncDefer.defer(*args, &block)
+
     else
-      $stderr.puts("SyncDefer: WARN: No reactor found. " \
-                   "Only cool.io and eventmachine are supported.")
-      $stderr.puts("           Called from: #{caller.last(5).inspect}")
-      args << block if block_given?
-      if args.size == 1
-        args.first.call
-      else
-        args.map(&:call)
-      end
+      fallback("No reactor found.", *args, block)
+    end
+  end
+
+  def root_fiber?
+    RootFiber == Fiber.current
+  end
+
+  def fallback message, *args, &block
+    $stderr.puts("SyncDefer: WARN: #{message}")
+    $stderr.puts("           Falling back to run the computation directly.")
+    $stderr.puts("           Called from: #{caller.last(5).inspect}")
+    args << block if block_given?
+    if args.size == 1
+      args.first.call
+    else
+      args.map(&:call)
     end
   end
 end