lib/cmds/io_handler.rb in cmds-0.2.9 vs lib/cmds/io_handler.rb in cmds-0.2.10

@@ -1,13 +1,40 @@
 class Cmds
+  # Class for handling IO from threads and passing it back via a {Queue} to
+  # the main thread for processing.
+  # 
+  # NOTE  These are one-use only! Don't try to reuse them.
+  # 
   class IOHandler
     attr_accessor :in, :out, :err
 
     def initialize
       @in = nil
       @out = $stdout
       @err = $stderr
+      
+      # Initialize a thread-safe queue for passing output from the IO threads
+      # back to the main thread
+      # 
+      # NOTE  This used to be done in {#start}, but I was seeing intermittent
+      #       failures on Travis from what look like thread race conditions,
+      #       guessing that it's from output arriving before {#start} is
+      #       called, which totally looks like it could happen.
+      #       
+      #       See the failure in
+      #       
+      #       https://travis-ci.org/nrser/qb/jobs/348609316
+      #       
+      #       Really, I'm surprised I haven't hit more issues with this
+      #       half-ass threading shit.
+      #       
+      #       Anyways, I moved the queue creation here, see if it helps.
+      # 
+      @queue = Queue.new
+      
+      # Flag that is set to `true` when {#start} is called.
+      @started = false
     end
     
     def out= value
       value = value.to_s if value.is_a? Pathname
       @out = value
@@ -20,31 +47,34 @@
 
     def on_out &block
       @out = block
     end
 
-    # called in seperate thread handling process IO
+    # called in separate thread handling process IO
     def thread_send_out line
       @queue << [:out, line]
     end
 
     def on_err &block
       @err = block
     end
 
-    # called in seperate thread handling process IO
+    # called in separate thread handling process IO
     def thread_send_err line
       @queue << [:err, line]
     end
-
+    
+    # called in separate thread handling process IO
     def thread_send_line sym, line
       @queue << [sym, line]
     end
 
     def start
-      # Initialize a thread-safe queue for passing output from the IO threads
-      # back to the main thread
-      @queue = Queue.new
+      if @started
+        raise "This handler has already been started / run"
+      end
+      
+      @started = true
       
       # if out is a proc, it's not done
       out_done = ! @out.is_a?(Proc)
       # same for err
       err_done = ! @err.is_a?(Proc)