another imap idle trial

Author: dutow

app/services/imap/gmail_client.rb

@@ -122,17 +122,18 @@ def idle_once(timeout: 1500)
       begin
         if @imap.respond_to?(:idle)
           # Break IDLE promptly on first response so the caller can FETCH.
-          # Response handlers run outside the monitor in the receiver thread,
-          # and idle's wait releases the monitor, so idle_done can be called
-          # directly without deadlock. Avoids a detached Thread that can
-          # outlive the connection and hit a torn-down monitor.
+          # idle_done must be called from a separate thread: the response
+          # handler runs inside the receiver thread's monitor lock, so a
+          # direct call would deadlock or extend the lock window and race
+          # with signal-driven shutdown. rescue nil handles the case where
+          # the connection is torn down before the thread runs.
           idle_done_called = false
           @imap.idle(timeout) do |resp|
             got_activity = true
             yield resp if block_given?
             unless idle_done_called
               idle_done_called = true
-              @imap.idle_done
+              Thread.new { @imap.idle_done rescue nil }
             end
           end
         else
@@ -159,6 +160,11 @@ def idle_once(timeout: 1500)
       got_activity ? :activity : :timeout
     end
 
+    def interrupt_idle!
+      @imap&.idle_done
+    rescue StandardError
+    end
+
     private
 
     def ensure_imap!

app/services/imap_idle_runner.rb

@@ -194,10 +194,7 @@ def short_error(e)
 
   def stop!
     @stop = true
-    begin
-      disconnect!
-    rescue StandardError
-    end
+    @client&.interrupt_idle!
   end
 
   def respond_to_logger_info?

script/imap_idle.rb

@@ -43,25 +43,27 @@
 
 runner = ImapIdleRunner.new(label: label, logger: logger)
 
-Signal.trap('TERM') do
-  logger.info('[imap_idle] SIGTERM received, stopping...') if logger
-  runner.stop!
-end
-Signal.trap('INT') do
-  logger.info('[imap_idle] SIGINT received, stopping...') if logger
+stop_r, stop_w = IO.pipe
+Signal.trap('TERM') { stop_w.write_nonblock("\0") rescue nil }
+Signal.trap('INT')  { stop_w.write_nonblock("\0") rescue nil }
+
+Thread.new do
+  IO.select([stop_r])
+  stop_r.close
+  logger.info('[imap_idle] Signal received, stopping...') if logger
   runner.stop!
 end
 
 logger.info("[imap_idle] Starting IMAP IDLE runner for #{label}") if logger
 
 begin
-  # Infinite loop: use stop! via signal to exit
   runner.run
 rescue SystemExit, Interrupt
   # normal exit
 rescue => e
   logger.error("[imap_idle] Fatal error: #{e.class}: #{e.message}") if logger
   raise
 ensure
+  stop_w.close rescue nil
   logger.info('[imap_idle] Exiting') if logger
 end

spec/services/imap/gmail_client_spec.rb

@@ -49,6 +49,10 @@
     # Simulate Net::IMAP#idle with yielding one response
     allow(imap_double).to receive(:respond_to?).with(:idle).and_return(true)
     allow(imap_double).to receive(:idle_done)
+    allow(Thread).to receive(:new).and_wrap_original do |m, *args, &blk|
+      blk.call
+      double('Thread', join: true)
+    end
     yielded = []
     expect(imap_double).to receive(:idle) do |timeout, &blk|
       blk.call(double('Resp', name: 'EXISTS', data: 1))