Implement PyCallThread as a library, and give a puma example

Gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 # To use the local path, you must also run things with:
 # bundle exec ruby -I/Users/seth/src/pycall.rb/ext/pycall
 # 
-gem 'pycall', path: '/Users/seth/src/pycall.rb', require: false
+# gem 'pycall', path: '/Users/seth/src/pycall.rb', require: false
 
-# gem 'pycall'
+gem 'pycall'
 gem 'puma', '~> 6.4.1'

Gemfile.lock

@@ -1,21 +1,17 @@
-PATH
-  remote: /Users/seth/src/pycall.rb
-  specs:
-    pycall (1.5.2)
-
 GEM
   remote: https://rubygems.org/
   specs:
     nio4r (2.7.3)
     puma (6.4.2)
       nio4r (~> 2.0)
+    pycall (1.5.2)
 
 PLATFORMS
   arm64-darwin-23
 
 DEPENDENCIES
   puma (~> 6.4.1)
-  pycall!
+  pycall
 
 BUNDLED WITH
    2.3.22

examples/puma/app.rb

@@ -0,0 +1,25 @@
+require_relative '../../lib/pycall_thread/pycall_thread'
+
+PyCallThread.init do
+  # Setup our local venv (using pdm, in .venv)
+  ENV['PYTHON'] = `pdm run which python`.strip
+  site_dir = `pdm run python -c 'import site; print(site.getsitepackages()[0])'`.strip
+
+  require 'pycall'
+
+  # This is to setup our local venv
+  site = PyCall.import_module('site')
+  site.addsitedir(site_dir)
+end
+
+class App
+  def call(env)
+    winequality = PyCallThread.run do
+      pandas = PyCall.import_module('pandas')
+      data = pandas.read_csv('https://archive.ics.uci.edu/ml/machine-learning-databases/wine-quality/winequality-red.csv', sep: ';')
+      data.to_html()
+    end
+
+    [200, { 'Content-Type' => 'text/html' }, [winequality]]
+  end
+end

examples/puma/config.ru

@@ -0,0 +1,3 @@
+require './app'
+
+run App.new

examples/puma/start_puma.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+
+# Start Puma with 3 threads on port 9292
+puma -t 3:3 -p 9292

pycall_thread.rb → lib/pycall_thread/pycall_thread.rb

@@ -20,7 +20,9 @@ def self.init(unsafe_return: :error, &require_pycall_block)
     # instead of doing it directly.
     @py_thread = Thread.new { pycall_thread_loop(&require_pycall_block) }
 
-    at_exit { stop_pycall_thread }
+    at_exit do
+      stop_pycall_thread
+    end
 
     nil
   end
@@ -30,26 +32,34 @@ def self.run(&block)
     init unless @initialized
 
     result_queue = Queue.new
-    @queue << -> { result_queue << block.call }
-    retval = result_queue.pop
+    @queue << -> do
+      begin
+        result_queue << { retval: block.call }
+      rescue => e
+        result_queue << { exception: e }
+      end
+    end
 
-    puts "pycall_thread.done, retval = #{retval.inspect}"
+    result = result_queue.pop
 
-    if python_object?(retval)
+    if result[:exception]
+      raise result[:exception]
+    elsif python_object?(result[:retval])
+      msg = "Trying to return a python object from a PyCallThread.run block is potentially not thread-safe. Please convert #{result.inspect} to a basic Ruby type (like string, array, number, boolean etc) before returning."
       case @unsafe_return
       when :error
-        raise "Trying to return a python object from PyCDO.lock_python_gil block is potentially not thread-safe. Please convert it to a basic Ruby type (like string, array, number, boolean etc) before returning."
+        raise msg
       when :warn
-        warn "Warning: Returning a Python object from PyCDO.lock_python_gil block is potentially not thread-safe. Please convert it to a basic Ruby type (like string, array, number, boolean etc) before returning."
+        warn "Warning: #{msg}"
       end
     end
 
-    puts "returning from pycall.run"
-    retval
+    result[:retval]
   end
 
   def self.stop_pycall_thread
     @queue << :stop
+    @py_thread.join
   end
 
   def self.pycall_thread_loop(&require_pycall_block)
@@ -68,6 +78,7 @@ def self.pycall_thread_loop(&require_pycall_block)
       block.call
     rescue => e
       puts "pycall_thread_loop(): exception in pycall_thread_loop #{e}"
+      puts e.backtrace.join("\n")
     end
 
     # If PyCall.finalize is not present, the main proces will hang at exit

pyproject.toml

@@ -3,6 +3,7 @@ requires-python = "==3.12.*"
 
 dependencies = [
     "pandas",
+    "psutil>=6.0.0",
 ]
 
 [tool.pdm]