text: # Copyright 2018-2021 Streamlit Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import sys
  import threading
  import gc
  from contextlib import contextmanager
  from enum import Enum
  
  from blinker import Signal
  
  from streamlit import config
  from streamlit import magic
  from streamlit import source_util
  from streamlit import util
  from streamlit.error_util import handle_uncaught_app_exception
  from streamlit.in_memory_file_manager import in_memory_file_manager
  from streamlit.report_thread import ReportThread, ReportContext
  from streamlit.report_thread import get_report_ctx
  from streamlit.script_request_queue import ScriptRequest
  from streamlit.state.session_state import (
      SessionState,
      SCRIPT_RUN_WITHOUT_ERRORS_KEY,
  )
  from streamlit.logger import get_logger
  from streamlit.proto.ClientState_pb2 import ClientState
  
  LOGGER = get_logger(__name__)
  
  
  class ScriptRunnerEvent(Enum):
      # The script started running.
      SCRIPT_STARTED = "SCRIPT_STARTED"
  
      # The script run stopped because of a compile error.
      SCRIPT_STOPPED_WITH_COMPILE_ERROR = "SCRIPT_STOPPED_WITH_COMPILE_ERROR"
  
      # The script run stopped because it ran to completion, or was
      # interrupted by the user.
      SCRIPT_STOPPED_WITH_SUCCESS = "SCRIPT_STOPPED_WITH_SUCCESS"
  
      # The ScriptRunner is done processing the ScriptEventQueue and
      # is shut down.
      SHUTDOWN = "SHUTDOWN"
  
  
  class ScriptRunner(object):
      def __init__(
          self,
          session_id,
          report,
          enqueue_forward_msg,
          client_state,
          request_queue,
          session_state,
          uploaded_file_mgr=None,
      ):
          """Initialize the ScriptRunner.
  
          (The ScriptRunner won't start executing until start() is called.)
  
          Parameters
          ----------
          session_id : str
              The ReportSession's id.
  
          report : Report
              The ReportSession's report.
  
          client_state : streamlit.proto.ClientState_pb2.ClientState
              The current state from the client (widgets and query params).
  
          request_queue : ScriptRequestQueue
              The queue that the ReportSession is publishing ScriptRequests to.
              ScriptRunner will continue running until the queue is empty,
              and then shut down.
  
          widget_mgr : WidgetManager
              The ReportSession's WidgetManager.
  
          uploaded_file_mgr : UploadedFileManager
              The File manager to store the data uploaded by the file_uploader widget.
  
          """
          self._session_id = session_id
          self._report = report
          self._enqueue_forward_msg = enqueue_forward_msg
          self._request_queue = request_queue
          self._uploaded_file_mgr = uploaded_file_mgr
  
          self._client_state = client_state
          self._session_state: SessionState = session_state
          self._session_state.set_widgets_from_proto(client_state.widget_states)
  
          self.on_event = Signal(
              doc="""Emitted when a ScriptRunnerEvent occurs.
  
              This signal is *not* emitted on the same thread that the
              ScriptRunner was created on.
  
              Parameters
              ----------
              event : ScriptRunnerEvent
  
              exception : BaseException | None
                  Our compile error. Set only for the
                  SCRIPT_STOPPED_WITH_COMPILE_ERROR event.
  
              widget_states : streamlit.proto.WidgetStates_pb2.WidgetStates | None
                  The ScriptRunner's final WidgetStates. Set only for the
                  SHUTDOWN event.
              """
          )
  
          # Set to true when we process a SHUTDOWN request
          self._shutdown_requested = False
  
          # Set to true while we're executing. Used by
          # maybe_handle_execution_control_request.
          self._execing = False
  
          # This is initialized in start()
          self._script_thread = None
  
      def __repr__(self) -> str:
          return util.repr_(self)
  
      def start(self):
          """Start a new thread to process the ScriptEventQueue.
  
          This must be called only once.
  
          """
          if self._script_thread is not None:
              raise Exception("ScriptRunner was already started")
  
          self._script_thread = ReportThread(
              session_id=self._session_id,
              enqueue=self._enqueue_forward_msg,
              query_string=self._client_state.query_string,
              session_state=self._session_state,
              uploaded_file_mgr=self._uploaded_file_mgr,
              target=self._process_request_queue,
              name="ScriptRunner.scriptThread",
          )
          self._script_thread.start()
  
      def _process_request_queue(self):
          """Process the ScriptRequestQueue and then exits.
  
          This is run in a separate thread.
  
          """
          LOGGER.debug("Beginning script thread")
  
          while not self._shutdown_requested and self._request_queue.has_request:
              request, data = self._request_queue.dequeue()
              if request == ScriptRequest.STOP:
                  LOGGER.debug("Ignoring STOP request while not running")
              elif request == ScriptRequest.SHUTDOWN:
                  LOGGER.debug("Shutting down")
                  self._shutdown_requested = True
              elif request == ScriptRequest.RERUN:
                  self._run_script(data)
              else:
                  raise RuntimeError("Unrecognized ScriptRequest: %s" % request)
  
          # Send a SHUTDOWN event before exiting. This includes the widget values
          # as they existed after our last successful script run, which the
          # ReportSession will pass on to the next ScriptRunner that gets
          # created.
          client_state = ClientState()
          client_state.query_string = self._client_state.query_string
          widget_states = self._session_state.as_widget_states()
          client_state.widget_states.widgets.extend(widget_states)
          self.on_event.send(ScriptRunnerEvent.SHUTDOWN, client_state=client_state)
  
      def _is_in_script_thread(self):
          """True if the calling function is running in the script thread"""
          return self._script_thread == threading.current_thread()
  
      def maybe_handle_execution_control_request(self):
          if not self._is_in_script_thread():
              # We can only handle execution_control_request if we're on the
              # script execution thread. However, it's possible for deltas to
              # be enqueued (and, therefore, for this function to be called)
              # in separate threads, so we check for that here.
              return
  
          if not self._execing:
              # If the _execing flag is not set, we're not actually inside
              # an exec() call. This happens when our script exec() completes,
              # we change our state to STOPPED, and a statechange-listener
              # enqueues a new ForwardEvent
              return
  
          # Pop the next request from our queue.
          request, data = self._request_queue.dequeue()
          if request is None:
              return
  
          LOGGER.debug("Received ScriptRequest: %s", request)
          if request == ScriptRequest.STOP:
              raise StopException()
          elif request == ScriptRequest.SHUTDOWN:
              self._shutdown_requested = True
              raise StopException()
          elif request == ScriptRequest.RERUN:
              raise RerunException(data)
          else:
              raise RuntimeError("Unrecognized ScriptRequest: %s" % request)
  
      def _install_tracer(self):
          """Install function that runs before each line of the script."""
  
          def trace_calls(frame, event, arg):
              self.maybe_handle_execution_control_request()
              return trace_calls
  
          # Python interpreters are not required to implement sys.settrace.
          if hasattr(sys, "settrace"):
              sys.settrace(trace_calls)
  
      @contextmanager
      def _set_execing_flag(self):
          """A context for setting the ScriptRunner._execing flag.
  
          Used by maybe_handle_execution_control_request to ensure that
          we only handle requests while we're inside an exec() call
          """
          if self._execing:
              raise RuntimeError("Nested set_execing_flag call")
          self._execing = True
          try:
              yield
          finally:
              self._execing = False
  
      def _run_script(self, rerun_data):
          """Run our script.
  
          Parameters
          ----------
          rerun_data: RerunData
              The RerunData to use.
  
          """
          assert self._is_in_script_thread()
  
          LOGGER.debug("Running script %s", rerun_data)
  
          # Reset DeltaGenerators, widgets, media files.
          in_memory_file_manager.clear_session_files()
  
          ctx = get_report_ctx()
          if ctx is None:
              # This should never be possible on the script_runner thread.
              raise RuntimeError(
                  "ScriptRunner thread has a null ReportContext. Something has gone very wrong!"
              )
  
          ctx.reset(query_string=rerun_data.query_string)
  
          self.on_event.send(ScriptRunnerEvent.SCRIPT_STARTED)
  
          # Compile the script. Any errors thrown here will be surfaced
          # to the user via a modal dialog in the frontend, and won't result
          # in their previous report disappearing.
  
          try:
              with source_util.open_python_file(self._report.script_path) as f:
                  filebody = f.read()
  
              if config.get_option("runner.magicEnabled"):
                  filebody = magic.add_magic(filebody, self._report.script_path)
  
              code = compile(
                  filebody,
                  # Pass in the file path so it can show up in exceptions.
                  self._report.script_path,
                  # We're compiling entire blocks of Python, so we need "exec"
                  # mode (as opposed to "eval" or "single").
                  mode="exec",
                  # Don't inherit any flags or "future" statements.
                  flags=0,
                  dont_inherit=1,
                  # Use the default optimization options.
                  optimize=-1,
              )
  
          except BaseException as e:
              # We got a compile error. Send an error event and bail immediately.
              LOGGER.debug("Fatal script error: %s" % e)
              self._session_state[SCRIPT_RUN_WITHOUT_ERRORS_KEY] = False
              self.on_event.send(
                  ScriptRunnerEvent.SCRIPT_STOPPED_WITH_COMPILE_ERROR, exception=e
              )
              return
  
          # If we get here, we've successfully compiled our script. The next step
          # is to run it. Errors thrown during execution will be shown to the
          # user as ExceptionElements.
  
          if config.get_option("runner.installTracer"):
              self._install_tracer()
  
          # This will be set to a RerunData instance if our execution
          # is interrupted by a RerunException.
          rerun_with_data = None
  
          try:
              # Create fake module. This gives us a name global namespace to
              # execute the code in.
              module = _new_module("__main__")
  
              # Install the fake module as the __main__ module. This allows
              # the pickle module to work inside the user's code, since it now
              # can know the module where the pickled objects stem from.
              # IMPORTANT: This means we can't use "if __name__ == '__main__'" in
              # our code, as it will point to the wrong module!!!
              sys.modules["__main__"] = module
  
              # Add special variables to the module's globals dict.
              # Note: The following is a requirement for the CodeHasher to
              # work correctly. The CodeHasher is scoped to
              # files contained in the directory of __main__.__file__, which we
              # assume is the main script directory.
              module.__dict__["__file__"] = self._report.script_path
  
              with modified_sys_path(self._report), self._set_execing_flag():
                  # Run callbacks for widgets whose values have changed.
                  if rerun_data.widget_states is not None:
                      # Update the WidgetManager with the new widget_states.
                      # The old states, used to skip callbacks if values
                      # haven't changed, are also preserved in the
                      # WidgetManager.
                      self._session_state.compact_state()
                      self._session_state.set_widgets_from_proto(rerun_data.widget_states)
  
                      self._session_state.call_callbacks()
  
                  ctx.on_script_start()
                  exec(code, module.__dict__)
                  self._session_state[SCRIPT_RUN_WITHOUT_ERRORS_KEY] = True
          except RerunException as e:
              rerun_with_data = e.rerun_data
  
          except StopException:
              pass
  
          except BaseException as e:
              self._session_state[SCRIPT_RUN_WITHOUT_ERRORS_KEY] = False
              handle_uncaught_app_exception(e)
  
          finally:
              self._on_script_finished(ctx)
  
          # Use _log_if_error() to make sure we never ever ever stop running the
          # script without meaning to.
          _log_if_error(_clean_problem_modules)
  
          if rerun_with_data is not None:
              self._run_script(rerun_with_data)
  
      def _on_script_finished(self, ctx: ReportContext) -> None:
          """Called when our script finishes executing, even if it finished
          early with an exception. We perform post-run cleanup here.
          """
          self._session_state.reset_triggers()
          self._session_state.cull_nonexistent(ctx.widget_ids_this_run.items())
          # Signal that the script has finished. (We use SCRIPT_STOPPED_WITH_SUCCESS
          # even if we were stopped with an exception.)
          self.on_event.send(ScriptRunnerEvent.SCRIPT_STOPPED_WITH_SUCCESS)
          # Delete expired files now that the script has run and files in use
          # are marked as active.
          in_memory_file_manager.del_expired_files()
  
          # Force garbage collection to run, to help avoid memory use building up
          # This is usually not an issue, but sometimes GC takes time to kick in and
          # causes apps to go over resource limits, and forcing it to run between
          # script runs is low cost, since we aren't doing much work anyway.
          if config.get_option("runner.postScriptGC"):
              gc.collect(2)
  
  
  class ScriptControlException(BaseException):
      """Base exception for ScriptRunner."""
  
      pass
  
  
  class StopException(ScriptControlException):
      """Silently stop the execution of the user's script."""
  
      pass
  
  
  class RerunException(ScriptControlException):
      """Silently stop and rerun the user's script."""
  
      def __init__(self, rerun_data):
          """Construct a RerunException
  
          Parameters
          ----------
          rerun_data : RerunData
              The RerunData that should be used to rerun the report
          """
          self.rerun_data = rerun_data
  
      def __repr__(self) -> str:
          return util.repr_(self)
  
  
  def _clean_problem_modules():
      """Some modules are stateful, so we have to clear their state."""
  
      if "keras" in sys.modules:
          try:
              keras = sys.modules["keras"]
              keras.backend.clear_session()  # type: ignore[attr-defined]
          except:
              pass
  
      if "matplotlib.pyplot" in sys.modules:
          try:
              plt = sys.modules["matplotlib.pyplot"]
              plt.close("all")  # type: ignore[attr-defined]
          except:
              pass
  
  
  def _new_module(name):
      """Create a new module with the given name."""
  
      import types
  
      return types.ModuleType(name)
  
  
  # Code modified from IPython (BSD license)
  # Source: https://github.com/ipython/ipython/blob/master/IPython/utils/syspathcontext.py#L42
  class modified_sys_path(object):
      """A context for prepending a directory to sys.path for a second."""
  
      def __init__(self, report):
          self._report = report
          self._added_path = False
  
      def __repr__(self) -> str:
          return util.repr_(self)
  
      def __enter__(self):
          if self._report.script_path not in sys.path:
              sys.path.insert(0, self._report.script_path)
              self._added_path = True
  
      def __exit__(self, type, value, traceback):
          if self._added_path:
              try:
                  sys.path.remove(self._report.script_path)
              except ValueError:
                  pass
  
          # Returning False causes any exceptions to be re-raised.
          return False
  
  
  # The reason this is not a decorator is because we want to make it clear at the
  # calling location that this function is being used.
  def _log_if_error(fn):
      try:
          fn()
      except Exception as e:
          LOGGER.warning(e)
  