Move parallel_execute to a new module.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

compose/utils.py

@@ -2,107 +2,13 @@ import codecs
 import hashlib
 import json
 import json.decoder
-import logging
-import sys
-from threading import Thread
 
 import six
-from docker.errors import APIError
-from six.moves.queue import Empty
-from six.moves.queue import Queue
 
 
-log = logging.getLogger(__name__)
-
 json_decoder = json.JSONDecoder()
 
 
-def perform_operation(func, arg, callback, index):
-    try:
-        callback((index, func(arg)))
-    except Exception as e:
-        callback((index, e))
-
-
-def parallel_execute(objects, func, index_func, msg):
-    """For a given list of objects, call the callable passing in the first
-    object we give it.
-    """
-    objects = list(objects)
-    stream = get_output_stream(sys.stdout)
-    writer = ParallelStreamWriter(stream, msg)
-
-    for obj in objects:
-        writer.initialize(index_func(obj))
-
-    q = Queue()
-
-    # TODO: limit the number of threads #1828
-    for obj in objects:
-        t = Thread(
-            target=perform_operation,
-            args=(func, obj, q.put, index_func(obj)))
-        t.daemon = True
-        t.start()
-
-    done = 0
-    errors = {}
-
-    while done < len(objects):
-        try:
-            msg_index, result = q.get(timeout=1)
-        except Empty:
-            continue
-
-        if isinstance(result, APIError):
-            errors[msg_index] = "error", result.explanation
-            writer.write(msg_index, 'error')
-        elif isinstance(result, Exception):
-            errors[msg_index] = "unexpected_exception", result
-        else:
-            writer.write(msg_index, 'done')
-        done += 1
-
-    if not errors:
-        return
-
-    stream.write("\n")
-    for msg_index, (result, error) in errors.items():
-        stream.write("ERROR: for {}  {} \n".format(msg_index, error))
-        if result == 'unexpected_exception':
-            raise error
-
-
-class ParallelStreamWriter(object):
-    """Write out messages for operations happening in parallel.
-
-    Each operation has it's own line, and ANSI code characters are used
-    to jump to the correct line, and write over the line.
-    """
-
-    def __init__(self, stream, msg):
-        self.stream = stream
-        self.msg = msg
-        self.lines = []
-
-    def initialize(self, obj_index):
-        self.lines.append(obj_index)
-        self.stream.write("{} {} ... \r\n".format(self.msg, obj_index))
-        self.stream.flush()
-
-    def write(self, obj_index, status):
-        position = self.lines.index(obj_index)
-        diff = len(self.lines) - position
-        # move up
-        self.stream.write("%c[%dA" % (27, diff))
-        # erase
-        self.stream.write("%c[2K\r" % 27)
-        self.stream.write("{} {} ... {}\r".format(self.msg, obj_index, status))
-        # move back down
-        self.stream.write("%c[%dB" % (27, diff))
-        self.stream.flush()
-
-
 def get_output_stream(stream):
     if six.PY3:
         return stream