Merge pull request #28 from solomiya-hatalyak/background-progress-emi…

…tter

[DS-2172] create async progress reporting

.travis.yml

@@ -13,4 +13,4 @@ install:
 script:
     - coverage run --source=. test.py
     - coverage report -m
-    - pycodestyle --format=pylint --count .
+    - pycodestyle --format=pylint --max-line-length=120 --count .

panoply/constants.py

@@ -1,2 +1,2 @@
-__version__ = "2.0.3"
+__version__ = "2.0.4"
 __package_name__ = "panoply-python-sdk"

panoply/datasource.py

@@ -1,9 +1,13 @@
 import base64
+import traceback
+from concurrent.futures import ThreadPoolExecutor
+from functools import wraps
+from threading import Event
 
 import backoff
-from . import events
 import requests
-import traceback
+
+from . import events
 from .errors import PanoplyException
 
 
@@ -143,3 +147,40 @@ def wrapper(*args):
                 return f(*args)
         return wrapper
     return _validate_token
+
+
+def background_progress(message, waiting_interval=10*60):
+    """ A decorator is used to emit progress while long operation is executed.
+        For example, for database's data sources such operations might be
+        declaration of the cursor or counting number of rows.
+        This decorator should only be used on methods that are waiting for
+        input/output operations to be completed.
+
+       Parameters
+       ----------
+       message : str
+           Message that will be emitted while waiting for operation to complete.
+       waiting_interval : float
+           Time in seconds to wait between progress emitting.
+           Defaults to 10 minutes
+    """
+    def _background_progress(func):
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            self = args[0]
+            self.log('Creating background progress emitter')
+            finished = Event()
+            with ThreadPoolExecutor(max_workers=1) as executor:
+                func_future = executor.submit(func, *args, **kwargs)
+                func_future.add_done_callback(lambda future: finished.set())
+
+                while not func_future.done():
+                    self.log(message)
+                    self.progress(None, None, message)
+                    finished.wait(timeout=waiting_interval)
+
+                return func_future.result()
+
+        return wrapper
+
+    return _background_progress