Move file to final location on close (#39)

* move file to final location on close

* fix for read mode

* change modes

Author: rahul003

tornasole_core/access_layer/file.py

@@ -1,18 +1,29 @@
 from .base import TSAccessBase
 import os
+import shutil
 
 def ensure_dir(file_path):
     directory = os.path.dirname(file_path)
     if directory and not os.path.exists(directory):
         os.makedirs(directory)
 
+
+WRITE_MODES = ['w', 'w+', 'wb', 'wb+', 'a', 'a+', 'ab', 'ab+']
+
+
 class TSAccessFile(TSAccessBase):
     def __init__(self, path, mode):
         super().__init__()
         self.path = path
         self.mode = mode
         ensure_dir(path)
-        self.open(path, mode)
+
+        if mode in WRITE_MODES:
+            self.temp_path = os.path.join('/tmp', self.path)
+            ensure_dir(self.temp_path)
+            self.open(self.temp_path, mode)
+        else:
+            self.open(self.path, mode)
 
     def open(self, path, mode):
         self._accessor = open(path, mode)
@@ -28,13 +39,14 @@ def flush(self):
 
     def close(self):
         self._accessor.close()
+        if self.mode in WRITE_MODES:
+            shutil.move(self.temp_path, self.path)
 
     def ingest_all(self):
         self._data = self._accessor.read()
         self._datalen = len(self._data)
         self._position = 0
 
-
     def read(self, n):
         assert self._position + n <= self._datalen
         res = self._data[self._position:self._position + n]