Better handling temporary files for running at scale (#1026)

* moved temporary files to default (os dependent) temp dir, added removal of temp files at termination when using .net.xml file path

* flake8 fix

flow/core/kernel/network/traci.py

@@ -1,4 +1,5 @@
 """Script containing the TraCI network kernel class."""
+import tempfile
 
 from flow.core.kernel.network import BaseKernelNetwork
 from flow.core.util import makexml, printxml, ensure_dir
@@ -54,10 +55,8 @@ def __init__(self, master_kernel, sim_params):
 
         # directories for the network-specific files that will be generated by
         # the `generate_network` method
-        self.net_path = os.path.dirname(os.path.abspath(__file__)) \
-            + '/debug/net/'
-        self.cfg_path = os.path.dirname(os.path.abspath(__file__)) \
-            + '/debug/cfg/'
+        self.net_path = os.path.join(tempfile.gettempdir(), 'flow/debug/net/')
+        self.cfg_path = os.path.join(tempfile.gettempdir(), 'flow/debug/cfg/')
 
         ensure_dir('%s' % self.net_path)
         ensure_dir('%s' % self.cfg_path)
@@ -221,31 +220,28 @@ def close(self):
         is to prevent them from building up in the debug folder. Note that in
         the case of import .net.xml files we do not want to delete them.
         """
+        # Those files are being created even if self.network.net_params.template is a path to .net.xml file
+        files = [self.cfg_path + self.guifn,
+                 self.cfg_path + self.addfn,
+                 self.cfg_path + self.roufn,
+                 self.cfg_path + self.sumfn]
+
         if self.network.net_params.template is None:
+            files += [self.net_path + self.nodfn,
+                      self.net_path + self.edgfn,
+                      self.net_path + self.cfgfn,
+                      self.net_path + self.confn,
+                      self.net_path + self.typfn,
+                      self.cfg_path + self.netfn]
+
+        for file in files:
             try:
-                os.remove(self.net_path + self.nodfn)
-                os.remove(self.net_path + self.edgfn)
-                os.remove(self.net_path + self.cfgfn)
-                os.remove(self.cfg_path + self.addfn)
-                os.remove(self.cfg_path + self.guifn)
-                os.remove(self.cfg_path + self.netfn)
-                os.remove(self.cfg_path + self.roufn)
-                os.remove(self.cfg_path + self.sumfn)
-            except FileNotFoundError:
+                os.remove(file)
+            except (FileNotFoundError, OSError):
                 # the files were never created
-                pass
-
-            # the connection file is not always created
-            try:
-                os.remove(self.net_path + self.confn)
-            except OSError:
-                pass
-
-            # neither is the type file
-            try:
-                os.remove(self.net_path + self.typfn)
-            except OSError:
-                pass
+                # the connection file is not always created
+                # neither is the type file
+                continue
 
     def get_edge(self, x):
         """See parent class."""