tuna: Improve sysfs.py

Improve sysfs.py

- Add docstring comments to classes and functions
- Make the code more readable by using os.path.join on file components
- Initialize class variables in the __init__ when possible
- Use "with" for opening files where possible
- add __repr__ to classes for debugging purposes
- Specify the type of exception where possible (replace bare exceptions)
- Replace old style has_key with __contains__

Signed-off-by: John Kacur <jkacur@redhat.com>

1 files changed, 37 insertions, 11 deletions

diff --git a/tuna/sysfs.py b/tuna/sysfs.py
index bce96af..1c903e1 100755
--- a/tuna/sysfs.py
+++ b/tuna/sysfs.py
@@ -1,38 +1,54 @@
 # -*- python -*-
 # -*- coding: utf-8 -*-
+"""
+classes for /sys/devices/system/cpu/
+so we can get topology information and do CPU hotplug operations
+"""
 
 import os
 
+
 class cpu:
+    """
+    class to query if a cpu is online or not
+    and to bring a cpu online or to take it offline
+    """
+
     def __init__(self, basedir, name):
         self.name = name
-        self.dir = "%s/%s" % (basedir, name)
+        self.dir = os.path.join(basedir, name)
+        self.online = None
         self.reload()
 
     def __lt__(self, other):
         # Previously it is assumed that name[:3] == "cpu" and name[3].isdigit(), so:
-        int(self.name[3:]) < int(other.name[3:])
+        return int(self.name[3:]) < int(other.name[3:])
 
     def readfile(self, name):
+        """ read file "name", typically the per cpu "online" file """
         try:
-            f = open("%s/%s" % (self.dir, name))
-            value = f.readline().strip()
-            f.close()
+            with open(os.path.join(self.dir, name)) as f:
+                value = f.readline().strip()
+                return value
         except:
             raise
-        return value
+
+    def __repr__(self):
+        return f'name={self.name}, online={self.online}, physical_package_id={self.physical_package_id}'
 
     def reload_online(self):
+        """ read the "online" file """
         self.online = True
         try:
             self.online = self.readfile("online") == "1"
-        except:
+        except FileNotFoundError:
             # boot CPU, usually cpu0, can't be brought offline, so
             # lacks the file and non root users can't read. In both
             # cases assume CPU is online.
             pass
 
     def reload(self):
+        """ Load or reload the values of this class """
         self.reload_online()
         if self.online:
             try:
@@ -43,17 +59,20 @@ class cpu:
             self.physical_package_id = None
 
     def set_online(self, online=True):
+        """ Turn a cpu on or off using the online file """
         try:
-            f = open("%s/online" % self.dir, "w")
-            f.write("%d\n" % (online and 1 or 0))
-            f.close()
+            with open(os.path.join(self.dir, "online"), "w") as f:
+                f.write("1" if online else "0")
         except:
             pass
 
         self.reload_online()
         return online == self.online
 
+
 class cpus:
+    """ a class that creates a dictionary of cpu information keyed by cpu  """
+
     def __init__(self, basedir="/sys/devices/system/cpu"):
         self.basedir = basedir
         self.cpus = {}
@@ -65,12 +84,17 @@ class cpus:
         return self.cpus[key]
 
     def keys(self):
+        """ Returns a list of keys, for example a key could be cpu9 """
         return list(self.cpus.keys())
 
-    def has_key(self, key):
+    def __contains__(self, key):
         return key in self.cpus
 
+    def __repr__(self):
+        return f'cpus={self.cpus}, sockets={self.sockets}, nr_cpus={self.nr_cpus}'
+
     def reload(self):
+        """ load or reload the values of this class """
         sockets_to_sort = []
         for name in os.listdir(self.basedir):
             if name[:3] != "cpu" or not name[3].isdigit():
@@ -96,9 +120,11 @@ class cpus:
         for socket in sockets_to_sort:
             self.sockets[socket].sort(key=lambda x: int(x.name[3:]))
 
+
 if __name__ == '__main__':
 
     cpus = cpus()
+    print(f'{cpus}')
 
     for socket in list(cpus.sockets.keys()):
         print("Socket %s" % socket)