X-Git-Url: https://code.grnet.gr/git/snf-image-creator/blobdiff_plain/e77e66a923367afd618cb5d7b977095cac119b75..5a380da9c7d19260ec8c033ae8b28b2f1c647d96:/image_creator/util.py

diff --git a/image_creator/util.py b/image_creator/util.py
index 161b73d..fb0d0fa 100644
--- a/image_creator/util.py
+++ b/image_creator/util.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+#
 # Copyright 2012 GRNET S.A. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or
@@ -31,39 +33,73 @@
 # interpreted as representing official policies, either expressed
 # or implied, of GRNET S.A.
 
-import sys
-import pbs
+"""This module provides various helper functions to be used by other parts of
+the package.
+"""
+
+import sh
 import hashlib
+import time
+import os
 
 
 class FatalError(Exception):
+    """Fatal Error exception of snf-image-creator"""
     pass
 
 
 def get_command(command):
+    """Return a file system binary command"""
     def find_sbin_command(command, exception):
         search_paths = ['/usr/local/sbin', '/usr/sbin', '/sbin']
         for fullpath in map(lambda x: "%s/%s" % (x, command), search_paths):
             if os.path.exists(fullpath) and os.access(fullpath, os.X_OK):
-                return pbs.Command(fullpath)
+                return sh.Command(fullpath)
         raise exception
 
     try:
-        return pbs.__getattr__(command)
-    except pbs.CommadNotFount as e:
+        return sh.__getattr__(command)
+    except sh.CommandNotFound as e:
         return find_sbin_command(command, e)
 
 
+def try_fail_repeat(command, *args):
+    """Execute a command multiple times until it succeeds"""
+    times = (0.1, 0.5, 1, 2)
+    i = iter(times)
+    while True:
+        try:
+            command(*args)
+            return
+        except sh.ErrorReturnCode:
+            try:
+                wait = i.next()
+            except StopIteration:
+                break
+            time.sleep(wait)
+
+    raise FatalError("Command: `%s %s' failed" % (command, " ".join(args)))
+
+
+def free_space(dirname):
+    """Compute the free space in a directory"""
+    stat = os.statvfs(dirname)
+    return stat.f_bavail * stat.f_frsize
+
+
 class MD5:
+    """Represents MD5 computations"""
     def __init__(self, output):
+        """Create an MD5 instance"""
         self.out = output
 
     def compute(self, filename, size):
+        """Compute the MD5 checksum of a file"""
+        MB = 2 ** 20
+        BLOCKSIZE = 4 * MB  # 4MB
 
-        BLOCKSIZE = 2 ** 22  # 4MB
-
-        progressbar = self.out.Progress("Calculating md5sum:", 'mb')
-        progressbar.max = ((size + 2 ** 20 - 1) // (2 ** 20))
+        prog_size = ((size + MB - 1) // MB)  # in MB
+        progressbar = self.out.Progress(prog_size, "Calculating md5sum", 'mb')
         md5 = hashlib.md5()
         with open(filename, "r") as src:
             left = size
@@ -72,7 +108,7 @@ class MD5:
                 data = src.read(length)
                 md5.update(data)
                 left -= length
-                progressbar.goto((size - left) // (2 ** 20))
+                progressbar.goto((size - left) // MB)
 
         checksum = md5.hexdigest()
         progressbar.success(checksum)