From 7b4126b7c774531c8a40e291e66286ec61586fe1 Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Tue, 1 Jul 2008 11:44:37 +0000
Subject: [PATCH] Add a FirstFree function to utils.py
This function will return the first unused integer based on a list of
used integers (e.g. [0, 1, 3] will return 2).
Reviewed-by: imsnah
---
lib/utils.py | 21 +++++++++++++++++++++
test/ganeti.utils_unittest.py | 12 +++++++++++-
2 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/lib/utils.py b/lib/utils.py
index 4e8cfe7e7..ade6b9b54 100644
--- a/lib/utils.py
+++ b/lib/utils.py
@@ -1039,6 +1039,27 @@ def WriteFile(file_name, fn=None, data=None,
return result
+def FirstFree(seq, base=0):
+ """Returns the first non-existing integer from seq.
+
+ The seq argument should be a sorted list of positive integers. The
+ first time the index of an element is smaller than the element
+ value, the index will be returned.
+
+ The base argument is used to start at a different offset,
+ i.e. [3, 4, 6] with offset=3 will return 5.
+
+ Example: [0, 1, 3] will return 2.
+
+ """
+ for idx, elem in enumerate(seq):
+ assert elem >= base, "Passed element is higher than base offset"
+ if elem > idx + base:
+ # idx is not used
+ return idx + base
+ return None
+
+
def all(seq, pred=bool):
"Returns True if pred(x) is True for every element in the iterable"
for elem in itertools.ifilterfalse(pred, seq):
diff --git a/test/ganeti.utils_unittest.py b/test/ganeti.utils_unittest.py
index c5f8cfda6..1d9bd2f1a 100755
--- a/test/ganeti.utils_unittest.py
+++ b/test/ganeti.utils_unittest.py
@@ -41,7 +41,7 @@ from ganeti.utils import IsProcessAlive, Lock, Unlock, RunCmd, \
RemoveFile, CheckDict, MatchNameComponent, FormatUnit, \
ParseUnit, AddAuthorizedKey, RemoveAuthorizedKey, \
ShellQuote, ShellQuoteArgs, TcpPing, ListVisibleFiles, \
- SetEtcHostsEntry, RemoveEtcHostsEntry
+ SetEtcHostsEntry, RemoveEtcHostsEntry, FirstFree
from ganeti.errors import LockError, UnitParseError
def _ChildHandler(signal, stack):
@@ -689,6 +689,16 @@ class TestUniqueSequence(unittest.TestCase):
self._test(["a", "b"], ["a", "b"])
self._test(["a", "b", "a"], ["a", "b"])
+class TestFirstFree(unittest.TestCase):
+ """Test case for the FirstFree function"""
+
+ def test(self):
+ """Test FirstFree"""
+ self.failUnlessEqual(FirstFree([0, 1, 3]), 2)
+ self.failUnlessEqual(FirstFree([]), None)
+ self.failUnlessEqual(FirstFree([3, 4, 6]), 0)
+ self.failUnlessEqual(FirstFree([3, 4, 6], base=3), 5)
+ self.failUnlessRaises(AssertionError, FirstFree, [0, 3, 4, 6], base=3)
if __name__ == '__main__':
unittest.main()
--
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