Initial commit

[ta/config-manager.git] / cmframework / src / cmframework / utils / cmtopologicalsort.py

diff --git a/cmframework/src/cmframework/utils/cmtopologicalsort.py b/cmframework/src/cmframework/utils/cmtopologicalsort.py
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+++ b/cmframework/src/cmframework/utils/cmtopologicalsort.py
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+# Copyright 2019 Nokia
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import print_function
+from cmframework.apis import cmerror
+
+
+class TopSort(object):
+    """
+    This class implements a topological sort algorithm.
+
+    It expects a dependency graph as an input and returns a sorted list as an
+    output. The returned list contains lists sorted accordingly to the dependency
+    graph:
+
+    Usage Example:
+        # The following graph indicates that 2 depends on 11, 9 depends on 11,8,10 and so on...
+        graph = {2: [11],
+                 9: [11, 8, 10],
+                10: [11, 3],
+                11: [7, 5],
+                8: [7, 3]}
+
+        sort = TopSort(graph)
+        try:
+            sorted = sort.sort()
+            for entry in sorted:
+                print('%r' % entry)
+        except cmerror.CMError as exp:
+           print('Got exception %s' % str(exp))
+
+    The above example will generate the following output:
+    [3, 5, 7]
+    [8, 11]
+    [2, 10]
+    [9]
+    """
+
+    def __init__(self, graph):
+        self.graph = graph
+        self.output = {}
+        self.recursionlevel = 0
+
+    def _get_dependent_entries(self, entry):
+        result = []
+        for e, deps in self.graph.iteritems():
+            if entry in deps:
+                result.append(e)
+        return result
+
+    def _update_dependent_entries(self, entry):
+        maximumrecursion = (len(self.graph)) * (len(self.graph))
+        if (self.recursionlevel + 1) >= maximumrecursion:
+            raise cmerror.CMError('cyclic dependency detected, graph %r' % self.graph)
+        self.recursionlevel += 1
+        dependententries = self._get_dependent_entries(entry)
+        entrydepth = self.output[entry]
+        for e in dependententries:
+            if e in self.output:
+                if entrydepth >= self.output[e]:
+                    self.output[e] = entrydepth + 1
+                    self._update_dependent_entries(e)
+
+    def sort(self):
+        for entry, deps in self.graph.iteritems():
+            depth = 0
+            if entry in self.output:
+                depth = self.output[entry]
+
+            # calculate new depth according to dependencies
+            newdepth = depth
+            for dep in deps:
+                if dep in self.output:
+                    weight = self.output[dep]
+                else:
+                    weight = 0
+                    self.output[dep] = 0
+                if weight >= newdepth:
+                    newdepth = weight + 1
+
+            # if our depth is changed we need to update the entries depending on us
+            self.output[entry] = newdepth
+            if newdepth > depth and entry in self.output:
+                self.recursionlevel = 0
+                self._update_dependent_entries(entry)
+
+        return self._getsorted()
+
+    def _getsorted(self):
+        import operator
+        sortedoutput = sorted(self.output.items(), key=operator.itemgetter(1))
+        result = {}
+        for entry in sortedoutput:
+            if entry[1] not in result:
+                result[entry[1]] = []
+            result[entry[1]].append(entry[0])
+
+        returned = []
+        for entry, data in result.iteritems():
+            returned.append(data)
+
+        return returned
+
+
+def main():
+    graph1 = {2: [11],
+              9: [11, 8, 10],
+              10: [11, 3],
+              11: [7, 5],
+              8: [7, 3]}
+
+    graph2 = {'playbook2.yaml': [], 'playbook1.yaml': ['playbook2.yaml']}
+
+    topsort1 = TopSort(graph1)
+    topsort2 = TopSort(graph2)
+
+    try:
+        print(graph1)
+        sortedlists1 = topsort1.sort()
+        for entry in sortedlists1:
+            print('%r' % entry)
+
+        print(graph2)
+        sortedlists2 = topsort2.sort()
+        for entry in sortedlists2:
+            print('%r' % entry)
+    except cmerror.CMError as exp:
+        print(str(exp))
+
+
+if __name__ == '__main__':
+    main()