Adding example to parse memory usage

examples/example_memory_usage.py

@@ -0,0 +1,61 @@
+"""Parses the output of "free -c 10 -s 1" """
+
+import parsley
+import subprocess
+
+
+def parse_memory_file(payload):
+    """Create a grammar that can parse the output of 'free' when called
+    with the -c option.
+    Return the results as a list of dictionaries of dictionaries """
+
+    memory_grammar = r"""
+        memory_reports = memory_report*
+
+        memory_report = headers_line mem_line:m buffers_line:b swap_line:s '\n'
+                        -> dict(zip(['memory', 'buffers', 'swap'], [m, b, s]))
+
+        headers_line = ws 'total' ws 'used' ws 'free' ws 'shared' ws
+                       'buffers' ws 'cached' '\n'
+
+        mem_line = 'Mem:' ws total:t ws used:u ws free:f ws shared:s ws
+                   buffers:b ws cached:c '\n' -> dict([t, u, f, s, b, c])
+
+        buffers_line = '-/+ buffers/cache:' ws used:u ws free:f '\n'
+                       -> dict([u, f])
+
+        swap_line = 'Swap:' ws total:t ws used:u ws free:f '\n'
+                       -> dict([t, u, f])
+
+        num = <digit+>
+        total = num:n -> ('total', n)
+        used = num:n -> ('used', n)
+        free = num:n -> ('free', n)
+        shared = num:n -> ('shared', n)
+        buffers = num:n -> ('buffers', n)
+        cached = num:n -> ('cached', n)
+        """
+
+    memory_parser = parsley.makeGrammar(memory_grammar, {})
+    memory_reports = memory_parser(payload).memory_reports()
+    return memory_reports
+
+
+def get_memory_usage():
+    """ Call free and save the output to a file"""
+    with open('memory_usage.txt', 'w') as memory_file:
+        p = subprocess.Popen(['free', '-c', '5', '-s', '1'],
+                             stdin=subprocess.PIPE,
+                             stdout=memory_file,
+                             stderr=memory_file)
+        p.communicate()
+
+if __name__ == '__main__':
+    get_memory_usage()
+    with open('memory_usage.txt', 'r') as memory_file:
+        memory_reports = parse_memory_file(memory_file.read())
+
+    for memory_report in memory_reports:
+        print memory_report['memory']['free']
+        print memory_report['memory']['used']
+        print memory_report['swap']['used']