add memory module

examples/config.test.json

@@ -12,6 +12,11 @@
             "type":"load",
             "freq":"30",
             "args":{}
+        },
+        {
+            "type":"meminfo",
+            "freq":"30",
+            "args":{}
         }
     ]
 }

pymonitor/monitors/meminfo.py

@@ -0,0 +1,63 @@
+import re
+
+memline_pattern = re.compile(r'^(?P<key>[^\\:]+)\:\s+(?P<value>[0-9]+)(\s(?P<unit>[a-zA-Z]+))?')
+
+computed_fields = {
+    "mempctused": lambda items: round((items["memtotal"]-items["memfree"])/items["memtotal"], 2),
+    "mempctfree": lambda items: 1-round((items["memtotal"]-items["memfree"])/items["memtotal"], 2),
+    "swappctused": lambda items: round((items["swaptotal"]-items["swapfree"])/items["swaptotal"], 2),
+    "swappctfree": lambda items: 1-round((items["swaptotal"]-items["swapfree"])/items["swaptotal"], 2)
+}
+
+def meminfo(whitelist=[]):
+    if not whitelist:
+        whitelist = ["swaptotal", "swapfree", "swapcached", 
+                     "memtotal",  "memfree",  "memavailable", "cached", 
+                     "active", "inactive", ]
+        
+    result = {}
+    with open("/proc/meminfo", "r") as f:
+        for line in f.read().strip().split("\n"):
+            matches = memline_pattern.match(line)
+            
+            value = int(matches.group("value"))
+            unit = matches.group("unit")
+            
+            if unit:
+                if unit == "kB":
+                    value*=1024
+                else:
+                    raise Exception("Unknown unit")
+            
+            name = ''.join(c for c in matches.group("key").lower() if 96<ord(c)<123)
+            if name in whitelist:
+                result[name] = value
+            
+        for key in computed_fields:
+            result[key] = computed_fields[key](result)
+    
+    return result
+
+mapping = {
+    "load": {
+        "properties": {
+            "swaptotal":    { "type": "long" },
+            "swapfree":     { "type": "long" },
+            "swapcached":   { "type": "long" },
+            "memtotal":     { "type": "long" },
+            "memfree":      { "type": "long" },
+            "memavailable": { "type": "long" },
+            "cached":       { "type": "long" },
+            "active":       { "type": "long" },
+            "inactive":     { "type": "long" },
+            "mempctused":   { "type": "double" },
+            "mempctfree":   { "type": "double" },
+            "swappctused":  { "type": "double" },
+            "swappctfree":  { "type": "double" }
+        }
+    }
+}
+
+if __name__ == '__main__':
+    for k,v in meminfo().items():
+        print("%s: %s"%(k,v))