updated the script to make use of command line arguments

g1gc scanner script can be generic and can be used for more applications
with wrapper tcollectors for each of them.
for eg: hbase regionserver and hadoop datanode on the same node

TESTS: tested on a local installation of tcollectors

collectors/0/g1gc.py

@@ -12,6 +12,7 @@
 # of the GNU Lesser General Public License along with this program.  If not,
 # see <http://www.gnu.org/licenses/>.
 #
+
 # To better understand G1 GC log,
 # please read Understanding G1 GC Logs (https://blogs.oracle.com/poonam/entry/understanding_g1_gc_logs)
 
@@ -59,6 +60,11 @@
   gc.g1.duration phase=mixed-pause     g1 mixed pause time (STW)
   gc.g1.duration phase=remark          g1 remark time (STW)
 
+
+Invoke this script with command line arguments
+eg: for hadoop hdfs namenode with g1gc enabled
+g1gc.py --prefix 'hadoop.namenode' --log_dir '/var/logs/hadoop/hdfs' --interval 10 --log_name_pattern 'gc-namenode.log.*'
+
 """
 
 import calendar
@@ -68,12 +74,13 @@
 import sys
 import time
 import traceback
+import argparse
+
+sys.path.append('/usr/local/tcollector')
 
 from datetime import datetime, timedelta
 from subprocess import Popen, PIPE
-
 from collectors.lib import utils
-from collectors.etc import g1gc_conf
 
 GC_START_TIME_PATTERN = 1
 PARALLEL_TIME_PATTERN = 2
@@ -129,6 +136,7 @@
 }
 
 # Utilities
+
 def get_file_end(file_handler):
     file_handler.seek(0, 2)
     return file_handler.tell()
@@ -356,7 +364,6 @@ def process_gc_log(collector):
             pos = collector['current_file_pos']
             collector['current_file_pos'] = get_file_end(file_handler)
             file_handler.seek(pos)
-
             # Do not use foreach loop because inside function process_gc_record
             # will call file_handler.readline(). The reason is that some GC
             # event are multiline and need to be processed as a whole
@@ -390,10 +397,26 @@ def process_gc_log(collector):
 
     return 0
 
+
+def _create_parser():
+    """Creates parser for g1gc scanner."""
+    parser = argparse.ArgumentParser(
+        description='G1GC log scanner')
+    parser.add_argument('--prefix', default='hadoop.namenode',
+        help='Prefix for the metrics')
+    parser.add_argument('--log_dir', default='/srv/var/hadoop/logs/hdfs',
+        help='Path to directory where the gc logs are')
+    parser.add_argument('--log_name_pattern', default='gc-namenode.log.*',
+        help='Regular expression pattern for the gc logs')
+    parser.add_argument('--interval', type=float, default=10,
+        help='Default interval to run the script and sleep')
+    return parser
+
 def main():
 
-    interval = g1gc_conf.get_interval()
-    config = g1gc_conf.get_gc_config()
+    parser = _create_parser()
+    arguments = parser.parse_args()
+
     counters = {'young': 0, 'mixed': 0, 'initialmark': 0,
                 'remark': 0, 'fullgc': 0}
     gensize = {'eden': 0, 'survivor': 0, 'heap': 0}
@@ -403,14 +426,15 @@ def main():
                  'gensize': gensize,
                  'current_file': None,
                  'current_file_pos': None,
-                 'prefix': config['prefix'],
-                 'log_dir': config['log_dir'],
-                 'log_name_pattern': config['log_name_pattern']}
+                 'prefix': arguments.prefix,
+                 'log_dir': arguments.log_dir,
+                 'log_name_pattern': arguments.log_name_pattern
+    }
 
     while True:
         process_gc_log(collector)
         sys.stdout.flush()
-        time.sleep(interval)
+        time.sleep(arguments.interval)
 
 if __name__ == '__main__':
     exit(main())