#!/srv/newsblur/venv/newsblur/bin/python
# -*- coding: utf-8 -*-

"""
Based on a plugin by BjØrn Ruberg.

Plugin to monitor PostgreSQL commits/rollbacks.  

"Why should I care?"
- Too many commits can really bog down the database, as it checks all
the tables for consitency after each change.  
- Software is often set to 'AutoCommit = 1', meaning a commit is done
after each transaction.  This is a good idea with brittle code so that
you can get some work done if not all, but when you're inserting 10,000
rows this can really suck.
- If you see a spike in rollbacks, some db programmer is probably
abusing their session, or a stored proceudre has gone horribly wrong
and isn't leaving a trace.  Time for the rolled-up newspaper.

Find out more at 
 http://www.postgresql.org/docs/8.2/interactive/monitoring-stats.html
 (where "8.2" can be the version of PostgreSQL you have installed)
"""

from vendor.munin.postgres import MuninPostgresPlugin

class MuninPostgresCommitsPlugin(MuninPostgresPlugin):
    dbname_in_args = True
    args = "--base 1000"
    vlabel = "Sessions per ${graph_period}"
    info = "Shows number of commits and rollbacks"
    fields = (
        ('commits', dict(
            label = "commits",
            info = "SQL sessions terminated with a commit command",
            type = "DERIVE",
            min = "0",
        )),
        ('rollbacks', dict(
            label = "rollbacks",
            info = "SQL sessions terminated with a rollback command",
            type = "DERIVE",
            min = "0",
        )),
    )

    @property
    def title(self):
        return "Postgres commits/rollbacks on %s" % self.dbname

    def execute(self):
        c = self.cursor()
        c.execute("SELECT xact_commit, xact_rollback FROM pg_stat_database WHERE datname = %s", (self.dbname,))
        values = {}
        for row in c.fetchall():
            values["commits"] = row[0]
            values["rollbacks"] = row[1]
        return values

if __name__ == "__main__":
    MuninPostgresCommitsPlugin().run()