Move common methods to library (#56)

* Move common methods to library

* method name should match behavior of method

Author: phumpal

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed [here](https://github.com/sensu-plugins/community/blob/master/HOW_WE_CHANGELOG.md).
 
 ## [Unreleased]
+### Added
+- Moves check_vsn and compute_lag to library method
 
 ## [2.0.0] - 2018-10-15
 ### Breaking Changes

bin/check-postgres-replication.rb

@@ -27,6 +27,7 @@
 #
 
 require 'sensu-plugins-postgres/pgpass'
+require 'sensu-plugins-postgres/pgutil'
 require 'sensu-plugin/check/cli'
 require 'pg'
 
@@ -97,18 +98,7 @@ class CheckPostgresReplicationStatus < Sensu::Plugin::Check::CLI
          description: 'Connection timeout (seconds)')
 
   include Pgpass
-
-  def compute_lag(master, slave, m_segbytes)
-    m_segment, m_offset = master.split('/')
-    s_segment, s_offset = slave.split('/')
-    ((m_segment.hex - s_segment.hex) * m_segbytes) + (m_offset.hex - s_offset.hex)
-  end
-
-  def check_vsn(conn)
-    pg_vsn = conn.exec("SELECT current_setting('server_version')").getvalue(0, 0)
-    pg_vsn = pg_vsn.split(' ')[0]
-    Gem::Version.new(pg_vsn) < Gem::Version.new('10.0') && Gem::Version.new(pg_vsn) >= Gem::Version.new('9.0')
-  end
+  include PgUtil
 
   def run
     ssl_mode = config[:ssl] ? 'require' : 'prefer'
@@ -123,7 +113,7 @@ def run
                              sslmode: ssl_mode,
                              connect_timeout: config[:timeout])
 
-    master = if check_vsn(conn_master)
+    master = if check_vsn_newer_than_postgres9(conn_master)
                conn_master.exec('SELECT pg_current_xlog_location()').getvalue(0, 0)
              else
                conn_master.exec('SELECT pg_current_wal_lsn()').getvalue(0, 0)
@@ -140,7 +130,7 @@ def run
                             sslmode: ssl_mode,
                             connect_timeout: config[:timeout])
 
-    slave = if check_vsn(conn_slave)
+    slave = if check_vsn_newer_than_postgres9(conn_slave)
               conn_slave.exec('SELECT pg_last_xlog_receive_location()').getvalue(0, 0)
             else
               conn_slave.exec('SELECT pg_last_wal_replay_lsn()').getvalue(0, 0)

lib/sensu-plugins-postgres/pgutil.rb

@@ -0,0 +1,13 @@
+module PgUtil
+  def check_vsn_newer_than_postgres9(conn)
+    pg_vsn = conn.exec("SELECT current_setting('server_version')").getvalue(0, 0)
+    pg_vsn = pg_vsn.split(' ')[0]
+    Gem::Version.new(pg_vsn) < Gem::Version.new('10.0') && Gem::Version.new(pg_vsn) >= Gem::Version.new('9.0')
+  end
+
+  def compute_lag(master, slave, m_segbytes)
+    m_segment, m_offset = master.split('/')
+    s_segment, s_offset = slave.split('/')
+    ((m_segment.hex - s_segment.hex) * m_segbytes) + (m_offset.hex - s_offset.hex)
+  end
+end