Improved mysql plugin

shows global variables
	shows slave statuses
	shows size and count of binary log files
	shows information_schema.processlist stats
	shows perf table stats
	shows auto increments stats from information schema
	shows perf index stats
	shows table lock waits summary by table
	shows time and operations of event waits
	shows file event statuses
	shows events statements stats from perf_schema
	shows schema statistics
	refactored plugin, provided multiple fields per insert

plugins/inputs/mysql/mysql_test.go

@@ -1,6 +1,7 @@
 package mysql
 
 import (
+	"database/sql"
 	"fmt"
 	"testing"
 
@@ -115,3 +116,47 @@ func TestMysqlDNSAddTimeout(t *testing.T) {
 		}
 	}
 }
+
+func TestParseValue(t *testing.T) {
+	testCases := []struct {
+		rawByte   sql.RawBytes
+		value     float64
+		boolValue bool
+	}{
+		{sql.RawBytes("Yes"), 1, true},
+		{sql.RawBytes("No"), 0, false},
+		{sql.RawBytes("ON"), 1, true},
+		{sql.RawBytes("OFF"), 0, false},
+		{sql.RawBytes("ABC"), 0, false},
+	}
+	for _, cases := range testCases {
+		if value, ok := parseValue(cases.rawByte); value != cases.value && ok != cases.boolValue {
+			t.Errorf("want %d with %t, got %d with %t", int(cases.value), cases.boolValue, int(value), ok)
+		}
+	}
+}
+
+func TestNewNamespace(t *testing.T) {
+	testCases := []struct {
+		words     []string
+		namespace string
+	}{
+		{
+			[]string{"thread", "info_scheme", "query update"},
+			"thread_info_scheme_query_update",
+		},
+		{
+			[]string{"thread", "info_scheme", "query_update"},
+			"thread_info_scheme_query_update",
+		},
+		{
+			[]string{"thread", "info", "scheme", "query", "update"},
+			"thread_info_scheme_query_update",
+		},
+	}
+	for _, cases := range testCases {
+		if got := newNamespace(cases.words...); got != cases.namespace {
+			t.Errorf("want %s, got %s", cases.namespace, got)
+		}
+	}
+}