mongo: add JournalEnabled function

Utility function for detecting at runtime whether the Mongo connected to has journaling enabled.
zhatin · Jul 29, 2014 · 62c08a9 · 62c08a9
1 parent 2761ba5
commit 62c08a9
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diff --git a/mongo/mongo.go b/mongo/mongo.go
@@ -19,6 +19,7 @@ import (
 	"github.com/juju/utils"
 	"github.com/juju/utils/apt"
 	"gopkg.in/mgo.v2"
+	"gopkg.in/mgo.v2/bson"
 
 	"github.com/juju/juju/network"
 	"github.com/juju/juju/replicaset"
@@ -89,6 +90,18 @@ func IsMaster(session *mgo.Session, obj WithAddresses) (bool, error) {
 	return machinePeerAddr == masterAddr, nil
 }
 
+// JournalEnabled reports whether mongo has journaling enabled.
+func JournalEnabled(session *mgo.Session) (bool, error) {
+	var result bson.M
+	if err := session.Run("serverStatus", &result); err != nil {
+		return false, err
+	}
+	// The Journaling (dur) document is present if journaling is enabled.
+	// http://docs.mongodb.org/manual/reference/server-status/
+	_, ok := result["dur"]
+	return ok, nil
+}
+
 // SelectPeerAddress returns the address to use as the
 // mongo replica set peer address by selecting it from the given addresses.
 func SelectPeerAddress(addrs []network.Address) string {

diff --git a/mongo/mongo_test.go b/mongo/mongo_test.go
@@ -370,6 +370,27 @@ func (s *MongoSuite) TestAddPPAInQuantal(c *gc.C) {
 	}})
 }
 
+func (s *MongoSuite) TestJournalEnabledDetected(c *gc.C) {
+	s.testJournalEnabled(c, true)
+}
+
+func (s *MongoSuite) TestJournalDisabledDetected(c *gc.C) {
+	s.testJournalEnabled(c, false)
+}
+
+func (s *MongoSuite) testJournalEnabled(c *gc.C, enabled bool) {
+	inst := &testing.MgoInstance{EnableJournal: enabled}
+	err := inst.Start(coretesting.Certs)
+	c.Assert(err, gc.IsNil)
+	defer inst.DestroyWithLog()
+	session, err := inst.Dial()
+	c.Assert(err, gc.IsNil)
+	defer session.Close()
+	isEnabled, err := mongo.JournalEnabled(session)
+	c.Assert(err, gc.IsNil)
+	c.Assert(isEnabled, gc.Equals, enabled)
+}
+
 // mockShellCommand creates a new command with the given
 // name and contents, and patches $PATH so that it will be
 // executed by preference. It returns the name of a file