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package collector
import (
"time"
"github.com/golang/glog"
"github.com/prometheus/client_golang/prometheus"
"gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
var (
oplogStatusCount = prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: Namespace,
Subsystem: "replset_oplog",
Name: "items_total",
Help: "The total number of changes in the oplog",
})
oplogStatusHeadTimestamp = prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: Namespace,
Subsystem: "replset_oplog",
Name: "head_timestamp",
Help: "The timestamp of the newest change in the oplog",
})
oplogStatusTailTimestamp = prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: Namespace,
Subsystem: "replset_oplog",
Name: "tail_timestamp",
Help: "The timestamp of the oldest change in the oplog",
})
oplogStatusSizeBytes = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Namespace: Namespace,
Subsystem: "replset_oplog",
Name: "size_bytes",
Help: "Size of oplog in bytes",
}, []string{"type"})
)
// OplogCollectionStats represents metrics about an oplog collection
type OplogCollectionStats struct {
Count float64 `bson:"count"`
Size float64 `bson:"size"`
StorageSize float64 `bson:"storageSize"`
}
// OplogStatus represents oplog metrics
type OplogStatus struct {
TailTimestamp float64
HeadTimestamp float64
CollectionStats *OplogCollectionStats
}
// BsonMongoTimestampToUnix converts a mongo timestamp to UNIX time
// there's gotta be a better way to do this, but it works for now :/
func BsonMongoTimestampToUnix(timestamp bson.MongoTimestamp) float64 {
return float64(timestamp >> 32)
}
// GetOplogTimestamp fetches the latest oplog timestamp
func GetOplogTimestamp(session *mgo.Session, returnTail bool) (float64, error) {
sortBy := "$natural"
if returnTail {
sortBy = "-$natural"
}
var (
err error
tries int
result struct {
Timestamp bson.MongoTimestamp `bson:"ts"`
}
)
maxTries := 2
for tries < maxTries {
err = session.DB("local").C("oplog.rs").Find(nil).Sort(sortBy).Limit(1).One(&result)
if err != nil {
tries++
time.Sleep(500 * time.Millisecond)
} else {
return BsonMongoTimestampToUnix(result.Timestamp), err
}
}
return 0, err
}
// GetOplogCollectionStats fetches oplog collection stats
func GetOplogCollectionStats(session *mgo.Session) (*OplogCollectionStats, error) {
results := &OplogCollectionStats{}
err := session.DB("local").Run(bson.M{"collStats": "oplog.rs"}, &results)
return results, err
}
// Export exports metrics to Prometheus
func (status *OplogStatus) Export(ch chan<- prometheus.Metric) {
oplogStatusSizeBytes.WithLabelValues("current").Set(0)
oplogStatusSizeBytes.WithLabelValues("storage").Set(0)
if status.CollectionStats != nil {
oplogStatusCount.Set(status.CollectionStats.Count)
oplogStatusSizeBytes.WithLabelValues("current").Set(status.CollectionStats.Size)
oplogStatusSizeBytes.WithLabelValues("storage").Set(status.CollectionStats.StorageSize)
}
if status.HeadTimestamp != 0 && status.TailTimestamp != 0 {
oplogStatusHeadTimestamp.Set(status.HeadTimestamp)
oplogStatusTailTimestamp.Set(status.TailTimestamp)
}
oplogStatusCount.Collect(ch)
oplogStatusHeadTimestamp.Collect(ch)
oplogStatusTailTimestamp.Collect(ch)
oplogStatusSizeBytes.Collect(ch)
}
// Describe describes metrics collected
func (status *OplogStatus) Describe(ch chan<- *prometheus.Desc) {
oplogStatusCount.Describe(ch)
oplogStatusHeadTimestamp.Describe(ch)
oplogStatusTailTimestamp.Describe(ch)
oplogStatusSizeBytes.Describe(ch)
}
// GetOplogStatus fetches oplog collection stats
func GetOplogStatus(session *mgo.Session) *OplogStatus {
oplogStatus := &OplogStatus{}
collectionStats, err := GetOplogCollectionStats(session)
if err != nil {
glog.Error("Failed to get local.oplog_rs collection stats.")
return nil
}
headTimestamp, err := GetOplogTimestamp(session, false)
tailTimestamp, err := GetOplogTimestamp(session, true)
if err != nil {
glog.Error("Failed to get oplog head or tail timestamps.")
return nil
}
oplogStatus.CollectionStats = collectionStats
oplogStatus.HeadTimestamp = headTimestamp
oplogStatus.TailTimestamp = tailTimestamp
return oplogStatus
}
|
