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// Copyright 2013 Prometheus Team
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package metric
import (
"fmt"
"github.com/prometheus/prometheus/coding"
"github.com/prometheus/prometheus/coding/indexable"
"github.com/prometheus/prometheus/model"
dto "github.com/prometheus/prometheus/model/generated"
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"github.com/prometheus/prometheus/storage/raw/leveldb"
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"time"
)
// diskFrontier describes an on-disk store of series to provide a
// representation of the known keyspace and time series values available.
//
// This is used to reduce the burden associated with LevelDB iterator
// management.
type diskFrontier struct {
firstFingerprint model . Fingerprint
firstSupertime time . Time
lastFingerprint model . Fingerprint
lastSupertime time . Time
}
func ( f * diskFrontier ) String ( ) string {
return fmt . Sprintf ( "diskFrontier from %s at %s to %s at %s" , f . firstFingerprint . ToRowKey ( ) , f . firstSupertime , f . lastFingerprint . ToRowKey ( ) , f . lastSupertime )
}
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func ( f * diskFrontier ) ContainsFingerprint ( fingerprint model . Fingerprint ) bool {
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return ! ( fingerprint . Less ( f . firstFingerprint ) || f . lastFingerprint . Less ( fingerprint ) )
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}
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func newDiskFrontier ( i leveldb . Iterator ) ( d * diskFrontier , err error ) {
if ! i . SeekToLast ( ) || i . Key ( ) == nil {
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return
}
lastKey , err := extractSampleKey ( i )
if err != nil {
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panic ( err )
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}
i . SeekToFirst ( )
firstKey , err := extractSampleKey ( i )
if i . Key ( ) == nil {
return
}
if err != nil {
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panic ( err )
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}
d = & diskFrontier { }
d . firstFingerprint = model . NewFingerprintFromRowKey ( * firstKey . Fingerprint . Signature )
d . firstSupertime = indexable . DecodeTime ( firstKey . Timestamp )
d . lastFingerprint = model . NewFingerprintFromRowKey ( * lastKey . Fingerprint . Signature )
d . lastSupertime = indexable . DecodeTime ( lastKey . Timestamp )
return
}
// seriesFrontier represents the valid seek frontier for a given series.
type seriesFrontier struct {
firstSupertime time . Time
lastSupertime time . Time
lastTime time . Time
}
func ( f seriesFrontier ) String ( ) string {
return fmt . Sprintf ( "seriesFrontier from %s to %s at %s" , f . firstSupertime , f . lastSupertime , f . lastTime )
}
// newSeriesFrontier furnishes a populated diskFrontier for a given
// fingerprint. A nil diskFrontier will be returned if the series cannot
// be found in the store.
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func newSeriesFrontier ( f model . Fingerprint , d diskFrontier , i leveldb . Iterator ) ( s * seriesFrontier , err error ) {
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var (
lowerSeek = firstSupertime
upperSeek = lastSupertime
)
// If we are either the first or the last key in the database, we need to use
// pessimistic boundary frontiers.
if f . Equal ( d . firstFingerprint ) {
lowerSeek = indexable . EncodeTime ( d . firstSupertime )
}
if f . Equal ( d . lastFingerprint ) {
upperSeek = indexable . EncodeTime ( d . lastSupertime )
}
key := & dto . SampleKey {
Fingerprint : f . ToDTO ( ) ,
Timestamp : upperSeek ,
}
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raw , err := coding . NewProtocolBuffer ( key ) . Encode ( )
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if err != nil {
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panic ( err )
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}
i . Seek ( raw )
if i . Key ( ) == nil {
return
}
retrievedKey , err := extractSampleKey ( i )
if err != nil {
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panic ( err )
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}
retrievedFingerprint := model . NewFingerprintFromRowKey ( * retrievedKey . Fingerprint . Signature )
// The returned fingerprint may not match if the original seek key lives
// outside of a metric's frontier. This is probable, for we are seeking to
// to the maximum allowed time, which could advance us to the next
// fingerprint.
//
//
if ! retrievedFingerprint . Equal ( f ) {
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i . Previous ( )
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retrievedKey , err = extractSampleKey ( i )
if err != nil {
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panic ( err )
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}
retrievedFingerprint := model . NewFingerprintFromRowKey ( * retrievedKey . Fingerprint . Signature )
// If the previous key does not match, we know that the requested
// fingerprint does not live in the database.
if ! retrievedFingerprint . Equal ( f ) {
return
}
}
s = & seriesFrontier {
lastSupertime : indexable . DecodeTime ( retrievedKey . Timestamp ) ,
lastTime : time . Unix ( * retrievedKey . LastTimestamp , 0 ) ,
}
key . Timestamp = lowerSeek
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raw , err = coding . NewProtocolBuffer ( key ) . Encode ( )
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if err != nil {
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panic ( err )
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}
i . Seek ( raw )
retrievedKey , err = extractSampleKey ( i )
if err != nil {
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panic ( err )
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}
retrievedFingerprint = model . NewFingerprintFromRowKey ( * retrievedKey . Fingerprint . Signature )
s . firstSupertime = indexable . DecodeTime ( retrievedKey . Timestamp )
return
}