feat: Add sampling store support to Badger (#4834)

## Which problem is this PR solving?
Related  #3305

## Description of the changes
-   Implemented badger db for sampling store

## How was this change tested?
- Added Unit test and also tested it with the already Implemented
integration test

## Checklist
- [x] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [x] I have signed all commits
- [x] I have added unit tests for the new functionality
- [x] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `yarn lint` and `yarn test`

---------

Signed-off-by: slayer321 <sachin.maurya7666@gmail.com>

plugin/storage/badger/factory.go

@@ -29,8 +29,10 @@ import (
 	"github.com/jaegertracing/jaeger/pkg/metrics"
 	"github.com/jaegertracing/jaeger/plugin"
 	depStore "github.com/jaegertracing/jaeger/plugin/storage/badger/dependencystore"
+	badgerSampling "github.com/jaegertracing/jaeger/plugin/storage/badger/samplingstore"
 	badgerStore "github.com/jaegertracing/jaeger/plugin/storage/badger/spanstore"
 	"github.com/jaegertracing/jaeger/storage/dependencystore"
+	"github.com/jaegertracing/jaeger/storage/samplingstore"
 	"github.com/jaegertracing/jaeger/storage/spanstore"
 )
 
@@ -170,6 +172,11 @@ func (f *Factory) CreateDependencyReader() (dependencystore.Reader, error) {
 	return depStore.NewDependencyStore(sr), nil
 }
 
+// CreateSamplingStore implements storage.SamplingStoreFactory
+func (f *Factory) CreateSamplingStore(maxBuckets int) (samplingstore.Store, error) {
+	return badgerSampling.NewSamplingStore(f.store), nil
+}
+
 // Close Implements io.Closer and closes the underlying storage
 func (f *Factory) Close() error {
 	close(f.maintenanceDone)

plugin/storage/badger/samplingstore/storage.go

@@ -0,0 +1,262 @@
+// Copyright (c) 2023 The Jaeger Authors.
+//
+// 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 samplingstore
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/dgraph-io/badger/v3"
+
+	"github.com/jaegertracing/jaeger/cmd/collector/app/sampling/model"
+	jaegermodel "github.com/jaegertracing/jaeger/model"
+)
+
+const (
+	throughputKeyPrefix    byte = 0x08
+	probabilitiesKeyPrefix byte = 0x09
+)
+
+type SamplingStore struct {
+	store *badger.DB
+}
+
+type ProbabilitiesAndQPS struct {
+	Hostname      string
+	Probabilities model.ServiceOperationProbabilities
+	QPS           model.ServiceOperationQPS
+}
+
+func NewSamplingStore(db *badger.DB) *SamplingStore {
+	return &SamplingStore{
+		store: db,
+	}
+}
+
+func (s *SamplingStore) InsertThroughput(throughput []*model.Throughput) error {
+	startTime := jaegermodel.TimeAsEpochMicroseconds(time.Now())
+	entriesToStore := make([]*badger.Entry, 0)
+	entries, err := s.createThroughputEntry(throughput, startTime)
+	if err != nil {
+		return err
+	}
+	entriesToStore = append(entriesToStore, entries)
+	err = s.store.Update(func(txn *badger.Txn) error {
+		for i := range entriesToStore {
+			err = txn.SetEntry(entriesToStore[i])
+			if err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+
+	return nil
+}
+
+func (s *SamplingStore) GetThroughput(start, end time.Time) ([]*model.Throughput, error) {
+	var retSlice []*model.Throughput
+	prefix := []byte{throughputKeyPrefix}
+
+	err := s.store.View(func(txn *badger.Txn) error {
+		opts := badger.DefaultIteratorOptions
+		it := txn.NewIterator(opts)
+		defer it.Close()
+
+		val := []byte{}
+		for it.Seek(prefix); it.ValidForPrefix(prefix); it.Next() {
+			item := it.Item()
+			k := item.Key()
+			startTime := k[1:9]
+			fmt.Printf("key=%s\n", k)
+			val, err := item.ValueCopy(val)
+			if err != nil {
+				return err
+			}
+			t, err := initalStartTime(startTime)
+			if err != nil {
+				return err
+			}
+			throughputs, err := decodeThroughtputValue(val)
+			if err != nil {
+				return err
+			}
+
+			if t.After(start) && (t.Before(end) || t.Equal(end)) {
+				retSlice = append(retSlice, throughputs...)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return retSlice, nil
+}
+
+func (s *SamplingStore) InsertProbabilitiesAndQPS(hostname string,
+	probabilities model.ServiceOperationProbabilities,
+	qps model.ServiceOperationQPS,
+) error {
+	startTime := jaegermodel.TimeAsEpochMicroseconds(time.Now())
+	entriesToStore := make([]*badger.Entry, 0)
+	entries, err := s.createProbabilitiesEntry(hostname, probabilities, qps, startTime)
+	if err != nil {
+		return err
+	}
+	entriesToStore = append(entriesToStore, entries)
+	err = s.store.Update(func(txn *badger.Txn) error {
+		// Write the entries
+		for i := range entriesToStore {
+			err = txn.SetEntry(entriesToStore[i])
+			if err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+
+	return nil
+}
+
+// GetLatestProbabilities implements samplingstore.Reader#GetLatestProbabilities.
+func (s *SamplingStore) GetLatestProbabilities() (model.ServiceOperationProbabilities, error) {
+	var retVal model.ServiceOperationProbabilities
+	var unMarshalProbabilities ProbabilitiesAndQPS
+	prefix := []byte{probabilitiesKeyPrefix}
+
+	err := s.store.View(func(txn *badger.Txn) error {
+		opts := badger.DefaultIteratorOptions
+		it := txn.NewIterator(opts)
+		defer it.Close()
+
+		val := []byte{}
+		for it.Seek(prefix); it.ValidForPrefix(prefix); it.Next() {
+			item := it.Item()
+			val, err := item.ValueCopy(val)
+			if err != nil {
+				return err
+			}
+			unMarshalProbabilities, err = decodeProbabilitiesValue(val)
+			if err != nil {
+				return err
+			}
+			retVal = unMarshalProbabilities.Probabilities
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return retVal, nil
+}
+
+func (s *SamplingStore) createProbabilitiesEntry(hostname string, probabilities model.ServiceOperationProbabilities, qps model.ServiceOperationQPS, startTime uint64) (*badger.Entry, error) {
+	pK, pV, err := s.createProbabilitiesKV(hostname, probabilities, qps, startTime)
+	if err != nil {
+		return nil, err
+	}
+
+	e := s.createBadgerEntry(pK, pV)
+
+	return e, nil
+}
+
+func (s *SamplingStore) createProbabilitiesKV(hostname string, probabilities model.ServiceOperationProbabilities, qps model.ServiceOperationQPS, startTime uint64) ([]byte, []byte, error) {
+	key := make([]byte, 16)
+	key[0] = probabilitiesKeyPrefix
+	pos := 1
+	binary.BigEndian.PutUint64(key[pos:], startTime)
+
+	var bb []byte
+	var err error
+	val := ProbabilitiesAndQPS{
+		Hostname:      hostname,
+		Probabilities: probabilities,
+		QPS:           qps,
+	}
+	bb, err = json.Marshal(val)
+	return key, bb, err
+}
+
+func (s *SamplingStore) createThroughputEntry(throughput []*model.Throughput, startTime uint64) (*badger.Entry, error) {
+	pK, pV, err := s.createThroughputKV(throughput, startTime)
+	if err != nil {
+		return nil, err
+	}
+
+	e := s.createBadgerEntry(pK, pV)
+
+	return e, nil
+}
+
+func (s *SamplingStore) createBadgerEntry(key []byte, value []byte) *badger.Entry {
+	return &badger.Entry{
+		Key:   key,
+		Value: value,
+	}
+}
+
+func (s *SamplingStore) createThroughputKV(throughput []*model.Throughput, startTime uint64) ([]byte, []byte, error) {
+	key := make([]byte, 16)
+	key[0] = throughputKeyPrefix
+	pos := 1
+	binary.BigEndian.PutUint64(key[pos:], startTime)
+
+	var bb []byte
+	var err error
+
+	bb, err = json.Marshal(throughput)
+	return key, bb, err
+}
+
+func decodeThroughtputValue(val []byte) ([]*model.Throughput, error) {
+	var throughput []*model.Throughput
+
+	err := json.Unmarshal(val, &throughput)
+	if err != nil {
+		return nil, err
+	}
+	return throughput, err
+}
+
+func decodeProbabilitiesValue(val []byte) (ProbabilitiesAndQPS, error) {
+	var probabilities ProbabilitiesAndQPS
+
+	err := json.Unmarshal(val, &probabilities)
+	if err != nil {
+		return ProbabilitiesAndQPS{}, err
+	}
+	return probabilities, nil
+}
+
+func initalStartTime(timeBytes []byte) (time.Time, error) {
+	var usec int64
+
+	buf := bytes.NewReader(timeBytes)
+
+	if err := binary.Read(buf, binary.BigEndian, &usec); err != nil {
+		panic(nil)
+	}
+
+	t := time.UnixMicro(usec)
+	return t, nil
+}