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service_names.go
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service_names.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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 spanstore
import (
"time"
"github.com/pkg/errors"
"github.com/uber/jaeger-lib/metrics"
"go.uber.org/zap"
"github.com/jaegertracing/jaeger/pkg/cache"
"github.com/jaegertracing/jaeger/pkg/cassandra"
casMetrics "github.com/jaegertracing/jaeger/pkg/cassandra/metrics"
)
const (
insertServiceName = `INSERT INTO service_names(service_name) VALUES (?)`
queryServiceNames = `SELECT service_name FROM service_names`
)
// ServiceNamesStorage stores known service names.
type ServiceNamesStorage struct {
session cassandra.Session
writeCacheTTL time.Duration
InsertStmt string
QueryStmt string
metrics *casMetrics.Table
serviceNames cache.Cache
logger *zap.Logger
}
// NewServiceNamesStorage returns a new ServiceNamesStorage
func NewServiceNamesStorage(
session cassandra.Session,
writeCacheTTL time.Duration,
metricsFactory metrics.Factory,
logger *zap.Logger,
) *ServiceNamesStorage {
return &ServiceNamesStorage{
session: session,
InsertStmt: insertServiceName,
QueryStmt: queryServiceNames,
metrics: casMetrics.NewTable(metricsFactory, "service_names"),
writeCacheTTL: writeCacheTTL,
logger: logger,
serviceNames: cache.NewLRUWithOptions(
10000,
&cache.Options{
TTL: writeCacheTTL,
InitialCapacity: 1000,
}),
}
}
// Write saves a single service name
func (s *ServiceNamesStorage) Write(serviceName string) error {
var err error
query := s.session.Query(s.InsertStmt)
if inCache := checkWriteCache(serviceName, s.serviceNames, s.writeCacheTTL); !inCache {
q := query.Bind(serviceName)
err2 := s.metrics.Exec(q, s.logger)
if err2 != nil {
err = err2
}
}
return err
}
// checks if the key is in cache; returns true if it is, otherwise puts it there and returns false
func checkWriteCache(key string, c cache.Cache, writeCacheTTL time.Duration) bool {
if writeCacheTTL == 0 {
return false
}
// even though there is a race condition between Get and Put, it's not a problem for storage,
// it simply means we might write the same service name twice.
inCache := c.Get(key)
if inCache == nil {
c.Put(key, key)
}
return inCache != nil
}
// GetServices returns all services traced by Jaeger
func (s *ServiceNamesStorage) GetServices() ([]string, error) {
iter := s.session.Query(s.QueryStmt).Iter()
var service string
var services []string
for iter.Scan(&service) {
services = append(services, service)
}
if err := iter.Close(); err != nil {
err = errors.Wrap(err, "Error reading service_names from storage")
return nil, err
}
return services, nil
}