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factory.go
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factory.go
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// Copyright 2019, OpenTelemetry 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 zpagesextension
import (
"errors"
"sync/atomic"
"go.uber.org/zap"
"github.com/open-telemetry/opentelemetry-collector/config/configmodels"
"github.com/open-telemetry/opentelemetry-collector/extension"
)
const (
// The value of extension "type" in configuration.
typeStr = "zpages"
)
// Factory is the factory for the extension.
type Factory struct {
}
var _ (extension.Factory) = (*Factory)(nil)
// Type gets the type of the config created by this factory.
func (f *Factory) Type() string {
return typeStr
}
// CreateDefaultConfig creates the default configuration for the extension.
func (f *Factory) CreateDefaultConfig() configmodels.Extension {
return &Config{
ExtensionSettings: configmodels.ExtensionSettings{
TypeVal: typeStr,
NameVal: typeStr,
},
Endpoint: "localhost:55679",
}
}
// CreateExtension creates the extension based on this config.
func (f *Factory) CreateExtension(
logger *zap.Logger,
cfg configmodels.Extension,
) (extension.ServiceExtension, error) {
config := cfg.(*Config)
if config.Endpoint == "" {
return nil, errors.New("\"endpoint\" is required when using the \"zpages\" extension")
}
// The runtime settings are global to the application, so while in principle it
// is possible to have more than one instance, running multiple does not bring
// any value to the service.
// In order to avoid this issue we will allow the creation of a single
// instance once per process while keeping the private function that allow
// the creation of multiple instances for unit tests. Summary: only a single
// instance can be created via the factory.
if !atomic.CompareAndSwapInt32(&instanceState, instanceNotCreated, instanceCreated) {
return nil, errors.New("only a single instance can be created per process")
}
return newServer(*config, logger)
}
// See comment in CreateExtension how these are used.
var instanceState int32
const (
instanceNotCreated int32 = 0
instanceCreated int32 = 1
)