/
provider.go
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/
provider.go
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// Copyright 2018 Google LLC. All Rights Reserved.
//
// 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 storage
import (
"fmt"
"sync"
"github.com/google/trillian/monitoring"
)
// NewProviderFunc is the signature of a function which can be registered to
// provide instances of storage providers.
type NewProviderFunc func(monitoring.MetricFactory) (Provider, error)
var (
spMu sync.RWMutex
spByName = make(map[string]NewProviderFunc)
)
// RegisterProvider registers the given storage Provider.
func RegisterProvider(name string, sp NewProviderFunc) error {
spMu.Lock()
defer spMu.Unlock()
_, exists := spByName[name]
if exists {
return fmt.Errorf("storage provider %v already registered", name)
}
spByName[name] = sp
return nil
}
// NewProvider returns a new Provider instance of the type specified by name.
func NewProvider(name string, mf monitoring.MetricFactory) (Provider, error) {
spMu.RLock()
defer spMu.RUnlock()
sp := spByName[name]
if sp == nil {
return nil, fmt.Errorf("no such storage provider %v", name)
}
return sp(mf)
}
// Providers returns a slice of all registered storage provider names.
func Providers() []string {
spMu.RLock()
defer spMu.RUnlock()
r := []string{}
for k := range spByName {
r = append(r, k)
}
return r
}
// Provider is an interface which allows Trillian binaries to use different
// storage implementations.
type Provider interface {
// LogStorage creates and returns a LogStorage implementation.
LogStorage() LogStorage
// AdminStorage creates and returns a AdminStorage implementation.
AdminStorage() AdminStorage
// Close closes the underlying storage.
Close() error
}