/
task.go
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/
task.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package task
import (
"sync"
"github.com/uber-go/tally"
"go.uber.org/fx/service"
)
var (
_globalBackendMu sync.RWMutex
_globalBackend Backend = &NopBackend{}
_globalBackendStatsClient = newStatsClient(tally.NoopScope)
_asyncMod service.Module
_asyncModErr error
_once sync.Once
)
// GlobalBackend returns global instance of the backend
// TODO (madhu): Make work with multiple backends
func GlobalBackend() Backend {
_globalBackendMu.RLock()
defer _globalBackendMu.RUnlock()
return _globalBackend
}
func globalBackendStatsClient() *statsClient {
_globalBackendMu.RLock()
defer _globalBackendMu.RUnlock()
return _globalBackendStatsClient
}
// New creates an async task queue ModuleProvider.
func New(createFunc BackendCreateFunc) service.ModuleProvider {
return service.ModuleProviderFromFunc("task", func(host service.Host) (service.Module, error) {
return newAsyncModuleSingleton(host, createFunc)
})
}
func newAsyncModuleSingleton(
host service.Host,
createFunc BackendCreateFunc,
) (service.Module, error) {
_once.Do(func() {
_asyncMod, _asyncModErr = newAsyncModule(host, createFunc)
})
return _asyncMod, _asyncModErr
}
func newAsyncModule(
host service.Host,
createFunc BackendCreateFunc,
) (service.Module, error) {
backend, err := createFunc(host)
if err != nil {
return nil, err
}
_globalBackendMu.Lock()
_globalBackend = backend
_globalBackendStatsClient = newStatsClient(host.Metrics())
_globalBackendMu.Unlock()
return backend, nil
}
// BackendCreateFunc creates a backend implementation
type BackendCreateFunc func(host service.Host) (Backend, error)