/
client_singleton.go
101 lines (88 loc) · 2.9 KB
/
client_singleton.go
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/*
*
* Copyright 2020 gRPC 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 client
import (
"fmt"
"sync"
"time"
"github.com/CloudmindsRobot/gmgo/grpc/xds/internal/client/bootstrap"
)
const defaultWatchExpiryTimeout = 15 * time.Second
// This is the Client returned by New(). It contains one client implementation,
// and maintains the refcount.
var singletonClient = &Client{}
// To override in tests.
var bootstrapNewConfig = bootstrap.NewConfig
// Client is a full fledged gRPC client which queries a set of discovery APIs
// (collectively termed as xDS) on a remote management server, to discover
// various dynamic resources.
//
// The xds client is a singleton. It will be shared by the xds resolver and
// balancer implementations, across multiple ClientConns and Servers.
type Client struct {
*clientImpl
// This mu protects all the fields, including the embedded clientImpl above.
mu sync.Mutex
refCount int
}
// New returns a new xdsClient configured by the bootstrap file specified in env
// variable GRPC_XDS_BOOTSTRAP.
func New() (*Client, error) {
singletonClient.mu.Lock()
defer singletonClient.mu.Unlock()
// If the client implementation was created, increment ref count and return
// the client.
if singletonClient.clientImpl != nil {
singletonClient.refCount++
return singletonClient, nil
}
// Create the new client implementation.
config, err := bootstrapNewConfig()
if err != nil {
return nil, fmt.Errorf("xds: failed to read bootstrap file: %v", err)
}
c, err := newWithConfig(config, defaultWatchExpiryTimeout)
if err != nil {
return nil, err
}
singletonClient.clientImpl = c
singletonClient.refCount++
return singletonClient, nil
}
// Close closes the client. It does ref count of the xds client implementation,
// and closes the gRPC connection to the management server when ref count
// reaches 0.
func (c *Client) Close() {
c.mu.Lock()
defer c.mu.Unlock()
c.refCount--
if c.refCount == 0 {
c.clientImpl.Close()
// Set clientImpl back to nil. So if New() is called after this, a new
// implementation will be created.
c.clientImpl = nil
}
}
// NewWithConfigForTesting is exported for testing only.
func NewWithConfigForTesting(config *bootstrap.Config, watchExpiryTimeout time.Duration) (*Client, error) {
cl, err := newWithConfig(config, watchExpiryTimeout)
if err != nil {
return nil, err
}
return &Client{clientImpl: cl, refCount: 1}, nil
}