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/*
* Minio Cloud Storage, (C) 2016 Minio, 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 main
import (
"net/rpc"
"sync"
"github.com/minio/dsync"
)
// ReconnectRPCClient is a wrapper type for rpc.Client which provides reconnect on first failure.
type ReconnectRPCClient struct {
mutex sync.Mutex
rpc *rpc.Client
addr string
endpoint string
}
// newClient constructs a ReconnectRPCClient object with addr and endpoint initialized.
// It _doesn't_ connect to the remote endpoint. See Call method to see when the
// connect happens.
func newClient(addr, endpoint string) *ReconnectRPCClient {
return &ReconnectRPCClient{
addr: addr,
endpoint: endpoint,
}
}
// Close closes the underlying socket file descriptor.
func (rpcClient *ReconnectRPCClient) Close() error {
rpcClient.mutex.Lock()
defer rpcClient.mutex.Unlock()
// If rpc client has not connected yet there is nothing to close.
if rpcClient.rpc == nil {
return nil
}
// Reset rpcClient.rpc to allow for subsequent calls to use a new
// (socket) connection.
clnt := rpcClient.rpc
rpcClient.rpc = nil
return clnt.Close()
}
// Call makes a RPC call to the remote endpoint using the default codec, namely encoding/gob.
func (rpcClient *ReconnectRPCClient) Call(serviceMethod string, args interface{}, reply interface{}) (err error) {
rpcClient.mutex.Lock()
defer rpcClient.mutex.Unlock()
dialCall := func() error {
// If the rpc.Client is nil, we attempt to (re)connect with the remote endpoint.
if rpcClient.rpc == nil {
clnt, derr := rpc.DialHTTPPath("tcp", rpcClient.addr, rpcClient.endpoint)
if derr != nil {
return derr
}
rpcClient.rpc = clnt
}
// If the RPC fails due to a network-related error, then we reset
// rpc.Client for a subsequent reconnect.
return rpcClient.rpc.Call(serviceMethod, args, reply)
}
if err = dialCall(); err == rpc.ErrShutdown {
rpcClient.rpc.Close()
rpcClient.rpc = nil
err = dialCall()
}
return err
}
func (rpcClient *ReconnectRPCClient) RLock(args dsync.LockArgs) (status bool, err error) {
err = rpcClient.Call("Dsync.RLock", &args, &status)
return status, err
}
func (rpcClient *ReconnectRPCClient) Lock(args dsync.LockArgs) (status bool, err error) {
err = rpcClient.Call("Dsync.Lock", &args, &status)
return status, err
}
func (rpcClient *ReconnectRPCClient) RUnlock(args dsync.LockArgs) (status bool, err error) {
err = rpcClient.Call("Dsync.RUnlock", &args, &status)
return status, err
}
func (rpcClient *ReconnectRPCClient) Unlock(args dsync.LockArgs) (status bool, err error) {
err = rpcClient.Call("Dsync.Unlock", &args, &status)
return status, err
}
func (rpcClient *ReconnectRPCClient) ForceUnlock(args dsync.LockArgs) (status bool, err error) {
err = rpcClient.Call("Dsync.ForceUnlock", &args, &status)
return status, err
}
func (rpcClient *ReconnectRPCClient) ServerAddr() string {
return rpcClient.addr
}
func (rpcClient *ReconnectRPCClient) ServiceEndpoint() string {
return rpcClient.endpoint
}
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