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93 lines
2.6 KiB
93 lines
2.6 KiB
/*
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* Minio Cloud Storage, (C) 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package main
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import (
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"net/rpc"
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"sync"
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)
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// RPCClient is a wrapper type for rpc.Client which provides reconnect on first failure.
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type RPCClient struct {
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sync.Mutex
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rpc *rpc.Client
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node string
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rpcPath string
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}
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// newClient constructs a RPCClient object with node and rpcPath initialized.
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// It _doesn't_ connect to the remote endpoint. See Call method to see when the
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// connect happens.
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func newClient(node, rpcPath string) *RPCClient {
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return &RPCClient{
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node: node,
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rpcPath: rpcPath,
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}
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}
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// Close closes the underlying socket file descriptor.
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func (rpcClient *RPCClient) Close() error {
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rpcClient.Lock()
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defer rpcClient.Unlock()
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// If rpc client has not connected yet there is nothing to close.
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if rpcClient.rpc == nil {
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return nil
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}
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// Reset rpcClient.rpc to allow for subsequent calls to use a new
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// (socket) connection.
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clnt := rpcClient.rpc
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rpcClient.rpc = nil
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return clnt.Close()
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}
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// Call makes a RPC call to the remote endpoint using the default codec, namely encoding/gob.
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func (rpcClient *RPCClient) Call(serviceMethod string, args interface{}, reply interface{}) error {
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rpcClient.Lock()
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defer rpcClient.Unlock()
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// If the rpc.Client is nil, we attempt to (re)connect with the remote endpoint.
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if rpcClient.rpc == nil {
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clnt, err := rpc.DialHTTPPath("tcp", rpcClient.node, rpcClient.rpcPath)
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if err != nil {
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return err
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}
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rpcClient.rpc = clnt
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}
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// If the RPC fails due to a network-related error, then we reset
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// rpc.Client for a subsequent reconnect.
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err := rpcClient.rpc.Call(serviceMethod, args, reply)
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if IsRPCError(err) {
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rpcClient.rpc = nil
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}
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return err
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}
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// IsRPCError returns true if the error value is due to a network related
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// failure, false otherwise.
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func IsRPCError(err error) bool {
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if err == nil {
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return false
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}
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// The following are net/rpc specific errors that indicate that
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// the connection may have been reset. Reset rpcClient.rpc to nil
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// to trigger a reconnect in future.
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if err == rpc.ErrShutdown {
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return true
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}
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return false
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}
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