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infrastructure.go
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// Copyright (c) 2014-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package zcashrpcclient
import (
"bytes"
"container/list"
"crypto/tls"
"crypto/x509"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"math"
"net"
"net/http"
"net/url"
"sync"
"sync/atomic"
"time"
"github.com/btcsuite/btcd/btcjson"
"github.com/btcsuite/go-socks/socks"
"github.com/btcsuite/websocket"
)
var (
// ErrInvalidAuth is an error to describe the condition where the client
// is either unable to authenticate or the specified endpoint is
// incorrect.
ErrInvalidAuth = errors.New("authentication failure")
// ErrInvalidEndpoint is an error to describe the condition where the
// websocket handshake failed with the specified endpoint.
ErrInvalidEndpoint = errors.New("the endpoint either does not support " +
"websockets or does not exist")
// ErrClientNotConnected is an error to describe the condition where a
// websocket client has been created, but the connection was never
// established. This condition differs from ErrClientDisconnect, which
// represents an established connection that was lost.
ErrClientNotConnected = errors.New("the client was never connected")
// ErrClientDisconnect is an error to describe the condition where the
// client has been disconnected from the RPC server. When the
// DisableAutoReconnect option is not set, any outstanding futures
// when a client disconnect occurs will return this error as will
// any new requests.
ErrClientDisconnect = errors.New("the client has been disconnected")
// ErrClientShutdown is an error to describe the condition where the
// client is either already shutdown, or in the process of shutting
// down. Any outstanding futures when a client shutdown occurs will
// return this error as will any new requests.
ErrClientShutdown = errors.New("the client has been shutdown")
// ErrNotWebsocketClient is an error to describe the condition of
// calling a Client method intended for a websocket client when the
// client has been configured to run in HTTP POST mode instead.
ErrNotWebsocketClient = errors.New("client is not configured for " +
"websockets")
// ErrClientAlreadyConnected is an error to describe the condition where
// a new client connection cannot be established due to a websocket
// client having already connected to the RPC server.
ErrClientAlreadyConnected = errors.New("websocket client has already " +
"connected")
)
const (
// sendBufferSize is the number of elements the websocket send channel
// can queue before blocking.
sendBufferSize = 50
// sendPostBufferSize is the number of elements the HTTP POST send
// channel can queue before blocking.
sendPostBufferSize = 100
// connectionRetryInterval is the amount of time to wait in between
// retries when automatically reconnecting to an RPC server.
connectionRetryInterval = time.Second * 5
)
// sendPostDetails houses an HTTP POST request to send to an RPC server as well
// as the original JSON-RPC command and a channel to reply on when the server
// responds with the result.
type sendPostDetails struct {
httpRequest *http.Request
jsonRequest *jsonRequest
}
// jsonRequest holds information about a json request that is used to properly
// detect, interpret, and deliver a reply to it.
type jsonRequest struct {
id uint64
method string
cmd interface{}
marshalledJSON []byte
responseChan chan *response
}
// Client represents a Bitcoin RPC client which allows easy access to the
// various RPC methods available on a Bitcoin RPC server. Each of the wrapper
// functions handle the details of converting the passed and return types to and
// from the underlying JSON types which are required for the JSON-RPC
// invocations
//
// The client provides each RPC in both synchronous (blocking) and asynchronous
// (non-blocking) forms. The asynchronous forms are based on the concept of
// futures where they return an instance of a type that promises to deliver the
// result of the invocation at some future time. Invoking the Receive method on
// the returned future will block until the result is available if it's not
// already.
type Client struct {
id uint64 // atomic, so must stay 64-bit aligned
// config holds the connection configuration assoiated with this client.
config *ConnConfig
// wsConn is the underlying websocket connection when not in HTTP POST
// mode.
wsConn *websocket.Conn
// httpClient is the underlying HTTP client to use when running in HTTP
// POST mode.
httpClient *http.Client
// mtx is a mutex to protect access to connection related fields.
mtx sync.Mutex
// disconnected indicated whether or not the server is disconnected.
disconnected bool
// retryCount holds the number of times the client has tried to
// reconnect to the RPC server.
retryCount int64
// Track command and their response channels by ID.
requestLock sync.Mutex
requestMap map[uint64]*list.Element
requestList *list.List
// Notifications.
ntfnHandlers *NotificationHandlers
ntfnStateLock sync.Mutex
ntfnState *notificationState
// Networking infrastructure.
sendChan chan []byte
sendPostChan chan *sendPostDetails
connEstablished chan struct{}
disconnect chan struct{}
shutdown chan struct{}
wg sync.WaitGroup
}
// NextID returns the next id to be used when sending a JSON-RPC message. This
// ID allows responses to be associated with particular requests per the
// JSON-RPC specification. Typically the consumer of the client does not need
// to call this function, however, if a custom request is being created and used
// this function should be used to ensure the ID is unique amongst all requests
// being made.
func (c *Client) NextID() uint64 {
return atomic.AddUint64(&c.id, 1)
}
// addRequest associates the passed jsonRequest with its id. This allows the
// response from the remote server to be unmarshalled to the appropriate type
// and sent to the specified channel when it is received.
//
// If the client has already begun shutting down, ErrClientShutdown is returned
// and the request is not added.
//
// This function is safe for concurrent access.
func (c *Client) addRequest(jReq *jsonRequest) error {
c.requestLock.Lock()
defer c.requestLock.Unlock()
// A non-blocking read of the shutdown channel with the request lock
// held avoids adding the request to the client's internal data
// structures if the client is in the process of shutting down (and
// has not yet grabbed the request lock), or has finished shutdown
// already (responding to each outstanding request with
// ErrClientShutdown).
select {
case <-c.shutdown:
return ErrClientShutdown
default:
}
element := c.requestList.PushBack(jReq)
c.requestMap[jReq.id] = element
return nil
}
// removeRequest returns and removes the jsonRequest which contains the response
// channel and original method associated with the passed id or nil if there is
// no association.
//
// This function is safe for concurrent access.
func (c *Client) removeRequest(id uint64) *jsonRequest {
c.requestLock.Lock()
defer c.requestLock.Unlock()
element := c.requestMap[id]
if element != nil {
delete(c.requestMap, id)
request := c.requestList.Remove(element).(*jsonRequest)
return request
}
return nil
}
// removeAllRequests removes all the jsonRequests which contain the response
// channels for outstanding requests.
//
// This function MUST be called with the request lock held.
func (c *Client) removeAllRequests() {
c.requestMap = make(map[uint64]*list.Element)
c.requestList.Init()
}
// trackRegisteredNtfns examines the passed command to see if it is one of
// the notification commands and updates the notification state that is used
// to automatically re-establish registered notifications on reconnects.
func (c *Client) trackRegisteredNtfns(cmd interface{}) {
// Nothing to do if the caller is not interested in notifications.
if c.ntfnHandlers == nil {
return
}
c.ntfnStateLock.Lock()
defer c.ntfnStateLock.Unlock()
switch bcmd := cmd.(type) {
case *btcjson.NotifyBlocksCmd:
c.ntfnState.notifyBlocks = true
case *btcjson.NotifyNewTransactionsCmd:
if bcmd.Verbose != nil && *bcmd.Verbose {
c.ntfnState.notifyNewTxVerbose = true
} else {
c.ntfnState.notifyNewTx = true
}
case *btcjson.NotifySpentCmd:
for _, op := range bcmd.OutPoints {
c.ntfnState.notifySpent[op] = struct{}{}
}
case *btcjson.NotifyReceivedCmd:
for _, addr := range bcmd.Addresses {
c.ntfnState.notifyReceived[addr] = struct{}{}
}
}
}
type (
// inMessage is the first type that an incoming message is unmarshaled
// into. It supports both requests (for notification support) and
// responses. The partially-unmarshaled message is a notification if
// the embedded ID (from the response) is nil. Otherwise, it is a
// response.
inMessage struct {
ID *float64 `json:"id"`
*rawNotification
*rawResponse
}
// rawNotification is a partially-unmarshaled JSON-RPC notification.
rawNotification struct {
Method string `json:"method"`
Params []json.RawMessage `json:"params"`
}
// rawResponse is a partially-unmarshaled JSON-RPC response. For this
// to be valid (according to JSON-RPC 1.0 spec), ID may not be nil.
rawResponse struct {
Result json.RawMessage `json:"result"`
Error *btcjson.RPCError `json:"error"`
}
)
// response is the raw bytes of a JSON-RPC result, or the error if the response
// error object was non-null.
type response struct {
result []byte
err error
}
// result checks whether the unmarshaled response contains a non-nil error,
// returning an unmarshaled btcjson.RPCError (or an unmarshaling error) if so.
// If the response is not an error, the raw bytes of the request are
// returned for further unmashaling into specific result types.
func (r rawResponse) result() (result []byte, err error) {
if r.Error != nil {
return nil, r.Error
}
return r.Result, nil
}
// handleMessage is the main handler for incoming notifications and responses.
func (c *Client) handleMessage(msg []byte) {
// Attempt to unmarshal the message as either a notification or
// response.
var in inMessage
err := json.Unmarshal(msg, &in)
if err != nil {
log.Warnf("Remote server sent invalid message: %v", err)
return
}
// JSON-RPC 1.0 notifications are requests with a null id.
if in.ID == nil {
ntfn := in.rawNotification
if ntfn == nil {
log.Warn("Malformed notification: missing " +
"method and parameters")
return
}
if ntfn.Method == "" {
log.Warn("Malformed notification: missing method")
return
}
// params are not optional: nil isn't valid (but len == 0 is)
if ntfn.Params == nil {
log.Warn("Malformed notification: missing params")
return
}
// Deliver the notification.
log.Tracef("Received notification [%s]", in.Method)
c.handleNotification(in.rawNotification)
return
}
// ensure that in.ID can be converted to an integer without loss of precision
if *in.ID < 0 || *in.ID != math.Trunc(*in.ID) {
log.Warn("Malformed response: invalid identifier")
return
}
if in.rawResponse == nil {
log.Warn("Malformed response: missing result and error")
return
}
id := uint64(*in.ID)
log.Tracef("Received response for id %d (result %s)", id, in.Result)
request := c.removeRequest(id)
// Nothing more to do if there is no request associated with this reply.
if request == nil || request.responseChan == nil {
log.Warnf("Received unexpected reply: %s (id %d)", in.Result,
id)
return
}
// Since the command was successful, examine it to see if it's a
// notification, and if is, add it to the notification state so it
// can automatically be re-established on reconnect.
c.trackRegisteredNtfns(request.cmd)
// Deliver the response.
result, err := in.rawResponse.result()
request.responseChan <- &response{result: result, err: err}
}
// shouldLogReadError returns whether or not the passed error, which is expected
// to have come from reading from the websocket connection in wsInHandler,
// should be logged.
func (c *Client) shouldLogReadError(err error) bool {
// No logging when the connetion is being forcibly disconnected.
select {
case <-c.shutdown:
return false
default:
}
// No logging when the connection has been disconnected.
if err == io.EOF {
return false
}
if opErr, ok := err.(*net.OpError); ok && !opErr.Temporary() {
return false
}
return true
}
// wsInHandler handles all incoming messages for the websocket connection
// associated with the client. It must be run as a goroutine.
func (c *Client) wsInHandler() {
out:
for {
// Break out of the loop once the shutdown channel has been
// closed. Use a non-blocking select here so we fall through
// otherwise.
select {
case <-c.shutdown:
break out
default:
}
_, msg, err := c.wsConn.ReadMessage()
if err != nil {
// Log the error if it's not due to disconnecting.
if c.shouldLogReadError(err) {
log.Errorf("Websocket receive error from "+
"%s: %v", c.config.Host, err)
}
break out
}
c.handleMessage(msg)
}
// Ensure the connection is closed.
c.Disconnect()
c.wg.Done()
log.Tracef("RPC client input handler done for %s", c.config.Host)
}
// disconnectChan returns a copy of the current disconnect channel. The channel
// is read protected by the client mutex, and is safe to call while the channel
// is being reassigned during a reconnect.
func (c *Client) disconnectChan() <-chan struct{} {
c.mtx.Lock()
ch := c.disconnect
c.mtx.Unlock()
return ch
}
// wsOutHandler handles all outgoing messages for the websocket connection. It
// uses a buffered channel to serialize output messages while allowing the
// sender to continue running asynchronously. It must be run as a goroutine.
func (c *Client) wsOutHandler() {
out:
for {
// Send any messages ready for send until the client is
// disconnected closed.
select {
case msg := <-c.sendChan:
err := c.wsConn.WriteMessage(websocket.TextMessage, msg)
if err != nil {
c.Disconnect()
break out
}
case <-c.disconnectChan():
break out
}
}
// Drain any channels before exiting so nothing is left waiting around
// to send.
cleanup:
for {
select {
case <-c.sendChan:
default:
break cleanup
}
}
c.wg.Done()
log.Tracef("RPC client output handler done for %s", c.config.Host)
}
// sendMessage sends the passed JSON to the connected server using the
// websocket connection. It is backed by a buffered channel, so it will not
// block until the send channel is full.
func (c *Client) sendMessage(marshalledJSON []byte) {
// Don't send the message if disconnected.
select {
case c.sendChan <- marshalledJSON:
case <-c.disconnectChan():
return
}
}
// reregisterNtfns creates and sends commands needed to re-establish the current
// notification state associated with the client. It should only be called on
// on reconnect by the resendRequests function.
func (c *Client) reregisterNtfns() error {
// Nothing to do if the caller is not interested in notifications.
if c.ntfnHandlers == nil {
return nil
}
// In order to avoid holding the lock on the notification state for the
// entire time of the potentially long running RPCs issued below, make a
// copy of it and work from that.
//
// Also, other commands will be running concurrently which could modify
// the notification state (while not under the lock of course) which
// also register it with the remote RPC server, so this prevents double
// registrations.
c.ntfnStateLock.Lock()
stateCopy := c.ntfnState.Copy()
c.ntfnStateLock.Unlock()
// Reregister notifyblocks if needed.
if stateCopy.notifyBlocks {
log.Debugf("Reregistering [notifyblocks]")
if err := c.NotifyBlocks(); err != nil {
return err
}
}
// Reregister notifynewtransactions if needed.
if stateCopy.notifyNewTx || stateCopy.notifyNewTxVerbose {
log.Debugf("Reregistering [notifynewtransactions] (verbose=%v)",
stateCopy.notifyNewTxVerbose)
err := c.NotifyNewTransactions(stateCopy.notifyNewTxVerbose)
if err != nil {
return err
}
}
// Reregister the combination of all previously registered notifyspent
// outpoints in one command if needed.
nslen := len(stateCopy.notifySpent)
if nslen > 0 {
outpoints := make([]btcjson.OutPoint, 0, nslen)
for op := range stateCopy.notifySpent {
outpoints = append(outpoints, op)
}
log.Debugf("Reregistering [notifyspent] outpoints: %v", outpoints)
if err := c.notifySpentInternal(outpoints).Receive(); err != nil {
return err
}
}
// Reregister the combination of all previously registered
// notifyreceived addresses in one command if needed.
nrlen := len(stateCopy.notifyReceived)
if nrlen > 0 {
addresses := make([]string, 0, nrlen)
for addr := range stateCopy.notifyReceived {
addresses = append(addresses, addr)
}
log.Debugf("Reregistering [notifyreceived] addresses: %v", addresses)
if err := c.notifyReceivedInternal(addresses).Receive(); err != nil {
return err
}
}
return nil
}
// ignoreResends is a set of all methods for requests that are "long running"
// are not be reissued by the client on reconnect.
var ignoreResends = map[string]struct{}{
"rescan": struct{}{},
}
// resendRequests resends any requests that had not completed when the client
// disconnected. It is intended to be called once the client has reconnected as
// a separate goroutine.
func (c *Client) resendRequests() {
// Set the notification state back up. If anything goes wrong,
// disconnect the client.
if err := c.reregisterNtfns(); err != nil {
log.Warnf("Unable to re-establish notification state: %v", err)
c.Disconnect()
return
}
// Since it's possible to block on send and more requests might be
// added by the caller while resending, make a copy of all of the
// requests that need to be resent now and work from the copy. This
// also allows the lock to be released quickly.
c.requestLock.Lock()
resendReqs := make([]*jsonRequest, 0, c.requestList.Len())
var nextElem *list.Element
for e := c.requestList.Front(); e != nil; e = nextElem {
nextElem = e.Next()
jReq := e.Value.(*jsonRequest)
if _, ok := ignoreResends[jReq.method]; ok {
// If a request is not sent on reconnect, remove it
// from the request structures, since no reply is
// expected.
delete(c.requestMap, jReq.id)
c.requestList.Remove(e)
} else {
resendReqs = append(resendReqs, jReq)
}
}
c.requestLock.Unlock()
for _, jReq := range resendReqs {
// Stop resending commands if the client disconnected again
// since the next reconnect will handle them.
if c.Disconnected() {
return
}
log.Tracef("Sending command [%s] with id %d", jReq.method,
jReq.id)
c.sendMessage(jReq.marshalledJSON)
}
}
// wsReconnectHandler listens for client disconnects and automatically tries
// to reconnect with retry interval that scales based on the number of retries.
// It also resends any commands that had not completed when the client
// disconnected so the disconnect/reconnect process is largely transparent to
// the caller. This function is not run when the DisableAutoReconnect config
// options is set.
//
// This function must be run as a goroutine.
func (c *Client) wsReconnectHandler() {
out:
for {
select {
case <-c.disconnect:
// On disconnect, fallthrough to reestablish the
// connection.
case <-c.shutdown:
break out
}
reconnect:
for {
select {
case <-c.shutdown:
break out
default:
}
wsConn, err := dial(c.config)
if err != nil {
c.retryCount++
log.Infof("Failed to connect to %s: %v",
c.config.Host, err)
// Scale the retry interval by the number of
// retries so there is a backoff up to a max
// of 1 minute.
scaledInterval := connectionRetryInterval.Nanoseconds() * c.retryCount
scaledDuration := time.Duration(scaledInterval)
if scaledDuration > time.Minute {
scaledDuration = time.Minute
}
log.Infof("Retrying connection to %s in "+
"%s", c.config.Host, scaledDuration)
time.Sleep(scaledDuration)
continue reconnect
}
log.Infof("Reestablished connection to RPC server %s",
c.config.Host)
// Reset the connection state and signal the reconnect
// has happened.
c.wsConn = wsConn
c.retryCount = 0
c.mtx.Lock()
c.disconnect = make(chan struct{})
c.disconnected = false
c.mtx.Unlock()
// Start processing input and output for the
// new connection.
c.start()
// Reissue pending requests in another goroutine since
// the send can block.
go c.resendRequests()
// Break out of the reconnect loop back to wait for
// disconnect again.
break reconnect
}
}
c.wg.Done()
log.Tracef("RPC client reconnect handler done for %s", c.config.Host)
}
// handleSendPostMessage handles performing the passed HTTP request, reading the
// result, unmarshalling it, and delivering the unmarshalled result to the
// provided response channel.
func (c *Client) handleSendPostMessage(details *sendPostDetails) {
jReq := details.jsonRequest
log.Tracef("Sending command [%s] with id %d", jReq.method, jReq.id)
httpResponse, err := c.httpClient.Do(details.httpRequest)
if err != nil {
jReq.responseChan <- &response{err: err}
return
}
// Read the raw bytes and close the response.
respBytes, err := ioutil.ReadAll(httpResponse.Body)
httpResponse.Body.Close()
if err != nil {
err = fmt.Errorf("error reading json reply: %v", err)
jReq.responseChan <- &response{err: err}
return
}
// Try to unmarshal the response as a regular JSON-RPC response.
var resp rawResponse
err = json.Unmarshal(respBytes, &resp)
if err != nil {
// When the response itself isn't a valid JSON-RPC response
// return an error which includes the HTTP status code and raw
// response bytes.
err = fmt.Errorf("status code: %d, response: %q",
httpResponse.StatusCode, string(respBytes))
jReq.responseChan <- &response{err: err}
return
}
res, err := resp.result()
jReq.responseChan <- &response{result: res, err: err}
}
// sendPostHandler handles all outgoing messages when the client is running
// in HTTP POST mode. It uses a buffered channel to serialize output messages
// while allowing the sender to continue running asynchronously. It must be run
// as a goroutine.
func (c *Client) sendPostHandler() {
out:
for {
// Send any messages ready for send until the shutdown channel
// is closed.
select {
case details := <-c.sendPostChan:
c.handleSendPostMessage(details)
case <-c.shutdown:
break out
}
}
// Drain any wait channels before exiting so nothing is left waiting
// around to send.
cleanup:
for {
select {
case details := <-c.sendPostChan:
details.jsonRequest.responseChan <- &response{
result: nil,
err: ErrClientShutdown,
}
default:
break cleanup
}
}
c.wg.Done()
log.Tracef("RPC client send handler done for %s", c.config.Host)
}
// sendPostRequest sends the passed HTTP request to the RPC server using the
// HTTP client associated with the client. It is backed by a buffered channel,
// so it will not block until the send channel is full.
func (c *Client) sendPostRequest(httpReq *http.Request, jReq *jsonRequest) {
// Don't send the message if shutting down.
select {
case <-c.shutdown:
jReq.responseChan <- &response{result: nil, err: ErrClientShutdown}
default:
}
c.sendPostChan <- &sendPostDetails{
jsonRequest: jReq,
httpRequest: httpReq,
}
}
// newFutureError returns a new future result channel that already has the
// passed error waitin on the channel with the reply set to nil. This is useful
// to easily return errors from the various Async functions.
func newFutureError(err error) chan *response {
responseChan := make(chan *response, 1)
responseChan <- &response{err: err}
return responseChan
}
// receiveFuture receives from the passed futureResult channel to extract a
// reply or any errors. The examined errors include an error in the
// futureResult and the error in the reply from the server. This will block
// until the result is available on the passed channel.
func receiveFuture(f chan *response) ([]byte, error) {
// Wait for a response on the returned channel.
r := <-f
return r.result, r.err
}
// sendPost sends the passed request to the server by issuing an HTTP POST
// request using the provided response channel for the reply. Typically a new
// connection is opened and closed for each command when using this method,
// however, the underlying HTTP client might coalesce multiple commands
// depending on several factors including the remote server configuration.
func (c *Client) sendPost(jReq *jsonRequest) {
// Generate a request to the configured RPC server.
protocol := "http"
if !c.config.DisableTLS {
protocol = "https"
}
url := protocol + "://" + c.config.Host
bodyReader := bytes.NewReader(jReq.marshalledJSON)
httpReq, err := http.NewRequest("POST", url, bodyReader)
if err != nil {
jReq.responseChan <- &response{result: nil, err: err}
return
}
httpReq.Close = true
httpReq.Header.Set("Content-Type", "application/json")
// Configure basic access authorization.
httpReq.SetBasicAuth(c.config.User, c.config.Pass)
log.Tracef("Sending command [%s] with id %d", jReq.method, jReq.id)
c.sendPostRequest(httpReq, jReq)
}
// sendRequest sends the passed json request to the associated server using the
// provided response channel for the reply. It handles both websocket and HTTP
// POST mode depending on the configuration of the client.
func (c *Client) sendRequest(jReq *jsonRequest) {
// Choose which marshal and send function to use depending on whether
// the client running in HTTP POST mode or not. When running in HTTP
// POST mode, the command is issued via an HTTP client. Otherwise,
// the command is issued via the asynchronous websocket channels.
if c.config.HTTPPostMode {
c.sendPost(jReq)
return
}
// Check whether the websocket connection has never been established,
// in which case the handler goroutines are not running.
select {
case <-c.connEstablished:
default:
jReq.responseChan <- &response{err: ErrClientNotConnected}
return
}
// Add the request to the internal tracking map so the response from the
// remote server can be properly detected and routed to the response
// channel. Then send the marshalled request via the websocket
// connection.
if err := c.addRequest(jReq); err != nil {
jReq.responseChan <- &response{err: err}
return
}
log.Tracef("Sending command [%s] with id %d", jReq.method, jReq.id)
c.sendMessage(jReq.marshalledJSON)
}
// sendCmd sends the passed command to the associated server and returns a
// response channel on which the reply will be delivered at some point in the
// future. It handles both websocket and HTTP POST mode depending on the
// configuration of the client.
func (c *Client) sendCmd(cmd interface{}) chan *response {
// Get the method associated with the command.
method, err := btcjson.CmdMethod(cmd)
if err != nil {
return newFutureError(err)
}
// Marshal the command.
id := c.NextID()
marshalledJSON, err := btcjson.MarshalCmd(id, cmd)
if err != nil {
return newFutureError(err)
}
// Generate the request and send it along with a channel to respond on.
responseChan := make(chan *response, 1)
jReq := &jsonRequest{
id: id,
method: method,
cmd: cmd,
marshalledJSON: marshalledJSON,
responseChan: responseChan,
}
c.sendRequest(jReq)
return responseChan
}
// sendCmdAndWait sends the passed command to the associated server, waits
// for the reply, and returns the result from it. It will return the error
// field in the reply if there is one.
func (c *Client) sendCmdAndWait(cmd interface{}) (interface{}, error) {
// Marshal the command to JSON-RPC, send it to the connected server, and
// wait for a response on the returned channel.
return receiveFuture(c.sendCmd(cmd))
}
// Disconnected returns whether or not the server is disconnected. If a
// websocket client was created but never connected, this also returns false.
func (c *Client) Disconnected() bool {
c.mtx.Lock()
defer c.mtx.Unlock()
select {
case <-c.connEstablished:
return c.disconnected
default:
return false
}
}
// doDisconnect disconnects the websocket associated with the client if it
// hasn't already been disconnected. It will return false if the disconnect is
// not needed or the client is running in HTTP POST mode.
//
// This function is safe for concurrent access.
func (c *Client) doDisconnect() bool {
if c.config.HTTPPostMode {
return false
}
c.mtx.Lock()
defer c.mtx.Unlock()
// Nothing to do if already disconnected.
if c.disconnected {
return false
}
log.Tracef("Disconnecting RPC client %s", c.config.Host)
close(c.disconnect)
if c.wsConn != nil {
c.wsConn.Close()
}
c.disconnected = true
return true
}
// doShutdown closes the shutdown channel and logs the shutdown unless shutdown
// is already in progress. It will return false if the shutdown is not needed.
//
// This function is safe for concurrent access.
func (c *Client) doShutdown() bool {
// Ignore the shutdown request if the client is already in the process
// of shutting down or already shutdown.
select {
case <-c.shutdown:
return false
default:
}
log.Tracef("Shutting down RPC client %s", c.config.Host)
close(c.shutdown)
return true
}
// Disconnect disconnects the current websocket associated with the client. The
// connection will automatically be re-established unless the client was
// created with the DisableAutoReconnect flag.
//
// This function has no effect when the client is running in HTTP POST mode.
func (c *Client) Disconnect() {
// Nothing to do if already disconnected or running in HTTP POST mode.
if !c.doDisconnect() {
return
}
c.requestLock.Lock()
defer c.requestLock.Unlock()
// When operating without auto reconnect, send errors to any pending
// requests and shutdown the client.
if c.config.DisableAutoReconnect {
for e := c.requestList.Front(); e != nil; e = e.Next() {
req := e.Value.(*jsonRequest)
req.responseChan <- &response{
result: nil,
err: ErrClientDisconnect,
}
}
c.removeAllRequests()
c.doShutdown()
}
}
// Shutdown shuts down the client by disconnecting any connections associated
// with the client and, when automatic reconnect is enabled, preventing future
// attempts to reconnect. It also stops all goroutines.
func (c *Client) Shutdown() {
// Do the shutdown under the request lock to prevent clients from
// adding new requests while the client shutdown process is initiated.
c.requestLock.Lock()
defer c.requestLock.Unlock()
// Ignore the shutdown request if the client is already in the process
// of shutting down or already shutdown.