In okhttp, it makes a 1 ms connection health check for every request. It has obvious influence in my application.
What's this check for?
Is it possible to add a config to disable the check?
if (doExtensiveChecks) {
try {
int readTimeout = socket.getSoTimeout();
try {
socket.setSoTimeout(1);
if (source.exhausted()) {
return false; // Stream is exhausted; socket is closed.
}
return true;
} finally {
socket.setSoTimeout(readTimeout);
}
} catch (SocketTimeoutException ignored) {
// Read timed out; socket is good.
} catch (IOException e) {
return false; // Couldn't read; socket is closed.
}
}
The most obvious fix would be to ensure you are using HTTP/2, which would skip this work on the socket and rely on pings etc.
FWIW extensive checks are based on the HTTP method, so should not be an issue with GET operations.
// We need the network to satisfy this request. Possibly for validating a conditional GET.
val doExtensiveHealthChecks = request.method != "GET"
val exchange = transmitter.newExchange(chain, doExtensiveHealthChecks)
Is this an option?
Related
I've been trying to use and understand the DirectoryWatcher class from Microsoft's Cloud Mirror sample. It uses ReadDirectoryChangesW to monitor changes to a directory. I don't think it's reporting all changes, to be honest. In any event, I had a question about the key part of the code, which is as follows:
concurrency::task<void> DirectoryWatcher::ReadChangesAsync()
{
auto token = _cancellationTokenSource.get_token();
return concurrency::create_task([this, token]
{
while (true)
{
DWORD returned;
winrt::check_bool(ReadDirectoryChangesW(
_dir.get(),
_notify.get(),
c_bufferSize,
TRUE,
FILE_NOTIFY_CHANGE_ATTRIBUTES,
&returned,
&_overlapped,
nullptr));
DWORD transferred;
if (GetOverlappedResultEx(_dir.get(), &_overlapped, &transferred, 1000, FALSE))
{
std::list<std::wstring> result;
FILE_NOTIFY_INFORMATION* next = _notify.get();
while (next != nullptr)
{
std::wstring fullPath(_path);
fullPath.append(L"\\");
fullPath.append(std::wstring_view(next->FileName, next->FileNameLength / sizeof(wchar_t)));
result.push_back(fullPath);
if (next->NextEntryOffset)
{
next = reinterpret_cast<FILE_NOTIFY_INFORMATION*>(reinterpret_cast<char*>(next) + next->NextEntryOffset);
}
else
{
next = nullptr;
}
}
_callback(result);
}
else if (GetLastError() != WAIT_TIMEOUT)
{
throw winrt::hresult_error(HRESULT_FROM_WIN32(GetLastError()));
}
else if (token.is_canceled())
{
wprintf(L"watcher cancel received\n");
concurrency::cancel_current_task();
return;
}
}
}, token);
}
After reviewing an answer to another question, here's what I don't understand about the code above: isn't the code potentially re-calling ReadDirectoryChangesW before the prior call has returned a result? Or is this code indeed correct? Thanks for any input.
Yes, I seem to have confirmed in my testing that there should be another while loop there around the call to GetOverlappedResultEx, similar to the sample code provided in that other answer. I think the notifications are firing properly with it.
Shouldn't there also be a call to CancelIo in there, too? Or is that not necessary for some reason?
I want to implement Play Install Referrer API and I found document and I read that but I have have some confusion. First I have implemented all code provided by google. But I want to know which type of url I need to create so that user can click on link and go to play store and install my app and then I get the referral detail..
I use this code:
InstallReferrerClient mReferrerClient;
mReferrerClient = newBuilder(this).build();
mReferrerClient.startConnection(this);
#Override
public void onInstallReferrerSetupFinished ( int responseCode){
switch (responseCode) {
case InstallReferrerClient.InstallReferrerResponse.OK:
// Connection established
/* ReferrerDetails response = null;
try {
response = mReferrerClient.getInstallReferrer();
response.getInstallReferrer();
response.getReferrerClickTimestampSeconds();
response.getInstallBeginTimestampSeconds();
} catch (RemoteException e) {
e.printStackTrace();
}*/
break;
case InstallReferrerClient.InstallReferrerResponse.FEATURE_NOT_SUPPORTED:
// API not available on the current Play Store app
break;
case InstallReferrerClient.InstallReferrerResponse.SERVICE_UNAVAILABLE:
// Connection could not be established
break;
}
}
#Override
public void onInstallReferrerServiceDisconnected () {
}
But which type of link I create so user go to play store and after install play store referral api give me data..
Sample url - "https://play.google.com/store/apps/details?id=com.dummy.app&referrer=referralCode%3D311566%26source%3DFacebook+App"
When using the Google Play Referrer API -
InstallReferrerClient mReferrerClient;
mReferrerClient = newBuilder(this).build();
mReferrerClient.startConnection(this);
#Override
public void onInstallReferrerSetupFinished ( int responseCode){
switch (responseCode) {
case InstallReferrerClient.InstallReferrerResponse.OK:
// Connection established
/* ReferrerDetails response = null;
try {
response = mReferrerClient.getInstallReferrer();
response.getInstallReferrer();
response.getReferrerClickTimestampSeconds();
response.getInstallBeginTimestampSeconds();
} catch (RemoteException e) {
e.printStackTrace();
}*/
// End the connection once you get the data
referrerClient.endConnection();
break;
case InstallReferrerClient.InstallReferrerResponse.FEATURE_NOT_SUPPORTED:
// API not available on the current Play Store app
break;
case InstallReferrerClient.InstallReferrerResponse.SERVICE_UNAVAILABLE:
// Connection could not be established
break;
}
}
#Override
public void onInstallReferrerServiceDisconnected () {
}
getInstallReferrer()
will return String 'referralCode=311566&source=Facebook App'
play install referral library i wants to describe this in simple wording, being a developer you wants to know about these elements how much time you app bundle take to install on the user devices from play store, and referral url , referral click time and many others elements , google make it easy for you know you have to use play install referral library for this purpose.
add this dependency
implementation 'com.android.installreferrer:installreferrer:1.1'
you can follow the guidelines from here:
play installer referral guidelines
declare this variable in any java activity
InstallReferrerClient referrerClient;
in on create method use this code below :
referrerClient = InstallReferrerClient.newBuilder(this).build();
referrerClient.startConnection(new InstallReferrerStateListener() {
#Override
public void onInstallReferrerSetupFinished(int responseCode) {
switch (responseCode) {
case InstallReferrerClient.InstallReferrerResponse.OK:
// Connection established.
break;
case InstallReferrerClient.InstallReferrerResponse.FEATURE_NOT_SUPPORTED:
// API not available on the current Play Store app.
break;
case InstallReferrerClient.InstallReferrerResponse.SERVICE_UNAVAILABLE:
// Connection couldn't be established.
break;
}
}
#Override
public void onInstallReferrerServiceDisconnected() {
// Try to restart the connection on the next request to
// Google Play by calling the startConnection() method.
}
});
inside onInstallReferrerSetupFinished stabled you can get these data easily,you code will be after that like this
ReferrerDetails response = null;
try {
response = referrerClient.getInstallReferrer();
} catch (RemoteException e) {
e.printStackTrace();
}
String referrerUrl = response.getInstallReferrer();
long referrerClickTime = response.getReferrerClickTimestampSeconds();
long appInstallTime = response.getInstallBeginTimestampSeconds();
boolean instantExperienceLaunched = response.getGooglePlayInstantParam();
whole code will be like this
referrerClient = InstallReferrerClient.newBuilder(this).build();
referrerClient.startConnection(new InstallReferrerStateListener() {
#Override
public void onInstallReferrerSetupFinished(int responseCode) {
switch (responseCode) {
case InstallReferrerClient.InstallReferrerResponse.OK:
// Connection established.
ReferrerDetails response = null;
try {
response = referrerClient.getInstallReferrer();
} catch (RemoteException e) {
e.printStackTrace();
}
String referrerUrl = response.getInstallReferrer();
long referrerClickTime = response.getReferrerClickTimestampSeconds();
long appInstallTime = response.getInstallBeginTimestampSeconds();
boolean instantExperienceLaunched = response.getGooglePlayInstantParam();
break;
case InstallReferrerClient.InstallReferrerResponse.FEATURE_NOT_SUPPORTED:
// API not available on the current Play Store app.
break;
case InstallReferrerClient.InstallReferrerResponse.SERVICE_UNAVAILABLE:
// Connection couldn't be established.
break;
}
}
#Override
public void onInstallReferrerServiceDisconnected() {
// Try to restart the connection on the next request to
// Google Play by calling the startConnection() method.
}
});
I use ConnectivityPlugin (CrossConnectivity.Current.IsConnected field) to check the Internet connection. The problem is that it only checks if the internet connection button is pressed. That is, if I am connected to the mobile network, but there is no Internet itself (for example, problems from the operator), then the CrossConnectivity.Current.IsConnected field for such a situation returns true (although there is no connection). Question: how to check whether there is access to the Internet? Thanks
You can use the Device.StartTimer(TimeSpan, Func) method.
Device.StartTimer(TimeSpan.FromSeconds(1), () =>
{
//insert checking of internet connection
}
Assuming "google.com" is always up and running:
if (CrossConnectivity.Current.IsConnected)
{
try {
Ping ping = new Ping();
String host = "google.com";
byte[] buffer = new byte[32];
int timeout = 1000;
PingOptions pingOptions = new PingOptions();
PingReply reply = ping.Send(host, timeout, buffer, pingOptions);
if (reply.Status == IPStatus.Success){
// Your code here...
}
}
catch (Exception) {
return false;
}
}
I recommend to add the following code to your App.xaml.cs class OnStart method and that take care of it.
CrossConnectivity.Current.ConnectivityChanged += (sender, e) =>
{
if (!CrossConnectivity.Current.IsConnected)
{
Console.WriteLine("Internet connectivity lost");
}
};
When I run my code I get:
Breaking on exception: String expected
What I am trying to do is connect to my server using a websocket. However, it seems that no matter if my server is online or not the client still crashes.
My code:
import 'dart:html';
WebSocket serverConn;
int connectionAttempts;
TextAreaElement inputField = querySelector("#inputField");
String key;
void submitMessage(Event e) {
if (serverConn.readyState == WebSocket.OPEN) {
querySelector("#chatLog").text = inputField.value;
inputField.value = "";
}
}
void recreateConnection(Event e) {
connectionAttempts++;
if (connectionAttempts <= 5) {
inputField.value = "Connection failed, reconnecting. Attempt" + connectionAttempts.toString() + "out of 5";
serverConn = new WebSocket("ws://127.0.0.1:8887");
serverConn.onClose.listen(recreateConnection);
serverConn.onError.listen(recreateConnection);
} else {
inputField.value = "Connections ran out, please refresh site";
}
}
void connected(Event e) {
serverConn.sendString(key);
if (serverConn.readyState == WebSocket.OPEN) {
inputField.value = "CONNECTED!";
inputField.readOnly = false;
}
}
void main() {
serverConn = new WebSocket("ws://127.0.0.1:8887");
serverConn.onClose.listen(recreateConnection);
serverConn.onError.listen(recreateConnection);
serverConn.onOpen.listen(connected);
//querySelector("#inputField").onInput.listen(submitMessage);
querySelector("#sendInput").onClick.listen(submitMessage);
}
My Dart Editor says nothing about where the problem comes from nor does it give any warning until run-time.
You need to initialize int connectionAttempts; with a valid value;
connectionAttempts++; fails with an exception on null.
You also need an onMessage handler to receive messages.
serverConn.onMessage.listen((MessageEvent e) {
recreateConnection should register an onOpen handler as well.
After serverConn = new WebSocket the listener registered in main() will not work
If you register a listener where only one single event is expected you can use first instead of listen
serverConn.onOpen.first.then(connected);
According to #JAre s comment.
Try to use a hardcoded string
querySelector("#chatLog").text = 'someValue';
to ensure this is not the culprit.
I am writing a kind of chat server app where a message received from one websocket client is sent out to all other websocket clients. To do this, I keep the connected clients in a list. When a client disconnects, I need to remove it from the list (so that future "sends" do not fail).
However, sometimes when a client disconnects, the server just gets an exception "connection reset by peer", and the code does not get chance to remove from the client list. Is there a way to guarantee a "nice" notification that the connection has been reset?
My code is:
void WsRequestHandler::handleRequest(HTTPServerRequest &req, HTTPServerResponse &resp)
{
int n;
Poco::Timespan timeOut(5,0);
try
{
req.set("Connection","Upgrade"); // knock out any extra tokens firefox may send such as "keep-alive"
ws = new WebSocket(req, resp);
ws->setKeepAlive(false);
connectedSockets->push_back(this);
do
{
flags = 0;
if (!ws->poll(timeOut,Poco::Net::Socket::SELECT_READ || Poco::Net::Socket::SELECT_ERROR))
{
// cout << ".";
}
else
{
n = ws->receiveFrame(buffer, sizeof(buffer), flags);
if (n > 0)
{
if ((flags & WebSocket::FRAME_OP_BITMASK) == WebSocket::FRAME_OP_BINARY)
{
// process and send out to all other clients
DoReceived(ws, buffer, n);
}
}
}
}
while ((flags & WebSocket::FRAME_OP_BITMASK) != WebSocket::FRAME_OP_CLOSE);
// client has closed, so remove from list
for (vector<WsRequestHandler *>::iterator it = connectedSockets->begin() ; it != connectedSockets->end(); ++it)
{
if (*it == this)
{
connectedSockets->erase(it);
logger->information("Connection closed %s", ws->peerAddress().toString());
break;
}
}
delete(ws);
ws = NULL;
}
catch (WebSocketException& exc)
{
//never gets called
}
}
See receiveFrame() documentation:
Returns the number of bytes received. A return value of 0 means that the peer has shut down or closed the connection.
So if receiveFrame() call returns zero, you can act acordingly.
I do not know if this is an answer to the question, but the implementation you have done does not deal with PING frames. This is currently (as of my POCO version: 1.7.5) not done automatically by the POCO framework. I put up a question about that recently. According to the RFC (6465), the ping and pong frames are used (among others) as a keep-alive function. This may therefore be critical to get right in order to get your connection stable over time. Much of this is guess-work from my side as I am experimenting with this now myself.
#Alex, you are a main developer of POCO I believe, a comment on my answer would be much appreciated.
I extended the catch, to do some exception handling for "Connection reset by peer".
catch (Poco::Net::WebSocketException& exc)
{
// Do something
}
catch (Poco::Exception& e)
{
// This is where the "Connection reset by peer" lands
}
A bit late to the party here... but I am using Poco and Websockets as well - and properly handling disconnects was tricky.
I ended up implementing a simple ping functionality myself where the client side sends an ACK message for every WS Frame it receives. A separate thread on the server side tries to read the ACK messages - and it will now detect when the client has disconnected by looking at flags | WebSocket::FRAME_OP_CLOSE.
//Serverside - POCO. Start thread for receiving ACK packages. Needed in order to detect when websocket is closed!
thread t0([&]()->void{
while((!KillFlag && ws!= nullptr && flags & WebSocket::FRAME_OP_BITMASK) != WebSocket::FRAME_OP_CLOSE && machineConnection != nullptr){
try{
if(ws == nullptr){
return;
}
if(ws->available() > 0){
int len = ws->receiveFrame(buffer, sizeof(buffer), flags);
}
else{
Util::Sleep(10);
}
}
catch(Poco::Exception &pex){
flags = flags | WebSocket::FRAME_OP_CLOSE;
return;
}
catch(...){
//log::info(string("Unknown exception in ACK Thread drained"));
return;
}
}
log::debug("OperatorWebHandler::HttpRequestHandler() Websocket Acking thread DONE");
});
on the client side I just send a dummy "ACK" message back to the server (JS) every time I receive a WS frame from the server (POCO).
websocket.onmessage = (evt) => {
_this.receivedData = JSON.parse(evt.data);
websocket.send("ACK");
};
It is not about disconnect handling, rather about the stability of the connection.
Had some issues with POCO Websocket server in StreamSocket mode and C# client. Sometimes the client sends Pong messages with zero length payload and disconnect occurs so I added Ping and Pong handling code.
int WebSocketImpl::receiveBytes(void* buffer, int length, int)
{
char mask[4];
bool useMask;
_frameFlags = 0;
for (;;) {
int payloadLength = receiveHeader(mask, useMask);
int frameOp = _frameFlags & WebSocket::FRAME_OP_BITMASK;
if (frameOp == WebSocket::FRAME_OP_PONG || frameOp ==
WebSocket::FRAME_OP_PING) {
std::vector<char> tmp(payloadLength);
if (payloadLength != 0) {
receivePayload(tmp.data(), payloadLength, mask, useMask);
}
if (frameOp == WebSocket::FRAME_OP_PING) {
sendBytes(tmp.data(), payloadLength, WebSocket::FRAME_OP_PONG);
}
continue;
}
if (payloadLength <= 0)
return payloadLength;
if (payloadLength > length)
throw WebSocketException(Poco::format("Insufficient buffer for
payload size %d", payloadLength),
WebSocket::WS_ERR_PAYLOAD_TOO_BIG);
return receivePayload(reinterpret_cast<char*>(buffer), payloadLength,
mask, useMask);
}
}