several fixes for client's keep alive connections

base/poco/Net/include/Poco/Net/HTTPClientSession.h

@@ -213,6 +213,19 @@ namespace Net
         Poco::Timespan getKeepAliveTimeout() const;
         /// Returns the connection timeout for HTTP connections.
 
+        void setKeepAliveMaxRequests(int max_requests);
+
+        int getKeepAliveMaxRequests() const;
+
+        int getKeepAliveRequest() const;
+
+        bool isKeepAliveExpired(double reliability = 1.0) const;
+        /// Returns if the connection is expired with some margin as fraction of timeout as reliability
+
+        double getKeepAliveReliability() const;
+        /// Returns the current fraction of keep alive timeout when connection is considered safe to use
+        /// It helps to avoid situation when a client uses nearly expired connection and receives NoMessageException
+
         virtual std::ostream & sendRequest(HTTPRequest & request);
         /// Sends the header for the given HTTP request to
         /// the server.
@@ -345,6 +358,8 @@ namespace Net
 
         void assign(HTTPClientSession & session);
 
+        void setKeepAliveRequest(int request);
+
         HTTPSessionFactory _proxySessionFactory;
         /// Factory to create HTTPClientSession to proxy.
     private:
@@ -353,6 +368,8 @@ namespace Net
         Poco::UInt16 _port;
         ProxyConfig _proxyConfig;
         Poco::Timespan _keepAliveTimeout;
+        int _keepAliveCurrentRequest = 0;
+        int _keepAliveMaxRequests = 1000;
         Poco::Timestamp _lastRequest;
         bool _reconnect;
         bool _mustReconnect;
@@ -361,6 +378,7 @@ namespace Net
         Poco::SharedPtr<std::ostream> _pRequestStream;
         Poco::SharedPtr<std::istream> _pResponseStream;
 
+        static const double _defaultKeepAliveReliabilityLevel;
         static ProxyConfig _globalProxyConfig;
 
         HTTPClientSession(const HTTPClientSession &);
@@ -450,9 +468,19 @@ namespace Net
         return _lastRequest;
     }
 
-    inline void HTTPClientSession::setLastRequest(Poco::Timestamp time)
+    inline double HTTPClientSession::getKeepAliveReliability() const
+    {
+        return _defaultKeepAliveReliabilityLevel;
+    }
+
+    inline int HTTPClientSession::getKeepAliveMaxRequests() const
+    {
+        return _keepAliveMaxRequests;
+    }
+
+    inline int HTTPClientSession::getKeepAliveRequest() const
     {
-        _lastRequest = time;
+        return _keepAliveCurrentRequest;
     }
 
 }

base/poco/Net/include/Poco/Net/HTTPMessage.h

@@ -120,6 +120,10 @@ namespace Net
         /// The value is set to "Keep-Alive" if keepAlive is
         /// true, or to "Close" otherwise.
 
+        void setKeepAliveTimeout(int timeout, int max_requests);
+        int getKeepAliveTimeout() const;
+        int getKeepAliveMaxRequests() const;
+
         bool getKeepAlive() const;
         /// Returns true if
         ///   * the message has a Connection header field and its value is "Keep-Alive"

base/poco/Net/include/Poco/Net/HTTPServerParams.h

@@ -44,7 +44,7 @@ namespace Net
         ///   - timeout:              60 seconds
         ///   - keepAlive:            true
         ///   - maxKeepAliveRequests: 0
-        ///   - keepAliveTimeout:     10 seconds
+        ///   - keepAliveTimeout:     15 seconds
 
         void setServerName(const std::string & serverName);
         /// Sets the name and port (name:port) that the server uses to identify itself.

base/poco/Net/include/Poco/Net/HTTPServerSession.h

@@ -56,6 +56,8 @@ namespace Net
         SocketAddress serverAddress();
         /// Returns the server's address.
 
+        void setKeepAliveTimeout(Poco::Timespan keepAliveTimeout);
+
     private:
         bool _firstRequest;
         Poco::Timespan _keepAliveTimeout;

base/poco/Net/src/HTTPClientSession.cpp

@@ -37,6 +37,7 @@ namespace Net {
 
 
 HTTPClientSession::ProxyConfig HTTPClientSession::_globalProxyConfig;
+const double HTTPClientSession::_defaultKeepAliveReliabilityLevel = 0.9;
 
 
 HTTPClientSession::HTTPClientSession():
@@ -220,7 +221,41 @@ void HTTPClientSession::setGlobalProxyConfig(const ProxyConfig& config)
 
 void HTTPClientSession::setKeepAliveTimeout(const Poco::Timespan& timeout)
 {
-	_keepAliveTimeout = timeout;
+    if (connected())
+    {
+        throw Poco::IllegalStateException("cannot change keep alive timeout on initiated connection, "
+                                          "That value is managed privately after connection is established.");
+    }
+    _keepAliveTimeout = timeout;
+}
+
+
+void HTTPClientSession::setKeepAliveMaxRequests(int max_requests)
+{
+    if (connected())
+    {
+        throw Poco::IllegalStateException("cannot change keep alive max requests on initiated connection, "
+                                          "That value is managed privately after connection is established.");
+    }
+    _keepAliveMaxRequests = max_requests;
+}
+
+
+void HTTPClientSession::setKeepAliveRequest(int request)
+{
+    _keepAliveCurrentRequest = request;
+}
+
+
+
+void HTTPClientSession::setLastRequest(Poco::Timestamp time)
+{
+    if (connected())
+    {
+        throw Poco::IllegalStateException("cannot change last request on initiated connection, "
+                                          "That value is managed privately after connection is established.");
+    }
+    _lastRequest = time;
 }
 
 
@@ -231,6 +266,8 @@ std::ostream& HTTPClientSession::sendRequest(HTTPRequest& request)
 	clearException();
 	_responseReceived = false;
 
+    _keepAliveCurrentRequest += 1;
+
 	bool keepAlive = getKeepAlive();
 	if (((connected() && !keepAlive) || mustReconnect()) && !_host.empty())
 	{
@@ -241,8 +278,10 @@ std::ostream& HTTPClientSession::sendRequest(HTTPRequest& request)
 	{
 		if (!connected())
 			reconnect();
-		if (!keepAlive)
-			request.setKeepAlive(false);
+        if (!request.has(HTTPMessage::CONNECTION))
+            request.setKeepAlive(keepAlive);
+        if (keepAlive && !request.has(HTTPMessage::CONNECTION_KEEP_ALIVE) && _keepAliveTimeout.totalSeconds() > 0)
+            request.setKeepAliveTimeout(_keepAliveTimeout.totalSeconds(), _keepAliveMaxRequests);
 		if (!request.has(HTTPRequest::HOST) && !_host.empty())
 			request.setHost(_host, _port);
 		if (!_proxyConfig.host.empty() && !bypassProxy())
@@ -324,6 +363,17 @@ std::istream& HTTPClientSession::receiveResponse(HTTPResponse& response)
 
 	_mustReconnect = getKeepAlive() && !response.getKeepAlive();
 
+    if (!_mustReconnect)
+    {
+        /// when server sends its keep alive timeout, client has to follow that value
+        auto timeout = response.getKeepAliveTimeout();
+        if (timeout > 0)
+            _keepAliveTimeout = std::min(_keepAliveTimeout, Poco::Timespan(timeout, 0));
+        auto max_requests = response.getKeepAliveMaxRequests();
+        if (max_requests > 0)
+            _keepAliveMaxRequests = std::min(_keepAliveMaxRequests, max_requests);
+    }
+
 	if (!_expectResponseBody || response.getStatus() < 200 || response.getStatus() == HTTPResponse::HTTP_NO_CONTENT || response.getStatus() == HTTPResponse::HTTP_NOT_MODIFIED)
 		_pResponseStream = new HTTPFixedLengthInputStream(*this, 0);
 	else if (response.getChunkedTransferEncoding())
@@ -430,15 +480,18 @@ std::string HTTPClientSession::proxyRequestPrefix() const
 	return result;
 }
 
+bool HTTPClientSession::isKeepAliveExpired(double reliability) const
+{
+    Poco::Timestamp now;
+    return Timespan(Timestamp::TimeDiff(reliability *_keepAliveTimeout.totalMicroseconds())) <= now - _lastRequest
+            || _keepAliveCurrentRequest > _keepAliveMaxRequests;
+}
 
 bool HTTPClientSession::mustReconnect() const
 {
 	if (!_mustReconnect)
-	{
-		Poco::Timestamp now;
-		return _keepAliveTimeout <= now - _lastRequest;
-	}
-	else return true;
+        return isKeepAliveExpired(_defaultKeepAliveReliabilityLevel);
+    return true;
 }
 
 
@@ -511,14 +564,21 @@ void HTTPClientSession::assign(Poco::Net::HTTPClientSession & session)
     if (buffered())
         throw Poco::LogicException("assign to a session with not empty buffered data");
 
-    attachSocket(session.detachSocket());
-    setLastRequest(session.getLastRequest());
+    poco_assert(!connected());
+
     setResolvedHost(session.getResolvedHost());
-    setKeepAlive(session.getKeepAlive());
+    setProxyConfig(session.getProxyConfig());
 
     setTimeout(session.getConnectionTimeout(), session.getSendTimeout(), session.getReceiveTimeout());
+    setKeepAlive(session.getKeepAlive());
+
+    setLastRequest(session.getLastRequest());
     setKeepAliveTimeout(session.getKeepAliveTimeout());
-    setProxyConfig(session.getProxyConfig());
+
+    _keepAliveMaxRequests = session._keepAliveMaxRequests;
+    _keepAliveCurrentRequest = session._keepAliveCurrentRequest;
+
+    attachSocket(session.detachSocket());
 
     session.reset();
 }

base/poco/Net/src/HTTPMessage.cpp

@@ -17,6 +17,7 @@
 #include "Poco/NumberFormatter.h"
 #include "Poco/NumberParser.h"
 #include "Poco/String.h"
+#include <format>
 
 
 using Poco::NumberFormatter;
@@ -179,4 +180,51 @@ bool HTTPMessage::getKeepAlive() const
 }
 
 
+void HTTPMessage::setKeepAliveTimeout(int timeout, int max_requests)
+{
+    add(HTTPMessage::CONNECTION_KEEP_ALIVE, std::format("timeout={}, max={}", timeout, max_requests));
+}
+
+
+int parseFromHeaderValues(const std::string_view header_value, const std::string_view param_name)
+{
+    auto param_value_pos = header_value.find(param_name);
+    if (param_value_pos == std::string::npos)
+        param_value_pos = header_value.size();
+    if (param_value_pos != header_value.size())
+        param_value_pos += param_name.size();
+
+    auto param_value_end = header_value.find(',', param_value_pos);
+    if (param_value_end == std::string::npos)
+        param_value_end = header_value.size();
+
+    auto timeout_value_substr = header_value.substr(param_value_pos, param_value_end - param_value_pos);
+    if (timeout_value_substr.empty())
+        return -1;
+
+    int value = 0;
+    auto [ptr, ec] = std::from_chars(timeout_value_substr.begin(), timeout_value_substr.end(), value);
+
+    if (ec == std::errc())
+        return value;
+
+    return -1;
+}
+
+
+int HTTPMessage::getKeepAliveTimeout() const
+{
+    const std::string& ka_header = get(HTTPMessage::CONNECTION_KEEP_ALIVE, HTTPMessage::EMPTY);
+    static const std::string_view timeout_param = "timeout=";
+    return parseFromHeaderValues(ka_header, timeout_param);
+}
+
+
+int HTTPMessage::getKeepAliveMaxRequests() const
+{
+    const std::string& ka_header = get(HTTPMessage::CONNECTION_KEEP_ALIVE, HTTPMessage::EMPTY);
+    static const std::string_view timeout_param = "max=";
+    return parseFromHeaderValues(ka_header, timeout_param);
+}
+
 } } // namespace Poco::Net

base/poco/Net/src/HTTPServerConnection.cpp

@@ -88,7 +88,18 @@ void HTTPServerConnection::run()
 
 						pHandler->handleRequest(request, response);
 						session.setKeepAlive(_pParams->getKeepAlive() && response.getKeepAlive() && session.canKeepAlive());
-					}
+
+                        /// all that fuzz is all about to make session close with less timeout than 15s (set in HTTPServerParams c-tor)
+                        if (_pParams->getKeepAlive() && response.getKeepAlive() && session.canKeepAlive())
+                        {
+                            int value = response.getKeepAliveTimeout();
+                            if (value < 0)
+                                value = request.getKeepAliveTimeout();
+                            if (value > 0)
+                                session.setKeepAliveTimeout(Poco::Timespan(value, 0));
+                        }
+
+                    }
 					else sendErrorResponse(session, HTTPResponse::HTTP_NOT_IMPLEMENTED);
 				}
 				catch (Poco::Exception&)

base/poco/Net/src/HTTPServerSession.cpp

@@ -33,6 +33,12 @@ HTTPServerSession::~HTTPServerSession()
 {
 }
 
+void HTTPServerSession::setKeepAliveTimeout(Poco::Timespan keepAliveTimeout)
+{
+    _keepAliveTimeout = keepAliveTimeout;
+}
+
+
 
 bool HTTPServerSession::hasMoreRequests()
 {