HttpServerConnection#StartStreaming(): release CpuBoundWork

so that /v1/events doesn't have to use IoBoundWorkSlot. IoBoundWorkSlot#~IoBoundWorkSlot() will wait for a free semaphore slot which will be almost immediately released by CpuBoundWork#~CpuBoundWork(). Just releasing the already aquired slot in HttpServerConnection#StartStreaming() is more efficient.

Author: Al2Klimov

lib/remote/eventshandler.cpp

@@ -105,8 +105,6 @@ bool EventsHandler::HandleRequest(
 	response.result(http::status::ok);
 	response.set(http::field::content_type, "application/json");
 
-	IoBoundWorkSlot dontLockTheIoThread (yc);
-
 	http::async_write(stream, response, yc);
 	stream.async_flush(yc);
 

lib/remote/httpserverconnection.cpp

@@ -12,7 +12,6 @@
 #include "base/configtype.hpp"
 #include "base/defer.hpp"
 #include "base/exception.hpp"
-#include "base/io-engine.hpp"
 #include "base/logger.hpp"
 #include "base/objectlock.hpp"
 #include "base/timer.hpp"
@@ -105,6 +104,9 @@ void HttpServerConnection::StartStreaming()
 
 	m_HasStartedStreaming = true;
 
+	VERIFY(m_HandlingRequest);
+	m_HandlingRequest->Done();
+
 	HttpServerConnection::Ptr keepAlive (this);
 
 	IoEngine::SpawnCoroutine(m_IoStrand, [this, keepAlive](asio::yield_context yc) {
@@ -418,6 +420,7 @@ bool ProcessRequest(
 	ApiUser::Ptr& authenticatedUser,
 	boost::beast::http::response<boost::beast::http::string_body>& response,
 	HttpServerConnection& server,
+	CpuBoundWork*& m_HandlingRequest,
 	bool& hasStartedStreaming,
 	std::chrono::steady_clock::duration& cpuBoundWorkTime,
 	boost::asio::yield_context& yc
@@ -431,6 +434,9 @@ bool ProcessRequest(
 		CpuBoundWork handlingRequest (yc);
 		cpuBoundWorkTime = std::chrono::steady_clock::now() - start;
 
+		Defer resetHandlingRequest ([&m_HandlingRequest] { m_HandlingRequest = nullptr; });
+		m_HandlingRequest = &handlingRequest;
+
 		HttpHandler::ProcessRequest(stream, authenticatedUser, request, response, yc, server);
 	} catch (const std::exception& ex) {
 		if (hasStartedStreaming) {
@@ -548,7 +554,7 @@ void HttpServerConnection::ProcessMessages(boost::asio::yield_context yc)
 
 			m_Seen = std::numeric_limits<decltype(m_Seen)>::max();
 
-			if (!ProcessRequest(*m_Stream, request, authenticatedUser, response, *this, m_HasStartedStreaming, cpuBoundWorkTime, yc)) {
+			if (!ProcessRequest(*m_Stream, request, authenticatedUser, response, *this, m_HandlingRequest, m_HasStartedStreaming, cpuBoundWorkTime, yc)) {
 				break;
 			}
 

lib/remote/httpserverconnection.hpp

@@ -4,6 +4,7 @@
 #define HTTPSERVERCONNECTION_H
 
 #include "remote/apiuser.hpp"
+#include "base/io-engine.hpp"
 #include "base/string.hpp"
 #include "base/tlsstream.hpp"
 #include <memory>
@@ -40,6 +41,7 @@ class HttpServerConnection final : public Object
 	boost::asio::io_context::strand m_IoStrand;
 	bool m_ShuttingDown;
 	bool m_HasStartedStreaming;
+	CpuBoundWork* m_HandlingRequest = nullptr;
 	boost::asio::deadline_timer m_CheckLivenessTimer;
 
 	HttpServerConnection(const String& identity, bool authenticated, const Shared<AsioTlsStream>::Ptr& stream, boost::asio::io_context& io);