rstudio/src/cpp/session/SessionClientEventService.cpp at master · UXScripts/rstudio · GitHub

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* SessionClientEventService.cpp

* This program is licensed to you under the terms of version 3 of the

* GNU Affero General Public License. This program is distributed WITHOUT

* ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING THOSE OF NON-INFRINGEMENT,

* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Please refer to the

* AGPL (http://www.gnu.org/licenses/agpl-3.0.txt) for more details.

#include "SessionClientEventService.hpp"

#include <algorithm>

#include <boost/function.hpp>

#include <core/BoostThread.hpp>

#include <core/Log.hpp>

#include <core/Error.hpp>

#include <core/BoostErrors.hpp>

#include <core/Thread.hpp>

#include <core/system/System.hpp>

#include <core/http/Request.hpp>

#include <session/SessionOptions.hpp>

#include <session/SessionHttpConnectionListener.hpp>

#include "SessionClientEventQueue.hpp"

using namespace core;

namespace session {

namespace {

const int kLastChanceWaitSeconds = 4;

bool hasEventIdLessThanOrEqualTo(const json::Value& event, int targetId)

{

const json::Object& eventJSON = event.get_obj();

int eventId = eventJSON.find("id")->second.get_int();

return eventId <= targetId;

}

} // anonymous namespace

ClientEventService& clientEventService()

{

static ClientEventService instance ;

return instance ;

}

Error ClientEventService::start(const std::string& clientId)

{

// set our clientid

setClientId(clientId, false);

// block all signals for launch of background thread (will cause it

// to never receive signals)

core::system::SignalBlocker signalBlocker;

Error error = signalBlocker.blockAll();

if (error)

return error ;

// launch the service thread

try

{

using boost::bind;

boost::thread serviceThread(bind(&ClientEventService::run, this));

serviceThread_ = serviceThread.move();

return Success();

}

catch(const boost::thread_resource_error& e)

{

return Error(boost::thread_error::ec_from_exception(e), ERROR_LOCATION);

}

void ClientEventService::stop()

{

try

{

if (serviceThread_.joinable())

{

serviceThread_.interrupt();

// wait for for the service thread to stop

if (!serviceThread_.timed_join(

boost::posix_time::seconds(kLastChanceWaitSeconds + 1)))

{

LOG_WARNING_MESSAGE("ClientEventService didn't stop on its own");

}

serviceThread_.detach();

}

catch(const boost::thread_interrupted& e)

{

// the main thread is the one who calls stop() and it should

// NEVER be interrupted for any reason

LOG_WARNING_MESSAGE("thread interrupted during stop");

}

void ClientEventService::setClientId(const std::string& clientId, bool clearEvents)

{

LOCK_MUTEX(mutex_)

{

clientId_ = clientId.c_str(); // avoid ref count

if (clearEvents)

clientEvents_.clear();

}

END_LOCK_MUTEX

if (clearEvents)

clientEventQueue().clear();

}

std::string ClientEventService::clientId()

{

LOCK_MUTEX(mutex_)

{

return std::string(clientId_.c_str()) ; // avoid ref-count

}

END_LOCK_MUTEX

// keep compiler happy

return std::string();

}

void ClientEventService::erasePreviouslyDeliveredEvents(int lastClientEventIdSeen)

{

LOCK_MUTEX(mutex_)

{

clientEvents_.erase(

std::remove_if(clientEvents_.begin(),

clientEvents_.end(),

boost::bind(hasEventIdLessThanOrEqualTo,

_1,

lastClientEventIdSeen)),

clientEvents_.end());

}

END_LOCK_MUTEX

}

bool ClientEventService::havePendingClientEvents()

{

LOCK_MUTEX(mutex_)

{

return !clientEvents_.empty();

}

END_LOCK_MUTEX

// keep compiler happy

return false;

}

void ClientEventService::addClientEvent(const json::Object& eventObject)

{

LOCK_MUTEX(mutex_)

{

clientEvents_.push_back(eventObject);

}

END_LOCK_MUTEX

}

void ClientEventService::setClientEventResult(

core::json::JsonRpcResponse* pResponse)

{

LOCK_MUTEX(mutex_)

{

pResponse->setResult(clientEvents_);

}

END_LOCK_MUTEX

}

void ClientEventService::run()

{

try

{

// default time durations

using namespace boost::posix_time;

time_duration maxRequestSec = seconds(50);

time_duration batchDelay = milliseconds(20);

time_duration maxTotalBatchDelay = seconds(2);

// make much shorter for desktop mode

if (session::options().programMode() == kSessionProgramModeDesktop)

{

batchDelay = milliseconds(2);

maxTotalBatchDelay = milliseconds(10);

}

// get alias to client event queue

ClientEventQueue& clientEventQueue = session::clientEventQueue();

// initialize state

int nextEventId = 0;

// accept loop

bool stopServer = false ;

while (!stopServer || clientEventQueue.hasEvents())

{

boost::shared_ptr<HttpConnection> ptrConnection ;

try

{

// wait for up to 1 second for a connection

long secondsToWait = stopServer ? kLastChanceWaitSeconds : 1;

ptrConnection =

httpConnectionListener().eventsConnectionQueue().dequeConnection(

boost::posix_time::seconds(secondsToWait));

// if we didn't get one then check for interruption requested

// and then continue waiting

if (!ptrConnection)

{

if (stopServer)

{

// This was our last chance. There are still some events

// left in the queue, but we waited and nobody came.

break;

}

// check for interruption and set stopServer flag if we were

if (boost::this_thread::interruption_requested())

throw boost::thread_interrupted();

// accept next request (assuming we weren't interrupted)

continue;

}

catch(const boost::thread_interrupted&)

{

stopServer = true;

continue;

}

// parse the json rpc request

json::JsonRpcRequest request;

Error error = json::parseJsonRpcRequest(ptrConnection->request().body(),

&request);

if (error)

{

ptrConnection->sendJsonRpcError(error);

continue;

}

// send an error back if this request came from the wrong client

if (request.clientId != clientId())

{

Error error = Error(json::errc::InvalidClientId,

ERROR_LOCATION);

ptrConnection->sendJsonRpcError(error);

continue;

}

// get the last event id seen by the client

int lastClientEventIdSeen = -1;

Error paramError = json::readParam(request.params,

&lastClientEventIdSeen);

if (paramError)

{

ptrConnection->sendJsonRpcError(paramError);

continue;

}

// remove all events already seen by the client from our internal list

erasePreviouslyDeliveredEvents(lastClientEventIdSeen);

// sync next event id to client (required so that when we resume

// from a suspend we provide client event ids in line with the

// client's expectations -- if we started with zero then the client

// would never see any events!)

nextEventId = std::max(nextEventId, lastClientEventIdSeen + 1);

// check for events (and wait a specified internal if there are none)

try

{

// wait for the specified maximum time

if (havePendingClientEvents() || clientEventQueue.hasEvents() ||

clientEventQueue.waitForEvent(maxRequestSec))

{

// ...got at least one event

// wait for additional events that occur in rapid succession

// but don't wait for more than the specified maximum seconds

boost::system_time maxBatchDelayTime =

boost::get_system_time() + maxTotalBatchDelay;

while ( clientEventQueue.waitForEvent(batchDelay) &&

(boost::get_system_time() < maxBatchDelayTime) )

{

}

catch(const boost::thread_interrupted& e)

{

// set flag so we terminate on the next accept loop iteration

stopServer = true ;

// NOTE: even if we are interrupted we still want to allow the

// response to be sent (e.g. need to send the client either

// an empty list of events back or perhaps even the quit event!)

}

// if this is the correct client then remove events from the

// queue and send them. otherwise, send an InvalidClientId error

// to this client. the currently active client will then pickup the

// events on the next iteration of the accept loop

if (request.clientId == clientId())

{

// deque the events

std::vector<ClientEvent> events;

clientEventQueue.remove(&events);

// convert to json and add event id

for (std::vector<ClientEvent>::const_iterator

it = events.begin(); it != events.end(); ++it)

{

json::Object event ;

it->asJsonObject(nextEventId++, &event);

addClientEvent(event);

}

// send them (pass false for kEventsPending b/c responses from the

// event service shouldn't interact with automatic event service

// starting/re-starting)

json::JsonRpcResponse response;

setClientEventResult(&response);

response.setField(kEventsPending, "false");

ptrConnection->sendJsonRpcResponse(response);

}

else

{

Error error(json::errc::InvalidClientId, ERROR_LOCATION);

ptrConnection->sendJsonRpcError(error);

}

CATCH_UNEXPECTED_EXCEPTION

}

} // namespace session

rstudio/src/cpp/session/SessionClientEventService.cpp at master · UXScripts/rstudio · GitHub

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