/usr/include/ableton/link/Controller.hpp is in ableton-link-dev 1.0.0+dfsg-2.
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*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* If you would like to incorporate Link into a proprietary software application,
* please contact <link-devs@ableton.com>.
*/
#pragma once
#include <ableton/discovery/Service.hpp>
#include <ableton/link/ClientSessionTimelines.hpp>
#include <ableton/link/Gateway.hpp>
#include <ableton/link/GhostXForm.hpp>
#include <ableton/link/NodeState.hpp>
#include <ableton/link/Peers.hpp>
#include <ableton/link/Sessions.hpp>
#include <mutex>
namespace ableton
{
namespace link
{
namespace detail
{
template <typename Clock>
GhostXForm initXForm(const Clock& clock)
{
// Make the current time map to a ghost time of 0 with ghost time
// increasing at the same rate as clock time
return {1.0, -clock.micros()};
}
// The timespan in which local modifications to the timeline will be
// preferred over any modifications coming from the network.
const auto kLocalModGracePeriod = std::chrono::seconds(1);
} // namespace detail
// function types corresponding to the Controller callback type params
using PeerCountCallback = std::function<void(std::size_t)>;
using TempoCallback = std::function<void(ableton::link::Tempo)>;
// The main Link controller
template <typename PeerCountCallback,
typename TempoCallback,
typename Clock,
typename IoContext>
class Controller
{
public:
using Ticks = typename Clock::Ticks;
Controller(Tempo tempo,
PeerCountCallback peerCallback,
TempoCallback tempoCallback,
Clock clock,
util::Injected<IoContext> io)
: mTempoCallback(std::move(tempoCallback))
, mClock(std::move(clock))
, mNodeId(NodeId::random())
, mSessionId(mNodeId)
, mGhostXForm(detail::initXForm(mClock))
, mSessionTimeline(clampTempo({tempo, Beats{0.}, std::chrono::microseconds{0}}))
, mClientTimeline({mSessionTimeline.tempo, Beats{0.},
mGhostXForm.ghostToHost(std::chrono::microseconds{0})})
, mRtClientTimeline(mClientTimeline)
, mRtClientTimelineTimestamp(0)
, mSessionPeerCounter(*this, std::move(peerCallback))
, mEnabled(false)
, mIo(std::move(io))
, mRealtimeIo(util::injectRef(*mIo))
, mPeers(util::injectRef(*mIo),
std::ref(mSessionPeerCounter),
SessionTimelineCallback{*this})
, mSessions({mSessionId, mSessionTimeline, {mGhostXForm, mClock.micros()}},
util::injectRef(mPeers),
MeasurePeer{*this},
JoinSessionCallback{*this},
util::injectRef(*mIo),
mClock)
, mDiscovery(
std::make_pair(NodeState{mNodeId, mSessionId, mSessionTimeline}, mGhostXForm),
GatewayFactory{*this},
util::injectVal(mIo->clone(UdpSendExceptionHandler{*this})))
{
}
Controller(const Controller&) = delete;
Controller(Controller&&) = delete;
Controller& operator=(const Controller&) = delete;
Controller& operator=(Controller&&) = delete;
void enable(const bool bEnable)
{
const bool bWasEnabled = mEnabled.exchange(bEnable);
if (bWasEnabled != bEnable)
{
mRealtimeIo.async([this, bEnable] {
if (bEnable)
{
// Always reset when first enabling to avoid hijacking
// tempo in existing sessions
resetState();
}
mDiscovery.enable(bEnable);
});
}
}
bool isEnabled() const
{
return mEnabled;
}
std::size_t numPeers() const
{
return mSessionPeerCounter.mSessionPeerCount;
}
// Get the current Link timeline. Thread-safe but may block, so
// it cannot be used from audio thread.
Timeline timeline() const
{
std::lock_guard<std::mutex> lock(mClientTimelineGuard);
return mClientTimeline;
}
// Set the timeline to be used, starting at the given
// time. Thread-safe but may block, so it cannot be used from audio thread.
void setTimeline(Timeline newTimeline, const std::chrono::microseconds atTime)
{
newTimeline = clampTempo(newTimeline);
{
std::lock_guard<std::mutex> lock(mClientTimelineGuard);
mClientTimeline = newTimeline;
}
mIo->async([this, newTimeline, atTime] {
handleTimelineFromClient(updateSessionTimelineFromClient(
mSessionTimeline, newTimeline, atTime, mGhostXForm));
});
}
// Non-blocking timeline access for a realtime context. NOT
// thread-safe. Must not be called from multiple threads
// concurrently and must not be called concurrently with setTimelineRtSafe.
Timeline timelineRtSafe() const
{
// Respect the session timing guard but don't block on it. If we
// can't access it because it's being modified we fall back to our
// cached version of the timeline.
const auto now = mClock.micros();
if (now - mRtClientTimelineTimestamp > detail::kLocalModGracePeriod
&& mSessionTimingGuard.try_lock())
{
const auto clientTimeline = updateClientTimelineFromSession(
mRtClientTimeline, mSessionTimeline, now, mGhostXForm);
mSessionTimingGuard.unlock();
if (clientTimeline != mRtClientTimeline)
{
mRtClientTimeline = clientTimeline;
}
}
return mRtClientTimeline;
}
// should only be called from the audio thread
void setTimelineRtSafe(Timeline newTimeline, const std::chrono::microseconds atTime)
{
newTimeline = clampTempo(newTimeline);
// Cache the new timeline for serving back to the client
mRtClientTimeline = newTimeline;
mRtClientTimelineTimestamp = mClock.micros();
// Update the session timeline from the new client timeline
mRealtimeIo.async([this, newTimeline, atTime] {
// Synchronize with the non-rt version of the client timeline
{
std::lock_guard<std::mutex> lock(mClientTimelineGuard);
mClientTimeline = newTimeline;
}
handleTimelineFromClient(updateSessionTimelineFromClient(
mSessionTimeline, newTimeline, atTime, mGhostXForm));
});
}
private:
void updateSessionTiming(const Timeline newTimeline, const GhostXForm newXForm)
{
const auto oldTimeline = mSessionTimeline;
const auto oldXForm = mGhostXForm;
if (oldTimeline != newTimeline || oldXForm != newXForm)
{
{
std::lock_guard<std::mutex> lock(mSessionTimingGuard);
mSessionTimeline = newTimeline;
mGhostXForm = newXForm;
}
// Update the client timeline based on the new session timing data
{
std::lock_guard<std::mutex> lock(mClientTimelineGuard);
mClientTimeline = updateClientTimelineFromSession(
mClientTimeline, mSessionTimeline, mClock.micros(), mGhostXForm);
}
// Push the change to the discovery service
mDiscovery.updateNodeState(
std::make_pair(NodeState{mNodeId, mSessionId, newTimeline}, newXForm));
if (oldTimeline.tempo != newTimeline.tempo)
{
mTempoCallback(newTimeline.tempo);
}
}
}
void handleTimelineFromClient(Timeline tl)
{
mSessions.resetTimeline(tl);
mPeers.setSessionTimeline(mSessionId, tl);
updateSessionTiming(std::move(tl), mGhostXForm);
}
void handleTimelineFromSession(SessionId id, Timeline timeline)
{
debug(mIo->log()) << "Received timeline with tempo: " << timeline.tempo.bpm()
<< " for session: " << id;
updateSessionTiming(
mSessions.sawSessionTimeline(std::move(id), std::move(timeline)), mGhostXForm);
}
void joinSession(const Session& session)
{
const bool sessionIdChanged = mSessionId != session.sessionId;
mSessionId = session.sessionId;
updateSessionTiming(session.timeline, session.measurement.xform);
if (sessionIdChanged)
{
debug(mIo->log()) << "Joining session " << session.sessionId << " with tempo "
<< session.timeline.tempo.bpm();
mSessionPeerCounter();
}
}
void resetState()
{
mNodeId = NodeId::random();
mSessionId = mNodeId;
const auto xform = detail::initXForm(mClock);
const auto hostTime = -xform.intercept;
// When creating the new timeline, make it continuous by finding
// the beat on the old session timeline corresponding to the
// current host time and mapping it to the new ghost time
// representation of the current host time.
const auto newTl = Timeline{mSessionTimeline.tempo,
mSessionTimeline.toBeats(mGhostXForm.hostToGhost(hostTime)),
xform.hostToGhost(hostTime)};
updateSessionTiming(newTl, xform);
mSessions.resetSession({mNodeId, newTl, {xform, hostTime}});
mPeers.resetPeers();
}
struct SessionTimelineCallback
{
void operator()(SessionId id, Timeline timeline)
{
mController.handleTimelineFromSession(std::move(id), std::move(timeline));
}
Controller& mController;
};
struct SessionPeerCounter
{
SessionPeerCounter(Controller& controller, PeerCountCallback callback)
: mController(controller)
, mCallback(std::move(callback))
, mSessionPeerCount(0)
{
}
void operator()()
{
const auto count =
mController.mPeers.uniqueSessionPeerCount(mController.mSessionId);
const auto oldCount = mSessionPeerCount.exchange(count);
if (oldCount != count)
{
if (count == 0)
{
// When the count goes down to zero, completely reset the
// state, effectively founding a new session
mController.resetState();
}
mCallback(count);
}
}
Controller& mController;
PeerCountCallback mCallback;
std::atomic<std::size_t> mSessionPeerCount;
};
struct MeasurePeer
{
template <typename Peer, typename Handler>
void operator()(Peer peer, Handler handler)
{
using It = typename Discovery::ServicePeerGateways::GatewayMap::iterator;
using ValueType = typename Discovery::ServicePeerGateways::GatewayMap::value_type;
mController.mDiscovery.withGatewaysAsync([peer, handler](It begin, const It end) {
const auto addr = peer.second;
const auto it = std::find_if(
begin, end, [&addr](const ValueType& vt) { return vt.first == addr; });
if (it != end)
{
it->second->measurePeer(std::move(peer.first), std::move(handler));
}
else
{
// invoke the handler with an empty result if we couldn't
// find the peer's gateway
handler(GhostXForm{});
}
});
}
Controller& mController;
};
struct JoinSessionCallback
{
void operator()(Session session)
{
mController.joinSession(std::move(session));
}
Controller& mController;
};
using IoType = typename util::Injected<IoContext>::type;
using ControllerPeers =
Peers<IoType&, std::reference_wrapper<SessionPeerCounter>, SessionTimelineCallback>;
using ControllerGateway =
Gateway<typename ControllerPeers::GatewayObserver, Clock, IoType&>;
using GatewayPtr = std::shared_ptr<ControllerGateway>;
struct GatewayFactory
{
GatewayPtr operator()(std::pair<NodeState, GhostXForm> state,
util::Injected<IoType&> io,
const asio::ip::address& addr)
{
if (addr.is_v4())
{
return GatewayPtr{new ControllerGateway{std::move(io), addr.to_v4(),
util::injectVal(makeGatewayObserver(mController.mPeers, addr)),
std::move(state.first), std::move(state.second), mController.mClock}};
}
else
{
throw std::runtime_error("Could not create peer gateway on non-ipV4 address");
}
}
Controller& mController;
};
struct UdpSendExceptionHandler
{
using Exception = discovery::UdpSendException;
void operator()(const Exception& exception)
{
mController.mDiscovery.repairGateway(exception.interfaceAddr);
}
Controller& mController;
};
TempoCallback mTempoCallback;
Clock mClock;
NodeId mNodeId;
SessionId mSessionId;
// Mutex that controls access to mGhostXForm and mSessionTimeline
mutable std::mutex mSessionTimingGuard;
GhostXForm mGhostXForm;
Timeline mSessionTimeline;
mutable std::mutex mClientTimelineGuard;
Timeline mClientTimeline;
mutable Timeline mRtClientTimeline;
std::chrono::microseconds mRtClientTimelineTimestamp;
SessionPeerCounter mSessionPeerCounter;
std::atomic<bool> mEnabled;
util::Injected<IoContext> mIo;
// A realtime facade over the provided IoContext. This should only
// be used by realtime code, non-realtime code should use mIo.
typename IoType::template RealTimeContext<IoType&> mRealtimeIo;
ControllerPeers mPeers;
using ControllerSessions = Sessions<ControllerPeers&,
MeasurePeer,
JoinSessionCallback,
typename util::Injected<IoContext>::type&,
Clock>;
ControllerSessions mSessions;
using Discovery =
discovery::Service<std::pair<NodeState, GhostXForm>, GatewayFactory, IoContext>;
Discovery mDiscovery;
};
} // namespace link
} // namespace ableton
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