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meshcat.cc
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meshcat.cc
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#include "drake/geometry/meshcat.h"
#include <fstream>
#include <future>
#include <map>
#include <sstream>
#include <string>
#include <thread>
#include <tuple>
#include <utility>
#include <App.h>
#include <fmt/format.h>
#include <msgpack.hpp>
#include "drake/common/find_resource.h"
#include "drake/common/never_destroyed.h"
#include "drake/common/unused.h"
namespace {
std::string LoadFile(const std::string& filename) {
const std::string resource = drake::FindResourceOrThrow(filename);
std::ifstream file(resource.c_str(), std::ios::in);
if (!file.is_open())
throw std::runtime_error("Error opening file: " + filename);
std::stringstream content;
content << file.rdbuf();
file.close();
return content.str();
}
} // namespace
namespace drake {
namespace geometry {
namespace {
constexpr static bool SSL = false;
struct PerSocketData {
// Intentionally left empty.
};
using WebSocket = uWS::WebSocket<SSL, true, PerSocketData>;
} // namespace
class Meshcat::WebSocketPublisher {
public:
DRAKE_NO_COPY_NO_MOVE_NO_ASSIGN(WebSocketPublisher);
WebSocketPublisher() : app_future(app_promise.get_future()) {}
// Call this from websocket thread.
void SetAppPromise(uWS::App* app, uWS::Loop* loop, int port,
us_listen_socket_t* listen_socket) {
app_promise.set_value(std::make_tuple(app, loop, port, listen_socket));
}
// Call this from main thread.
void GetAppFuture() {
std::tie(app_, loop_, port_, listen_socket_) = app_future.get();
}
int port() const {
DRAKE_DEMAND(port_ > 0);
return port_;
}
template <typename T>
void SetProperty(const std::string& path, const std::string& property,
const T& value) {
DRAKE_ASSERT(app_ != nullptr);
DRAKE_ASSERT(loop_ != nullptr);
std::stringstream message;
msgpack::zone z;
msgpack::pack(message, std::map<std::string, msgpack::object>(
{{"type", msgpack::object("set_property", z)},
{"path", msgpack::object(path, z)},
{"property", msgpack::object(property, z)},
{"value", msgpack::object(value, z)}}));
// Note: Must pass path and property by value because they will go out of
// scope.
loop_->defer([this, path, property, msg = message.str()]() {
app_->publish("all", msg, uWS::OpCode::BINARY, false);
set_properties_[path + "/" + property] = msg;
});
}
void SendTree(WebSocket* ws) {
// TODO(russt): Generalize this to publishing the entire scene tree.
for (const auto& [key, msg] : set_properties_) {
unused(key);
ws->send(msg);
}
}
void Shutdown() {
// This can be extremely slow. See discussion at
// https://github.com/uNetworking/uWebSockets/discussions/809
us_listen_socket_close(0, listen_socket_);
}
private:
std::promise<std::tuple<uWS::App*, uWS::Loop*, int, us_listen_socket_t*>>
app_promise{};
std::future<std::tuple<uWS::App*, uWS::Loop*, int, us_listen_socket_t*>>
app_future{};
int port_{-1};
us_listen_socket_t* listen_socket_;
// Only loop_->defer() should be called from outside the websocket_thread. See
// the documentation for uWebSockets for further details:
// https://github.com/uNetworking/uWebSockets/blob/d94bf2cd43bed5e0de396a8412f156e15c141e98/misc/READMORE.md#threading
uWS::Loop* loop_{nullptr};
// The remaining variables should only be accessed from the websocket_thread.
uWS::App* app_{nullptr};
std::map<std::string, std::string> set_properties_{};
};
Meshcat::Meshcat() {
// A std::promise is made in the WebSocketPublisher.
publisher_ = std::make_unique<WebSocketPublisher>();
websocket_thread_ = std::thread(&Meshcat::WebsocketMain, this);
// The std::promise is full-filled in WebsocketMain; we wait here to obtain
// that value.
publisher_->GetAppFuture();
}
Meshcat::~Meshcat() {
publisher_->Shutdown();
JoinWebSocketThread();
}
std::string Meshcat::web_url() const {
return fmt::format("http://localhost:{}", publisher_->port());
}
std::string Meshcat::ws_url() const {
return fmt::format("ws://localhost:{}", publisher_->port());
}
void Meshcat::JoinWebSocketThread() { websocket_thread_.join(); }
void Meshcat::SetProperty(const std::string& path, const std::string& property,
bool value) {
publisher_->SetProperty(path, property, value);
}
void Meshcat::WebsocketMain() {
// Preload the three files we will serve (always).
static const drake::never_destroyed<std::string> index_html(
LoadFile("drake/external/meshcat/dist/index.html"));
static const drake::never_destroyed<std::string> main_min_js(
LoadFile("drake/external/meshcat/dist/main.min.js"));
static const drake::never_destroyed<std::string> favicon_ico(
LoadFile("drake/doc/favicon.ico"));
int port = 7001;
const int kMaxPort = 7099;
uWS::App::WebSocketBehavior<PerSocketData> behavior;
behavior.open = [this](WebSocket* ws) {
ws->subscribe("all");
// Update this new connection with previously published data.
publisher_->SendTree(ws);
};
uWS::App app =
uWS::App()
.get("/*",
[&](uWS::HttpResponse<SSL>* res, uWS::HttpRequest* req) {
if (req->getUrl() == "/main.min.js") {
res->end(main_min_js.access());
} else if (req->getUrl() == "/favicon.ico") {
res->end(favicon_ico.access());
} else {
res->end(index_html.access());
}
})
.ws<PerSocketData>("/*", std::move(behavior));
us_listen_socket_t* listen_socket = nullptr;
do {
app.listen(
port, LIBUS_LISTEN_EXCLUSIVE_PORT,
[port, &listen_socket](us_listen_socket_t* socket) {
if (socket) {
std::cout
<< "Meshcat listening for connections at http://127.0.0.1:"
<< port << std::endl;
listen_socket = socket;
}
});
} while (listen_socket == nullptr && port++ <= kMaxPort);
publisher_->SetAppPromise(&app, uWS::Loop::get(), port, listen_socket);
app.run();
}
} // namespace geometry
} // namespace drake