Use libuv for the controller's event loop

cmake/libpoly.cmake

@@ -98,6 +98,8 @@ endif()
 find_package(Xcb ${XRANDR_VERSION} REQUIRED COMPONENTS RANDR)
 find_package(Xcb REQUIRED COMPONENTS ${XORG_EXTENSIONS})
 
+find_package(LibUV 1.10.0 REQUIRED)
+
 # FreeBSD Support
 if(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
   find_package(LibInotify REQUIRED)

cmake/modules/FindLibUV.cmake

@@ -0,0 +1,13 @@
+# This module defines
+# LIBUV_FOUND
+# LIBUV_INCLUDE_DIR
+# LIBUV_INCLUDE_DIRS
+# LIBUV_LIBRARY
+# LIBUV_LIBRARIES
+# LIBUV_VERSION
+
+find_package_impl("libuv" "LIBUV" "")
+
+if(LIBUV_FOUND AND NOT TARGET LibUV::LibUV)
+  create_imported_target("LibUV::LibUV" "${LIBUV_INCLUDE_DIR}" "${LIBUV_LIBRARY}")
+endif()

include/components/controller.hpp

@@ -52,6 +52,9 @@ class controller
   bool enqueue(event&& evt);
   bool enqueue(string&& input_data);
 
+  void conn_cb(int status, int events);
+  void ipc_cb(int status, int events);
+
  protected:
   void read_events();
   void process_eventqueue();
@@ -84,8 +87,6 @@ class controller
   unique_ptr<ipc> m_ipc;
   unique_ptr<inotify_watch> m_confwatch;
 
-  array<unique_ptr<file_descriptor>, 2> m_queuefd{};
-
   /**
    * \brief State flag
    */

include/modules/meta/base.hpp

@@ -169,6 +169,19 @@ namespace modules {
     void sleep(chrono::duration<double> duration);
     template <class Clock, class Duration>
     void sleep_until(chrono::time_point<Clock, Duration> point);
+
+    /**
+     * Wakes up the module.
+     *
+     * It should be possible to interrupt any blocking operation inside a
+     * module using this function.
+     *
+     * In addition, after a wake up whatever was woken up should immediately
+     * check whether the module is still running.
+     *
+     * Modules that don't follow this, could stall the operation of whatever
+     * code called this function.
+     */
     void wakeup();
     string get_format() const;
     string get_output();

src/CMakeLists.txt

@@ -151,6 +151,7 @@ if(BUILD_LIBPOLY)
     Cairo::CairoFC
     moodycamel
     xpp
+    LibUV::LibUV
     )
 
   if (TARGET i3ipc++)

src/components/controller.cpp

@@ -1,5 +1,7 @@
 #include "components/controller.hpp"
 
+#include <uv.h>
+
 #include <csignal>
 #include <utility>
 
@@ -25,22 +27,9 @@
 
 POLYBAR_NS
 
-array<int, 2> g_eventpipe{{-1, -1}};
 sig_atomic_t g_reload{0};
 sig_atomic_t g_terminate{0};
 
-void interrupt_handler(int signum) {
-  if (g_reload || g_terminate) {
-    return;
-  }
-
-  g_terminate = 1;
-  g_reload = (signum == SIGUSR1);
-  if (write(g_eventpipe[PIPE_WRITE], &g_terminate, 1) == -1) {
-    throw system_error("Failed to write to eventpipe");
-  }
-}
-
 /**
  * Build controller instance
  */
@@ -70,23 +59,6 @@ controller::controller(connection& conn, signal_emitter& emitter, const logger&
   m_swallow_limit = m_conf.deprecated("settings", "eventqueue-swallow", "throttle-output", m_swallow_limit);
   m_swallow_update = m_conf.deprecated("settings", "eventqueue-swallow-time", "throttle-output-for", m_swallow_update);
 
-  if (pipe(g_eventpipe.data()) == 0) {
-    m_queuefd[PIPE_READ] = make_unique<file_descriptor>(g_eventpipe[PIPE_READ]);
-    m_queuefd[PIPE_WRITE] = make_unique<file_descriptor>(g_eventpipe[PIPE_WRITE]);
-  } else {
-    throw system_error("Failed to create event channel pipes");
-  }
-
-  m_log.trace("controller: Install signal handler");
-  struct sigaction act {};
-  memset(&act, 0, sizeof(act));
-  act.sa_handler = &interrupt_handler;
-  sigaction(SIGINT, &act, nullptr);
-  sigaction(SIGQUIT, &act, nullptr);
-  sigaction(SIGTERM, &act, nullptr);
-  sigaction(SIGUSR1, &act, nullptr);
-  sigaction(SIGALRM, &act, nullptr);
-
   m_log.trace("controller: Setup user-defined modules");
   size_t created_modules{0};
   created_modules += setup_modules(alignment::LEFT);
@@ -102,17 +74,6 @@ controller::controller(connection& conn, signal_emitter& emitter, const logger&
  * Deconstruct controller
  */
 controller::~controller() {
-  m_log.trace("controller: Uninstall sighandler");
-  signal(SIGINT, SIG_DFL);
-  signal(SIGQUIT, SIG_DFL);
-  signal(SIGTERM, SIG_DFL);
-  signal(SIGALRM, SIG_DFL);
-
-  if (g_reload) {
-    // Cause SIGUSR1 to be ignored until registered in the new polybar process
-    signal(SIGUSR1, SIG_IGN);
-  }
-
   m_log.trace("controller: Detach signal receiver");
   m_sig.detach(this);
 
@@ -211,93 +172,16 @@ bool controller::enqueue(string&& input_data) {
   return false;
 }
 
-/**
- * Read events from configured file descriptors
- */
-void controller::read_events() {
-  m_log.info("Entering event loop (thread-id=%lu)", this_thread::get_id());
+void controller::conn_cb(int status, int events) {
+  // TODO handle negative status
 
-  int fd_connection{-1};
-  int fd_confwatch{-1};
-  int fd_ipc{-1};
-
-  vector<int> fds;
-  fds.emplace_back(*m_queuefd[PIPE_READ]);
-  fds.emplace_back((fd_connection = m_connection.get_file_descriptor()));
-
-  if (m_confwatch) {
-    m_log.trace("controller: Attach config watch");
-    m_confwatch->attach(IN_MODIFY | IN_IGNORED);
-    fds.emplace_back((fd_confwatch = m_confwatch->get_file_descriptor()));
-  }
-
-  if (m_ipc) {
-    fds.emplace_back((fd_ipc = m_ipc->get_file_descriptor()));
-  }
-
-  while (!g_terminate) {
-    fd_set readfds{};
-    FD_ZERO(&readfds);
-
-    int maxfd{0};
-    for (auto&& fd : fds) {
-      FD_SET(fd, &readfds);
-      maxfd = std::max(maxfd, fd);
-    }
-
-    // Wait until event is ready on one of the configured streams
-    int events = select(maxfd + 1, &readfds, nullptr, nullptr, nullptr);
-
-    // Check for errors
-    if (events == -1) {
-      /*
-       * The Interrupt errno is generated when polybar is stopped, so it
-       * shouldn't generate an error message
-       */
-      if (errno != EINTR) {
-        m_log.err("select failed in event loop: %s", strerror(errno));
-      }
-
-      break;
-    }
-
-    if (g_terminate || m_connection.connection_has_error()) {
-      break;
-    }
-
-    // Process event on the internal fd
-    if (m_queuefd[PIPE_READ] && FD_ISSET(static_cast<int>(*m_queuefd[PIPE_READ]), &readfds)) {
-      char buffer[BUFSIZ];
-      if (read(static_cast<int>(*m_queuefd[PIPE_READ]), &buffer, BUFSIZ) == -1) {
-        m_log.err("Failed to read from eventpipe (err: %s)", strerror(errno));
-      }
-    }
-
-    // Process event on the config inotify watch fd
-    unique_ptr<inotify_event> confevent;
-    if (fd_confwatch > -1 && FD_ISSET(fd_confwatch, &readfds) && (confevent = m_confwatch->await_match())) {
-      if (confevent->mask & IN_IGNORED) {
-        // IN_IGNORED: file was deleted or filesystem was unmounted
-        //
-        // This happens in some configurations of vim when a file is saved,
-        // since it is not actually issuing calls to write() but rather
-        // moves a file into the original's place after moving the original
-        // file to a different location (and subsequently deleting it).
-        //
-        // We need to re-attach the watch to the new file in this case.
-        fds.erase(
-            std::remove_if(fds.begin(), fds.end(), [fd_confwatch](int fd) { return fd == fd_confwatch; }), fds.end());
-        m_confwatch = inotify_util::make_watch(m_confwatch->path());
-        m_confwatch->attach(IN_MODIFY | IN_IGNORED);
-        fds.emplace_back((fd_confwatch = m_confwatch->get_file_descriptor()));
-      }
-      m_log.info("Configuration file changed");
+  if (m_connection.connection_has_error()) {
     g_terminate = 1;
-      g_reload = 1;
+    g_reload = 0;
+    uv_stop(uv_default_loop());
+    return;
   }
 
-    // Process event on the xcb connection fd
-    if (fd_connection > -1 && FD_ISSET(fd_connection, &readfds)) {
   shared_ptr<xcb_generic_event_t> evt{};
   while ((evt = shared_ptr<xcb_generic_event_t>(xcb_poll_for_event(m_connection), free)) != nullptr) {
     try {
@@ -310,13 +194,79 @@ void controller::read_events() {
   }
 }
 
-    // Process event on the ipc fd
-    if (fd_ipc > -1 && FD_ISSET(fd_ipc, &readfds)) {
+void controller::ipc_cb(int status, int events) {
+  // TODO handle negative status
   m_ipc->receive_message();
-      fds.erase(std::remove_if(fds.begin(), fds.end(), [fd_ipc](int fd) { return fd == fd_ipc; }), fds.end());
-      fds.emplace_back((fd_ipc = m_ipc->get_file_descriptor()));
 }
+
+static void conn_cb_wrapper(uv_poll_t* handle, int status, int events) {
+  static_cast<controller*>(handle->data)->conn_cb(status, events);
 }
+
+static void ipc_cb_wrapper(uv_poll_t* handle, int status, int events) {
+  static_cast<controller*>(handle->data)->ipc_cb(status, events);
+}
+
+static void signal_cb_wrapper(uv_signal_t* handle, int signum) {
+  g_terminate = 1;
+  g_reload = (signum == SIGUSR1);
+  uv_stop(handle->loop);
+}
+
+static void confwatch_cb_wrapper(uv_fs_event_t* handle, const char* fname, int events, int status) {
+  // TODO handle error
+  std::cout << fname << std::endl;
+  g_terminate = 1;
+  g_reload = 1;
+  uv_stop(handle->loop);
+}
+
+/**
+ * Read events from configured file descriptors
+ */
+void controller::read_events() {
+  m_log.info("Entering event loop (thread-id=%lu)", this_thread::get_id());
+
+  auto loop = uv_default_loop();
+
+  auto conn_handle = std::make_unique<uv_poll_t>();
+  uv_poll_init(loop, conn_handle.get(), m_connection.get_file_descriptor());
+  conn_handle->data = this;
+
+  uv_poll_start(conn_handle.get(), UV_READABLE, conn_cb_wrapper);
+
+  std::vector<unique_ptr<uv_signal_t>> handles;
+
+  for (auto s : {SIGINT, SIGQUIT, SIGTERM, SIGUSR1, SIGALRM}) {
+    auto signal_handle = std::make_unique<uv_signal_t>();
+    uv_signal_init(loop, signal_handle.get());
+    signal_handle->data = this;
+
+    uv_signal_start(signal_handle.get(), signal_cb_wrapper, s);
+    handles.push_back(std::move(signal_handle));
+  }
+
+  auto conf_handle = std::unique_ptr<uv_fs_event_t>(nullptr);
+
+  if (m_confwatch) {
+    conf_handle = std::make_unique<uv_fs_event_t>();
+    uv_fs_event_init(loop, conf_handle.get());
+    conf_handle->data = this;
+
+    uv_fs_event_start(conf_handle.get(), confwatch_cb_wrapper, m_confwatch->path().c_str(), 0);
+  }
+
+  auto ipc_handle = std::unique_ptr<uv_poll_t>(nullptr);
+
+  if (m_ipc) {
+    ipc_handle = std::make_unique<uv_poll_t>();
+    uv_poll_init(loop, ipc_handle.get(), m_ipc->get_file_descriptor());
+    ipc_handle->data = this;
+    uv_poll_start(ipc_handle.get(), UV_READABLE, ipc_cb_wrapper);
+  }
+
+  uv_run(loop, UV_RUN_DEFAULT);
+  uv_loop_close(loop);
 }
 
 /**

src/modules/xwindow.cpp

@@ -1,11 +1,11 @@
 #include "modules/xwindow.hpp"
+
 #include "drawtypes/label.hpp"
+#include "modules/meta/base.inl"
 #include "utils/factory.hpp"
 #include "x11/atoms.hpp"
 #include "x11/connection.hpp"
 
-#include "modules/meta/base.inl"
-
 POLYBAR_NS
 
 namespace modules {
@@ -138,6 +138,6 @@ namespace modules {
     }
     return false;
   }
-}
+}  // namespace modules
 
 POLYBAR_NS_END