wip: Inter-process messaging

cmake/build/options.cmake

@@ -79,5 +79,7 @@ set(SETTING_PATH_MEMORY_INFO "/proc/meminfo"
   CACHE STRING "Path to file containing memory info")
 set(SETTING_PATH_TEMPERATURE_INFO "/sys/class/thermal/thermal_zone%zone%/temp"
   CACHE STRING "Path to file containing the current temperature")
+set(SETTING_PATH_MESSAGING_FIFO "/tmp/lemonbuddy_mqueue.%pid%"
+  CACHE STRING "Path to file containing the current temperature")
 
 # }}}

include/components/controller.hpp

@@ -4,8 +4,8 @@
 #include "components/bar.hpp"
 #include "components/config.hpp"
 #include "components/eventloop.hpp"
+#include "components/ipc.hpp"
 #include "components/logger.hpp"
-#include "components/signals.hpp"
 #include "config.hpp"
 #include "utils/command.hpp"
 #include "utils/inotify.hpp"
@@ -17,12 +17,13 @@ LEMONBUDDY_NS
 class controller {
  public:
   explicit controller(connection& conn, const logger& logger, const config& config, unique_ptr<eventloop> eventloop,
-      unique_ptr<bar> bar, inotify_util::watch_t& confwatch)
+      unique_ptr<bar> bar, unique_ptr<ipc> ipc, inotify_util::watch_t& confwatch)
       : m_connection(conn)
       , m_log(logger)
       , m_conf(config)
       , m_eventloop(forward<decltype(eventloop)>(eventloop))
       , m_bar(forward<decltype(bar)>(bar))
+      , m_ipc(forward<decltype(ipc)>(ipc))
       , m_confwatch(confwatch) {}
 
   ~controller();
@@ -53,6 +54,7 @@ class controller {
   const config& m_conf;
   unique_ptr<eventloop> m_eventloop;
   unique_ptr<bar> m_bar;
+  unique_ptr<ipc> m_ipc;
 
   stateflag m_running{false};
   stateflag m_reload{false};
@@ -67,7 +69,7 @@ class controller {
   inotify_util::watch_t& m_confwatch;
   command_util::command_t m_command;
 
-  bool m_writeback = false;
+  bool m_writeback{false};
 };
 
 namespace {
@@ -83,7 +85,8 @@ namespace {
         configure_logger(),
         configure_config(),
         configure_eventloop(),
-        configure_bar());
+        configure_bar(),
+        configure_ipc());
     // clang-format on
   }
 }

include/components/ipc.hpp

@@ -0,0 +1,54 @@
+#pragma once
+
+#include "common.hpp"
+#include "components/logger.hpp"
+
+LEMONBUDDY_NS
+
+/**
+ * Component used for inter-process communication.
+ *
+ * A unique messaging channel will be setup for each
+ * running process which will allow messages and
+ * events to be sent to the process externally.
+ */
+class ipc {
+ public:
+  struct message_internal {
+    static constexpr auto prefix{"app:"};
+  };
+  struct message_command {
+    static constexpr auto prefix{"cmd:"};
+  };
+  struct message_custom {
+    static constexpr auto prefix{"custom:"};
+  };
+
+  explicit ipc(const logger& logger) : m_log(logger) {}
+  ~ipc();
+
+  void receive_messages();
+
+ protected:
+  void parse(string payload);
+
+ private:
+  const logger& m_log;
+
+  stateflag m_running{false};
+
+  string m_fifo;
+  int m_fd;
+};
+
+namespace {
+  /**
+   * Configure injection module
+   */
+  template <typename T = unique_ptr<ipc>>
+  di::injector<T> configure_ipc() {
+    return di::make_injector(configure_logger());
+  }
+}
+
+LEMONBUDDY_NS_END

include/config.hpp.cmake

@@ -39,6 +39,7 @@
 #define PATH_CPU_INFO "@SETTING_PATH_CPU_INFO@"
 #define PATH_MEMORY_INFO "@SETTING_PATH_MEMORY_INFO@"
 #define PATH_TEMPERATURE_INFO "@SETTING_PATH_TEMPERATURE_INFO@"
+#define PATH_MESSAGING_FIFO "@SETTING_PATH_MESSAGING_FIFO@"
 
 auto print_build_info = []() {
   // clang-format off

src/components/controller.cpp

@@ -2,6 +2,12 @@
 #include <mutex>
 
 #include "components/controller.hpp"
+
+#include "components/bar.hpp"
+#include "components/config.hpp"
+#include "components/eventloop.hpp"
+#include "components/ipc.hpp"
+#include "components/logger.hpp"
 #include "components/signals.hpp"
 #include "modules/backlight.hpp"
 #include "modules/battery.hpp"
@@ -56,6 +62,11 @@ controller::~controller() {
     m_eventloop.reset();
   }
 
+  if (m_ipc) {
+    m_log.info("Deconstructing ipc");
+    m_ipc.reset();
+  }
+
   if (m_bar) {
     m_log.info("Deconstructing bar");
     m_bar.reset();
@@ -94,30 +105,23 @@ void controller::bootstrap(bool writeback, bool dump_wmname) {
   // Listen for events on the root window to be able to
   // break the blocking wait call when cleaning up
   m_log.trace("controller: Listen for events on the root window");
-  try {
   const uint32_t value_list[2]{XCB_EVENT_MASK_PROPERTY_CHANGE | XCB_EVENT_MASK_STRUCTURE_NOTIFY};
   m_connection.change_window_attributes_checked(m_connection.root(), XCB_CW_EVENT_MASK, value_list);
-  } catch (const exception& err) {
-    throw application_error("Failed to change root window event mask: " + string{err.what()});
-  }
 
-  try {
   m_log.trace("controller: Setup bar");
   m_bar->bootstrap(m_writeback || dump_wmname);
   m_bar->bootstrap_tray();
-  } catch (const exception& err) {
-    throw application_error("Failed to setup bar renderer: " + string{err.what()});
-  }
 
   if (dump_wmname) {
     std::cout << m_bar->settings().wmname << std::endl;
     return;
   }
 
-  m_log.trace("controller: Attach eventloop callbacks");
+  m_log.trace("controller: Attach eventloop update callback");
   m_eventloop->set_update_cb(bind(&controller::on_update, this));
 
   if (!m_writeback) {
+    m_log.trace("controller: Attach eventloop input callback");
     g_signals::bar::action_click = bind(&controller::on_mouse_event, this, placeholders::_1);
     m_eventloop->set_input_db(bind(&controller::on_unrecognized_action, this, placeholders::_1));
   }
@@ -138,6 +142,11 @@ bool controller::run() {
   install_sigmask();
   install_confwatch();
 
+#if DEBUG
+  // Start listening for ipc messages
+  m_threads.emplace_back(thread(&ipc::receive_messages, m_ipc.get()));
+#endif
+
   // Listen for X events in separate thread
   if (!m_writeback) {
     m_threads.emplace_back(thread(&controller::wait_for_xevent, this));

src/components/ipc.cpp

@@ -0,0 +1,67 @@
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#include "components/ipc.hpp"
+#include "config.hpp"
+#include "utils/file.hpp"
+#include "utils/io.hpp"
+#include "utils/string.hpp"
+
+LEMONBUDDY_NS
+
+/**
+ * Interrupt the blocked listener and
+ * remove the file handler
+ */
+ipc::~ipc() {
+  m_running = false;
+
+  if (!m_fifo.empty()) {
+    m_log.info("Interrupting ipc message receiver");
+
+    auto f{make_unique<file_util::file_ptr>(m_fifo)};
+    char p[1]{'q'};
+
+    fwrite(p, sizeof(char), sizeof(p), (*f)());
+    unlink(m_fifo.c_str());
+  }
+}
+
+/**
+ * Start listening for event messages
+ */
+void ipc::receive_messages() {
+  m_running = true;
+  m_fifo = string_util::replace(PATH_MESSAGING_FIFO, "%pid%", to_string(getpid()));
+
+  if (mkfifo(m_fifo.c_str(), 0666) == -1) {
+    m_log.err("Failed to create messaging channel");
+  }
+
+  m_log.info("Listening for ipc messages on: %s", m_fifo);
+
+  while ((m_fd = open(m_fifo.c_str(), O_RDONLY)) != -1 && m_running) {
+    parse(io_util::readline(m_fd));
+    close(m_fd);
+  }
+}
+
+/**
+ * Process received message and delegate
+ * valid events to the target modules
+ */
+void ipc::parse(string payload) {
+  if (payload.empty()) {
+    return;
+  } else if (payload.find(message_internal::prefix) == 0) {
+    m_log.info("Received internal message: (payload=%s)", payload);
+  } else if (payload.find(message_command::prefix) == 0) {
+    m_log.info("Received command message: (payload=%s)", payload);
+  } else if (payload.find(message_custom::prefix) == 0) {
+    m_log.info("Received custom message: (payload=%s)", payload);
+  } else {
+    m_log.info("Received unknown message: (payload=%s)", payload);
+  }
+}
+
+LEMONBUDDY_NS_END

src/utils/io.cpp

@@ -37,26 +37,24 @@ namespace io_util {
   }
 
   string readline(int read_fd, int& bytes_read) {
-    std::stringstream buffer;
+    stringstream buffer;
     char char_;
-
+    int bytes = 0;
     bytes_read = 0;
 
-    while ((bytes_read += ::read(read_fd, &char_, 1)) > 0) {
-      buffer << char_;
+    while ((bytes = ::read(read_fd, &char_, 1)) > 0) {
+      if (bytes <= 0)
+        break;
       if (char_ == '\n' || char_ == '\x00')
         break;
+      bytes_read += bytes;
+      buffer << char_;
     }
 
-    if (bytes_read == 0) {
-      // Reached EOF
-    } else if (bytes_read == -1) {
-      // Read failed
-    } else {
-      return string_util::strip_trailing_newline(buffer.str());
-    }
-
+    if (bytes_read <= 0)
       return "";
+
+    return string_util::strip_trailing_newline(buffer.str());
   }
 
   string readline(int read_fd) {