support for linux scheduler and timer

config.cake

@@ -221,7 +221,9 @@ elif cake.system.isLinux():
   compiler.addLibrary('c++')
   compiler.addLibrary('c')
   compiler.addLibrary('pthread')
-
+  compiler.addLibrary('rt')
+  compiler.addLibrary('uuid')	
+
   #compiler.addProgramFlag('-Wl,--trace')
   #compiler.addProgramFlag('-Wl,-v')
 

include/cppcoro/detail/linux.hpp

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <mqueue.h>
+#include <sys/epoll.h>
+#include <sys/timerfd.h>
+#include <sys/eventfd.h>
+#include <fcntl.h>
+#include <uuid/uuid.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
+#include <linux/limits.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+
+typedef int DWORD;
+#define INFINITE (DWORD)-1
+
+namespace cppcoro
+{
+	namespace detail
+	{
+		namespace linux
+		{
+			enum message_type
+			{
+				CALLBACK_TYPE,
+				RESUME_TYPE
+			};
+
+			struct message
+			{
+				enum message_type m_type;
+				void* m_ptr;
+			};
+
+			struct io_state : linux::message
+			{
+				using callback_type = void(io_state* state);
+				callback_type* m_callback;
+			};
+
+			class message_queue
+			{
+			private:
+				mqd_t m_mqdt;
+				char m_qname[NAME_MAX];
+				int m_epollfd;
+				struct epoll_event m_ev;
+				message_queue();
+			public:
+				message_queue(size_t queue_length);
+				~message_queue();
+				bool enqueue_message(void* message, message_type type);
+				bool dequeue_message(void*& message, message_type& type, bool wait);
+			};
+
+			int create_event_fd();
+			int create_timer_fd();
+			int create_epoll_fd();
+
+		}
+	}
+}

include/cppcoro/io_service.hpp

@@ -13,6 +13,10 @@
 # include <cppcoro/detail/win32.hpp>
 #endif
 
+#if CPPCORO_OS_LINUX
+#include <cppcoro/detail/linux.hpp>
+#endif
+
 #include <optional>
 #include <chrono>
 #include <cstdint>
@@ -42,8 +46,12 @@ namespace cppcoro
 		/// actively processing events.
 		/// Note that the number of active threads may temporarily go
 		/// above this number.
-		io_service(std::uint32_t concurrencyHint);
-
+#if CPPCORO_OS_WINNT
+	        io_service(std::uint32_t concurrencyHint);
+#endif
+#if CPPCORO_OS_LINUX
+	        io_service(size_t queue_length);
+#endif
 		~io_service();
 
 		io_service(io_service&& other) = delete;
@@ -147,6 +155,10 @@ namespace cppcoro
 
 		void try_reschedule_overflow_operations() noexcept;
 
+	  void queue_overflow_operation_to_head(schedule_operation* operation) noexcept;
+
+	  void queue_overflow_operation_to_tail(schedule_operation* operation) noexcept;
+
 		bool try_enter_event_loop() noexcept;
 		void exit_event_loop() noexcept;
 
@@ -169,6 +181,9 @@ namespace cppcoro
 		detail::win32::safe_handle m_iocpHandle;
 #endif
 
+#if CPPCORO_OS_LINUX
+	        detail::linux::message_queue* m_mq;
+#endif
 		// Head of a linked-list of schedule operations that are
 		// ready to run but that failed to be queued to the I/O
 		// completion port (eg. due to low memory).

lib/build.cake

@@ -65,20 +65,28 @@ sources = script.cwd([
   'cancellation_source.cpp',
   'cancellation_registration.cpp',
   'lightweight_manual_reset_event.cpp',
+  'io_service.cpp',
   ])
 
 extras = script.cwd([
   'build.cake',
   'use.cake',
   ])
 
+if variant.platform == "linux":
+  detailIncludes.extend(cake.path.join(env.expand('${CPPCORO}'), 'include', 'cppcoro', 'detail', [
+    'linux.hpp',
+    ]))
+  sources.extend(script.cwd([
+    'linux.cpp',
+    ]))
+
 if variant.platform == "windows":
   detailIncludes.extend(cake.path.join(env.expand('${CPPCORO}'), 'include', 'cppcoro', 'detail', [
     'win32.hpp',
     ]))
   sources.extend(script.cwd([
     'win32.cpp',
-    'io_service.cpp',
     'file.cpp',
     'readable_file.cpp',
     'writable_file.cpp',