Implement async send.

CMakeLists.txt

@@ -47,6 +47,7 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/Modules/")
   ADD_TEST(ev_timer ${LUA} ${CMAKE_CURRENT_SOURCE_DIR}/test/test_ev_timer.lua ${CMAKE_CURRENT_SOURCE_DIR}/test/ ${CMAKE_CURRENT_BINARY_DIR}/)
   ADD_TEST(ev_idle ${LUA} ${CMAKE_CURRENT_SOURCE_DIR}/test/test_ev_idle.lua ${CMAKE_CURRENT_SOURCE_DIR}/test/ ${CMAKE_CURRENT_BINARY_DIR}/)
   ADD_TEST(ev_signal ${LUA} ${CMAKE_CURRENT_SOURCE_DIR}/test/test_ev_signal.lua ${CMAKE_CURRENT_SOURCE_DIR}/test/ ${CMAKE_CURRENT_BINARY_DIR}/)
+  ADD_TEST(ev_async ${LUA} ${CMAKE_CURRENT_SOURCE_DIR}/test/test_ev_async.lua ${CMAKE_CURRENT_SOURCE_DIR}/test/ ${CMAKE_CURRENT_BINARY_DIR}/)
   ADD_TEST(ev_child ${LUA} ${CMAKE_CURRENT_SOURCE_DIR}/test/test_ev_child.lua ${CMAKE_CURRENT_SOURCE_DIR}/test/ ${CMAKE_CURRENT_BINARY_DIR}/)
   ADD_TEST(ev_stat ${LUA} ${CMAKE_CURRENT_SOURCE_DIR}/test/test_ev_stat.lua ${CMAKE_CURRENT_SOURCE_DIR}/test/ ${CMAKE_CURRENT_BINARY_DIR}/)
   SET_TESTS_PROPERTIES(ev_io ev_loop ev_timer ev_signal ev_idle ev_child ev_stat

README.md

@@ -170,6 +170,20 @@ order for it to take effect.
 The on_async function will be called with these arguments (return
 values are ignored):
 
+### string = ev.Async.export(async, loop)
+
+Export serialized send for multi-threading signalization (low-level API).
+
+### async_send = ev.Async.import(string)
+
+Import serialized send for multi-threading signalization (low-level API).
+
+Return a function which will act as `async:send(loop)` when called.
+
+Calling the function beyond the lifespan of either the exported loop or async
+object will result in undefined behavior (crash/corruption). The same applies
+with an ill-formed string.
+
 ### on_async(loop, idle, revents)
 
 The loop is the event loop for which the idle object is
@@ -250,6 +264,11 @@ also `EV_TIMEOUT` C definition.
 If this bit is set, the watcher was triggered by a signal. See
 also `EV_SIGNAL` C definition.
 
+### ev.ASYNC (constant)
+
+If this bit is set, the watcher has been asynchronously notified. See also
+`EV_ASYNC` C definition.
+
 ### ev.CHILD (constant)
 
 If this bit is set, the watcher was triggered by a child signal.
@@ -448,6 +467,13 @@ Ensures that the watcher is neither active nor pending.
 
 See also `ev_async_stop()` C function (document as `ev_TYPE_stop()`).
 
+### async:send(loop)
+
+Sends/signals/activates the given "ev_async" watcher, that is, feeds an
+"EV_ASYNC" event on the watcher into the event loop, and instantly returns.
+
+See also `ev_async_send()` C function.
+
 ## ev.Child object methods
 
 ### child:start(loop [, is_daemon])

async_lua_ev.c

@@ -12,6 +12,12 @@ static int luaopen_ev_async(lua_State *L) {
     lua_pushcfunction(L, async_new);
     lua_setfield(L, -2, "new");
 
+    lua_pushcfunction(L, async_export);
+    lua_setfield(L, -2, "export");
+
+    lua_pushcfunction(L, async_import);
+    lua_setfield(L, -2, "import");
+
     return 1;
 }
 
@@ -23,6 +29,7 @@ static int luaopen_ev_async(lua_State *L) {
 static int create_async_mt(lua_State *L) {
 
     static luaL_Reg fns[] = {
+        { "send",          async_send },
         { "stop",          async_stop },
         { "start",         async_start },
         { NULL, NULL }
@@ -50,6 +57,69 @@ static int async_new(lua_State* L) {
     return 1;
 }
 
+struct async_serialized {
+  ev_async*       async;
+  struct ev_loop* loop;
+};
+
+static int async_sz_send(lua_State *L) {
+    void *udata = lua_touserdata(L, lua_upvalueindex(1));
+    struct async_serialized* data = (struct async_serialized*)udata;
+
+    ev_async_send(data->loop, data->async);
+
+    return 0;
+}
+
+/**
+ * Export serialized send for multi-threading signalization (low-level API).
+ *
+ * Return string.
+ *
+ * Usage:
+ *     string = Async.export(async, loop)
+ *
+ * [+1, -0, ?]
+ */
+static int async_export(lua_State *L) {
+    ev_async*       async  = check_async(L, 1);
+    struct ev_loop* loop   = *check_loop_and_init(L, 2);
+
+    struct async_serialized data;
+    data.async = async;
+    data.loop  = loop;
+    lua_pushlstring(L, (const char*)&data, sizeof(struct async_serialized));
+
+    return 1;
+}
+
+/**
+ * Import serialized send for multi-threading signalization (low-level API).
+ *
+ * Return a function which will act as async:send(loop) when called.
+ *
+ * Calling the function beyond the lifespan of either the exported loop or
+ * async object will result in undefined behavior (crash/corruption). The same
+ * applies with an ill-formed string.
+ *
+ * Usage:
+ *     async_send = Async.import(string)
+ *
+ * [+1, -0, ?]
+ */
+static int async_import(lua_State *L) {
+    size_t len;
+    const char* str = luaL_checklstring(L, 1, &len);
+    if ( len != sizeof(struct async_serialized) )
+      luaL_error(L, "invalid data size");
+
+    void* data = lua_newuserdata(L, sizeof(struct async_serialized));
+    memcpy(data, str, sizeof(struct async_serialized));
+    lua_pushcclosure(L, async_sz_send, 1);
+
+    return 1;
+}
+
 /**
  * @see watcher_cb()
  *
@@ -59,6 +129,24 @@ static void async_cb(struct ev_loop* loop, ev_async* async, int revents) {
     watcher_cb(loop, async, revents);
 }
 
+/**
+ * Sends/signals/activates the given "ev_async" watcher, that is, feeds an
+ * "EV_ASYNC" event on the watcher into the event loop, and instantly returns.
+ *
+ * Usage:
+ *     async:send(loop)
+ *
+ * [+0, -0, e]
+ */
+static int async_send(lua_State *L) {
+    ev_async*       async  = check_async(L, 1);
+    struct ev_loop* loop   = *check_loop_and_init(L, 2);
+
+    ev_async_send(loop, async);
+
+    return 0;
+}
+
 /**
  * Stops the async so it won't be called by the specified event loop.
  *

lua_ev.h

@@ -177,7 +177,10 @@ static int               io_getfd(lua_State *L);
 static int               luaopen_ev_async(lua_State *L);
 static int               create_async_mt(lua_State *L);
 static int               async_new(lua_State* L);
+static int               async_import(lua_State* L);
+static int               async_export(lua_State* L);
 static void              async_cb(struct ev_loop* loop, ev_async* async, int revents);
+static int               async_send(lua_State *L);
 static int               async_stop(lua_State *L);
 static int               async_start(lua_State *L);
 

test/test_ev_async.lua

@@ -0,0 +1,40 @@
+print '1..20'
+
+local src_dir, build_dir = ...
+package.path  = src_dir .. "?.lua;" .. package.path
+package.cpath = build_dir .. "?.so;" .. package.cpath
+
+local tap   = require("tap")
+local ev = require("ev")
+local help  = require("help")
+local dump  = require("dumper").dump
+local ok    = tap.ok
+
+local noleaks = help.collect_and_assert_no_watchers
+local loop = ev.Loop.default
+
+function test_basic()
+   local async1 = ev.Async.new(
+      function(loop, async, revents)
+         ok(true, 'async callback')
+         ok(ev.ASYNC == revents, 'ev.ASYNC(' .. ev.ASYNC .. ') == revents (' .. revents .. ')')
+      end)
+   async1:start(loop)
+   async1:send(loop)
+   loop:loop()
+end
+
+function test_export()
+   local async1 = ev.Async.new(
+      function(loop, async, revents)
+         ok(true, 'async callback')
+         ok(ev.ASYNC == revents, 'ev.ASYNC(' .. ev.ASYNC .. ') == revents (' .. revents .. ')')
+      end)
+   local send = ev.Async.import(ev.Async.export(async1, loop))
+   async1:start(loop)
+   send()
+   loop:loop()
+end
+
+noleaks(test_basic, "test_basic")
+noleaks(test_basic, "test_export")