Add mg_wakeup()

examples/multi-threaded/main.c

@@ -4,29 +4,15 @@
 // Multithreading example.
 // For each incoming request, we spawn a separate thread, that sleeps for
 // some time to simulate long processing time, produces an output and
-// hands over that output to the request handler function.
-//
-// We pass POST body to the worker thread, and respond with a calculated CRC
+// sends that output to the parent connection.
 
 #include "mongoose.h"
 
-#define LISTENING_ADDR "http://localhost:8000"
-
-struct thread_data {
-  struct mg_queue queue;  // Worker -> Connection queue
-  struct mg_str body;     // Copy of message body
-};
-
-// These two helper UDP connections are used to wake up mongoose thread
-static struct mg_connection *s_wakeup_server;
-static struct mg_connection *s_wakeup_client;
-#define WAKEUP_URL "udp://127.0.0.1:40111"
-
 static void start_thread(void *(*f)(void *), void *p) {
 #ifdef _WIN32
-#define usleep(x) Sleep((x) / 1000)
   _beginthread((void(__cdecl *)(void *)) f, 0, p);
 #else
+#define closesocket(x) close(x)
 #include <pthread.h>
   pthread_t thread_id = (pthread_t) 0;
   pthread_attr_t attr;
@@ -37,72 +23,53 @@ static void start_thread(void *(*f)(void *), void *p) {
 #endif
 }
 
-static void *worker_thread(void *param) {
-  struct thread_data *d = (struct thread_data *) param;
-  char buf[100];  // On-stack buffer for the message queue
+struct thread_data {
+  struct mg_mgr *mgr;
+  unsigned long conn_id;  // Parent connection ID
+  struct mg_str message;  // Original HTTP request
+};
 
-  mg_queue_init(&d->queue, buf, sizeof(buf));  // Init queue
-  usleep(1 * 1000 * 1000);                     // Simulate long execution time
-
-  // Send a response to the connection
-  if (d->body.len == 0) {
-    mg_queue_printf(&d->queue, "Send me POST data");
-  } else {
-    uint32_t crc = mg_crc32(0, d->body.ptr, d->body.len);
-    mg_queue_printf(&d->queue, "crc32: %#x", crc);
-    free((char *) d->body.ptr);
-  }
-
-  // Wake up Mongoose thread by sending something to one of its connections
-  mg_send(s_wakeup_client, "hi", 2);
-
-  // Wait until connection reads our message, then it is safe to quit
-  while (d->queue.tail != d->queue.head) usleep(1000);
-  MG_INFO(("done, cleaning up..."));
-  free(d);
+static void *thread_function(void *param) {
+  struct thread_data *p = (struct thread_data *) param;
+  sleep(2);                                 // Simulate long execution
+  mg_wakeup(p->mgr, p->conn_id, "hi!", 3);  // Respond to parent
+  free((void *) p->message.ptr);            // Free all resources that were
+  free(p);                                  // passed to us
   return NULL;
 }
 
-static void wfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
-  if (ev == MG_EV_READ) {
-    c->recv.len = 0;  // Discard received data
-  }
-  (void) ev_data, (void) fn_data;
-}
-
 // HTTP request callback
 static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
   if (ev == MG_EV_HTTP_MSG) {
-    // Received HTTP request. Allocate thread data and spawn a worker thread
     struct mg_http_message *hm = (struct mg_http_message *) ev_data;
-    struct thread_data *d = (struct thread_data *) calloc(1, sizeof(*d));
-    d->body = mg_strdup(hm->body);   // Pass received body to the worker
-    start_thread(worker_thread, d);  // Start a thread
-    *(void **) c->data = d;          // Memorise data pointer in c->data
-  } else if (ev == MG_EV_POLL) {
-    // Poll event. Delivered to us every mg_mgr_poll interval or faster
-    struct thread_data *d = *(struct thread_data **) c->data;
-    size_t len;
-    char *buf;
-    // Check if we have a message from the worker
-    if (d != NULL && (len = mg_queue_next(&d->queue, &buf)) > 0) {
-      // Got message from worker. Send a response and cleanup
-      mg_http_reply(c, 200, "", "%.*s\n", (int) len, buf);
-      mg_queue_del(&d->queue, len);  // Delete message
-      *(void **) c->data = NULL;     // Forget about thread data
+    if (mg_http_match_uri(hm, "/fast")) {
+      // Single-threaded code path, for performance comparison
+      // The /fast URI responds immediately
+      mg_http_reply(c, 200, "Host: foo.com\r\n", "hi\n");
+    } else {
+      // Multithreading code path
+      struct thread_data *data = calloc(1, sizeof(*data));  // Worker owns it
+      data->message = mg_strdup(hm->message);               // Pass message
+      data->conn_id = c->id;
+      data->mgr = c->mgr;
+      start_thread(thread_function, data);  // Start thread and pass data
     }
+  } else if (ev == MG_EV_WAKEUP) {
+    struct mg_str *data = (struct mg_str *) ev_data;
+    mg_http_reply(c, 200, "", "Result: %.*s\n", data->len, data->ptr);
   }
   (void) fn_data;
 }
 
 int main(void) {
   struct mg_mgr mgr;
-  mg_mgr_init(&mgr);
+  mg_mgr_init(&mgr);        // Initialise event manager
   mg_log_set(MG_LL_DEBUG);  // Set debug log level
-  mg_http_listen(&mgr, LISTENING_ADDR, fn, NULL);
-  s_wakeup_server = mg_listen(&mgr, WAKEUP_URL, wfn, NULL);
-  s_wakeup_client = mg_connect(&mgr, WAKEUP_URL, wfn, NULL);
-  for (;;) mg_mgr_poll(&mgr, 5000);  // Event loop. Use 5s poll interval
-  mg_mgr_free(&mgr);                 // Cleanup
+  mg_http_listen(&mgr, "http://localhost:8000", fn, NULL);  // Create listener
+  mg_wakeup_init(&mgr);  // Initialise wakeup socket pair
+  for (;;) {             // Event loop
+    mg_mgr_poll(&mgr, 1000);
+  }
+  mg_mgr_free(&mgr);
   return 0;
 }