Merge pull request #2556 from cesanta/mt12m

add multi-threaded one to many example

examples/multi-threaded-12m/Makefile

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+SOURCES = main.c mongoose.c       # Source code files
+CFLAGS = -W -Wall -Wextra -g -I.  # Build options
+
+# Mongoose build options. See https://mongoose.ws/documentation/#build-options
+CFLAGS_MONGOOSE +=
+
+ifeq ($(OS),Windows_NT)
+  # Windows settings. Assume MinGW compiler. To use VC: make CC=cl CFLAGS=/MD
+  PROG ?= example.exe                 # Use .exe suffix for the binary
+  CC = gcc                            # Use MinGW gcc compiler
+  CFLAGS += -lws2_32                  # Link against Winsock library
+  CFLAGS += -Wno-cast-function-type   # Thread functions return void instead of void *
+  DELETE = cmd /C del /f /q /s        # Command prompt command to delete files
+else
+  # Mac, Linux
+  PROG ?= example
+  CFLAGS += -lpthread                 # Link against POSIX threads library
+  DELETE = rm -rf
+endif
+
+all: $(PROG)
+	$(RUN) ./$(PROG) $(ARGS)
+
+$(PROG): $(SOURCES)
+	$(CC) $(SOURCES) $(CFLAGS) $(CFLAGS_MONGOOSE) $(CFLAGS_EXTRA) -o $@
+
+clean:
+	$(DELETE) $(PROG) *.o *.obj *.exe *.dSYM

examples/multi-threaded-12m/README.md

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+See detailed tutorial at https://mongoose.ws/tutorials/multi-threaded/

examples/multi-threaded-12m/main.c

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+// Copyright (c) 2020-2023 Cesanta Software Limited
+// All rights reserved
+//
+// Multithreading example.
+// On creation, we spawn a separate thread that sleeps for
+// some time to simulate some processing time, then produces an output and
+// sends that output to the parent connection.
+// That connection then broadcasts that data to all connected WebSocket
+// connections
+
+#include "mongoose.h"
+
+static void start_thread(void *(*f)(void *), void *p) {
+#ifdef _WIN32
+  _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;
+  (void) pthread_attr_init(&attr);
+  (void) pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+  pthread_create(&thread_id, &attr, f, p);
+  pthread_attr_destroy(&attr);
+#endif
+}
+
+struct thread_data {
+  struct mg_mgr *mgr;
+  unsigned long conn_id;  // Parent connection ID
+};
+
+static void *thread_function(void *param) {
+  struct thread_data *p = (struct thread_data *) param;
+  printf("THREAD STARTED\n");
+  for (;;) {
+    sleep(2);
+    mg_wakeup(p->mgr, p->conn_id, "hi!", 3);  // Send to parent
+  }
+  // Free all resources that were passed to us
+  free(p);
+  return NULL;
+}
+
+// HTTP request callback
+static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
+  if (ev == MG_EV_OPEN && c->is_listening) {
+    // Start worker thread
+    struct thread_data *data = calloc(1, sizeof(*data));  // Worker owns it
+    data->conn_id = c->id;
+    data->mgr = c->mgr;
+    start_thread(thread_function, data);  // Start thread and pass data
+  } else if (ev == MG_EV_HTTP_MSG) {
+    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
+    if (mg_http_match_uri(hm, "/websocket")) {
+      mg_ws_upgrade(c, hm, NULL);  // Upgrade HTTP to Websocket
+      c->data[0] = 'W';            // Set some unique mark on a connection
+    } else {
+      // Serve static files
+      // struct mg_http_serve_opts opts = {.root_dir = s_web_root};
+      // mg_http_serve_dir(c, ev_data, &opts);
+    }
+  } else if (ev == MG_EV_WS_MSG) {
+    // Got websocket frame. Received data is wm->data. Echo it back!
+    struct mg_ws_message *wm = (struct mg_ws_message *) ev_data;
+    mg_ws_send(c, wm->data.ptr, wm->data.len, WEBSOCKET_OP_TEXT);
+    mg_iobuf_del(&c->recv, 0, c->recv.len);
+  } else if (ev == MG_EV_WAKEUP) {
+    struct mg_str *data = (struct mg_str *) ev_data;
+    // Broadcast message to all connected websocket clients.
+    // Traverse over all connections
+    for (struct mg_connection *wc = c->mgr->conns; wc != NULL; wc = wc->next) {
+      // Send only to marked connections
+      if (wc->data[0] == 'W')
+        mg_ws_send(wc, data->ptr, data->len, WEBSOCKET_OP_TEXT);
+    }
+  }
+  (void) fn_data;
+}
+
+int main(void) {
+  struct mg_mgr mgr;
+  mg_mgr_init(&mgr);        // Initialise event manager
+  mg_log_set(MG_LL_DEBUG);  // Set debug log level
+  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;
+}

examples/multi-threaded-12m/mongoose.c

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+../../mongoose.c

examples/multi-threaded-12m/mongoose.h

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+../../mongoose.h