c++ - 使用 mongoose 5.4 时未调用 mg_wakeup_server_ex () 回调

Question

我正在使用 Mongoose 5.4下面是代码行

char* eventToOCC = NULL;

static int websocket_data_push(struct mg_connection *conn, enum mg_event ev)
{
    if ((ev == MG_POLL) && (NULL != conn->uri) && (NULL != eventToOCC))
    {
        if (strcmp(conn->uri, "/web") == 0 && conn->is_websocket) {
            mg_websocket_printf(conn, WEBSOCKET_OPCODE_TEXT, "%s",
                                eventToOCC);
        }
    }
    return MG_FALSE;
}


void SampleClass::sendEventsToClinet(char* evString)
{
    if(evString != NULL)
    {
        eventToOCC = evString;
        printf("EVENT SENT is ---%s---\n",evString);
        mg_wakeup_server_ex(mgserver, websocket_data_push, "%lu %s",
                            (unsigned long) time(NULL), (const char *) evString);
    }
    else
    {
        printf("Connection Pointer is NULL\n");
    }
    return ;
}

这里，每当调用 mg_wakeup_server_ex() 时，回调都不会被调用。我不怀疑 C++ 方法调用 C 方法，因为它在少数情况下有效。仅在某些地方，不会调用 websocket_data_push () 回调。你能帮忙吗!!!

Answer 1

mg_wakeup_server_ex 唤醒服务器线程，其中调用mg_poll_server。

来自 Mongoose 文档 mg_wakeup_server_ex :

Sends string message to a server. Function func is called for every active connection. String message is passed in struct mg_connection::callback_param. This function is designed to push data to the connected clients, and can be called from any thread. There is a limitation on the length of the message, currently at 8 kilobytes.

由于它使用socketpair进行通信，如果从服务器线程调用它会死锁。在这种情况下，您应该替换为 mg_iterate_over_connections。

你的代码将变成这样:

static int websocket_data_push(struct mg_connection *conn, enum mg_event ev)
{
    const char* msg = (const char*)conn->callback_param;
    if ((ev == MG_POLL) && (NULL != conn->uri) && (NULL != msg))
    {
        if (strcmp(conn->uri, "/web") == 0 && conn->is_websocket) 
        {
            mg_websocket_printf(conn, WEBSOCKET_OPCODE_TEXT, msg);
        }
    }
    return MG_FALSE;
}  
void SampleClass::sendEventsToClient(const char* evString)
{
    if(evString != NULL)
    {
        char msg[8*1024];
        snprintf(msg, sizeof(msg),"%lu %s", (unsigned long) time(NULL), evString);
        mg_iterate_over_connections(mgserver, websocket_data_push,(void*)&msg);
    }
    else
    {
        printf("Connection Pointer is NULL\n");
    }
}

如果您想使用 mg_wakeup_server_ex，您应该从线程中调用它，例如使用 mg_start_thread 创建的线程。