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diff --git a/doc/DMM_DeveloperManual.md b/doc/DMM_DeveloperManual.md index 51e4be5..2646e60 100644 --- a/doc/DMM_DeveloperManual.md +++ b/doc/DMM_DeveloperManual.md @@ -29,6 +29,11 @@ [**7 How to use the incidental apps to test the protocol stack**](#7-how-to-use-the-incidental-apps-to-test-the-protocol-stack)<br> [**7.1 App introduction**](#7.1-app-introduction)<br> [**7.2 Test implementation**](#7.2-Test-implementation)<br> +[**8. DMM-RTC mode**](#8.-dmm-rtc-mode)<br> +[**8.1 RTC Stack Init and Run**](#8.1-rtc-stack-init-and-run)<br> +[**8.2 RTC epoll**](#8.2-rtc-epoll)<br> +[**8.3 RTC Limitations**](#8.3-rtc-limitations)<br> +[**8.3.1 F-Stack RTC Limitations**](#8.3.1-f-stack-rtc-limitations)<br> **1. Introduction**<br> ============================ @@ -1116,4 +1121,131 @@ The following table is an introduction to some parameters in the code. -x | flag print +**8. DMM-RTC mode**<br> +============================ +DMM-RTC mode is one of the basic model types of DMM, where nSocket and stack belong to the same process. +In this mode we need to handle the stack initialization at the time of DMM framework initialization. +Spceial care need to be taken for epoll_wait. +Need to mention the depoly type as 1 in module_config.json which tells DMM that nSocket and stack belong to the same process + +**8.1 RTC Stack Init and Run**<br> +------------------------- +RTC stack init need to be handled at the time of framework initialization. +Showing F-Stack stack registration function where dmm_fstack_init handles the F-Stack initialization +~~~C + +int +fstack_stack_register (nstack_proc_cb * proc_fun, nstack_event_cb * event_ops) +{ +#define NSTACK_MK_DECL(ret, fn, args) proc_fun->socket_ops.pf##fn = (void*)ff_##fn; +#include "declare_syscalls.h" +#undef NSTACK_MK_DECL + g_dmm_fstack.p_epoll_ctl = dlsym (event_ops->handle, "ff_epoll_ctl"); + g_dmm_fstack.p_epoll_create = dlsym (event_ops->handle, "ff_epoll_create"); + g_dmm_fstack.p_epoll_wait = dlsym (event_ops->handle, "ff_epoll_wait"); + g_dmm_fstack.p_close = dlsym (event_ops->handle, "ff_close"); + g_dmm_fstack.regVal = *event_ops; + + proc_fun->socket_ops.pfselect = NULL; + + proc_fun->extern_ops.module_init = dmm_fstack_init; + proc_fun->extern_ops.ep_ctl = fstack_ep_ctl_ops; + proc_fun->extern_ops.ep_getevt = NULL; + proc_fun->extern_ops.run = fr_run; + proc_fun->extern_ops.ep_prewait = dmm_fstack_epoll; + return 0; +} + +~~~ + +If a stack need to launch a function on all cores it need to call nstack_run with a loop function implemented by the user as its argument +Consider the below F-Stack application which explains the usage of nstack_run +~~~C + +int +main (int argc, char *argv[]) +{ + + int opt = 1; + int addrlen = sizeof (address); + + if ((server_fd = socket (AF_INET, SOCK_STREAM, 0)) == 0) + { + printf ("socket failed\n"); + exit (EXIT_FAILURE); + } + if (bind (server_fd, (struct sockaddr *) &address, sizeof (address)) < 0) + { + printf ("bind failed"); + exit (EXIT_FAILURE); + } + printf ("bind success\n"); + if (listen (server_fd, 3) < 0) + { + printf ("listen"); + exit (EXIT_FAILURE); + } + printf ("listen success\n"); + nstack_run ((void *) loop); + return 0; +} + +~~~ +~~~C +int +loop (void *arg) +{ + int new_socket, valread; + int addrlen = sizeof (address); + char buffer[1024] = { 0 }; + char hello[1024] = { 0 }; + sprintf (hello, "Hello from server\t PROC_ID : %d", getpid ()); + printf ("before accept\n"); + if ((new_socket = accept (server_fd, (struct sockaddr *) &address, + (socklen_t *) & addrlen)) < 0) + { + printf ("accept failed"); + return -1; + } + + printf ("accept success\n"); + valread = read (new_socket, buffer, 1024); + printf ("%s\n", buffer); + send (new_socket, hello, strlen (hello), 0); + printf ("Hello message sent\n"); + return 0; +} + +~~~ + +**8.2 RTC epoll** +------------------------- +RTC stack module init creates an epoll fd by calling stack's epoll_create function and make the epoll_fd global. +Whenever application calls epoll_ctl, stack's epoll_ctl will be called with the global epoll_fd. +An RTC Stack application must call nstack_epoll_prewait before calling epoll_wait. +nstack_epoll_prewait updates ep_item if any event occurs. +epoll_wait checks ep_item whether any event has occured and updates the same to the application. + +Below figure depicts the DMM F-Stack-RTC epoll architecture. + + + +------------------------- +Figure: F-Stack-RTC-epoll + +During the F-Stack module init a global epoll fd will be created by calling ff_epoll_create. +epoll_create allocates fd and nsep_epollInfo_t. +epoll_ctl calls ff_epoll_ctl with the global epoll fd created during the module init. +Non-blocking nstack_epoll_prewait will be called in a loop from application before epoll_wait to check any events have occured on global epoll fd, +in case of any events nstack_event_callback function will be called which updates the epitem. +epoll_wait checks epitem whether some event has occured or not and returns updtae to the application. + +**8.3 RTC Limitations** +------------------------- +**8.3.1 F-Stack RTC Limitations** +------------------------------------------- +No need to call ff_init as regular F-Stack applications call. +Need to call nstack_run insted of ff_run. +Must call nstack_epoll_prewait before calling epoll_wait. +In case of multi-stack and multi-socket application with F-Stack as one of the stacks, should not give timeout value for epoll_wait. |