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libusb的异步也有这样的问题

来源:程序员人生   发布时间:2016-11-29 08:43:01 阅读次数:5487次

1. 最近1直在关注异步机制,不论是网络库asio,libuv,还是libusb库,其实异步机制都是差不多的,都是基于回调函数、系统轮询实现的。

2. 下面是对1款USB产品做得测试结果,Windows环境下,用libusb异步API写的程序:


说明:用 Bus Hound 抓包,查看返回数值发现上面3个命令只有R是成功的(即有返回值),却对应在了B命令上,致使调用了B的回调。这就是异步容易致使的问题,也就是如果不停地发送命令,其中有1条命令失败,而超时未过,回来的结果如果没有别的辨别,致使调用失败指令的回调,而致使比较严重的后果。

#include <errno.h> #include <pthread.h> #include <semaphore.h> #include <signal.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <windows.h> #include "libusb.h" #define EP_IN (6 | LIBUSB_ENDPOINT_IN) #define EP_OUT (2 | LIBUSB_ENDPOINT_OUT) typedef enum { SAVE_IMAGE = 0x55, UPLOAD_IMAGE = 0xAA }BULK_REQCODE; typedef enum { SAVE_IMAGE_VAL = 0x00, UPLOAD_B_VAL = 0x00, UPLOAD_G_VAL = 0x01, UPLOAD_R_VAL = 0x02 }BULK_VALUE; static struct libusb_device_handle *devh = NULL; static unsigned char imgbuf_save[8]; static unsigned char imgbuf_upload[8]; static unsigned char imgbuf_R[2048*240]; static unsigned char imgbuf_G[2048*240]; static unsigned char imgbuf_B[2048*240]; static struct libusb_transfer *img_save = NULL; static struct libusb_transfer *img_R = NULL; static struct libusb_transfer *img_G = NULL; static struct libusb_transfer *img_B = NULL; static struct libusb_transfer *img_R_upload = NULL; static struct libusb_transfer *img_G_upload = NULL; static struct libusb_transfer *img_B_upload = NULL; static int img_idx = 0; static volatile sig_atomic_t do_exit = 0; static int ii=0; static pthread_t poll_thread; static sem_t exit_sem; static void request_exit(sig_atomic_t code) { do_exit = code; sem_post(&exit_sem); } static void *poll_thread_main(void *arg) //轮询是不是main——thread结束 { int r = 0; printf("poll thread running\n"); while (!do_exit) { struct timeval tv = { 1, 0 }; r = libusb_handle_events_timeout(NULL, &tv); //处理任何待以处理的事件 if (r < 0) { request_exit(2); break; } } printf("poll thread shutting down\n"); return NULL; } static int find_dpfp_device(void) { devh = libusb_open_device_with_vid_pid(NULL, 0x04b4, 0x8623); return devh ? 0 : -EIO; } static void LIBUSB_CALL cb_img(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "upload_img_R_over callback : " << transfer->status << std::endl; } static void LIBUSB_CALL save_img(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "save Image callback : " << transfer->status << std::endl; } static void LIBUSB_CALL upload_img_B(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "upload_img_B callback : " << transfer->status << std::endl; } static void LIBUSB_CALL upload_img_B_over(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "upload_img_B_over callback : " << transfer->status << std::endl; } static void LIBUSB_CALL upload_img_G(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "upload_img_G callback : " << transfer->status << std::endl; } static void LIBUSB_CALL upload_img_G_over(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "upload_img_G_over callback : " << transfer->status << std::endl; } static void LIBUSB_CALL upload_img_R(struct libusb_transfer *transfer) { if (transfer->status != LIBUSB_TRANSFER_COMPLETED) { fprintf(stderr, "img transfer status %d?\n", transfer->status); request_exit(2); return; } std::cout << "upload_img_R callback : " << transfer->status << std::endl; } //由于该装备处理多命令异步发送过来的时候,只处理最后1条 static int LIBUSB_CALL submit_trans() { int r=0; r = libusb_submit_transfer(img_save); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_save); //异步取消之条件交传输 printf("1"); } r = libusb_submit_transfer(img_B_upload); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_B_upload); //异步取消之条件交传输 printf("1"); } r = libusb_submit_transfer(img_B); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_B); //异步取消之条件交传输 printf("1"); } r = libusb_submit_transfer(img_G_upload); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_G_upload); //异步取消之条件交传输 printf("1"); } r = libusb_submit_transfer(img_G); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_G); //异步取消之条件交传输 printf("1"); } r = libusb_submit_transfer(img_R_upload); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_R_upload); //异步取消之条件交传输 printf("1"); } r = libusb_submit_transfer(img_R); //提交1个传输并立即返回 if (r < 0) { libusb_cancel_transfer(img_R); //异步取消之条件交传输 printf("1"); } return r; } static int alloc_transfers(void) { img_save = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_save) return -ENOMEM; img_R = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_R) return -ENOMEM; img_R_upload = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_R_upload) return -ENOMEM; img_G = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_G) return -ENOMEM; img_G_upload = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_G_upload) return -ENOMEM; img_B = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_B) return -ENOMEM; img_B_upload = libusb_alloc_transfer(0); //0参数表明配置1个异步传输 if (!img_B_upload) return -ENOMEM; imgbuf_save[0] = (u_char)(SAVE_IMAGE); imgbuf_save[1] = 0x00; imgbuf_save[2] = 0x00; imgbuf_save[3] = 0x00; imgbuf_save[4] = (uchar)((0xff00 & 0x00f0)>>8); imgbuf_save[5] = (uchar)(0x00ff & 0x00f0); imgbuf_save[6] = 0x00; imgbuf_save[7] = (u_char)(SAVE_IMAGE_VAL); libusb_fill_bulk_transfer(img_save, devh, EP_OUT, imgbuf_save, sizeof(imgbuf_save), save_img, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 imgbuf_upload[0] = (u_char)UPLOAD_IMAGE; imgbuf_upload[1] = 0x00; imgbuf_upload[2] = 0x00; imgbuf_upload[3] = 0x00; imgbuf_upload[4] = (uchar)((0xff00 & 0x00f0)>>8); imgbuf_upload[5] = (uchar)(0x00ff & 0x00f0); imgbuf_upload[6] = 0x00; imgbuf_upload[7] = (u_char)UPLOAD_B_VAL; libusb_fill_bulk_transfer(img_B_upload, devh, EP_OUT, imgbuf_upload, sizeof(imgbuf_upload), upload_img_B, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 libusb_fill_bulk_transfer(img_B, devh, EP_IN, imgbuf_B, sizeof(imgbuf_B), upload_img_B_over, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 imgbuf_upload[0] = (u_char)UPLOAD_IMAGE; imgbuf_upload[1] = 0x00; imgbuf_upload[2] = 0x00; imgbuf_upload[3] = 0x00; imgbuf_upload[4] = (uchar)((0xff00 & 0x00f0)>>8); imgbuf_upload[5] = (uchar)(0x00ff & 0x00f0); imgbuf_upload[6] = 0x00; imgbuf_upload[7] = (u_char)UPLOAD_G_VAL; libusb_fill_bulk_transfer(img_G_upload, devh, EP_OUT, imgbuf_upload, sizeof(imgbuf_upload), upload_img_G, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 libusb_fill_bulk_transfer(img_G, devh, EP_IN, imgbuf_G, sizeof(imgbuf_G), upload_img_G_over, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 imgbuf_upload[0] = (u_char)UPLOAD_IMAGE; imgbuf_upload[1] = 0x00; imgbuf_upload[2] = 0x00; imgbuf_upload[3] = 0x00; imgbuf_upload[4] = (uchar)((0xff00 & 0x00f0)>>8); imgbuf_upload[5] = (uchar)(0x00ff & 0x00f0); imgbuf_upload[6] = 0x00; imgbuf_upload[7] = (u_char)UPLOAD_R_VAL; libusb_fill_bulk_transfer(img_R_upload, devh, EP_OUT, imgbuf_upload, sizeof(imgbuf_upload), upload_img_R, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 libusb_fill_bulk_transfer(img_R, devh, EP_IN, imgbuf_R, sizeof(imgbuf_R), cb_img, NULL, 5000); //该辅助函数来填充所需的libusb_transfer批量传输字段 return 0; } int main(void) { libusb_init(NULL); //初始libusb库 int r = find_dpfp_device(); if(r!=0) { printf("%s\n", "not found dev" ); return 0; } r = libusb_claim_interface(devh, 0); //声明装备接口 if (r < 0) { fprintf(stderr, "usb_claim_interface error %d %s\n", r, strerror(-r)); goto out; } std::cout << "claimed interface" << std::endl; r = pthread_create(&poll_thread, NULL, poll_thread_main, NULL); //子线程poll_thread_main用来处理USB事件 if (r) goto out; r = alloc_transfers(); //配置1个异步bulk传输和1个中断传输,先alloc然后fill_XX_transfer if (r < 0) { request_exit(1); pthread_join(poll_thread, NULL); //函数pthread_join用来等待1个线程的结束 goto out; } r = submit_trans(); //submit1个传输 if (r < 0) { request_exit(1); pthread_join(poll_thread, NULL); //失败等待线程结束 goto out; } while (!do_exit) sem_wait(&exit_sem); //等待退出信号量 printf("shutting down...\n"); pthread_join(poll_thread, NULL); out_release: libusb_release_interface(devh, 0); out: libusb_close(devh); libusb_exit(NULL); sem_destroy(&exit_sem); return r >= 0 ? r : -r; }


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