Speed up by ignoring std::cout

Test Code

  1. #include <iostream>
  2.  
  3. int main(int argc, char *argv[])
  4. {
  5. 	//std::cout.setstate(std::ios_base::badbit);
  6. 	for(int i = 0; i < 100; i ++) {
  7. 		for(int i = 0; i < 100; i ++) {
  8. 			;//std::cout << "" << std::endl;
  9. 		}
  10. 	}
  11. 	return 0;
  12. }

Test it without std::cout

  1. root@imx6ul7d:~/tmp# time ./t1_1 
  2.  
  3. real    0m0.041s
  4. user    0m0.020s
  5. sys     0m0.000s

Test it with std::cout, but redirect to /dev/null

  1. root@imx6ul7d:~/tmp# time ./t1_0 > /dev/null
  2.  
  3. real    0m0.096s
  4. user    0m0.030s
  5. sys     0m0.030s

Test it with std::cout, but set io state

  1. root@imx6ul7d:~/tmp# time ./t1_2
  2.  
  3. real    0m0.061s
  4. user    0m0.040s
  5. sys     0m0.000s

Profile : Linux

Example 1

Add -pg

  1. arm-linux-gnueabihf-g++ -Wall -g -pg hello.cpp -o hello -std=c++17

Test

  1. root@imx6ul7d:~# gprof -b hello 
  2. Flat profile:
  3.  
  4. Each sample counts as 0.01 seconds.
  5.   %   cumulative   self              self     total           
  6.  time   seconds   seconds    calls   s/call   s/call  name    
  7. 100.00      3.45     3.45        1     3.45     3.45  hehe()
  8.   0.00      3.45     0.00        4     0.00     0.00  std::_Optional_base<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::_M_is_engaged() const
  9. ......

Routes stream to specified buffer

Developer Command Prompt for VS 2019

  1. cl basic_ios_rdbuf.cpp /EHsc

MSDN Source Code

  1. #include <ios>
  2. #include <iostream>
  3. #include <fstream>
  4.  
  5. int main( ) 
  6. {
  7.    using namespace std;
  8.    ofstream file( "rdbuf.txt" );
  9.    streambuf *x = cout.rdbuf( file.rdbuf( ) );
  10.    cout << "test" << endl; // Goes to file
  11.    cout.rdbuf(x);
  12.    cout << "test2" << endl; //normal
  13. }

IPC Performance : Socket on ARM

Test Environment

CPU: Freescale i.MX6UL rev1.1 528 MHz
DRAM: 512 MiB

Test Code

  1. #include <stdlib.h>
  2. #include <sys/types.h>
  3. #include <sys/socket.h> 
  4. #include <netinet/in.h>
  5. #include <errno.h>
  6. #include <string.h>
  7. #include <unistd.h>
  8. #include <fcntl.h>
  9.  
  10. #define CLTIP "127.0.0.1"
  11. #define SRVPORT 10172
  12. #define MAX_NUM 1024
  13.  
  14. int main(int argc, char* argv[])
  15. {
  16. 	struct timeval tv_sta, tv_end;
  17.  
  18. 	gettimeofday(&tv_sta, NULL);
  19.  
  20. 	int i = 0;
  21. 	int total = 1;
  22. 	int is_printf = 1;
  23. 	if (argc > 1) {
  24. 		total = atoi(argv[1]);
  25. 	}
  26. 	if (argc > 2) {
  27. 		is_printf = atoi(argv[2]);
  28. 	}
  29.  
  30. 	for (i = 0; i < total; i++) {
  31.  
  32. 		int clientsock = socket(PF_INET, SOCK_STREAM, 0);
  33. 		if (clientsock < 0)
  34. 		{
  35. 			printf("socket creation failed\n");
  36. 			exit(-1);
  37. 		}
  38. 		if (is_printf)
  39. 			printf("socket create successfully.\n");
  40.  
  41. 		struct sockaddr_in clientAddr;
  42. 		clientAddr.sin_family = AF_INET;
  43. 		clientAddr.sin_port = htons((u_short)SRVPORT);
  44. 		clientAddr.sin_addr.s_addr = inet_addr(CLTIP);
  45.  
  46. 		int flags = fcntl(clientsock, F_GETFL, 0);
  47. 		fcntl(clientsock, F_SETFL, flags | O_NONBLOCK);
  48.  
  49. 		int n;
  50. 		if ((n = connect(clientsock, (struct sockaddr*) & clientAddr, sizeof(struct sockaddr))) < 0)
  51. 		{
  52. 			if (errno != EINPROGRESS) {
  53. 				printf("Connect error.IP[%s], port[%d]\n", CLTIP, clientAddr.sin_port);
  54. 				exit(-1);
  55. 			}
  56. 		}
  57.  
  58. 		if (n != 0) {
  59.  
  60. 			fd_set rset, wset;
  61. 			FD_ZERO(&rset);
  62. 			FD_SET(clientsock, &rset);
  63. 			wset = rset;
  64. 			struct timeval tval;
  65. 			tval.tv_sec = 1;
  66. 			tval.tv_usec = 0;
  67. 			if ((n = select(clientsock + 1, &rset, &wset, NULL, 3 ? &tval : NULL)) == 0) {
  68. 				printf("Connect TIMEOUT.IP[%s], port[%d]\n", CLTIP, clientAddr.sin_port);
  69. 				exit(-1);
  70. 			}
  71. 			if (FD_ISSET(clientsock, &rset) || FD_ISSET(clientsock, &wset)) {
  72. 				int error;
  73. 				int len = sizeof(error);
  74. 				if (getsockopt(clientsock, SOL_SOCKET, SO_ERROR, &error, &len) < 0) {
  75. 					printf("pending error");
  76. 					exit(-1);
  77. 				}
  78. 			}
  79. 			else {
  80. 				printf("select error: clientsock not set");
  81. 				exit(-1);
  82. 			}
  83.  
  84. 		}
  85. 		fcntl(clientsock, F_SETFL, flags);
  86.  
  87. 		if (is_printf)
  88. 			printf("Connect to IP[%s], port[%d]\n", CLTIP, clientAddr.sin_port);
  89.  
  90. 		const char* sendBuf = "{\"signalType\":\"CONFIG\", \"signalData\":[{\"id\":\"CONF_NAME\", \"value\":\"PPS_MChip1\"}]}";
  91. 		char recvBuf[MAX_NUM] = { 0 };
  92.  
  93. 		//while(gets(sendBuf) != '\0')
  94. 		{
  95. 			if (send(clientsock, sendBuf, strlen(sendBuf), 0) == -1)
  96. 			{
  97. 				printf("send error!\n");
  98. 			}
  99. 			if (is_printf)
  100. 				printf("send to server:%s\n", sendBuf);
  101. 			//memset(sendBuf, 0, sizeof(sendBuf));
  102.  
  103. 			{
  104. 				int timeOut = 3000;
  105. 				int nRet = 0;
  106. 				struct timeval timeout;
  107. 				fd_set recvset;
  108. 				FD_ZERO(&recvset);
  109. 				FD_SET(clientsock, &recvset);
  110. 				timeout.tv_sec = timeOut / 1000;
  111. 				timeout.tv_usec = timeOut % 1000;
  112. 				nRet = select(clientsock + 1, &recvset, 0, 0, &timeout);
  113. 				if (nRet <= 0)
  114. 				{
  115. 					printf("clientsock recv select is error!\n");
  116. 					exit(-1);
  117. 				}
  118. 			}
  119.  
  120. 			if (recv(clientsock, recvBuf, MAX_NUM, 0) == -1)
  121. 			{
  122. 				printf("rev error!\n");
  123. 			}
  124. 			if (is_printf)
  125. 				printf("receive from server:%s\n", recvBuf);
  126. 			if (strcmp(recvBuf, "Goodbye,my dear client!") == 0)
  127. 			{
  128. 				//break;
  129. 			}
  130. 			memset(recvBuf, 0, sizeof(recvBuf));
  131. 		}
  132. 		close(clientsock);
  133.  
  134. 	}
  135.  
  136. 	gettimeofday(&tv_end, NULL);
  137.  
  138. 	int total_millisecond = (tv_end.tv_sec * 1000 + tv_end.tv_usec / 1000) - (tv_sta.tv_sec * 1000 + tv_sta.tv_usec / 1000);
  139. 	int average_millisecond = (total_millisecond / total);
  140.  
  141. 	printf("total_millisecond : %ld total_nums : %d\n", total_millisecond, total);
  142. 	printf("average_millisecond   : %ld\n", average_millisecond);
  143.  
  144. 	return 0;
  145. }

Test Result

  1. root@imx6ul7d:~/tmp# ./a.out 1 0
  2. total_millisecond : 13 total_nums : 1
  3. average_millisecond   : 13
  4. root@imx6ul7d:~/tmp# ./a.out 10 0
  5. total_millisecond : 104 total_nums : 10
  6. average_millisecond   : 10
  7. root@imx6ul7d:~/tmp# ./a.out 100 0 
  8. total_millisecond : 1023 total_nums : 100
  9. average_millisecond   : 10
  10. root@imx6ul7d:~/tmp# ./a.out 1000 0
  11. total_millisecond : 10801 total_nums : 1000
  12. average_millisecond   : 10

How to expose a local server behind a NAT or firewall to the internet

Download FRP Server & Client

Modify frps.ini

  1. [root@VM_0_5_centos frp_0.25.3_linux_amd64]# cat frps.ini
  2. [common]
  3. bind_port = xxxxxx
  4. dashboard_port = xxxxxx
  5. dashboard_user = xxxxxxxxxxxxxxxx
  6. dashboard_pwd = xxxxxxxxxxxxxxxx
  7. allow_ports = xxxxx-xxxxx
  8. token = xxxxxxxxxxxxxxxx
  9. max_pool_count = 10
  10. pool_count = 3

Start frps

  1. [root@VM_0_5_centos frp_0.25.3_linux_amd64]# ./frps -c ./frps.ini

Modify frpc.ini

  1. root@imx6ul7d:~/frp# cat frpc.ini 
  2. [common]
  3. server_addr = qinuu.com
  4. server_port = xxxxxx
  5. token = xxxxxxxxxxxxxxxx
  6. [ssh]
  7. type = tcp
  8. local_ip = 127.0.0.1
  9. local_port = 22
  10. remote_port = xxxxxx

Start frpc

root@imx6ul7d:~/frp# ./frpc -c ./frpc.ini

Start a systemd service

[root@VM_0_5_centos frp_0.25.3_linux_amd64]# cat /lib/systemd/system/frps.service
[Unit]
Description=Frp Server Service
After=network.target
 
[Service]
Type=simple
User=nobody
Restart=on-failure
RestartSec=5s
ExecStart=/usr/local/frp/frp_0.25.3_linux_amd64/frps -c /usr/local/frp/frp_0.25.3_linux_amd64/frps.ini
 
[Install]
WantedBy=multi-user.targethis
 
[root@VM_0_5_centos frp_0.25.3_linux_amd64]# systemctl start frps
[root@VM_0_5_centos frp_0.25.3_linux_amd64]# systemctl enable frps
[root@VM_0_5_centos frp_0.25.3_linux_amd64]# systemctl status frps

Cross compile wget with openssl for ARM

Config OpenSSL

tar xvf openssl-1.1.1b.tar.gz 
cd openssl-1.1.1b/
mkdir __install
./config --prefix=$PWD/__install no-asm shared

Edit Makefile

PLATFORM=linux-armv4
CROSS_COMPILE=arm-linux-gnueabihf-
delete "-m32" "-m64"

Compile OpenSSL

make
make install

Config Wget && Make

tar zxvf wget-1.20.1.tar.gz
cd wget-1.20.1
./configure --prefix=$PWD/__install --host=arm-linux CC=arm-linux-gnueabihf-gcc --with-ssl=openssl --with-libssl-prefix=/root/Downloads/wget_arm/openssl-1.1.1b/__install --without-zlib
make 
make install