Reload the application
Sometimes you want to update the configuration file and gracefully reload the application. Here is a way to do so.
Among Unix Signals, SIGHUP can be used to restart an application (SIGHUP allows child processes to gracefully exist after they have completed the current job).
Place the code below in the global scope, before the application main(int argc,char ** argv) function:
static cppcms::service* srv;
static volatile bool got_sighup;
bool handler()
{
got_sighup = true;
srv->shutdown();
}
And in main():
while(1) {
srv = new cppcms::service(argc,argv);
srv->applications_pool().mount( cppcms::applications_factory<my_application>());
srv->run();
if(got_sighup) {
got_sighup = false;
continue;
}
break;
}
So when the application gets SIGHUP, it restarts and reloads the configuration file. It exits upon SIGTERM.
Important note (to be confirmed by Artyom): the above method does not work if in your configuration file (config.js) you have service.api = "http", i.e. if you use the internal browser. If you do, you will encounter the error: "system: Address already in use", meaning that the internal http server cannot reuse the IP same address (e.g. 127.0.0.1:8080). The method works with fastcgi or cgi.
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<h1>include <iostream></h1>
<h1>include <string></h1>
<h1>include <cstring></h1>
include <sys/socket.h>
include <netinet/in.h>
include <unistd.h>
int main() {
int server_fd, client_fd;
struct sockaddr_in address;
int addrlen = sizeof(address);
// HTML content to be served
std::string html =
"HTTP/1.1 200 OK\r\n"
"Content-Type: text/html\r\n\r\n"
"<!DOCTYPE html>"
"<html>"
"<head><title>My C++ Web</title></head>"
"<body><h1>Welcome to a Simple Web Page!</h1><p>This is served from C++.</p></body>"
"</html>";
// Create socket
server_fd = socket(AF_INET, SOCK_STREAM, 0);
if (server_fd == 0) {
perror("socket failed");
exit(EXIT_FAILURE);
}
// Bind
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons(8080);
if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
perror("bind failed");
exit(EXIT_FAILURE);
}
// Listen
if (listen(server_fd, 3) < 0) {
perror("listen");
exit(EXIT_FAILURE);
}
std::cout << "Server is running on http://localhost:8080" << std::endl;
while (true) {
// Accept client
client_fd = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen);
if (client_fd < 0) {
perror("accept");
exit(EXIT_FAILURE);
}
char buffer[3000] = {0};
read(client_fd, buffer, 3000); // Read client request
std::cout << "Request:\n" << buffer << std::endl;
// Send response
send(client_fd, html.c_str(), html.size(), 0);
close(client_fd); // Close connection
}
return 0;
}
<h1>include <iostream></h1>
<h1>include <string></h1>
<h1>include <cstring></h1>
include <sys/socket.h>
include <netinet/in.h>
include <unistd.h>
int main() {
int server_fd, client_fd;
struct sockaddr_in address;
int addrlen = sizeof(address);
// HTML content to be served
std::string html =
"HTTP/1.1 200 OK\r\n"
"Content-Type: text/html\r\n\r\n"
"<!DOCTYPE html>"
"<html>"
"<head><title>My C++ Web</title></head>"
"<body><h1>Welcome to a Simple Web Page!</h1><p>This is served from C++.</p></body>"
"</html>";
// Create socket
server_fd = socket(AF_INET, SOCK_STREAM, 0);
if (server_fd == 0) {
perror("socket failed");
exit(EXIT_FAILURE);
}
// Bind
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons(8080);
if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
perror("bind failed");
exit(EXIT_FAILURE);
}
// Listen
if (listen(server_fd, 3) < 0) {
perror("listen");
exit(EXIT_FAILURE);
}
std::cout << "Server is running on http://localhost:8080" << std::endl;
while (true) {
// Accept client
client_fd = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen);
if (client_fd < 0) {
perror("accept");
exit(EXIT_FAILURE);
}
char buffer[3000] = {0};
read(client_fd, buffer, 3000); // Read client request
std::cout << "Request:\n" << buffer << std::endl;
// Send response
send(client_fd, html.c_str(), html.size(), 0);
close(client_fd); // Close connection
}
return 0;
}
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