546 lines
17 KiB
C++
546 lines
17 KiB
C++
#include "server.hpp"
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#include <csignal>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <fcntl.h>
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#include <memory>
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#include <netdb.h>
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#include <netinet/tcp.h>
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#include <pthread.h>
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#include <sys/epoll.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <unistd.h>
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#include <vector>
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#include "connection.hpp"
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#include "connection_registry.hpp"
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// Static thread-local storage for read buffer (used across different functions)
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static thread_local std::vector<char> g_read_buffer;
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std::shared_ptr<Server> Server::create(const weaseldb::Config &config,
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ConnectionHandler &handler,
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const std::vector<int> &listen_fds) {
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// Use std::shared_ptr constructor with private access
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// We can't use make_shared here because constructor is private
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return std::shared_ptr<Server>(new Server(config, handler, listen_fds));
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}
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Server::Server(const weaseldb::Config &config, ConnectionHandler &handler,
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const std::vector<int> &provided_listen_fds)
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: config_(config), handler_(handler), connection_registry_(),
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listen_fds_(provided_listen_fds) {
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// Server takes ownership of all provided listen fds
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// Ensure all listen fds are non-blocking for safe epoll usage
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for (int fd : listen_fds_) {
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int flags = fcntl(fd, F_GETFL, 0);
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if (flags == -1) {
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perror("fcntl F_GETFL");
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std::abort();
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}
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if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
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perror("fcntl F_SETFL O_NONBLOCK");
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std::abort();
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}
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}
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// Setup shutdown pipe for graceful shutdown
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setup_shutdown_pipe();
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// Create epoll instances immediately for createLocalConnection() support
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create_epoll_instances();
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// If empty vector provided, listen_fds_ will be empty (no listening)
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// Server works purely with createLocalConnection()
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}
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Server::~Server() {
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if (shutdown_pipe_[0] != -1) {
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int e;
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do {
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e = close(shutdown_pipe_[0]);
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} while (e == -1 && errno == EINTR);
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shutdown_pipe_[0] = -1;
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}
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if (shutdown_pipe_[1] != -1) {
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int e;
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do {
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e = close(shutdown_pipe_[1]);
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} while (e == -1 && errno == EINTR);
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shutdown_pipe_[1] = -1;
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}
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// Close all epoll instances
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for (int epollfd : epoll_fds_) {
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if (epollfd != -1) {
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int e;
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do {
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e = close(epollfd);
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} while (e == -1 && errno == EINTR);
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}
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}
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epoll_fds_.clear();
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// Close all listen sockets (Server always owns them)
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for (int fd : listen_fds_) {
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if (fd != -1) {
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int e;
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do {
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e = close(fd);
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} while (e == -1 && errno == EINTR);
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}
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}
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// Clean up unix socket file if it exists
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if (!config_.server.unix_socket_path.empty()) {
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unlink(config_.server.unix_socket_path.c_str());
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}
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}
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void Server::run() {
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// Shutdown pipe and epoll instances are now created in constructor
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// Create I/O threads locally in this call frame
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// CRITICAL: By owning threads in run()'s call frame, we guarantee they are
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// joined before run() returns, eliminating any race conditions in ~Server()
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std::vector<std::thread> threads;
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start_io_threads(threads);
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// Wait for all threads to complete before returning
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// This ensures all I/O threads are fully stopped before the Server
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// destructor can be called, preventing race conditions during connection
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// cleanup
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for (auto &thread : threads) {
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thread.join();
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}
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// At this point, all threads are joined and it's safe to destroy the Server
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}
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void Server::shutdown() {
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if (shutdown_pipe_[1] != -1) {
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char val = 1;
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// write() is async-signal-safe per POSIX - safe to use in signal handler
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// Write single byte to avoid partial write complexity
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while (write(shutdown_pipe_[1], &val, 1) == -1) {
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if (errno != EINTR) {
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abort(); // graceful shutdown didn't work. Let's go ungraceful.
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}
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}
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}
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}
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void Server::releaseBackToServer(std::unique_ptr<Connection> connection) {
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if (!connection) {
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return; // Nothing to release
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}
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// Try to get the server from the connection's weak_ptr
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if (auto server = connection->server_.lock()) {
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// Server still exists - pass unique_ptr directly
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server->receiveConnectionBack(std::move(connection));
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}
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// If server is gone, connection will be automatically cleaned up when
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// unique_ptr destructs
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}
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void Server::receiveConnectionBack(std::unique_ptr<Connection> connection) {
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if (!connection) {
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return; // Nothing to process
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}
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// Re-add the connection to epoll for continued processing
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struct epoll_event event{};
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if (!connection->hasMessages()) {
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event.events = EPOLLIN | EPOLLONESHOT;
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} else {
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event.events = EPOLLOUT | EPOLLONESHOT;
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}
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int fd = connection->getFd();
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event.data.fd = fd;
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// Store connection in registry before adding to epoll
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// This mirrors the pattern used in process_connection_batch
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size_t epoll_index = connection->getEpollIndex();
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int epollfd = epoll_fds_[epoll_index];
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connection_registry_.store(fd, std::move(connection));
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if (epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &event) == -1) {
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perror("epoll_ctl MOD in receiveConnectionBack");
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// Remove from registry and clean up on failure
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(void)connection_registry_.remove(fd);
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}
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}
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int Server::createLocalConnection() {
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int sockets[2];
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if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) != 0) {
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perror("socketpair");
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return -1;
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}
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int server_fd = sockets[0]; // Server keeps this end
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int client_fd = sockets[1]; // Return this end to caller
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int flags = fcntl(server_fd, F_GETFL, 0);
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if (flags == -1) {
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std::fprintf(stderr,
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"Server::createLocalConnection: fcntl F_GETFL failed\n");
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std::abort();
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}
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if (fcntl(server_fd, F_SETFL, flags | O_NONBLOCK) == -1) {
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std::fprintf(stderr,
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"Server::createLocalConnection: fcntl F_SETFL failed\n");
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std::abort();
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}
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// Create sockaddr_storage for the connection
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struct sockaddr_storage addr{};
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addr.ss_family = AF_UNIX;
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// Calculate epoll_index for connection distribution
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size_t epoll_index =
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connection_distribution_counter_.fetch_add(1, std::memory_order_relaxed) %
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epoll_fds_.size();
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// Create Connection object
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auto connection = std::unique_ptr<Connection>(new Connection(
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addr, server_fd, connection_id_.fetch_add(1, std::memory_order_relaxed),
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epoll_index, &handler_, *this));
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// Store in registry
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connection_registry_.store(server_fd, std::move(connection));
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// Add to appropriate epoll instance
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struct epoll_event event{};
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event.events = EPOLLIN | EPOLLONESHOT;
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event.data.fd = server_fd;
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int epollfd = epoll_fds_[epoll_index];
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if (epoll_ctl(epollfd, EPOLL_CTL_ADD, server_fd, &event) == -1) {
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perror("epoll_ctl ADD local connection");
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connection_registry_.remove(server_fd);
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int e;
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do {
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e = close(server_fd);
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} while (e == -1 && errno == EINTR);
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do {
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e = close(client_fd);
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} while (e == -1 && errno == EINTR);
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return -1;
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}
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return client_fd;
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}
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void Server::setup_shutdown_pipe() {
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if (pipe(shutdown_pipe_) == -1) {
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perror("pipe");
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std::abort();
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}
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// Set both ends to close-on-exec
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if (fcntl(shutdown_pipe_[0], F_SETFD, FD_CLOEXEC) == -1 ||
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fcntl(shutdown_pipe_[1], F_SETFD, FD_CLOEXEC) == -1) {
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perror("fcntl FD_CLOEXEC");
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std::abort();
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}
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}
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void Server::create_epoll_instances() {
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// Create multiple epoll instances to reduce contention
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epoll_fds_.resize(config_.server.epoll_instances);
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for (int i = 0; i < config_.server.epoll_instances; ++i) {
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epoll_fds_[i] = epoll_create1(EPOLL_CLOEXEC);
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if (epoll_fds_[i] == -1) {
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perror("epoll_create1");
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std::abort();
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}
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// Add shutdown pipe to each epoll instance
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struct epoll_event shutdown_event;
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shutdown_event.events = EPOLLIN;
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shutdown_event.data.fd = shutdown_pipe_[0];
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if (epoll_ctl(epoll_fds_[i], EPOLL_CTL_ADD, shutdown_pipe_[0],
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&shutdown_event) == -1) {
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perror("epoll_ctl shutdown pipe");
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std::abort();
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}
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// Add all listen sockets to each epoll instance with EPOLLEXCLUSIVE to
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// prevent thundering herd
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for (int listen_fd : listen_fds_) {
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struct epoll_event listen_event;
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listen_event.events = EPOLLIN | EPOLLEXCLUSIVE;
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listen_event.data.fd = listen_fd;
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if (epoll_ctl(epoll_fds_[i], EPOLL_CTL_ADD, listen_fd, &listen_event) ==
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-1) {
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perror("epoll_ctl listen socket");
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std::abort();
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}
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}
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}
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}
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int Server::get_epoll_for_thread(int thread_id) const {
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// Round-robin assignment of threads to epoll instances
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return epoll_fds_[thread_id % epoll_fds_.size()];
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}
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void Server::start_io_threads(std::vector<std::thread> &threads) {
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int io_threads = config_.server.io_threads;
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for (int thread_id = 0; thread_id < io_threads; ++thread_id) {
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threads.emplace_back([this, thread_id]() {
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pthread_setname_np(pthread_self(),
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("io-" + std::to_string(thread_id)).c_str());
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// Each thread uses its assigned epoll instance (round-robin)
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int epollfd = get_epoll_for_thread(thread_id);
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std::vector<epoll_event> events(config_.server.event_batch_size);
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std::vector<std::unique_ptr<Connection>> batch(
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config_.server.event_batch_size);
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std::vector<int> batch_events(config_.server.event_batch_size);
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std::vector<int>
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ready_listen_fds; // Reused across iterations to avoid allocation
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for (;;) {
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int event_count = epoll_wait(epollfd, events.data(),
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config_.server.event_batch_size, -1);
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if (event_count == -1) {
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if (errno == EINTR) {
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continue;
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}
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perror("epoll_wait");
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abort();
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}
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ready_listen_fds.clear(); // Clear from previous iteration
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int batch_count = 0;
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for (int i = 0; i < event_count; ++i) {
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// Check for shutdown event
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if (events[i].data.fd == shutdown_pipe_[0]) {
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return;
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}
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// Check for new connections on any listen socket
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bool isListenSocket =
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std::find(listen_fds_.begin(), listen_fds_.end(),
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events[i].data.fd) != listen_fds_.end();
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if (isListenSocket) {
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ready_listen_fds.push_back(events[i].data.fd);
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continue;
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}
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// Handle existing connection events
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int fd = events[i].data.fd;
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std::unique_ptr<Connection> conn = connection_registry_.remove(fd);
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assert(conn);
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if (events[i].events & (EPOLLERR | EPOLLHUP)) {
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// unique_ptr will automatically delete on scope exit
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continue;
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}
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// Transfer ownership from registry to batch processing
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batch[batch_count] = std::move(conn);
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batch_events[batch_count] = events[i].events;
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batch_count++;
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}
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// Process existing connections in batch
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if (batch_count > 0) {
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process_connection_batch(
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epollfd, std::span(batch).subspan(0, batch_count),
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std::span(batch_events).subspan(0, batch_count));
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}
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// Only accept on listen sockets that epoll indicates are ready
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for (int listen_fd : ready_listen_fds) {
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for (;;) {
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struct sockaddr_storage addr;
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socklen_t addrlen = sizeof(addr);
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int fd = accept4(listen_fd, (struct sockaddr *)&addr, &addrlen,
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SOCK_NONBLOCK);
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if (fd == -1) {
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if (errno == EAGAIN || errno == EWOULDBLOCK)
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break; // Try next listen socket
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if (errno == EINTR)
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continue;
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perror("accept4");
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abort();
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}
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// Check connection limit
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if (config_.server.max_connections > 0 &&
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active_connections_.load(std::memory_order_relaxed) >=
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config_.server.max_connections) {
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int e;
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do {
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e = close(fd);
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} while (e == -1 && errno == EINTR);
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continue;
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}
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// Enable keepalive
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int keepalive = 1;
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if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive,
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sizeof(keepalive)) == -1) {
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perror("setsockopt SO_KEEPALIVE");
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}
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// Add to epoll with no interests
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struct epoll_event event{};
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event.events = 0;
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event.data.fd = fd;
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if (epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event) == -1) {
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perror("epoll_ctl ADD");
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(void)connection_registry_.remove(fd);
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}
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// Transfer ownership from registry to batch processing
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size_t epoll_index = thread_id % epoll_fds_.size();
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batch[batch_count] = std::unique_ptr<Connection>(new Connection(
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addr, fd,
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connection_id_.fetch_add(1, std::memory_order_relaxed),
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epoll_index, &handler_, *this));
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batch_events[batch_count] =
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EPOLLIN; // New connections always start with read
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batch_count++;
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// Process batch if full
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if (batch_count == config_.server.event_batch_size) {
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process_connection_batch(
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epollfd, {batch.data(), (size_t)batch_count},
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{batch_events.data(), (size_t)batch_count});
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batch_count = 0;
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}
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} // End inner accept loop
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} // End loop over listen_fds_
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// Process remaining accepted connections
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if (batch_count > 0) {
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process_connection_batch(
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epollfd, std::span(batch).subspan(0, batch_count),
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std::span(batch_events).subspan(0, batch_count));
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batch_count = 0;
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}
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}
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});
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}
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}
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void Server::process_connection_reads(std::unique_ptr<Connection> &conn,
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int events) {
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assert(conn);
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// Handle EPOLLIN - read data and process it
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if (events & EPOLLIN) {
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auto buf_size = config_.server.read_buffer_size;
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g_read_buffer.resize(buf_size);
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char *buf = g_read_buffer.data();
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int r = conn->readBytes(buf, buf_size);
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if (r < 0) {
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// Error or EOF - connection should be closed
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conn.reset();
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return;
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}
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if (r == 0) {
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// No data available (EAGAIN) - skip read processing but continue
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return;
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}
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// Call handler with unique_ptr - handler can take ownership if needed
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handler_.on_data_arrived(std::string_view{buf, size_t(r)}, conn);
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// If handler took ownership (conn is now null), return true to indicate
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// processing is done
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if (!conn) {
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return;
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}
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}
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}
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void Server::process_connection_writes(std::unique_ptr<Connection> &conn,
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int events) {
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assert(conn);
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// Send immediately if we have outgoing messages (either from EPOLLOUT or
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// after reading)
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if ((events & EPOLLOUT) || ((events & EPOLLIN) && conn->hasMessages())) {
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bool error = conn->writeBytes();
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if (error) {
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conn.reset(); // Connection should be closed
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return;
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}
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// Call handler with unique_ptr - handler can take ownership if needed
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handler_.on_write_progress(conn);
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// If handler took ownership (conn is now null), return true to indicate
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// processing is done
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if (!conn) {
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return;
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}
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// Check if we should close the connection according to application
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if (!conn->hasMessages() && conn->closeConnection_) {
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conn.reset(); // Connection should be closed
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return;
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}
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}
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}
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void Server::process_connection_batch(
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int epollfd, std::span<std::unique_ptr<Connection>> batch,
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std::span<const int> events) {
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// First process writes for each connection
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for (size_t i = 0; i < batch.size(); ++i) {
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if (batch[i]) {
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process_connection_writes(batch[i], events[i]);
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}
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}
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// Then process reads for each connection
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for (size_t i = 0; i < batch.size(); ++i) {
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if (batch[i]) {
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process_connection_reads(batch[i], events[i]);
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}
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}
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// Call post-batch handler - handlers can take ownership here
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handler_.on_post_batch(batch);
|
|
|
|
// Transfer all remaining connections back to epoll
|
|
for (auto &conn_ptr : batch) {
|
|
if (conn_ptr) {
|
|
int fd = conn_ptr->getFd();
|
|
|
|
struct epoll_event event{};
|
|
if (!conn_ptr->hasMessages()) {
|
|
event.events = EPOLLIN | EPOLLONESHOT;
|
|
} else {
|
|
event.events = EPOLLOUT | EPOLLONESHOT;
|
|
}
|
|
|
|
event.data.fd = fd; // Use file descriptor for epoll
|
|
// Put connection back in registry since handler didn't take ownership.
|
|
// Must happen before epoll_ctl
|
|
connection_registry_.store(fd, std::move(conn_ptr));
|
|
if (epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &event) == -1) {
|
|
perror("epoll_ctl MOD");
|
|
(void)connection_registry_.remove(fd);
|
|
}
|
|
}
|
|
}
|
|
}
|