Improved documentation and fixed bugs
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@@ -0,0 +1,238 @@
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <string.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/epoll.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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// This is a bare-bones epoll HTTP server to get a practical
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// req/sec limit.
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//
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// Compile:
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// gcc fast_epoll.c -o fast_epoll -Wall -Wextra -O2 -DNDEBUG
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int main()
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{
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int epoll_fd = epoll_create1(0);
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if (epoll_fd < 0) {
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perror("epoll_create1");
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return -1;
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}
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int listen_fd = socket(AF_INET, SOCK_STREAM, 0);
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if (listen_fd == -1) {
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perror("socket");
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return -1;
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}
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{
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int flags = fcntl(listen_fd, F_GETFL, 0);
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if (flags < 0) {
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perror("fcntl");
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return -1;
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}
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flags |= O_NONBLOCK;
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if (fcntl(listen_fd, F_SETFL, flags) < 0) {
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perror("fcntl");
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return -1;
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}
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}
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int one = 1;
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if (setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, (char*) &one, sizeof(one)) < 0) {
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perror("setsockopt");
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close(listen_fd);
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return -1;
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}
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struct sockaddr_in bind_buf;
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bind_buf.sin_family = AF_INET;
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bind_buf.sin_port = htons(3333);
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bind_buf.sin_addr.s_addr = inet_addr("127.0.0.1");
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if (bind(listen_fd, (struct sockaddr*) &bind_buf, sizeof(bind_buf)) < 0) {
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perror("bind");
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close(listen_fd);
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return -1;
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}
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if (listen(listen_fd, 32) < 0) {
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perror("listen");
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close(listen_fd);
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return -1;
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}
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struct epoll_event epoll_buf;
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epoll_buf.data.fd = -1;
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epoll_buf.events = EPOLLIN;
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if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, listen_fd, &epoll_buf) < 0) {
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perror("epoll_ctl");
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return -1;
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}
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#define CAPACITY (1<<9)
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#define IBUFCAP (1<<9)
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#define OBUFCAP (1<<9)
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#define MAXEXCH 100
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int num_fds = 0;
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int fds[CAPACITY];
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int free_idx[CAPACITY];
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char ibufs[CAPACITY][IBUFCAP];
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char obufs[CAPACITY][OBUFCAP];
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int sent[CAPACITY];
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int received[CAPACITY];
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int exchanged[CAPACITY];
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for (int i = 0; i < CAPACITY; i++)
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free_idx[i] = i;
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for (;;) {
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struct epoll_event batch[CAPACITY];
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int num = epoll_wait(epoll_fd, batch, CAPACITY, -1);
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for (int i = 0; i < num; i++) {
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if (batch[i].data.fd < 0) {
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while (num_fds < CAPACITY) {
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int accepted_fd = accept4(listen_fd, NULL, NULL, SOCK_NONBLOCK);
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if (accepted_fd < 0) {
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if (errno == EINTR)
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continue;
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if (errno == EAGAIN || errno == EWOULDBLOCK)
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break;
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__builtin_trap();
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}
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int num_free = CAPACITY - num_fds;
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int idx = free_idx[num_free-1];
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struct epoll_event epoll_buf;
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epoll_buf.data.fd = idx;
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epoll_buf.events = EPOLLIN;
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if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, accepted_fd, &epoll_buf)) {
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perror("epoll_ctl");
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__builtin_trap();
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}
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fds[idx] = accepted_fd;
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sent[idx] = 0;
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received[idx] = 0;
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exchanged[idx] = 0;
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num_fds++;
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}
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} else {
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int flags = batch[i].events;
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int idx = batch[i].data.fd;
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int fd = fds[idx];
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char *ibuf = ibufs[idx];
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char *obuf = obufs[idx];
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int remove = 0;
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if (flags & EPOLLIN) {
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for (;;) {
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if (received[idx] == IBUFCAP)
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__builtin_trap();
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int ret = recv(fd, ibuf + received[idx], IBUFCAP - received[idx], 0);
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if (ret < 0) {
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if (errno == EINTR)
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continue;
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if (errno == EAGAIN || errno == EWOULDBLOCK)
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break;
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remove = 1;
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break;
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}
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if (ret == 0) {
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remove = 1;
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break;
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}
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received[idx] += ret;
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}
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if (!remove) {
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int found = -1;
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for (int i = 0; i < received[idx]; i++) {
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if (3 < received[idx] - i
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&& ibuf[i+0] == '\r'
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&& ibuf[i+1] == '\n'
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&& ibuf[i+2] == '\r'
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&& ibuf[i+3] == '\n') {
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found = i;
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break;
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}
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}
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if (found > -1) {
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char resp[] = "HTTP/1.1 204 OK\r\nConnection: Keep-Alive\r\n\r\n";
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memcpy(obuf + sent[idx], resp, sizeof(resp)-1);
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sent[idx] += sizeof(resp)-1;
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int head_len = found+4;
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memcpy(ibuf, ibuf + received[idx], received[idx] - head_len);
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received[idx] -= head_len;
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struct epoll_event epoll_buf;
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epoll_buf.data.fd = idx;
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epoll_buf.events = EPOLLOUT;
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if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, fd, &epoll_buf) < 0) {
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perror("epoll_ctl");
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__builtin_trap();
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}
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}
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}
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}
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if (!remove && (flags & EPOLLOUT)) {
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int flushed = 0;
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do {
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int ret = send(fd, obuf + flushed, sent[idx] - flushed, 0);
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if (ret < 0) {
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if (errno == EINTR)
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continue;
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if (errno == EAGAIN || errno == EWOULDBLOCK)
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break;
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__builtin_trap();
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}
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if (ret == 0)
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__builtin_trap();
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flushed += ret;
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} while (flushed < sent[idx]);
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memmove(obuf, obuf + flushed, sent[idx] - flushed);
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sent[idx] -= flushed;
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if (sent[idx] == 0) {
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struct epoll_event epoll_buf;
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epoll_buf.data.fd = idx;
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epoll_buf.events = EPOLLIN;
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if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, fd, &epoll_buf) < 0) {
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perror("epoll_ctl");
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__builtin_trap();
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}
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}
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exchanged[idx]++;
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if (exchanged[idx] == MAXEXCH)
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remove = 1;
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}
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if (remove) {
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close(fds[idx]);
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fds[idx] = -1;
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int num_free = CAPACITY - num_fds;
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free_idx[num_free] = idx;
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num_fds--;
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}
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}
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}
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}
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close(epoll_fd);
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}
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