sample: ch12: 基于 I/O 多路复用的并发 echo 服务器

sample/ch12/Makefile

@@ -20,6 +20,7 @@ OBJS += echoservert_pre.o
 OBJS += echo_cnt.o
 OBJS += echoserverp.o
 OBJS += select.o
+OBJS += echoservers.o
 
 PROGRAMS += hello
 PROGRAMS += echoservert
@@ -29,6 +30,7 @@ PROGRAMS += goodcnt
 PROGRAMS += echoservert_pre
 PROGRAMS += echoserverp
 PROGRAMS += select
+PROGRAMS += echoservers
 
 PHONY += all
 PHONY += clean
@@ -100,5 +102,11 @@ select: select.o echo.o csapp.o
 select.o: select.c $(csapp_h)
 	$(CC) $(CFLAGS) $(INCLUDES) -c $< -o $@
 
+echoservers: echoservers.o csapp.o
+	$(CC) $(CFLAGS) $^ $(LIBS) -o $@
+
+echoservers.o: echoservers.c $(csapp_h)
+	$(CC) $(CFLAGS) $(INCLUDES) -c $< -o $@
+
 clean:
 	rm -f $(OBJS) $(PROGRAMS)

sample/ch12/echoservers.c

@@ -0,0 +1,126 @@
+/*
+ * p654~p656
+ *
+ * 基于 I/O 多路复用的并发 echo 服务器。每次服务器迭代都回送来自每个准备好的描述
+ * 符的文本行
+ *
+ * unix> make echoservers
+ * unix> ./echoservers
+ */
+
+#include "csapp.h"
+
+typedef struct {                /* Represents a pool of connected descriptors */
+
+        int maxfd;              /* Largest descriptor in read_set */
+        fd_set read_set;        /* Set of all active descriptors */
+
+        fd_set ready_set;       /* Subset of descriptors ready for reading */
+        int nready;             /* Number of ready descriptors from select */
+
+        int maxi;               /* Highwater index into client array */
+        int clientfd[FD_SETSIZE]; /* Set of active descriptors */
+        rio_t clientrio[FD_SETSIZE]; /* Set of active read buffers */
+} pool;
+
+int byte_cnt = 0;               /* Counts total bytes received by server */
+
+void init_pool(int listenfd, pool *p)
+{
+        /* Initially, there are no connected descriptors */
+        int i;
+        p->maxi = -1;
+        for (i = 0; i < FD_SETSIZE; i++)
+                p->clientfd[i] = -1;
+
+        /* Initially, listenfd is only member of select read set */
+        p->maxfd = listenfd;
+        FD_ZERO(&p->read_set);
+        FD_SET(listenfd, &p->read_set);
+}
+
+void add_client(int connfd, pool *p)
+{
+        int i;
+        p->nready--;
+        for (i = 0; i < FD_SETSIZE; i++) /* Find an available slot */
+                if (p->clientfd[i] < 0) {
+                        /* Add connected descriptor to the pool */
+                        p->clientfd[i] = connfd;
+                        Rio_readinitb(&p->clientrio[i], connfd);
+
+                        /* Add the descriptor to descriptor set */
+                        FD_SET(connfd, &p->read_set);
+
+                        /* Update max descriptor and pool highwater mark */
+                        if (connfd > p->maxfd)
+                                p->maxfd = connfd;
+                        if (i > p->maxi)
+                                p->maxi = i;
+                        break;
+                }
+        if (i == FD_SETSIZE)    /* Couldn't find an empty slot */
+                app_error("add_client error: Too many clients");
+}
+
+void check_client(pool *p)
+{
+        int i, connfd, n;
+        char buf[MAXLINE];
+        rio_t rio;
+
+        for (i = 0; (i <= p->maxi) && (p->nready > 0); i++) {
+                connfd = p->clientfd[i];
+                rio = p->clientrio[i];
+
+                /* If the descriptor is ready, echo a text line from it */
+                if ((connfd > 0) && (FD_ISSET(connfd, &p->ready_set))) {
+                        p->nready--;
+                        if ((n = Rio_readlineb(&rio, buf, MAXLINE)) != 0) {
+                                byte_cnt += n;
+                                printf("Server received %d (%d total) bytes on fd %d\n",
+                                       n, byte_cnt, connfd);
+                                Rio_writen(connfd, buf, n);
+                        }
+
+                        /* EOF detected, remove descriptor from pool */
+                        else {
+                                Close(connfd);
+                                FD_CLR(connfd, &p->read_set);
+                                p->clientfd[i] = -1;
+                        }
+                }
+        }
+}
+
+int main(int argc, char **argv)
+{
+        int listenfd, connfd, port;
+        socklen_t clientlen = sizeof(struct sockaddr_in);
+        struct sockaddr_in clientaddr;
+        static pool pool;
+
+        if (argc != 2) {
+                fprintf(stderr, "usage: %s <port>\n", argv[0]);
+                exit(0);
+        }
+        port = atoi(argv[1]);
+
+        listenfd = Open_listenfd(port);
+        init_pool(listenfd, &pool);
+
+        while (1) {
+                /* Wait for listening/connected descriptor(s) to become ready */
+                pool.ready_set = pool.read_set;
+                pool.nready = Select(pool.maxfd+1, &pool.ready_set, NULL, NULL, NULL);
+
+                /* If listening descriptor ready, add new client to pool */
+                if (FD_ISSET(listenfd, &pool.ready_set)) {
+                        connfd = Accept(listenfd, (SA *)&clientaddr, &clientlen);
+                        add_client(connfd, &pool);
+                }
+
+                /* Echo a text line from each ready connected descriptor */
+                check_client(&pool);
+        }
+}