学习到了常用函数 system

2024-05-26 08:24:54 +08:00
parent 6f754aa23d
commit 6f28a3384a
16 changed files with 1066 additions and 0 deletions
--- a/C16-并发/parallel/signal/slowcat2.c
+++ b/C16-并发/parallel/signal/slowcat2.c
@@ -0,0 +1,102 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define CPS     10
+#define BUFSIZE CPS
+#define BURST   100   //!! token上限
+
+// static volatile int token = 0;
+static volatile sig_atomic_t token = 0;   //!!! 保证原子
+
+static void alrm_handler(int s)
+{
+    alarm(1);   //!! 产生新的alarm
+    token++;
+    if (token > BURST)
+        token = BURST;
+}
+
+/***********************************************************************
+ * @brief    slowcat
+ * @details  流量控制，令牌桶实现
+ * @param    argc
+ * @param    argv
+ * @return   int
+ ***********************************************************************/
+int main(int argc, char **argv)
+{
+    int  sfd, dfd = 1;
+    char buf[BUFSIZE];
+    int  len, ret, pos;
+
+    if (argc < 2)
+    {
+        fprintf(stderr, "Usage: %s <src>\n", argv[0]);
+        exit(1);
+    }
+
+    signal(SIGALRM, alrm_handler);
+    alarm(1);
+
+    do   //!!!
+    {
+        sfd = open(argv[1], O_RDONLY);
+        if (sfd < 0)
+        {
+            //!!!
+            if (errno != EINTR)
+            {
+                perror("open");
+                exit(1);
+            }
+        }
+    } while (sfd < 0);
+
+    while (1)
+    {
+        while (token <= 0)
+            pause();   //!
+
+        token--;       //!!! 这条指令不一定原子
+
+        //* 阻塞在这里的时候，token会自增
+        while ((len = read(sfd, buf, BUFSIZE)) < 0)
+        {
+            //!!!
+            if (EINTR == errno)
+                continue;
+
+            perror("read");
+            break;
+        }
+        if (len == 0)
+            break;
+
+        pos = 0;
+        while (len > 0)
+        {
+            /* 可能没写完被别的中断打断 */
+            ret = write(dfd, buf + pos, len);
+            if (ret < 0)
+            {
+                //!!!
+                if (EINTR == errno)
+                    continue;
+                perror("write");
+                exit(1);
+            }
+            pos += ret;
+            len -= ret;
+        }
+
+        // sleep(1);   //! 能实现，但是移植性不好
+    }
+
+    close(sfd);
+
+    exit(0);
+}