Changeset 22cdd39 for lib

Timestamp:

03/30/10 14:30:48 (12 years ago)

Author:

Perry Lorier <perry@…>

Branches:

4.0.1-hotfixes, cachetimestamps, develop, dpdk-ndag, etsilive, getfragoff, help, libtrace4, master, ndag_format, pfring, rc-4.0.1, rc-4.0.2, rc-4.0.3, rc-4.0.4, ringdecrementfix, ringperformance, ringtimestampfixes

Children:

7283767

Parents:

212f9da2

Message:

Correctly accumulate data into large buffers for write

File:

• lib/iow-stdio.c (modified) (3 diffs)

lib/iow-stdio.c

@@ -118 +118 @@
 static off_t stdio_wwrite(iow_t *iow, const char *buffer, off_t len)
 {
-        struct iovec iov[2];
-        int err;
+        int towrite = len;
         /* Round down size to the nearest multiple of MIN_WRITE_SIZE */
 
-        assert(len >= 0);
-        
-        if (DATA(iow)->offset + len >= MIN_WRITE_SIZE) {
-                int amount;
-                iov[0].iov_base = DATA(iow)->buffer;
-                iov[0].iov_len = DATA(iow)->offset;
-                iov[1].iov_base = (void*)buffer; /* cast away constness, which is safe here */
-                iov[1].iov_len = len - (DATA(iow)->offset+len) % MIN_WRITE_SIZE;
-                err=writev(DATA(iow)->fd, iov, 2);
+        assert(towrite >= 0);
+
+        while (DATA(iow)->offset + towrite >= MIN_WRITE_SIZE) {
+                int err;
+                struct iovec iov[2];
+                int total = towrite - (DATA(iow)->offset+towrite) % MIN_WRITE_SIZE;
+                int amount = total;
+                int count=0;
+                if (DATA(iow)->offset) {
+                        iov[count].iov_base = DATA(iow)->buffer;
+                        iov[count].iov_len = min(DATA(iow)->offset,amount);
+                        amount -= iov[count].iov_len;
+                        ++count;
+                }
+                if (towrite) {
+                        iov[count].iov_base = (void*)buffer;    /* cast away constness, which is safe 
+                                                                 * here 
+                                                                 */
+                        iov[count].iov_len = amount;
+                        amount -= iov[count].iov_len;
+                        ++count;
+                }
+                assert(amount == 0);
+                err=writev(DATA(iow)->fd, iov, count);
                 if (err==-1)
                         return -1;
+                if (err != total)
+                        fprintf(stderr,"Wrote %d/%d\n",err,total);
+
                 /* Drop off "err" bytes from the beginning of the buffers */
-                amount = min(DATA(iow)->offset, err);
+                amount = min(DATA(iow)->offset, err); /* How much we took out of the buffer */
+                memmove(DATA(iow)->buffer, 
+                        DATA(iow)->buffer+amount,
+                        DATA(iow)->offset-amount);
                 DATA(iow)->offset -= amount;
-                err -= amount;
+
+                err -= amount; /* How much was written */
+
+                assert(err <= towrite);
+
                 buffer += err;
-                len -= err;
+                towrite -= err;
+
+                assert(DATA(iow)->offset == 0);
         }
 
@@ -144 +170 @@
          * that this is true
          */
-        assert(DATA(iow)->offset + len <= MIN_WRITE_SIZE);
-        assert(len >= 0);
-
-        /* Copy the remainder into the buffer to write next time. */
-        memcpy(DATA(iow)->buffer + DATA(iow)->offset, buffer, len);
-        DATA(iow)->offset += len;
+        assert(DATA(iow)->offset + towrite <= MIN_WRITE_SIZE);
+        assert(towrite >= 0);
+
+        if (towrite > 0) {
+                /* Copy the remainder into the buffer to write next time. */
+                memcpy(DATA(iow)->buffer + DATA(iow)->offset, buffer, towrite);
+                DATA(iow)->offset += towrite;
+        }
 
         return len;
@@ -165 +193 @@
                 fcntl(DATA(iow)->fd,F_SETFL, err & ~O_DIRECT);
         }
-        write(DATA(iow)->fd, DATA(iow)->buffer, DATA(iow)->offset);
+#endif
+        err=write(DATA(iow)->fd, DATA(iow)->buffer, DATA(iow)->offset);
         DATA(iow)->offset = 0;
-#endif
         close(DATA(iow)->fd);
         free(iow->data);