[core] network_write prefer writev() over write()

When writev() is available, always use writev() instead of write()
(Silently ignores config option to use write() if writev() is available)
(Still uses sendfile() instead of writev() when config selects sendfile)

src/network_write.c

@@ -131,6 +131,7 @@ static int network_write_accounting(const int fd, chunkqueue * const cq, off_t *
 /* write next chunk(s); finished chunks are removed afterwards after successful writes.
  * return values: similar as backends (0 success, -1 error, -2 remote close, -3 try again later (EINTR/EAGAIN)) */
 /* next chunk must be MEM_CHUNK. use write()/send() */
+#if !defined(NETWORK_WRITE_USE_WRITEV)
 static int network_write_mem_chunk(const int fd, chunkqueue * const cq, off_t * const p_max_bytes, log_error_st * const errh) {
     chunk* const c = cq->first;
     off_t c_len = (off_t)buffer_string_length(c->mem) - c->offset;
@@ -140,6 +141,7 @@ static int network_write_mem_chunk(const int fd, chunkqueue * const cq, off_t *
     ssize_t wr = network_write_data_len(fd, c->mem->ptr + c->offset, c_len);
     return network_write_accounting(fd, cq, p_max_bytes, errh, wr, c_len);
 }
+#endif
 
 
 
@@ -498,30 +500,6 @@ static int network_write_file_chunk_sendfile(const int fd, chunkqueue * const cq
  *   -2 : remote close
  */
 
-static int network_write_chunkqueue_write(const int fd, chunkqueue * const cq, off_t max_bytes, log_error_st * const errh) {
-    while (NULL != cq->first) {
-        int rc = -1;
-
-        switch (cq->first->type) {
-        case MEM_CHUNK:
-            rc = network_write_mem_chunk(fd, cq, &max_bytes, errh);
-            break;
-        case FILE_CHUNK:
-          #ifdef NETWORK_WRITE_USE_MMAP
-            rc = network_write_file_chunk_mmap(fd, cq, &max_bytes, errh);
-          #else
-            rc = network_write_file_chunk_no_mmap(fd, cq, &max_bytes, errh);
-          #endif
-            break;
-        }
-
-        if (__builtin_expect( (0 != rc), 0)) return (-3 == rc) ? 0 : rc;
-    }
-
-    return 0;
-}
-
-#if defined(NETWORK_WRITE_USE_WRITEV)
 static int network_write_chunkqueue_writev(const int fd, chunkqueue * const cq, off_t max_bytes, log_error_st * const errh) {
     while (NULL != cq->first) {
         int rc = -1;
@@ -548,7 +526,6 @@ static int network_write_chunkqueue_writev(const int fd, chunkqueue * const cq,
 
     return 0;
 }
-#endif
 
 #if defined(NETWORK_WRITE_USE_SENDFILE)
 static int network_write_chunkqueue_sendfile(const int fd, chunkqueue * const cq, off_t max_bytes, log_error_st * const errh) {
@@ -631,12 +608,8 @@ int network_write_init(server *srv) {
         break;
       #endif
     case NETWORK_BACKEND_WRITEV:
-      #if defined(NETWORK_WRITE_USE_WRITEV)
-        srv->network_backend_write = network_write_chunkqueue_writev;
-        break;
-      #endif
     case NETWORK_BACKEND_WRITE:
-        srv->network_backend_write = network_write_chunkqueue_write;
+        srv->network_backend_write = network_write_chunkqueue_writev;
         break;
     default:
         return -1;