Author: stefan2
Date: Sat May 7 13:49:59 2011
New Revision: 1100536
URL: http://svn.apache.org/viewvc?rev=1100536&view=rev
Log:
Partly redo r1072299 as it minimizes the APR for small buffers on Win32
and document the rationales. Also, handle the case that APR might fail
*after* writing some data.
* subversion/libsvn_subr/io.c
(svn_io_file_write_full): optimize & document
Modified:
subversion/trunk/subversion/libsvn_subr/io.c
Modified: subversion/trunk/subversion/libsvn_subr/io.c
URL:
http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/io.c?rev=1100536&r1=1100535&r2=1100536&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_subr/io.c (original)
+++ subversion/trunk/subversion/libsvn_subr/io.c Sat May 7 13:49:59 2011
@@ -3162,25 +3162,38 @@ svn_io_file_write_full(apr_file_t *file,
apr_size_t nbytes, apr_size_t *bytes_written,
apr_pool_t *pool)
{
- apr_status_t rv = apr_file_write_full(file, buf, nbytes, bytes_written);
-
+ /* We cannot simply call apr_file_write_full on Win32 as it may fail
+ for larger values of NBYTES. In that case, we have to emulate the
+ "_full" part here. Thus, always call apr_file_write directly on
+ Win32 as this minimizes overhead for small data buffers. */
#ifdef WIN32
#define MAXBUFSIZE 30*1024
+ apr_size_t bw = nbytes;
+ apr_size_t to_write = nbytes;
+
+ /* try a simple "write everything at once" first */
+ apr_status_t rv = apr_file_write(file, buf, &bw);
+ buf = (char *)buf + bw;
+ to_write -= bw;
+
+ /* if the OS cannot handle that, use smaller chunks */
if (rv == APR_FROM_OS_ERROR(ERROR_NOT_ENOUGH_MEMORY)
&& nbytes > MAXBUFSIZE)
{
- apr_size_t bw = 0;
- *bytes_written = 0;
-
do {
- rv = apr_file_write_full(file, buf,
- nbytes > MAXBUFSIZE ? MAXBUFSIZE : nbytes,
&bw);
- *bytes_written += bw;
+ bw = to_write > MAXBUFSIZE ? MAXBUFSIZE : to_write;
+ rv = apr_file_write(file, buf, &bw);
buf = (char *)buf + bw;
- nbytes -= bw;
- } while (rv == APR_SUCCESS && nbytes > 0);
+ to_write -= bw;
+ } while (rv == APR_SUCCESS && to_write > 0);
}
+
+ /* bytes_written may actually be NULL */
+ if (bytes_written)
+ *bytes_written = nbytes - to_write;
#undef MAXBUFSIZE
+#else
+ apr_status_t rv = apr_file_write_full(file, buf, nbytes, bytes_written);
#endif
return svn_error_return(do_io_file_wrapper_cleanup(
