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authorBjörn Gustavsson <[email protected]>2016-03-29 09:10:13 +0200
committerBjörn Gustavsson <[email protected]>2016-04-04 14:37:15 +0200
commit5ae46e823a8a52ed4e5b960ff62975894b1a8302 (patch)
treeb782b23d89d388ad4daa922ebc4ddea269802e35
parent1244cebc4b369cfd53ae775ea7380c61ed98ed64 (diff)
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Handle multi-giga byte writes to files
Test cases that write 4Gb to a file at once would fail on OS X and FreeBSD. By running a simple test program on OS X (El Capitan 10.11.4/Darwin 15.4.0), I found that writev() can handle more than 4Gb of data, while write() only can handle less than 2Gb. (Note that efile_drv.c will use write() if there is only one element in the io vector, and writev() if there is more than one.) It is tempting to attempt to piggy-back on the existing mechanism for segmenting write operations in efile_drv.c, but because of the complex code I find it too dangerous, both from a correctness and performance perspective. Instead do the change in unix_efile.c, which is considerably simpler.
-rw-r--r--erts/emulator/drivers/unix/unix_efile.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/erts/emulator/drivers/unix/unix_efile.c b/erts/emulator/drivers/unix/unix_efile.c
index ac9b681d03..c097bc1950 100644
--- a/erts/emulator/drivers/unix/unix_efile.c
+++ b/erts/emulator/drivers/unix/unix_efile.c
@@ -638,12 +638,21 @@ efile_writev(Efile_error* errInfo, /* Where to return error codes */
do {
w = writev(fd, &iov[cnt], b);
} while (w < 0 && errno == EINTR);
+ if (w < 0 && errno == EINVAL) {
+ goto single_write;
+ }
} else
+ single_write:
/* Degenerated io vector - use regular write */
#endif
{
do {
- w = write(fd, iov[cnt].iov_base, iov[cnt].iov_len);
+ size_t iov_len = iov[cnt].iov_len;
+ size_t limit = 1024*1024*1024; /* 1GB */
+ if (iov_len > limit) {
+ iov_len = limit;
+ }
+ w = write(fd, iov[cnt].iov_base, iov_len);
} while (w < 0 && errno == EINTR);
ASSERT(w <= iov[cnt].iov_len ||
(w == -1 && errno != EINTR));