diff options
| author |  Johannes Schindelin <johannes.schindelin@gmx.de> | 2021-11-02 15:46:05 +0000 |
|---|---|---|
| committer |  Junio C Hamano <gitster@pobox.com> | 2021-11-03 11:22:26 -0700 |
| commit | df7000cd910a5f6991f73991b87d838a5d75e2fc (patch) | |
| tree | c86f0b59fd5f40fdbb7fdecf80ce4058b6cf9767 /t | |
| parent | test-genzeros: allow more than 2G zeros in Windows (diff) | |
| download | tgif-df7000cd910a5f6991f73991b87d838a5d75e2fc.tar.xz | |
test-tool genzeros: generate large amounts of data more efficiently
In this developer's tests, producing one gigabyte worth of NULs in a
busy loop that writes out individual bytes, unbuffered, took ~27sec.
Writing chunked 256kB buffers instead only took ~0.6sec
This matters because we are about to introduce a pair of test cases that
want to be able to produce 5GB of NULs, and we cannot use `/dev/zero`
because of the HP NonStop platform's lack of support for that device.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 't')
| -rw-r--r-- | t/helper/test-genzeros.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/t/helper/test-genzeros.c b/t/helper/test-genzeros.c index b1197e91a8..8ca988d621 100644 --- a/t/helper/test-genzeros.c +++ b/t/helper/test-genzeros.c @@ -3,7 +3,10 @@ int cmd__genzeros(int argc, const char **argv) { + /* static, so that it is NUL-initialized */ + static const char zeros[256 * 1024]; intmax_t count; + ssize_t n; if (argc > 2) { fprintf(stderr, "usage: %s [<count>]\n", argv[0]); @@ -12,9 +15,19 @@ int cmd__genzeros(int argc, const char **argv) count = argc > 1 ? strtoimax(argv[1], NULL, 0) : -1; - while (count < 0 || count--) { - if (putchar(0) == EOF) + /* Writing out individual NUL bytes is slow... */ + while (count < 0) + if (write(1, zeros, ARRAY_SIZE(zeros)) < 0) return -1; + + while (count > 0) { + n = write(1, zeros, count < ARRAY_SIZE(zeros) ? + count : ARRAY_SIZE(zeros)); + + if (n < 0) + return -1; + + count -= n; } return 0; |