[PATCH] shuf: avoid locking standard output when using --input-range

[Collin Funk]

Here is the throughput before this patch:

    # write_permuted_numbers
    $ ./src/shuf-prev -i 0-100000000 | pv -r > /dev/null
    [ 153MiB/s]

    # write_random_numbers
    $ timeout 10 ./src/shuf-prev -i 0-100000 -r | pv -r > /dev/null
    [78.6MiB/s]

Here is the throughput after this patch:

    # write_permuted_numbers
    $ timeout 10 ./src/shuf -i 0-100000000 | pv -r > /dev/null
    [ 308MiB/s]

    # write_random_numbers
    $ timeout 10 ./src/shuf -i 0-100000 -r | pv -r > /dev/null
    [ 196MiB/s]

* src/shuf.c (write_permuted_numbers, write_random_numbers): Prefer
fputs and fputc which may be unlocked over printf which locks standard
output.
---
 src/shuf.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/shuf.c b/src/shuf.c
index f87b85dd0..948ee88f3 100644
--- a/src/shuf.c
+++ b/src/shuf.c
@@ -325,7 +325,9 @@ write_permuted_numbers (size_t n_lines, size_t lo_input,
   for (size_t i = 0; i < n_lines; i++)
     {
       unsigned long int n = lo_input + permutation[i];
-      if (printf ("%lu%c", n, eolbyte) < 0)
+      char buf[INT_BUFSIZE_BOUND (uintmax_t)];
+      if (fputs (umaxtostr (n, buf), stdout) < 0
+          || fputc (eolbyte, stdout) < 0)
         return -1;
     }
 
@@ -343,7 +345,9 @@ write_random_numbers (struct randint_source *s, size_t 
count,
   for (size_t i = 0; i < count; i++)
     {
       unsigned long int j = lo_input + randint_choose (s, range);
-      if (printf ("%lu%c", j, eolbyte) < 0)
+      char buf[INT_BUFSIZE_BOUND (uintmax_t)];
+      if (fputs (umaxtostr (j, buf), stdout) < 0
+          || fputc (eolbyte, stdout) < 0)
         return -1;
     }
 
-- 
2.53.0