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/* The writer part of a test program for non-blocking communication.
Copyright (C) 2011-2021 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* This program implements 4 tests:
test == 0:
Test blocking write() with blocking read().
Timeline Main process Child process
0 s Start Start, read(10000)
1 s write(20000) Return from read(10000)
2 s Next read(10000)
2 s Return from write(20000) Return from read(10000)
test == 1:
Test non-blocking write() with blocking read().
Timeline Main process Child process
0 s Start Start, read(10000)
1 s write(20000) Return from read(10000)
Return with at least 10000,
Repeatedly continue
write() of the rest
2 s Next read(10000)
2 s Return from write(10000) Return from read(10000)
test == 2:
Test blocking write() with non-blocking read().
Timeline Main process Child process
0 s Start Start, read(10000)
repeatedly polling
1 s write(20000) Return from read(10000)
2 s Next read(10000)
2 s Return from write(20000) Return from read(10000)
test == 3:
Test non-blocking write() with non-blocking read().
*/
#include "test-nonblocking-misc.h"
/* Execute the writer loop.
Returns 0 if successful, 1 if data_block_size is too small. */
static int
main_writer_loop (int test, size_t data_block_size, int fd,
bool has_large_buffer)
{
int too_small = 0;
unsigned char *data;
/* Set up the data to transfer. */
data = init_data (data_block_size);
switch (test)
{
TIMING_DECLS
ssize_t ret;
case 0: /* Test blocking write() with blocking read(). */
case 2: /* Test blocking write() with non-blocking read(). */
{
int saved_errno;
usleep (1000000);
dbgfprintf (stderr, "%s:1: >> write (%lu)\n", PROG_ROLE,
(unsigned long) (2 * data_block_size));
START_TIMING
ret = write (fd, data, 2 * data_block_size);
saved_errno = errno;
END_TIMING
dbgfprintf (stderr, "%s:1: << write -> %ld%s\n", PROG_ROLE,
(long) ret, dbgstrerror (ret < 0, saved_errno));
ASSERT (ret == 2 * data_block_size);
if (!has_large_buffer)
{
/* This assertion fails if data_block_size is too small. */
if (!(spent_time > 0.5))
{
fprintf (stderr,
"%s:1: spent_time = %g, data_block_size too small\n",
PROG_ROLE, spent_time);
too_small = 1;
}
}
ASSERT (spent_time < 1.5);
}
break;
case 1: /* Test non-blocking write() with blocking read(). */
case 3: /* Test non-blocking write() with non-blocking read(). */
{
size_t bytes_written;
int saved_errno;
usleep (1000000);
bytes_written = 0;
while (bytes_written < 2 * data_block_size)
{
dbgfprintf (stderr, "%s:2: >> write (%lu)\n", PROG_ROLE,
(unsigned long) (2 * data_block_size - bytes_written));
START_TIMING
ret = write (fd, data + bytes_written,
2 * data_block_size - bytes_written);
saved_errno = errno;
END_TIMING
dbgfprintf (stderr, "%s:2: << write -> %ld%s\n", PROG_ROLE,
(long) ret, dbgstrerror (ret < 0, saved_errno));
if (ret < 0 && bytes_written >= data_block_size)
{
ASSERT (saved_errno == EAGAIN || saved_errno == EWOULDBLOCK);
ASSERT (spent_time < 0.5);
break;
}
/* This assertion fails if the non-blocking flag is effectively not
set on fd. */
ASSERT (spent_time < 0.5);
if (ret < 0)
{
ASSERT (saved_errno == EAGAIN || saved_errno == EWOULDBLOCK);
usleep (SMALL_DELAY);
}
else
{
/* This assertion fails if data_block_size is too small. */
if (!(ret > 0))
{
fprintf (stderr,
"%s:1: spent_time = %g, data_block_size too small\n",
PROG_ROLE, spent_time);
too_small = 1;
}
bytes_written += ret;
}
}
ASSERT (bytes_written >= data_block_size);
while (bytes_written < 2 * data_block_size)
{
dbgfprintf (stderr, "%s:3: >> write (%lu)\n", PROG_ROLE,
(unsigned long) (2 * data_block_size - bytes_written));
START_TIMING
ret = write (fd, data + bytes_written,
2 * data_block_size - bytes_written);
saved_errno = errno;
END_TIMING
dbgfprintf (stderr, "%s:3: << write -> %ld%s\n", PROG_ROLE,
(long) ret, dbgstrerror (ret < 0, saved_errno));
ASSERT (spent_time < 0.5);
if (ret < 0)
{
ASSERT (saved_errno == EAGAIN || saved_errno == EWOULDBLOCK);
usleep (SMALL_DELAY);
}
else
{
ASSERT (ret > 0);
bytes_written += ret;
}
}
}
break;
default:
abort ();
}
free (data);
return too_small;
}
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