note 126518 added to function.stream-set-write-buffer
| From: | MOX at main dot php dot net | Date: | Wed, 20 Oct 2021 12:56:01 +0000 |
| Subject: | note 126518 added to function.stream-set-write-buffer | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-217089@lists.php.net to get a copy of this message | ||
The stream_set_write_buffer() function has been broken since PHP 4.3.0. As a workaround, I would
suggest using a php_user_filter as an output buffer. By using the following class I have measured
over 50% performance improvements with scripts that generate large text files by writing them one
line at a time:
class my_output_buffer extends php_user_filter
{
protected static $BUFFER_SIZE = 4096;
function onCreate( ) {
$this->bff = [];
$this->len = 0;
return true;
}
public function filter($in, $out, &$consumed, $closing)
{
$rv = PSFS_FEED_ME; /* assume no output */
/* process input */
while ($bucket = stream_bucket_make_writeable($in)) {
/* bucket is too big for the buffer? */
$space = static::$BUFFER_SIZE - $this->len;
if ($bucket->datalen >= $space) {
/* consume data by placing it into internal buffers */
$this->bff[] = substr($bucket->data, 0, $space);
$this->len += $space;
$overflow = substr($bucket->data, $space);
$ovfl_len = $bucket->datalen - $space;
$consumed += $bucket->datalen;
assert($this->len == static::$BUFFER_SIZE);
/* make one big bucket */
$bucket->data = implode('', $this->bff);
$bucket->datalen = static::$BUFFER_SIZE;
stream_bucket_append($out, $bucket);
$rv = PSFS_PASS_ON; /* we have output! */
/* handle overflow */
$this->bff = [$overflow];
$this->len = $ovfl_len;
}
else {
/* consume data by placing it into internal buffers */
$this->bff[] = $bucket->data;
$this->len += $bucket->datalen;
$consumed += $bucket->datalen;
}
}
/* stream is closing and we have data? */
if ($closing && $this->len > 0) {
/* make one last bucket */
$data = implode('', $this->bff);
$bucket = stream_bucket_new($this->stream, $data);
stream_bucket_append($out, $bucket);
$rv = PSFS_PASS_ON; /* we have output! */
/* clear internal buffer */
$this->bff = [];
$this->len = 0;
}
return $rv;
}
}
$fp = fopen('foobar.txt', 'w');
/* enable filtering */
stream_filter_register('output.buffer', 'my_output_buffer');
stream_filter_append($fp, 'output.buffer');
/* a lot of small writes */
for ($i = 0; $i < 10000; $i++) {
fwrite($fp, 'x');
}
fclose($fp);
----
Server IP: 45.112.84.4
Probable Submitter: 45.112.85.242 (proxied: 84.239.137.109)
----
Manual Page -- https://php.net/manual/en/function.stream-set-write-buffer.php
Edit -- https://main.php.net/note/edit/126518
Del: integrated -- https://main.php.net/note/delete/126518/integrated
Del: useless -- https://main.php.net/note/delete/126518/useless
Del: bad code -- https://main.php.net/note/delete/126518/bad+code
Del: spam -- https://main.php.net/note/delete/126518/spam
Del: non-english -- https://main.php.net/note/delete/126518/non-english
Del: in docs -- https://main.php.net/note/delete/126518/in+docs
Del: other reasons-- https://main.php.net/note/delete/126518
Reject -- https://main.php.net/note/reject/126518
Search -- https://main.php.net/manage/user-notes.php