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<?php
namespace bandwidthThrottle;
use bandwidthThrottle\tokenBucket\BlockingConsumer;
use bandwidthThrottle\tokenBucket\TokenBucket;
use bandwidthThrottle\tokenBucket\storage\StorageException;
/**
* Stream filter which uses a token bucket for traffic shaping.
*
* When the filter is created with stream_filter_append() or
* stream_filter_prepend(), the $param parameter is expected to be an
* instance of TokenBucket.
*
* This filter can shape traffic in both directions. I.e. you can append it
* to an output stream as well to an input stream.
*
* Example:
* <code>
* use bandwidthThrottle\TokenBucketFilter;
* use bandwidthThrottle\tokenBucket\TokenBucket;
* use bandwidthThrottle\tokenBucket\Rate;
* use bandwidthThrottle\tokenBucket\storage\SingleProcessStorage;
*
* $in = fopen(__DIR__ . "/video.mpg", "r");
* $out = fopen("php://output", "w");
*
* $storage = new SingleProcessStorage();
* $rate = new Rate(100 * 1024, Rate::SECOND); // Rate of 100KiB/s
* $bucket = new TokenBucket(100 * 1024, $rate, $storage);
*
* stream_filter_register("throttle", TokenBucketFilter::class);
* stream_filter_append($out, "throttle", STREAM_FILTER_WRITE, $bucket);
*
* stream_copy_to_stream($in, $out);
* </code>
*
* @author Markus Malkusch <markus@malkusch.de>
* @link bitcoin:1335STSwu9hST4vcMRppEPgENMHD2r1REK Donations
* @license WTFPL
*/
final class TokenBucketFilter extends \php_user_filter
{
/**
* @var BlockingConsumer The blocking token bucket consumer.
*/
private $tokenConsumer;
/**
* @var TokenBucket The token bucket.
*/
private $tokenBucket;
/**
* Builds the token bucket consumer.
*
* @throws \InvalidArgumentException The token bucket was not passed in the $params parameter.
*/
public function onCreate()
{
if (!$this->params instanceof TokenBucket) {
throw new \InvalidArgumentException(
"An instance of TokenBucket must be passed as \$params parameter."
);
}
$this->tokenBucket = $this->params;
$this->tokenConsumer = new BlockingConsumer($this->tokenBucket);
}
/**
* Traffic shaping.
*
* @param resource $in The input stream.
* @param resource $out The ouput stream.
* @param int $consumed The amount of consumed bytes.
* @param bool $closing If the stream is closing.
*
* @return int The processing state.
*
* @SuppressWarnings("unused")
* @SuppressWarnings("short")
*/
public function filter($in, $out, &$consumed, $closing)
{
try {
while ($bucket = stream_bucket_make_writeable($in)) {
$chunks = str_split($bucket->data, $this->tokenBucket->getCapacity());
foreach ($chunks as $chunk) {
$tokens = strlen($chunk);
$this->tokenConsumer->consume($tokens);
$consumed += $tokens;
}
stream_bucket_append($out, $bucket);
}
return PSFS_PASS_ON;
} catch (StorageException $e) {
trigger_error($e->getMessage(), E_USER_ERROR);
return PSFS_ERR_FATAL;
} catch (\LengthException $e) {
/*
* This case would be a logic error, as the stream chunk is already
* splitted to the bucket's capacity.
*/
trigger_error($e->getMessage(), E_USER_ERROR);
return PSFS_ERR_FATAL;
}
}
}
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