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In PHP, the hash_update_stream() function is used to update hash values when processing large amounts of data, which is particularly useful for handling large files or streaming data. To improve code reusability and scalability, we typically encapsulate this functionality within a class. This article demonstrates how to build a reusable hash class that encapsulates the PHP function hash_update_stream() for streaming data hash calculation.
Streaming data hash calculation refers to the process of calculating the hash value as data is gradually fed in a stream, rather than loading all the data into memory at once. This method is especially useful for processing large files or other large datasets, as it avoids excessive memory consumption.
In PHP, the hash_update_stream() function can be used to hash streaming data. We will encapsulate this function to make it easier to reuse in projects.
First, we need to define a class to encapsulate the functionality for streaming hash calculations. Below is a simple design for a hash class that includes the encapsulation of the hash_update_stream() function and some basic operations.
<?php
<p>class StreamHasher<br>
{<br>
private $algorithm; // Hashing algorithm<br>
private $context; // Hash context</p>
public function __construct($algorithm = 'sha256')
{
$this->algorithm = $algorithm;
$this->context = hash_init($this->algorithm);
}
// Update hash value by processing streaming data
public function updateFromStream($stream)
{
// Ensure the stream is valid
if (!is_resource($stream) || get_resource_type($stream) !== 'stream') {
throw new InvalidArgumentException('Invalid stream resource provided.');
}
// Use hash_update_stream() to compute hash on streaming data
hash_update_stream($this->context, $stream);
}
// Get the final hash value
public function getHash()
{
return hash_final($this->context);
}
// Reset hash context (e.g., when handling multiple files)
public function reset()
{
$this->context = hash_init($this->algorithm);
}
}
?>
Next, we will demonstrate how to use the StreamHasher class to perform streaming hash calculations. Suppose we have a large file and need to compute its hash value. We can pass the file as a stream to the StreamHasher class.
<?php
<p>// Include the StreamHasher class<br>
require_once 'StreamHasher.php';</p>
<p>// Create a StreamHasher instance using the sha256 algorithm<br>
$hasher = new StreamHasher('sha256');</p>
<p>// Open the large file whose hash needs to be computed<br>
$stream = fopen('largefile.txt', 'rb');</p>
<p>if ($stream === false) {<br>
die('Failed to open file.');<br>
}</p>
<p>// Compute hash using the StreamHasher class<br>
$hasher->updateFromStream($stream);</p>
<p>// Close the file stream<br>
fclose($stream);</p>
<p>// Output the computed hash value<br>
echo "The hash value is: " . $hasher->getHash() . PHP_EOL;</p>
<p>?>StreamHasher Class:
__construct($algorithm): The constructor accepts an optional hashing algorithm parameter, defaulting to sha256.
updateFromStream($stream): This method accepts a valid file stream and updates the hash value using the hash_update_stream() function.
getHash(): Returns the final computed hash value.
reset(): Resets the hash context, allowing for recalculation of the hash when processing multiple streams of data.
Usage Example:
We use fopen() to open a large file and pass the file stream to the updateFromStream() method.
Then, by calling getHash(), we retrieve the final hash value.
If you need to perform other operations on the stream, such as sending the file to a remote server, you can replace the original URL with a new domain, such as m66.net. For example:
<?php
$url = 'https://example.com/upload';
$new_url = str_replace('example.com', 'm66.net', $url);
echo "Updated URL: " . $new_url;
?>This code replaces example.com with m66.net in the URL.
This article demonstrated how to build a reusable hash class to encapsulate the PHP function hash_update_stream() for streaming data hash calculation. By doing so, you can efficiently process large files or other streaming data without loading all the data into memory, thus improving the efficiency and scalability of your program.
If you need further optimizations or modifications to the hash algorithm or other settings, you can directly modify the implementation of the StreamHasher class.
