Collaboration diagram for dev.filechampion.filechampion4j.CalculateChecksum:

Classes
class	ChecksumTask

Public Member Functions
	CalculateChecksum (byte[] inputData) throws IllegalArgumentException

byte[]	getChecksum (String hashAlgorithm) throws NoSuchAlgorithmException, InterruptedException, ExecutionException, IOException

Private Member Functions
byte[]	calculateSmallChecksum ()

byte[]	calculateChecksum () throws InterruptedException, ExecutionException, IOException

Private Attributes
MessageDigest	md

final byte[]	inputData

int	byteSize

Static Private Attributes
static final int	MIN_CHUNK_SIZE = 1024 * 1024

static final int	MAX_CHUNK_SIZE = 3 * 1024 * 1024

Detailed Description

This class is used to calculate the checksums of a file. It is optimized for large files and uses multiple threads to calculate the checksum in parallel.

Definition at line 20 of file CalculateChecksum.java.

Constructor & Destructor Documentation

◆ CalculateChecksum()

dev.filechampion.filechampion4j.CalculateChecksum.CalculateChecksum ( byte[] inputData ) throws IllegalArgumentException

Creates a new instance of the this class.

Parameters

inputData (bytep[]) The input data to calculate the checksum for.

Exceptions

IllegalArgumentException Thrown if the input data is null or empty.

Definition at line 32 of file CalculateChecksum.java.

                                                                               {
        if (inputData == null || inputData.length == 0) {
            throw new IllegalArgumentException("Input data must contain at least one byte.");
        }
        this.inputData = inputData;
        this.byteSize = inputData.length;
    }

References dev.filechampion.filechampion4j.CalculateChecksum.inputData.

Member Function Documentation

◆ calculateChecksum()

byte[] dev.filechampion.filechampion4j.CalculateChecksum.calculateChecksum ( ) throws InterruptedException, ExecutionException, IOException

private

Calculates the checksum for large input data.

Returns: (byte[]) The calculated checksum.

Exceptions

InterruptedException	Thrown if the thread is interrupted.
ExecutionException	Thrown if the execution fails.
IOException	Thrown if an I/O error occurs.

Definition at line 72 of file CalculateChecksum.java.

                                                                                                     {
        ByteArrayInputStream bais = new ByteArrayInputStream(inputData);
        int numProcessors = Runtime.getRuntime().availableProcessors();
        ThreadPoolExecutor executor = new ThreadPoolExecutor(numProcessors, numProcessors,
                0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>());
        long fileSize = inputData.length;
        long chunkSize = Math.max(MIN_CHUNK_SIZE, Math.min(fileSize / numProcessors, MAX_CHUNK_SIZE));
        int numChunks = (int) Math.ceil((double) fileSize / chunkSize);
        byte[] buffer = new byte[(int) chunkSize];
        List<Future<?>> futures = new ArrayList<>(numChunks);
        for (int i = 0; i < numChunks; i++) {
            int bytesRead = bais.read(buffer, 0, (int) Math.min(chunkSize, fileSize - i * chunkSize));
            Future<?> future = executor.submit(new ChecksumTask(md, buffer, bytesRead));
            futures.add(future);
        }
        // wait for all futures to complete
        for (Future<?> future : futures) {
            future.get();
        }
        executor.shutdown();
        bais.close();
        return md.digest();
    }

References dev.filechampion.filechampion4j.CalculateChecksum.inputData, dev.filechampion.filechampion4j.CalculateChecksum.MAX_CHUNK_SIZE, dev.filechampion.filechampion4j.CalculateChecksum.md, and dev.filechampion.filechampion4j.CalculateChecksum.MIN_CHUNK_SIZE.

Referenced by dev.filechampion.filechampion4j.CalculateChecksum.getChecksum().

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◆ calculateSmallChecksum()

byte[] dev.filechampion.filechampion4j.CalculateChecksum.calculateSmallChecksum ( )

private

Calculates the checksum for small input data.

Returns: (byte[]) The calculated checksum.

Definition at line 61 of file CalculateChecksum.java.

                                            {
        return md.digest(inputData);
    }

References dev.filechampion.filechampion4j.CalculateChecksum.inputData, and dev.filechampion.filechampion4j.CalculateChecksum.md.

Referenced by dev.filechampion.filechampion4j.CalculateChecksum.getChecksum().

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◆ getChecksum()

byte[] dev.filechampion.filechampion4j.CalculateChecksum.getChecksum ( String hashAlgorithm ) throws NoSuchAlgorithmException, InterruptedException, ExecutionException, IOException

Calculates the checksum for the input data.

Parameters

hashAlgorithm (String) The hash algorithm to use. Must be one of: MD5, SHA-1, SHA-256, SHA-512.

Returns: (byte[]) The calculated checksum.

Exceptions

NoSuchAlgorithmException	Thrown if the algorithm is not available.
InterruptedException	Thrown if the thread is interrupted.
ExecutionException	Thrown if the execution fails.
IOException	Thrown if an I/O error occurs.

Definition at line 49 of file CalculateChecksum.java.

                                                                                                                                           {
        md = MessageDigest.getInstance(hashAlgorithm);
        if (byteSize < MIN_CHUNK_SIZE * 2) {
            return calculateSmallChecksum();
        }
        return calculateChecksum() ;
    }