org.apache.kafka.common.utils.Utils Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.common.utils;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.config.ConfigException;
import org.apache.kafka.common.network.TransferableChannel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.event.Level;
import java.io.Closeable;
import java.io.DataOutput;
import java.io.EOFException;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.StandardCopyOption;
import java.nio.file.StandardOpenOption;
import java.nio.file.attribute.BasicFileAttributes;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Properties;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public final class Utils {
private Utils() {}
// This matches URIs of formats: host:port and protocol:\\host:port
// IPv6 is supported with [ip] pattern
private static final Pattern HOST_PORT_PATTERN = Pattern.compile(".*?\\[?([0-9a-zA-Z\\-%._:]*)\\]?:([0-9]+)");
private static final Pattern VALID_HOST_CHARACTERS = Pattern.compile("([0-9a-zA-Z\\-%._:]*)");
// Prints up to 2 decimal digits. Used for human readable printing
private static final DecimalFormat TWO_DIGIT_FORMAT = new DecimalFormat("0.##",
DecimalFormatSymbols.getInstance(Locale.ENGLISH));
private static final String[] BYTE_SCALE_SUFFIXES = new String[] {"B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"};
public static final String NL = System.getProperty("line.separator");
private static final Logger log = LoggerFactory.getLogger(Utils.class);
/**
* Get a sorted list representation of a collection.
* @param collection The collection to sort
* @param The class of objects in the collection
* @return An unmodifiable sorted list with the contents of the collection
*/
public static > List sorted(Collection collection) {
List res = new ArrayList<>(collection);
Collections.sort(res);
return Collections.unmodifiableList(res);
}
/**
* Turn the given UTF8 byte array into a string
*
* @param bytes The byte array
* @return The string
*/
public static String utf8(byte[] bytes) {
return new String(bytes, StandardCharsets.UTF_8);
}
/**
* Read a UTF8 string from a byte buffer. Note that the position of the byte buffer is not affected
* by this method.
*
* @param buffer The buffer to read from
* @param length The length of the string in bytes
* @return The UTF8 string
*/
public static String utf8(ByteBuffer buffer, int length) {
return utf8(buffer, 0, length);
}
/**
* Read a UTF8 string from the current position till the end of a byte buffer. The position of the byte buffer is
* not affected by this method.
*
* @param buffer The buffer to read from
* @return The UTF8 string
*/
public static String utf8(ByteBuffer buffer) {
return utf8(buffer, buffer.remaining());
}
/**
* Read a UTF8 string from a byte buffer at a given offset. Note that the position of the byte buffer
* is not affected by this method.
*
* @param buffer The buffer to read from
* @param offset The offset relative to the current position in the buffer
* @param length The length of the string in bytes
* @return The UTF8 string
*/
public static String utf8(ByteBuffer buffer, int offset, int length) {
if (buffer.hasArray())
return new String(buffer.array(), buffer.arrayOffset() + buffer.position() + offset, length, StandardCharsets.UTF_8);
else
return utf8(toArray(buffer, offset, length));
}
/**
* Turn a string into a utf8 byte[]
*
* @param string The string
* @return The byte[]
*/
public static byte[] utf8(String string) {
return string.getBytes(StandardCharsets.UTF_8);
}
/**
* Get the absolute value of the given number. If the number is Int.MinValue return 0. This is different from
* java.lang.Math.abs or scala.math.abs in that they return Int.MinValue (!).
*/
public static int abs(int n) {
return (n == Integer.MIN_VALUE) ? 0 : Math.abs(n);
}
/**
* Get the minimum of some long values.
* @param first Used to ensure at least one value
* @param rest The remaining values to compare
* @return The minimum of all passed values
*/
public static long min(long first, long... rest) {
long min = first;
for (long r : rest) {
if (r < min)
min = r;
}
return min;
}
/**
* Get the maximum of some long values.
* @param first Used to ensure at least one value
* @param rest The remaining values to compare
* @return The maximum of all passed values
*/
public static long max(long first, long... rest) {
long max = first;
for (long r : rest) {
if (r > max)
max = r;
}
return max;
}
public static short min(short first, short second) {
return (short) Math.min(first, second);
}
/**
* Get the length for UTF8-encoding a string without encoding it first
*
* @param s The string to calculate the length for
* @return The length when serialized
*/
public static int utf8Length(CharSequence s) {
int count = 0;
for (int i = 0, len = s.length(); i < len; i++) {
char ch = s.charAt(i);
if (ch <= 0x7F) {
count++;
} else if (ch <= 0x7FF) {
count += 2;
} else if (Character.isHighSurrogate(ch)) {
count += 4;
++i;
} else {
count += 3;
}
}
return count;
}
/**
* Read the given byte buffer from its current position to its limit into a byte array.
* @param buffer The buffer to read from
*/
public static byte[] toArray(ByteBuffer buffer) {
return toArray(buffer, 0, buffer.remaining());
}
/**
* Read a byte array from its current position given the size in the buffer
* @param buffer The buffer to read from
* @param size The number of bytes to read into the array
*/
public static byte[] toArray(ByteBuffer buffer, int size) {
return toArray(buffer, 0, size);
}
/**
* Convert a ByteBuffer to a nullable array.
* @param buffer The buffer to convert
* @return The resulting array or null if the buffer is null
*/
public static byte[] toNullableArray(ByteBuffer buffer) {
return buffer == null ? null : toArray(buffer);
}
/**
* Wrap an array as a nullable ByteBuffer.
* @param array The nullable array to wrap
* @return The wrapping ByteBuffer or null if array is null
*/
public static ByteBuffer wrapNullable(byte[] array) {
return array == null ? null : ByteBuffer.wrap(array);
}
/**
* Read a byte array from the given offset and size in the buffer
* @param buffer The buffer to read from
* @param offset The offset relative to the current position of the buffer
* @param size The number of bytes to read into the array
*/
public static byte[] toArray(ByteBuffer buffer, int offset, int size) {
byte[] dest = new byte[size];
if (buffer.hasArray()) {
System.arraycopy(buffer.array(), buffer.position() + buffer.arrayOffset() + offset, dest, 0, size);
} else {
int pos = buffer.position();
buffer.position(pos + offset);
buffer.get(dest);
buffer.position(pos);
}
return dest;
}
/**
* Starting from the current position, read an integer indicating the size of the byte array to read,
* then read the array. Consumes the buffer: upon returning, the buffer's position is after the array
* that is returned.
* @param buffer The buffer to read a size-prefixed array from
* @return The array
*/
public static byte[] getNullableSizePrefixedArray(final ByteBuffer buffer) {
final int size = buffer.getInt();
return getNullableArray(buffer, size);
}
/**
* Read a byte array of the given size. Consumes the buffer: upon returning, the buffer's position
* is after the array that is returned.
* @param buffer The buffer to read a size-prefixed array from
* @param size The number of bytes to read out of the buffer
* @return The array
*/
public static byte[] getNullableArray(final ByteBuffer buffer, final int size) {
if (size > buffer.remaining()) {
// preemptively throw this when the read is doomed to fail, so we don't have to allocate the array.
throw new BufferUnderflowException();
}
final byte[] oldBytes = size == -1 ? null : new byte[size];
if (oldBytes != null) {
buffer.get(oldBytes);
}
return oldBytes;
}
/**
* Returns a copy of src byte array
* @param src The byte array to copy
* @return The copy
*/
public static byte[] copyArray(byte[] src) {
return Arrays.copyOf(src, src.length);
}
/**
* Compares two character arrays for equality using a constant-time algorithm, which is needed
* for comparing passwords. Two arrays are equal if they have the same length and all
* characters at corresponding positions are equal.
*
* All characters in the first array are examined to determine equality.
* The calculation time depends only on the length of this first character array; it does not
* depend on the length of the second character array or the contents of either array.
*
* @param first the first array to compare
* @param second the second array to compare
* @return true if the arrays are equal, or false otherwise
*/
public static boolean isEqualConstantTime(char[] first, char[] second) {
if (first == second) {
return true;
}
if (first == null || second == null) {
return false;
}
if (second.length == 0) {
return first.length == 0;
}
// time-constant comparison that always compares all characters in first array
boolean matches = first.length == second.length;
for (int i = 0; i < first.length; ++i) {
int j = i < second.length ? i : 0;
if (first[i] != second[j]) {
matches = false;
}
}
return matches;
}
/**
* Sleep for a bit
* @param ms The duration of the sleep
*/
public static void sleep(long ms) {
try {
Thread.sleep(ms);
} catch (InterruptedException e) {
// this is okay, we just wake up early
Thread.currentThread().interrupt();
}
}
/**
* Instantiate the class
*/
public static T newInstance(Class c) {
if (c == null)
throw new KafkaException("class cannot be null");
try {
return c.getDeclaredConstructor().newInstance();
} catch (NoSuchMethodException e) {
throw new KafkaException("Could not find a public no-argument constructor for " + c.getName(), e);
} catch (ReflectiveOperationException | RuntimeException e) {
throw new KafkaException("Could not instantiate class " + c.getName(), e);
}
}
/**
* Look up the class by name and instantiate it.
* @param klass class name
* @param base super class of the class to be instantiated
* @param the type of the base class
* @return the new instance
*/
public static T newInstance(String klass, Class base) throws ClassNotFoundException {
return Utils.newInstance(loadClass(klass, base));
}
/**
* Look up a class by name.
* @param klass class name
* @param base super class of the class for verification
* @param the type of the base class
* @return the new class
*/
public static Class loadClass(String klass, Class base) throws ClassNotFoundException {
return Class.forName(klass, true, Utils.getContextOrKafkaClassLoader()).asSubclass(base);
}
/**
* Cast {@code klass} to {@code base} and instantiate it.
* @param klass The class to instantiate
* @param base A know baseclass of klass.
* @param the type of the base class
* @throws ClassCastException If {@code klass} is not a subclass of {@code base}.
* @return the new instance.
*/
public static T newInstance(Class klass, Class base) {
return Utils.newInstance(klass.asSubclass(base));
}
/**
* Construct a new object using a class name and parameters.
*
* @param className The full name of the class to construct.
* @param params A sequence of (type, object) elements.
* @param The type of object to construct.
* @return The new object.
* @throws ClassNotFoundException If there was a problem constructing the object.
*/
public static T newParameterizedInstance(String className, Object... params)
throws ClassNotFoundException {
Class[] argTypes = new Class[params.length / 2];
Object[] args = new Object[params.length / 2];
try {
Class c = Class.forName(className, true, Utils.getContextOrKafkaClassLoader());
for (int i = 0; i < params.length / 2; i++) {
argTypes[i] = (Class) params[2 * i];
args[i] = params[(2 * i) + 1];
}
@SuppressWarnings("unchecked")
Constructor constructor = (Constructor) c.getConstructor(argTypes);
return constructor.newInstance(args);
} catch (NoSuchMethodException e) {
throw new ClassNotFoundException(String.format("Failed to find " +
"constructor with %s for %s", Utils.join(argTypes, ", "), className), e);
} catch (InstantiationException e) {
throw new ClassNotFoundException(String.format("Failed to instantiate " +
"%s", className), e);
} catch (IllegalAccessException e) {
throw new ClassNotFoundException(String.format("Unable to access " +
"constructor of %s", className), e);
} catch (InvocationTargetException e) {
throw new KafkaException(String.format("The constructor of %s threw an exception", className), e.getCause());
}
}
/**
* Generates 32 bit murmur2 hash from byte array
* @param data byte array to hash
* @return 32 bit hash of the given array
*/
@SuppressWarnings("fallthrough")
public static int murmur2(final byte[] data) {
int length = data.length;
int seed = 0x9747b28c;
// 'm' and 'r' are mixing constants generated offline.
// They're not really 'magic', they just happen to work well.
final int m = 0x5bd1e995;
final int r = 24;
// Initialize the hash to a random value
int h = seed ^ length;
int length4 = length / 4;
for (int i = 0; i < length4; i++) {
final int i4 = i * 4;
int k = (data[i4 + 0] & 0xff) + ((data[i4 + 1] & 0xff) << 8) + ((data[i4 + 2] & 0xff) << 16) + ((data[i4 + 3] & 0xff) << 24);
k *= m;
k ^= k >>> r;
k *= m;
h *= m;
h ^= k;
}
// Handle the last few bytes of the input array
switch (length % 4) {
case 3:
h ^= (data[(length & ~3) + 2] & 0xff) << 16;
case 2:
h ^= (data[(length & ~3) + 1] & 0xff) << 8;
case 1:
h ^= data[length & ~3] & 0xff;
h *= m;
}
h ^= h >>> 13;
h *= m;
h ^= h >>> 15;
return h;
}
/**
* Extracts the hostname from a "host:port" address string.
* @param address address string to parse
* @return hostname or null if the given address is incorrect
*/
public static String getHost(String address) {
Matcher matcher = HOST_PORT_PATTERN.matcher(address);
return matcher.matches() ? matcher.group(1) : null;
}
/**
* Extracts the port number from a "host:port" address string.
* @param address address string to parse
* @return port number or null if the given address is incorrect
*/
public static Integer getPort(String address) {
Matcher matcher = HOST_PORT_PATTERN.matcher(address);
return matcher.matches() ? Integer.parseInt(matcher.group(2)) : null;
}
/**
* Basic validation of the supplied address. checks for valid characters
* @param address hostname string to validate
* @return true if address contains valid characters
*/
public static boolean validHostPattern(String address) {
return VALID_HOST_CHARACTERS.matcher(address).matches();
}
/**
* Formats hostname and port number as a "host:port" address string,
* surrounding IPv6 addresses with braces '[', ']'
* @param host hostname
* @param port port number
* @return address string
*/
public static String formatAddress(String host, Integer port) {
return host.contains(":")
? "[" + host + "]:" + port // IPv6
: host + ":" + port;
}
/**
* Formats a byte number as a human readable String ("3.2 MB")
* @param bytes some size in bytes
* @return
*/
public static String formatBytes(long bytes) {
if (bytes < 0) {
return String.valueOf(bytes);
}
double asDouble = (double) bytes;
int ordinal = (int) Math.floor(Math.log(asDouble) / Math.log(1024.0));
double scale = Math.pow(1024.0, ordinal);
double scaled = asDouble / scale;
String formatted = TWO_DIGIT_FORMAT.format(scaled);
try {
return formatted + " " + BYTE_SCALE_SUFFIXES[ordinal];
} catch (IndexOutOfBoundsException e) {
//huge number?
return String.valueOf(asDouble);
}
}
/**
* Create a string representation of an array joined by the given separator
* @param strs The array of items
* @param separator The separator
* @return The string representation.
*/
public static String join(T[] strs, String separator) {
return join(Arrays.asList(strs), separator);
}
/**
* Create a string representation of a collection joined by the given separator
* @param collection The list of items
* @param separator The separator
* @return The string representation.
*/
public static String join(Collection collection, String separator) {
Objects.requireNonNull(collection);
return mkString(collection.stream(), "", "", separator);
}
/**
* Create a string representation of a stream surrounded by `begin` and `end` and joined by `separator`.
*
* @return The string representation.
*/
public static String mkString(Stream stream, String begin, String end, String separator) {
Objects.requireNonNull(stream);
StringBuilder sb = new StringBuilder();
sb.append(begin);
Iterator iter = stream.iterator();
while (iter.hasNext()) {
sb.append(iter.next());
if (iter.hasNext())
sb.append(separator);
}
sb.append(end);
return sb.toString();
}
/**
* Converts a {@code Map} class into a string, concatenating keys and values
* Example:
* {@code mkString({ key: "hello", keyTwo: "hi" }, "|START|", "|END|", "=", ",")
* => "|START|key=hello,keyTwo=hi|END|"}
*/
public static String mkString(Map map, String begin, String end,
String keyValueSeparator, String elementSeparator) {
StringBuilder bld = new StringBuilder();
bld.append(begin);
String prefix = "";
for (Map.Entry entry : map.entrySet()) {
bld.append(prefix).append(entry.getKey()).
append(keyValueSeparator).append(entry.getValue());
prefix = elementSeparator;
}
bld.append(end);
return bld.toString();
}
/**
* Converts an extensions string into a {@code Map}.
*
* Example:
* {@code parseMap("key=hey,keyTwo=hi,keyThree=hello", "=", ",") => { key: "hey", keyTwo: "hi", keyThree: "hello" }}
*
*/
public static Map parseMap(String mapStr, String keyValueSeparator, String elementSeparator) {
Map map = new HashMap<>();
if (!mapStr.isEmpty()) {
String[] attrvals = mapStr.split(elementSeparator);
for (String attrval : attrvals) {
String[] array = attrval.split(keyValueSeparator, 2);
map.put(array[0], array[1]);
}
}
return map;
}
/**
* Read a properties file from the given path
* @param filename The path of the file to read
* @return the loaded properties
*/
public static Properties loadProps(String filename) throws IOException {
return loadProps(filename, null);
}
/**
* Read a properties file from the given path
* @param filename The path of the file to read
* @param onlyIncludeKeys When non-null, only return values associated with these keys and ignore all others
* @return the loaded properties
*/
public static Properties loadProps(String filename, List onlyIncludeKeys) throws IOException {
Properties props = new Properties();
if (filename != null) {
try (InputStream propStream = Files.newInputStream(Paths.get(filename))) {
props.load(propStream);
}
} else {
System.out.println("Did not load any properties since the property file is not specified");
}
if (onlyIncludeKeys == null || onlyIncludeKeys.isEmpty())
return props;
Properties requestedProps = new Properties();
onlyIncludeKeys.forEach(key -> {
String value = props.getProperty(key);
if (value != null)
requestedProps.setProperty(key, value);
});
return requestedProps;
}
/**
* Converts a Properties object to a Map, calling {@link #toString} to ensure all keys and values
* are Strings.
*/
public static Map propsToStringMap(Properties props) {
Map result = new HashMap<>();
for (Map.Entry entry : props.entrySet())
result.put(entry.getKey().toString(), entry.getValue().toString());
return result;
}
/**
* Get the stack trace from an exception as a string
*/
public static String stackTrace(Throwable e) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
return sw.toString();
}
/**
* Read a buffer into a Byte array for the given offset and length
*/
public static byte[] readBytes(ByteBuffer buffer, int offset, int length) {
byte[] dest = new byte[length];
if (buffer.hasArray()) {
System.arraycopy(buffer.array(), buffer.arrayOffset() + offset, dest, 0, length);
} else {
buffer.mark();
buffer.position(offset);
buffer.get(dest);
buffer.reset();
}
return dest;
}
/**
* Read the given byte buffer into a Byte array
*/
public static byte[] readBytes(ByteBuffer buffer) {
return Utils.readBytes(buffer, 0, buffer.limit());
}
/**
* Reads bytes from a source buffer and returns a new buffer.
* The content of the new buffer will start at this buffer's current
* position. Changes to this buffer's content will be visible in the new
* buffer, and vice versa; the two buffers' position, limit, and mark
* values will be independent.
*
*
The new buffer's position will be zero, its limit will be the number of bytes
* read i.e. bytesToRead, it's capacity will be the number of bytes remaining in
* source buffer , its mark will be undefined, and its byte order will be {@link ByteOrder#BIG_ENDIAN BIG_ENDIAN}.
*
*
Since JDK 13, this method could be replaced with slice(int index, int length).
*
* @param srcBuf Source buffer where data is read from
* @param bytesToRead Number of bytes to read
* @return Destination buffer or null if bytesToRead is < 0
*
* @see ByteBuffer#slice()
*/
public static ByteBuffer readBytes(ByteBuffer srcBuf, int bytesToRead) {
if (bytesToRead < 0)
return null;
final ByteBuffer dstBuf = srcBuf.slice();
dstBuf.limit(bytesToRead);
srcBuf.position(srcBuf.position() + bytesToRead);
return dstBuf;
}
/**
* Read a file as string and return the content. The file is treated as a stream and no seek is performed.
* This allows the program to read from a regular file as well as from a pipe/fifo.
*/
public static String readFileAsString(String path) throws IOException {
try {
byte[] allBytes = Files.readAllBytes(Paths.get(path));
return new String(allBytes, StandardCharsets.UTF_8);
} catch (IOException ex) {
throw new IOException("Unable to read file " + path, ex);
}
}
/**
* Check if the given ByteBuffer capacity
* @param existingBuffer ByteBuffer capacity to check
* @param newLength new length for the ByteBuffer.
* returns ByteBuffer
*/
public static ByteBuffer ensureCapacity(ByteBuffer existingBuffer, int newLength) {
if (newLength > existingBuffer.capacity()) {
ByteBuffer newBuffer = ByteBuffer.allocate(newLength);
existingBuffer.flip();
newBuffer.put(existingBuffer);
return newBuffer;
}
return existingBuffer;
}
/**
* Creates a set
* @param elems the elements
* @param the type of element
* @return Set
*/
@SafeVarargs
public static Set mkSet(T... elems) {
Set result = new HashSet<>((int) (elems.length / 0.75) + 1);
for (T elem : elems)
result.add(elem);
return result;
}
/**
* Creates a sorted set
* @param elems the elements
* @param the type of element, must be comparable
* @return SortedSet
*/
@SafeVarargs
public static > SortedSet mkSortedSet(T... elems) {
SortedSet result = new TreeSet<>();
for (T elem : elems)
result.add(elem);
return result;
}
/**
* Creates a map entry (for use with {@link Utils#mkMap(java.util.Map.Entry[])})
*
* @param k The key
* @param v The value
* @param The key type
* @param The value type
* @return An entry
*/
public static Map.Entry mkEntry(final K k, final V v) {
return new AbstractMap.SimpleEntry<>(k, v);
}
/**
* Creates a map from a sequence of entries
*
* @param entries The entries to map
* @param The key type
* @param The value type
* @return A map
*/
@SafeVarargs
public static Map mkMap(final Map.Entry... entries) {
final LinkedHashMap result = new LinkedHashMap<>();
for (final Map.Entry entry : entries) {
result.put(entry.getKey(), entry.getValue());
}
return result;
}
/**
* Creates a {@link Properties} from a map
*
* @param properties A map of properties to add
* @return The properties object
*/
public static Properties mkProperties(final Map properties) {
final Properties result = new Properties();
for (final Map.Entry entry : properties.entrySet()) {
result.setProperty(entry.getKey(), entry.getValue());
}
return result;
}
/**
* Creates a {@link Properties} from a map
*
* @param properties A map of properties to add
* @return The properties object
*/
public static Properties mkObjectProperties(final Map properties) {
final Properties result = new Properties();
for (final Map.Entry entry : properties.entrySet()) {
result.put(entry.getKey(), entry.getValue());
}
return result;
}
/**
* Recursively delete the given file/directory and any subfiles (if any exist)
*
* @param rootFile The root file at which to begin deleting
*/
public static void delete(final File rootFile) throws IOException {
if (rootFile == null)
return;
Files.walkFileTree(rootFile.toPath(), new SimpleFileVisitor() {
@Override
public FileVisitResult visitFileFailed(Path path, IOException exc) throws IOException {
// If the root path did not exist, ignore the error; otherwise throw it.
if (exc instanceof NoSuchFileException && path.toFile().equals(rootFile))
return FileVisitResult.TERMINATE;
throw exc;
}
@Override
public FileVisitResult visitFile(Path path, BasicFileAttributes attrs) throws IOException {
Files.delete(path);
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path path, IOException exc) throws IOException {
// KAFKA-8999: if there's an exception thrown previously already, we should throw it
if (exc != null) {
throw exc;
}
Files.delete(path);
return FileVisitResult.CONTINUE;
}
});
}
/**
* Returns an empty collection if this list is null
* @param other
* @return
*/
public static List safe(List other) {
return other == null ? Collections.emptyList() : other;
}
/**
* Get the ClassLoader which loaded Kafka.
*/
public static ClassLoader getKafkaClassLoader() {
return Utils.class.getClassLoader();
}
/**
* Get the Context ClassLoader on this thread or, if not present, the ClassLoader that
* loaded Kafka.
*
* This should be used whenever passing a ClassLoader to Class.forName
*/
public static ClassLoader getContextOrKafkaClassLoader() {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
if (cl == null)
return getKafkaClassLoader();
else
return cl;
}
/**
* Attempts to move source to target atomically and falls back to a non-atomic move if it fails.
* This function also flushes the parent directory to guarantee crash consistency.
*
* @throws IOException if both atomic and non-atomic moves fail, or parent dir flush fails.
*/
public static void atomicMoveWithFallback(Path source, Path target) throws IOException {
atomicMoveWithFallback(source, target, true);
}
/**
* Attempts to move source to target atomically and falls back to a non-atomic move if it fails.
* This function allows callers to decide whether to flush the parent directory. This is needed
* when a sequence of atomicMoveWithFallback is called for the same directory and we don't want
* to repeatedly flush the same parent directory.
*
* @throws IOException if both atomic and non-atomic moves fail,
* or parent dir flush fails if needFlushParentDir is true.
*/
public static void atomicMoveWithFallback(Path source, Path target, boolean needFlushParentDir) throws IOException {
try {
Files.move(source, target, StandardCopyOption.ATOMIC_MOVE);
} catch (IOException outer) {
try {
log.warn("Failed atomic move of {} to {} retrying with a non-atomic move", source, target, outer);
Files.move(source, target, StandardCopyOption.REPLACE_EXISTING);
log.debug("Non-atomic move of {} to {} succeeded after atomic move failed", source, target);
} catch (IOException inner) {
inner.addSuppressed(outer);
throw inner;
}
} finally {
if (needFlushParentDir) {
flushDir(target.toAbsolutePath().normalize().getParent());
}
}
}
/**
* Flushes dirty directories to guarantee crash consistency.
*
* Note: We don't fsync directories on Windows OS because otherwise it'll throw AccessDeniedException (KAFKA-13391)
*
* @throws IOException if flushing the directory fails.
*/
public static void flushDir(Path path) throws IOException {
if (path != null && !OperatingSystem.IS_WINDOWS && !OperatingSystem.IS_ZOS) {
try (FileChannel dir = FileChannel.open(path, StandardOpenOption.READ)) {
dir.force(true);
}
}
}
/**
* Flushes dirty directories to guarantee crash consistency with swallowing {@link NoSuchFileException}
*
* @throws IOException if flushing the directory fails.
*/
public static void flushDirIfExists(Path path) throws IOException {
try {
flushDir(path);
} catch (NoSuchFileException e) {
log.warn("Failed to flush directory {}", path);
}
}
/**
* Flushes dirty file with swallowing {@link NoSuchFileException}
*/
public static void flushFileIfExists(Path path) throws IOException {
try (FileChannel fileChannel = FileChannel.open(path, StandardOpenOption.READ)) {
fileChannel.force(true);
} catch (NoSuchFileException e) {
log.warn("Failed to flush file {}", path, e);
}
}
/**
* Closes all the provided closeables.
* @throws IOException if any of the close methods throws an IOException.
* The first IOException is thrown with subsequent exceptions
* added as suppressed exceptions.
*/
public static void closeAll(Closeable... closeables) throws IOException {
IOException exception = null;
for (Closeable closeable : closeables) {
try {
if (closeable != null)
closeable.close();
} catch (IOException e) {
if (exception != null)
exception.addSuppressed(e);
else
exception = e;
}
}
if (exception != null)
throw exception;
}
@FunctionalInterface
public interface SwallowAction {
void run() throws Throwable;
}
public static void swallow(final Logger log, final Level level, final String what, final SwallowAction code) {
swallow(log, level, what, code, null);
}
/**
* Run the supplied code. If an exception is thrown, it is swallowed and registered to the firstException parameter.
*/
public static void swallow(final Logger log, final Level level, final String what, final SwallowAction code,
final AtomicReference firstException) {
if (code != null) {
try {
code.run();
} catch (Throwable t) {
switch (level) {
case INFO:
log.info(what, t);
break;
case DEBUG:
log.debug(what, t);
break;
case ERROR:
log.error(what, t);
break;
case TRACE:
log.trace(what, t);
break;
case WARN:
default:
log.warn(what, t);
}
if (firstException != null)
firstException.compareAndSet(null, t);
}
}
}
/**
* An {@link AutoCloseable} interface without a throws clause in the signature
*
* This is used with lambda expressions in try-with-resources clauses
* to avoid casting un-checked exceptions to checked exceptions unnecessarily.
*/
@FunctionalInterface
public interface UncheckedCloseable extends AutoCloseable {
@Override
void close();
}
/**
* Closes {@code maybeCloseable} if it implements the {@link AutoCloseable} interface,
* and if an exception is thrown, it is logged at the WARN level.
*/
public static void maybeCloseQuietly(Object maybeCloseable, String name) {
if (maybeCloseable instanceof AutoCloseable)
closeQuietly((AutoCloseable) maybeCloseable, name);
}
/**
* Closes {@code closeable} and if an exception is thrown, it is logged at the WARN level.
* Be cautious when passing method references as an argument. For example:
*
* {@code closeQuietly(task::stop, "source task");}
*
* Although this method gracefully handles null {@link AutoCloseable} objects, attempts to take a method
* reference from a null object will result in a {@link NullPointerException}. In the example code above,
* it would be the caller's responsibility to ensure that {@code task} was non-null before attempting to
* use a method reference from it.
*/
public static void closeQuietly(AutoCloseable closeable, String name) {
closeQuietly(closeable, name, log);
}
/**
* Closes {@code closeable} and if an exception is thrown, it is logged with the provided logger at the WARN level.
* Be cautious when passing method references as an argument. For example:
*
* {@code closeQuietly(task::stop, "source task");}
*
* Although this method gracefully handles null {@link AutoCloseable} objects, attempts to take a method
* reference from a null object will result in a {@link NullPointerException}. In the example code above,
* it would be the caller's responsibility to ensure that {@code task} was non-null before attempting to
* use a method reference from it.
*/
public static void closeQuietly(AutoCloseable closeable, String name, Logger logger) {
if (closeable != null) {
try {
closeable.close();
} catch (Throwable t) {
logger.warn("Failed to close {} with type {}", name, closeable.getClass().getName(), t);
}
}
}
/**
* Closes {@code closeable} and if an exception is thrown, it is registered to the firstException parameter.
* Be cautious when passing method references as an argument. For example:
*
* {@code closeQuietly(task::stop, "source task");}
*
* Although this method gracefully handles null {@link AutoCloseable} objects, attempts to take a method
* reference from a null object will result in a {@link NullPointerException}. In the example code above,
* it would be the caller's responsibility to ensure that {@code task} was non-null before attempting to
* use a method reference from it.
*/
public static void closeQuietly(AutoCloseable closeable, String name, AtomicReference firstException) {
if (closeable != null) {
try {
closeable.close();
} catch (Throwable t) {
firstException.compareAndSet(null, t);
log.error("Failed to close {} with type {}", name, closeable.getClass().getName(), t);
}
}
}
/**
* close all closable objects even if one of them throws exception.
* @param firstException keeps the first exception
* @param name message of closing those objects
* @param closeables closable objects
*/
public static void closeAllQuietly(AtomicReference firstException, String name, AutoCloseable... closeables) {
for (AutoCloseable closeable : closeables) closeQuietly(closeable, name, firstException);
}
/**
* Invokes every function in `all` even if one or more functions throws an exception.
*
* If any of the functions throws an exception, the first one will be rethrown at the end with subsequent exceptions
* added as suppressed exceptions.
*/
// Note that this is a generalised version of `closeAll`. We could potentially make it more general by
// changing the signature to `public List tryAll(all: List[Callable])`
public static void tryAll(List> all) throws Throwable {
Throwable exception = null;
for (Callable call : all) {
try {
call.call();
} catch (Throwable t) {
if (exception != null)
exception.addSuppressed(t);
else
exception = t;
}
}
if (exception != null)
throw exception;
}
/**
* A cheap way to deterministically convert a number to a positive value. When the input is
* positive, the original value is returned. When the input number is negative, the returned
* positive value is the original value bit AND against 0x7fffffff which is not its absolute
* value.
*
* Note: changing this method in the future will possibly cause partition selection not to be
* compatible with the existing messages already placed on a partition since it is used
* in producer's partition selection logic {@link org.apache.kafka.clients.producer.KafkaProducer}
*
* @param number a given number
* @return a positive number.
*/
public static int toPositive(int number) {
return number & 0x7fffffff;
}
/**
* Read a size-delimited byte buffer starting at the given offset.
* @param buffer Buffer containing the size and data
* @param start Offset in the buffer to read from
* @return A slice of the buffer containing only the delimited data (excluding the size)
*/
public static ByteBuffer sizeDelimited(ByteBuffer buffer, int start) {
int size = buffer.getInt(start);
if (size < 0) {
return null;
} else {
ByteBuffer b = buffer.duplicate();
b.position(start + 4);
b = b.slice();
b.limit(size);
b.rewind();
return b;
}
}
/**
* Read data from the channel to the given byte buffer until there are no bytes remaining in the buffer. If the end
* of the file is reached while there are bytes remaining in the buffer, an EOFException is thrown.
*
* @param channel File channel containing the data to read from
* @param destinationBuffer The buffer into which bytes are to be transferred
* @param position The file position at which the transfer is to begin; it must be non-negative
* @param description A description of what is being read, this will be included in the EOFException if it is thrown
*
* @throws IllegalArgumentException If position is negative
* @throws EOFException If the end of the file is reached while there are remaining bytes in the destination buffer
* @throws IOException If an I/O error occurs, see {@link FileChannel#read(ByteBuffer, long)} for details on the
* possible exceptions
*/
public static void readFullyOrFail(FileChannel channel, ByteBuffer destinationBuffer, long position,
String description) throws IOException {
if (position < 0) {
throw new IllegalArgumentException("The file channel position cannot be negative, but it is " + position);
}
int expectedReadBytes = destinationBuffer.remaining();
readFully(channel, destinationBuffer, position);
if (destinationBuffer.hasRemaining()) {
throw new EOFException(String.format("Failed to read `%s` from file channel `%s`. Expected to read %d bytes, " +
"but reached end of file after reading %d bytes. Started read from position %d.",
description, channel, expectedReadBytes, expectedReadBytes - destinationBuffer.remaining(), position));
}
}
/**
* Read data from the channel to the given byte buffer until there are no bytes remaining in the buffer or the end
* of the file has been reached.
*
* @param channel File channel containing the data to read from
* @param destinationBuffer The buffer into which bytes are to be transferred
* @param position The file position at which the transfer is to begin; it must be non-negative
*
* @throws IllegalArgumentException If position is negative
* @throws IOException If an I/O error occurs, see {@link FileChannel#read(ByteBuffer, long)} for details on the
* possible exceptions
*/
public static void readFully(FileChannel channel, ByteBuffer destinationBuffer, long position) throws IOException {
if (position < 0) {
throw new IllegalArgumentException("The file channel position cannot be negative, but it is " + position);
}
long currentPosition = position;
int bytesRead;
do {
bytesRead = channel.read(destinationBuffer, currentPosition);
currentPosition += bytesRead;
} while (bytesRead != -1 && destinationBuffer.hasRemaining());
}
/**
* Read data from the input stream to the given byte buffer until there are no bytes remaining in the buffer or the
* end of the stream has been reached.
*
* @param inputStream Input stream to read from
* @param destinationBuffer The buffer into which bytes are to be transferred (it must be backed by an array)
* @return number of byte read from the input stream
* @throws IOException If an I/O error occurs
*/
public static int readFully(InputStream inputStream, ByteBuffer destinationBuffer) throws IOException {
if (!destinationBuffer.hasArray())
throw new IllegalArgumentException("destinationBuffer must be backed by an array");
int initialOffset = destinationBuffer.arrayOffset() + destinationBuffer.position();
byte[] array = destinationBuffer.array();
int length = destinationBuffer.remaining();
int totalBytesRead = 0;
do {
int bytesRead = inputStream.read(array, initialOffset + totalBytesRead, length - totalBytesRead);
if (bytesRead == -1)
break;
totalBytesRead += bytesRead;
} while (length > totalBytesRead);
destinationBuffer.position(destinationBuffer.position() + totalBytesRead);
return totalBytesRead;
}
public static void writeFully(FileChannel channel, ByteBuffer sourceBuffer) throws IOException {
while (sourceBuffer.hasRemaining())
channel.write(sourceBuffer);
}
/**
* Trying to write data in source buffer to a {@link TransferableChannel}, we may need to call this method multiple
* times since this method doesn't ensure the data in the source buffer can be fully written to the destination channel.
*
* @param destChannel The destination channel
* @param position From which the source buffer will be written
* @param length The max size of bytes can be written
* @param sourceBuffer The source buffer
*
* @return The length of the actual written data
* @throws IOException If an I/O error occurs
*/
public static int tryWriteTo(TransferableChannel destChannel,
int position,
int length,
ByteBuffer sourceBuffer) throws IOException {
ByteBuffer dup = sourceBuffer.duplicate();
dup.position(position);
dup.limit(position + length);
return destChannel.write(dup);
}
/**
* Write the contents of a buffer to an output stream. The bytes are copied from the current position
* in the buffer.
* @param out The output to write to
* @param buffer The buffer to write from
* @param length The number of bytes to write
* @throws IOException For any errors writing to the output
*/
public static void writeTo(DataOutput out, ByteBuffer buffer, int length) throws IOException {
if (buffer.hasArray()) {
out.write(buffer.array(), buffer.position() + buffer.arrayOffset(), length);
} else {
int pos = buffer.position();
for (int i = pos; i < length + pos; i++)
out.writeByte(buffer.get(i));
}
}
public static List toList(Iterable iterable) {
return toList(iterable.iterator());
}
public static List toList(Iterator iterator) {
List res = new ArrayList<>();
while (iterator.hasNext())
res.add(iterator.next());
return res;
}
public static List toList(Iterator iterator, Predicate predicate) {
List res = new ArrayList<>();
while (iterator.hasNext()) {
T e = iterator.next();
if (predicate.test(e)) {
res.add(e);
}
}
return res;
}
public static int to32BitField(final Set bytes) {
int value = 0;
for (final byte b : bytes)
value |= 1 << checkRange(b);
return value;
}
private static byte checkRange(final byte i) {
if (i > 31)
throw new IllegalArgumentException("out of range: i>31, i = " + i);
if (i < 0)
throw new IllegalArgumentException("out of range: i<0, i = " + i);
return i;
}
public static Set from32BitField(final int intValue) {
Set result = new HashSet<>();
for (int itr = intValue, count = 0; itr != 0; itr >>>= 1) {
if ((itr & 1) != 0)
result.add((byte) count);
count++;
}
return result;
}
/**
* A Collector that offers two kinds of convenience:
* 1. You can specify the concrete type of the returned Map
* 2. You can turn a stream of Entries directly into a Map without having to mess with a key function
* and a value function. In particular, this is handy if all you need to do is apply a filter to a Map's entries.
*
*
* One thing to be wary of: These types are too "distant" for IDE type checkers to warn you if you
* try to do something like build a TreeMap of non-Comparable elements. You'd get a runtime exception for that.
*
* @param mapSupplier The constructor for your concrete map type.
* @param The Map key type
* @param The Map value type
* @param The type of the Map itself.
* @return new Collector, M, M>
*/
public static > Collector, M, M> entriesToMap(final Supplier mapSupplier) {
return new Collector, M, M>() {
@Override
public Supplier supplier() {
return mapSupplier;
}
@Override
public BiConsumer> accumulator() {
return (map, entry) -> map.put(entry.getKey(), entry.getValue());
}
@Override
public BinaryOperator combiner() {
return (map, map2) -> {
map.putAll(map2);
return map;
};
}
@Override
public Function finisher() {
return map -> map;
}
@Override
public Set characteristics() {
return EnumSet.of(Characteristics.UNORDERED, Characteristics.IDENTITY_FINISH);
}
};
}
@SafeVarargs
public static Set union(final Supplier> constructor, final Set... set) {
final Set result = constructor.get();
for (final Set s : set) {
result.addAll(s);
}
return result;
}
@SafeVarargs
public static Set intersection(final Supplier> constructor, final Set first, final Set... set) {
final Set result = constructor.get();
result.addAll(first);
for (final Set s : set) {
result.retainAll(s);
}
return result;
}
public static Set diff(final Supplier> constructor, final Set left, final Set right) {
final Set result = constructor.get();
result.addAll(left);
result.removeAll(right);
return result;
}
public static Map filterMap(final Map map, final Predicate> filterPredicate) {
return map.entrySet().stream().filter(filterPredicate).collect(Collectors.toMap(Entry::getKey, Entry::getValue));
}
/**
* Convert a properties to map. All keys in properties must be string type. Otherwise, a ConfigException is thrown.
* @param properties to be converted
* @return a map including all elements in properties
*/
public static Map propsToMap(Properties properties) {
return castToStringObjectMap(properties);
}
/**
* Cast a map with arbitrary type keys to be keyed on String.
* @param inputMap A map with unknown type keys
* @return A map with the same contents as the input map, but with String keys
* @throws ConfigException if any key is not a String
*/
public static Map castToStringObjectMap(Map inputMap) {
Map map = new HashMap<>(inputMap.size());
for (Map.Entry entry : inputMap.entrySet()) {
if (entry.getKey() instanceof String) {
String k = (String) entry.getKey();
map.put(k, entry.getValue());
} else {
throw new ConfigException(String.valueOf(entry.getKey()), entry.getValue(), "Key must be a string.");
}
}
return map;
}
/**
* Convert timestamp to an epoch value
* @param timestamp the timestamp to be converted, the accepted formats are:
* (1) yyyy-MM-dd'T'HH:mm:ss.SSS, ex: 2020-11-10T16:51:38.198
* (2) yyyy-MM-dd'T'HH:mm:ss.SSSZ, ex: 2020-11-10T16:51:38.198+0800
* (3) yyyy-MM-dd'T'HH:mm:ss.SSSX, ex: 2020-11-10T16:51:38.198+08
* (4) yyyy-MM-dd'T'HH:mm:ss.SSSXX, ex: 2020-11-10T16:51:38.198+0800
* (5) yyyy-MM-dd'T'HH:mm:ss.SSSXXX, ex: 2020-11-10T16:51:38.198+08:00
*
* @return epoch value of a given timestamp (i.e. the number of milliseconds since January 1, 1970, 00:00:00 GMT)
* @throws ParseException for timestamp that doesn't follow ISO8601 format or the format is not expected
*/
public static long getDateTime(String timestamp) throws ParseException, IllegalArgumentException {
if (timestamp == null) {
throw new IllegalArgumentException("Error parsing timestamp with null value");
}
final String[] timestampParts = timestamp.split("T");
if (timestampParts.length < 2) {
throw new ParseException("Error parsing timestamp. It does not contain a 'T' according to ISO8601 format", timestamp.length());
}
final String secondPart = timestampParts[1];
if (!(secondPart.contains("+") || secondPart.contains("-") || secondPart.contains("Z"))) {
timestamp = timestamp + "Z";
}
SimpleDateFormat simpleDateFormat = new SimpleDateFormat();
// strictly parsing the date/time format
simpleDateFormat.setLenient(false);
try {
simpleDateFormat.applyPattern("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
final Date date = simpleDateFormat.parse(timestamp);
return date.getTime();
} catch (final ParseException e) {
simpleDateFormat.applyPattern("yyyy-MM-dd'T'HH:mm:ss.SSSX");
final Date date = simpleDateFormat.parse(timestamp);
return date.getTime();
}
}
@SuppressWarnings("unchecked")
public static Iterator covariantCast(Iterator iterator) {
return (Iterator) iterator;
}
/**
* Checks if a string is null, empty or whitespace only.
* @param str a string to be checked
* @return true if the string is null, empty or whitespace only; otherwise, return false.
*/
public static boolean isBlank(String str) {
return str == null || str.trim().isEmpty();
}
/**
* Get an array containing all of the {@link Object#toString string representations} of a given enumerable type.
* @param enumClass the enum class; may not be null
* @return an array with the names of every value for the enum class; never null, but may be empty
* if there are no values defined for the enum
*/
public static String[] enumOptions(Class> enumClass) {
Objects.requireNonNull(enumClass);
if (!enumClass.isEnum()) {
throw new IllegalArgumentException("Class " + enumClass + " is not an enumerable type");
}
return Stream.of(enumClass.getEnumConstants())
.map(Object::toString)
.toArray(String[]::new);
}
/**
* Ensure that the class is concrete (i.e., not abstract), and that it subclasses a given base class.
* If it is abstract or does not subclass the given base class, throw a {@link ConfigException}
* with a friendly error message suggesting a list of concrete child subclasses (if any are known).
* @param baseClass the expected superclass; may not be null
* @param klass the class to check; may not be null
* @throws ConfigException if the class is not concrete
*/
public static void ensureConcreteSubclass(Class baseClass, Class klass) {
Objects.requireNonNull(baseClass);
Objects.requireNonNull(klass);
if (!baseClass.isAssignableFrom(klass)) {
String inheritFrom = baseClass.isInterface() ? "implement" : "extend";
String baseClassType = baseClass.isInterface() ? "interface" : "class";
throw new ConfigException("Class " + klass + " does not " + inheritFrom + " the " + baseClass.getSimpleName() + " " + baseClassType);
}
if (Modifier.isAbstract(klass.getModifiers())) {
String childClassNames = Stream.of(klass.getClasses())
.filter(baseClass::isAssignableFrom)
.filter(c -> !Modifier.isAbstract(c.getModifiers()))
.filter(c -> Modifier.isPublic(c.getModifiers()))
.map(Class::getName)
.collect(Collectors.joining(", "));
String message = "This class is abstract and cannot be created.";
if (!Utils.isBlank(childClassNames))
message += " Did you mean " + childClassNames + "?";
throw new ConfigException(message);
}
}
/**
* Convert time instant to readable string for logging
* @param timestamp the timestamp of the instant to be converted.
*
* @return string value of a given timestamp in the format "yyyy-MM-dd HH:mm:ss,SSS"
*/
public static String toLogDateTimeFormat(long timestamp) {
final DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss,SSS XXX");
return Instant.ofEpochMilli(timestamp).atZone(ZoneId.systemDefault()).format(dateTimeFormatter);
}
/**
* Replace the given string suffix with the new suffix. If the string doesn't end with the given suffix throw an exception.
*/
public static String replaceSuffix(String str, String oldSuffix, String newSuffix) {
if (!str.endsWith(oldSuffix))
throw new IllegalArgumentException("Expected string to end with " + oldSuffix + " but string is " + str);
return str.substring(0, str.length() - oldSuffix.length()) + newSuffix;
}
/**
* Find all key/value pairs whose keys begin with the given prefix, and remove that prefix from all
* resulting keys.
* @param map the map to filter key/value pairs from
* @param prefix the prefix to search keys for
* @return a {@link Map} containing a key/value pair for every key/value pair in the {@code map}
* parameter whose key begins with the given {@code prefix} and whose corresponding keys have
* the prefix stripped from them; may be empty, but never null
* @param the type of values stored in the map
*/
public static Map entriesWithPrefix(Map map, String prefix) {
return entriesWithPrefix(map, prefix, true);
}
/**
* Find all key/value pairs whose keys begin with the given prefix, optionally removing that prefix
* from all resulting keys.
* @param map the map to filter key/value pairs from
* @param prefix the prefix to search keys for
* @param strip whether the keys of the returned map should not include the prefix
* @return a {@link Map} containing a key/value pair for every key/value pair in the {@code map}
* parameter whose key begins with the given {@code prefix}; may be empty, but never null
* @param the type of values stored in the map
*/
public static Map entriesWithPrefix(Map map, String prefix, boolean strip) {
Map result = new HashMap<>();
for (Map.Entry entry : map.entrySet()) {
if (entry.getKey().startsWith(prefix) && entry.getKey().length() > prefix.length()) {
if (strip)
result.put(entry.getKey().substring(prefix.length()), entry.getValue());
else
result.put(entry.getKey(), entry.getValue());
}
}
return result;
}
/**
* A runnable that can throw checked exception.
*/
@FunctionalInterface
public interface ThrowingRunnable {
void run() throws Exception;
}
}