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/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.util;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
/**
* This utility class contains miscellaneous functions.
*/
public class Utils {
/**
* An 0-size byte array.
*/
public static final byte[] EMPTY_BYTES = {};
/**
* An 0-size int array.
*/
public static final int[] EMPTY_INT_ARRAY = {};
private static final HashMap RESOURCES = new HashMap<>();
private Utils() {
// utility class
}
/**
* Calculate the index of the first occurrence of the pattern in the byte
* array, starting with the given index. This methods returns -1 if the
* pattern has not been found, and the start position if the pattern is
* empty.
*
* @param bytes the byte array
* @param pattern the pattern
* @param start the start index from where to search
* @return the index
*/
public static int indexOf(byte[] bytes, byte[] pattern, int start) {
if (pattern.length == 0) {
return start;
}
if (start > bytes.length) {
return -1;
}
int last = bytes.length - pattern.length + 1;
int patternLen = pattern.length;
next:
for (; start < last; start++) {
for (int i = 0; i < patternLen; i++) {
if (bytes[start + i] != pattern[i]) {
continue next;
}
}
return start;
}
return -1;
}
/**
* Calculate the hash code of the given byte array.
*
* @param value the byte array
* @return the hash code
*/
public static int getByteArrayHash(byte[] value) {
int len = value.length;
int h = len;
if (len < 50) {
for (int i = 0; i < len; i++) {
h = 31 * h + value[i];
}
} else {
int step = len / 16;
for (int i = 0; i < 4; i++) {
h = 31 * h + value[i];
h = 31 * h + value[--len];
}
for (int i = 4 + step; i < len; i += step) {
h = 31 * h + value[i];
}
}
return h;
}
/**
* Compare two byte arrays. This method will always loop over all bytes and
* doesn't use conditional operations in the loop to make sure an attacker
* can not use a timing attack when trying out passwords.
*
* @param test the first array
* @param good the second array
* @return true if both byte arrays contain the same bytes
*/
public static boolean compareSecure(byte[] test, byte[] good) {
if ((test == null) || (good == null)) {
return (test == null) && (good == null);
}
int len = test.length;
if (len != good.length) {
return false;
}
if (len == 0) {
return true;
}
// don't use conditional operations inside the loop
int bits = 0;
for (int i = 0; i < len; i++) {
// this will never reset any bits
bits |= test[i] ^ good[i];
}
return bits == 0;
}
/**
* Copy the contents of the source array to the target array. If the size if
* the target array is too small, a larger array is created.
*
* @param source the source array
* @param target the target array
* @return the target array or a new one if the target array was too small
*/
public static byte[] copy(byte[] source, byte[] target) {
int len = source.length;
if (len > target.length) {
target = new byte[len];
}
System.arraycopy(source, 0, target, 0, len);
return target;
}
/**
* Create an array of bytes with the given size. If this is not possible
* because not enough memory is available, an OutOfMemoryError with the
* requested size in the message is thrown.
*
* This method should be used if the size of the array is user defined, or
* stored in a file, so wrong size data can be distinguished from regular
* out-of-memory.
*
*
* @param len the number of bytes requested
* @return the byte array
* @throws OutOfMemoryError if the allocation was too large
*/
public static byte[] newBytes(int len) {
if (len == 0) {
return EMPTY_BYTES;
}
try {
return new byte[len];
} catch (OutOfMemoryError e) {
Error e2 = new OutOfMemoryError("Requested memory: " + len);
e2.initCause(e);
throw e2;
}
}
/**
* Creates a copy of array of bytes with the new size. If this is not possible
* because not enough memory is available, an OutOfMemoryError with the
* requested size in the message is thrown.
*
* This method should be used if the size of the array is user defined, or
* stored in a file, so wrong size data can be distinguished from regular
* out-of-memory.
*
*
* @param bytes source array
* @param len the number of bytes in the new array
* @return the byte array
* @throws OutOfMemoryError if the allocation was too large
* @see Arrays#copyOf(byte[], int)
*/
public static byte[] copyBytes(byte[] bytes, int len) {
if (len == 0) {
return EMPTY_BYTES;
}
try {
return Arrays.copyOf(bytes, len);
} catch (OutOfMemoryError e) {
Error e2 = new OutOfMemoryError("Requested memory: " + len);
e2.initCause(e);
throw e2;
}
}
/**
* Create a new byte array and copy all the data. If the size of the byte
* array is zero, the same array is returned.
*
* @param b the byte array (may not be null)
* @return a new byte array
*/
public static byte[] cloneByteArray(byte[] b) {
if (b == null) {
return null;
}
int len = b.length;
if (len == 0) {
return EMPTY_BYTES;
}
return Arrays.copyOf(b, len);
}
/**
* Get the used memory in KB.
* This method possibly calls System.gc().
*
* @return the used memory
*/
public static long getMemoryUsed() {
collectGarbage();
Runtime rt = Runtime.getRuntime();
return rt.totalMemory() - rt.freeMemory() >> 10;
}
/**
* Get the free memory in KB.
* This method possibly calls System.gc().
*
* @return the free memory
*/
public static long getMemoryFree() {
collectGarbage();
return Runtime.getRuntime().freeMemory() >> 10;
}
/**
* Get the maximum memory in KB.
*
* @return the maximum memory
*/
public static long getMemoryMax() {
return Runtime.getRuntime().maxMemory() >> 10;
}
public static long getGarbageCollectionTime() {
long totalGCTime = 0;
for (GarbageCollectorMXBean gcMXBean : ManagementFactory.getGarbageCollectorMXBeans()) {
long collectionTime = gcMXBean.getCollectionTime();
if(collectionTime > 0) {
totalGCTime += collectionTime;
}
}
return totalGCTime;
}
public static long getGarbageCollectionCount() {
long totalGCCount = 0;
int poolCount = 0;
for (GarbageCollectorMXBean gcMXBean : ManagementFactory.getGarbageCollectorMXBeans()) {
long collectionCount = gcMXBean.getCollectionTime();
if(collectionCount > 0) {
totalGCCount += collectionCount;
poolCount += gcMXBean.getMemoryPoolNames().length;
}
}
poolCount = Math.max(poolCount, 1);
return (totalGCCount + (poolCount >> 1)) / poolCount;
}
/**
* Run Java memory garbage collection.
*/
public static synchronized void collectGarbage() {
Runtime runtime = Runtime.getRuntime();
long garbageCollectionCount = getGarbageCollectionCount();
while (garbageCollectionCount == getGarbageCollectionCount()) {
runtime.gc();
Thread.yield();
}
}
/**
* Create a new ArrayList with an initial capacity of 4.
*
* @param the type
* @return the object
*/
public static ArrayList newSmallArrayList() {
return new ArrayList<>(4);
}
/**
* Find the top limit values using given comparator and place them as in a
* full array sort, in descending order.
*
* @param the type of elements
* @param array the array.
* @param fromInclusive the start index, inclusive
* @param toExclusive the end index, exclusive
* @param comp the comparator.
*/
public static void sortTopN(X[] array, int fromInclusive, int toExclusive, Comparator comp) {
int highInclusive = array.length - 1;
if (highInclusive > 0 && toExclusive > fromInclusive) {
partialQuickSort(array, 0, highInclusive, comp, fromInclusive, toExclusive - 1);
Arrays.sort(array, fromInclusive, toExclusive, comp);
}
}
/**
* Partial quick sort.
*
*
* Works with elements from {@code low} to {@code high} indexes, inclusive.
*
*
* Moves smallest elements to {@code low..start-1} positions and largest
* elements to {@code end+1..high} positions. Middle elements are placed
* into {@code start..end} positions. All these regions aren't fully sorted.
*
*
* @param the type of elements
* @param array the array to sort
* @param low the lower index with data, inclusive
* @param high the higher index with data, inclusive, {@code high > low}
* @param comp the comparator
* @param start the start index of requested region, inclusive
* @param end the end index of requested region, inclusive, {@code end >= start}
*/
private static void partialQuickSort(X[] array, int low, int high,
Comparator comp, int start, int end) {
if (low >= start && high <= end) {
// Don't sort blocks entirely contained in the middle region
return;
}
int i = low, j = high;
// use a random pivot to protect against
// the worst case order
int p = low + MathUtils.randomInt(high - low);
X pivot = array[p];
int m = (low + high) >>> 1;
X temp = array[m];
array[m] = pivot;
array[p] = temp;
while (i <= j) {
while (comp.compare(array[i], pivot) < 0) {
i++;
}
while (comp.compare(array[j], pivot) > 0) {
j--;
}
if (i <= j) {
temp = array[i];
array[i++] = array[j];
array[j--] = temp;
}
}
if (low < j && /* Intersection with middle region */ start <= j) {
partialQuickSort(array, low, j, comp, start, end);
}
if (i < high && /* Intersection with middle region */ i <= end) {
partialQuickSort(array, i, high, comp, start, end);
}
}
/**
* Get a resource from the resource map.
*
* @param name the name of the resource
* @return the resource data
* @throws IOException on failure
*/
public static byte[] getResource(String name) throws IOException {
byte[] data = RESOURCES.get(name);
if (data == null) {
data = loadResource(name);
if (data != null) {
RESOURCES.put(name, data);
}
}
return data;
}
private static byte[] loadResource(String name) throws IOException {
InputStream in = Utils.class.getResourceAsStream("data.zip");
if (in == null) {
in = Utils.class.getResourceAsStream(name);
if (in == null) {
return null;
}
return IOUtils.readBytesAndClose(in, 0);
}
try (ZipInputStream zipIn = new ZipInputStream(in)) {
while (true) {
ZipEntry entry = zipIn.getNextEntry();
if (entry == null) {
break;
}
String entryName = entry.getName();
if (!entryName.startsWith("/")) {
entryName = "/" + entryName;
}
if (entryName.equals(name)) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
IOUtils.copy(zipIn, out);
zipIn.closeEntry();
return out.toByteArray();
}
zipIn.closeEntry();
}
} catch (IOException e) {
// if this happens we have a real problem
e.printStackTrace();
}
return null;
}
/**
* Calls a static method via reflection. This will try to use the method
* where the most parameter classes match exactly (this algorithm is simpler
* than the one in the Java specification, but works well for most cases).
*
* @param classAndMethod a string with the entire class and method name, eg.
* "java.lang.System.gc"
* @param params the method parameters
* @return the return value from this call
* @throws Exception on failure
*/
public static Object callStaticMethod(String classAndMethod,
Object... params) throws Exception {
int lastDot = classAndMethod.lastIndexOf('.');
String className = classAndMethod.substring(0, lastDot);
String methodName = classAndMethod.substring(lastDot + 1);
return callMethod(null, Class.forName(className), methodName, params);
}
/**
* Calls an instance method via reflection. This will try to use the method
* where the most parameter classes match exactly (this algorithm is simpler
* than the one in the Java specification, but works well for most cases).
*
* @param instance the instance on which the call is done
* @param methodName a string with the method name
* @param params the method parameters
* @return the return value from this call
* @throws Exception on failure
*/
public static Object callMethod(
Object instance,
String methodName,
Object... params) throws Exception {
return callMethod(instance, instance.getClass(), methodName, params);
}
private static Object callMethod(
Object instance, Class clazz,
String methodName,
Object... params) throws Exception {
Method best = null;
int bestMatch = 0;
boolean isStatic = instance == null;
for (Method m : clazz.getMethods()) {
if (Modifier.isStatic(m.getModifiers()) == isStatic &&
m.getName().equals(methodName)) {
int p = match(m.getParameterTypes(), params);
if (p > bestMatch) {
bestMatch = p;
best = m;
}
}
}
if (best == null) {
throw new NoSuchMethodException(methodName);
}
return best.invoke(instance, params);
}
/**
* Creates a new instance. This will try to use the constructor where the
* most parameter classes match exactly (this algorithm is simpler than the
* one in the Java specification, but works well for most cases).
*
* @param className a string with the entire class, eg. "java.lang.Integer"
* @param params the constructor parameters
* @return the newly created object
* @throws Exception on failure
*/
public static Object newInstance(String className, Object... params)
throws Exception {
Constructor best = null;
int bestMatch = 0;
for (Constructor c : Class.forName(className).getConstructors()) {
int p = match(c.getParameterTypes(), params);
if (p > bestMatch) {
bestMatch = p;
best = c;
}
}
if (best == null) {
throw new NoSuchMethodException(className);
}
return best.newInstance(params);
}
private static int match(Class[] params, Object[] values) {
int len = params.length;
if (len == values.length) {
int points = 1;
for (int i = 0; i < len; i++) {
Class pc = getNonPrimitiveClass(params[i]);
Object v = values[i];
Class vc = v == null ? null : v.getClass();
if (pc == vc) {
points++;
} else if (vc == null) {
// can't verify
} else if (!pc.isAssignableFrom(vc)) {
return 0;
}
}
return points;
}
return 0;
}
/**
* Convert primitive class names to java.lang.* class names.
*
* @param clazz the class (for example: int)
* @return the non-primitive class (for example: java.lang.Integer)
*/
public static Class getNonPrimitiveClass(Class clazz) {
if (!clazz.isPrimitive()) {
return clazz;
} else if (clazz == boolean.class) {
return Boolean.class;
} else if (clazz == byte.class) {
return Byte.class;
} else if (clazz == char.class) {
return Character.class;
} else if (clazz == double.class) {
return Double.class;
} else if (clazz == float.class) {
return Float.class;
} else if (clazz == int.class) {
return Integer.class;
} else if (clazz == long.class) {
return Long.class;
} else if (clazz == short.class) {
return Short.class;
} else if (clazz == void.class) {
return Void.class;
}
return clazz;
}
/**
* Parses the specified string to boolean value.
*
* @param value
* string to parse
* @param defaultValue
* value to return if value is null or on parsing error
* @param throwException
* throw exception on parsing error or return default value instead
* @return parsed or default value
* @throws IllegalArgumentException
* on parsing error if {@code throwException} is true
*/
public static boolean parseBoolean(String value, boolean defaultValue, boolean throwException) {
if (value == null) {
return defaultValue;
}
switch (value.length()) {
case 1:
if (value.equals("1") || value.equalsIgnoreCase("t") || value.equalsIgnoreCase("y")) {
return true;
}
if (value.equals("0") || value.equalsIgnoreCase("f") || value.equalsIgnoreCase("n")) {
return false;
}
break;
case 2:
if (value.equalsIgnoreCase("no")) {
return false;
}
break;
case 3:
if (value.equalsIgnoreCase("yes")) {
return true;
}
break;
case 4:
if (value.equalsIgnoreCase("true")) {
return true;
}
break;
case 5:
if (value.equalsIgnoreCase("false")) {
return false;
}
}
if (throwException) {
throw new IllegalArgumentException(value);
}
return defaultValue;
}
/**
* Get the system property. If the system property is not set, or if a
* security exception occurs, the default value is returned.
*
* @param key the key
* @param defaultValue the default value
* @return the value
*/
public static String getProperty(String key, String defaultValue) {
try {
return System.getProperty(key, defaultValue);
} catch (SecurityException se) {
return defaultValue;
}
}
/**
* Get the system property. If the system property is not set, or if a
* security exception occurs, the default value is returned.
*
* @param key the key
* @param defaultValue the default value
* @return the value
*/
public static int getProperty(String key, int defaultValue) {
String s = getProperty(key, null);
if (s != null) {
try {
return Integer.decode(s);
} catch (NumberFormatException e) {
// ignore
}
}
return defaultValue;
}
/**
* Get the system property. If the system property is not set, or if a
* security exception occurs, the default value is returned.
*
* @param key the key
* @param defaultValue the default value
* @return the value
*/
public static boolean getProperty(String key, boolean defaultValue) {
return parseBoolean(getProperty(key, null), defaultValue, false);
}
/**
* Scale the value with the available memory. If 1 GB of RAM is available,
* the value is returned, if 2 GB are available, then twice the value, and
* so on.
*
* @param value the value to scale
* @return the scaled value
*/
public static int scaleForAvailableMemory(int value) {
long maxMemory = Runtime.getRuntime().maxMemory();
if (maxMemory != Long.MAX_VALUE) {
// we are limited by an -XmX parameter
return (int) (value * maxMemory / (1024 * 1024 * 1024));
}
try {
OperatingSystemMXBean mxBean = ManagementFactory
.getOperatingSystemMXBean();
// this method is only available on the class
// com.sun.management.OperatingSystemMXBean, which mxBean
// is an instance of under the Oracle JDK, but it is not present on
// Android and other JDK's
Method method = Class.forName(
"com.sun.management.OperatingSystemMXBean").
getMethod("getTotalPhysicalMemorySize");
long physicalMemorySize = ((Number) method.invoke(mxBean)).longValue();
return (int) (value * physicalMemorySize / (1024 * 1024 * 1024));
} catch (Exception e) {
// ignore
} catch (Error error) {
// ignore
}
return value;
}
/**
* Returns the current value of the high-resolution time source.
*
* @return time in nanoseconds, never equal to 0
* @see System#nanoTime()
*/
public static long currentNanoTime() {
long time = System.nanoTime();
if (time == 0L) {
time = 1L;
}
return time;
}
/**
* Returns the current value of the high-resolution time source plus the
* specified offset.
*
* @param ms
* additional offset in milliseconds
* @return time in nanoseconds, never equal to 0
* @see System#nanoTime()
*/
public static long currentNanoTimePlusMillis(int ms) {
return nanoTimePlusMillis(System.nanoTime(), ms);
}
/**
* Returns the current value of the high-resolution time source plus the
* specified offset.
*
* @param nanoTime
* time in nanoseconds
* @param ms
* additional offset in milliseconds
* @return time in nanoseconds, never equal to 0
* @see System#nanoTime()
*/
public static long nanoTimePlusMillis(long nanoTime, int ms) {
long time = nanoTime + ms * 1_000_000L;
if (time == 0L) {
time = 1L;
}
return time;
}
public static ThreadPoolExecutor createSingleThreadExecutor(String threadName) {
return createSingleThreadExecutor(threadName, new LinkedBlockingQueue<>());
}
public static ThreadPoolExecutor createSingleThreadExecutor(String threadName, BlockingQueue workQueue) {
return new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, workQueue,
r -> {
Thread thread = new Thread(r, threadName);
thread.setDaemon(true);
return thread;
});
}
/**
* Makes sure that all currently submitted tasks are processed before this method returns.
* It is assumed that there will be no new submissions to this executor, once this method has started.
* It is assumed that executor is single-threaded, and flush is done by submitting a dummy task
* and waiting for its completion.
* @param executor to flush
*/
public static void flushExecutor(ThreadPoolExecutor executor) {
if (executor != null) {
try {
executor.submit(() -> {}).get();
} catch (InterruptedException ignore) {/**/
} catch (RejectedExecutionException ex) {
shutdownExecutor(executor);
} catch (ExecutionException e) {
throw new RuntimeException(e);
}
}
}
public static void shutdownExecutor(ThreadPoolExecutor executor) {
if (executor != null) {
executor.shutdown();
try {
executor.awaitTermination(1, TimeUnit.DAYS);
} catch (InterruptedException ignore) {/**/}
}
}
/**
* The utility methods will try to use the provided class factories to
* convert binary name of class to Class object. Used by H2 OSGi Activator
* in order to provide a class from another bundle ClassLoader.
*/
public interface ClassFactory {
/**
* Check whether the factory can return the named class.
*
* @param name the binary name of the class
* @return true if this factory can return a valid class for the
* provided class name
*/
boolean match(String name);
/**
* Load the class.
*
* @param name the binary name of the class
* @return the class object
* @throws ClassNotFoundException If the class is not handle by this
* factory
*/
Class loadClass(String name)
throws ClassNotFoundException;
}
}