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8223593: Refactor code for reallocating storage

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Reviewed-by: prappo, plevart, rriggs, smarks
This commit is contained in:
Ivan Gerasimov 2019-05-21 18:40:29 -07:00
parent 54d0b2a8d6
commit 218204b1a3
11 changed files with 129 additions and 247 deletions
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21
src/java.base/share/classes/java/io/BufferedInputStream.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -26,6 +26,7 @@
package java.io;
import jdk.internal.misc.Unsafe;
import jdk.internal.util.ArraysSupport;
/**
* A <code>BufferedInputStream</code> adds
@ -53,14 +54,6 @@ class BufferedInputStream extends FilterInputStream {
private static int DEFAULT_BUFFER_SIZE = 8192;
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;
/**
* As this class is used early during bootstrap, it's motivated to use
* Unsafe.compareAndSetObject instead of AtomicReferenceFieldUpdater
@ -220,7 +213,7 @@ class BufferedInputStream extends FilterInputStream {
byte[] buffer = getBufIfOpen();
if (markpos < 0)
pos = 0; /* no mark: throw away the buffer */
else if (pos >= buffer.length) /* no room left in buffer */
else if (pos >= buffer.length) { /* no room left in buffer */
if (markpos > 0) { /* can throw away early part of the buffer */
int sz = pos - markpos;
System.arraycopy(buffer, markpos, buffer, 0, sz);
@ -229,11 +222,10 @@ class BufferedInputStream extends FilterInputStream {
} else if (buffer.length >= marklimit) {
markpos = -1; /* buffer got too big, invalidate mark */
pos = 0; /* drop buffer contents */
} else if (buffer.length >= MAX_BUFFER_SIZE) {
throw new OutOfMemoryError("Required array size too large");
} else { /* grow buffer */
int nsz = (pos <= MAX_BUFFER_SIZE - pos) ?
pos * 2 : MAX_BUFFER_SIZE;
int nsz = ArraysSupport.newLength(pos,
1, /* minimum growth */
pos /* preferred growth */);
if (nsz > marklimit)
nsz = marklimit;
byte[] nbuf = new byte[nsz];
@ -248,6 +240,7 @@ class BufferedInputStream extends FilterInputStream {
}
buffer = nbuf;
}
}
count = pos;
int n = getInIfOpen().read(buffer, pos, buffer.length - pos);
if (n > 0)

50
src/java.base/share/classes/java/io/ByteArrayOutputStream.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -29,6 +29,8 @@ import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.Objects;
import jdk.internal.util.ArraysSupport;
/**
* This class implements an output stream in which the data is
* written into a byte array. The buffer automatically grows as data
@ -84,48 +86,20 @@ public class ByteArrayOutputStream extends OutputStream {
* at least the number of elements specified by the minimum
* capacity argument.
*
* @param minCapacity the desired minimum capacity
* @throws OutOfMemoryError if {@code minCapacity < 0}. This is
* interpreted as a request for the unsatisfiably large capacity
* @param minCapacity the desired minimum capacity.
* @throws OutOfMemoryError if {@code minCapacity < 0} and
* {@code minCapacity - buf.length > 0}. This is interpreted as a
* request for the unsatisfiably large capacity.
* {@code (long) Integer.MAX_VALUE + (minCapacity - Integer.MAX_VALUE)}.
*/
private void ensureCapacity(int minCapacity) {
// overflow-conscious code
if (minCapacity - buf.length > 0)
grow(minCapacity);
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
private void grow(int minCapacity) {
// overflow-conscious code
int oldCapacity = buf.length;
int newCapacity = oldCapacity << 1;
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity - MAX_ARRAY_SIZE > 0)
newCapacity = hugeCapacity(minCapacity);
buf = Arrays.copyOf(buf, newCapacity);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
int minGrowth = minCapacity - oldCapacity;
if (minGrowth > 0) {
buf = Arrays.copyOf(buf, ArraysSupport.newLength(oldCapacity,
minGrowth, oldCapacity /* preferred growth */));
}
}
/**

19
src/java.base/share/classes/java/lang/StringLatin1.java
View File

@ -35,6 +35,7 @@ import java.util.stream.IntStream;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.HotSpotIntrinsicCandidate;
import jdk.internal.util.ArraysSupport;
import static java.lang.String.LATIN1;
import static java.lang.String.UTF16;
@ -42,14 +43,6 @@ import static java.lang.String.checkOffset;
final class StringLatin1 {
/**
* The maximum size of array to allocate (unless necessary).
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
public static char charAt(byte[] value, int index) {
if (index < 0 || index >= value.length) {
throw new StringIndexOutOfBoundsException(index);
@ -353,15 +346,7 @@ final class StringLatin1 {
i += targLen;
while ((j = indexOf(value, valLen, targ, targLen, i)) > 0) {
if (++p == pos.length) {
int cap = p + (p >> 1);
// overflow-conscious code
if (cap - MAX_ARRAY_SIZE > 0) {
if (p == MAX_ARRAY_SIZE) {
throw new OutOfMemoryError();
}
cap = MAX_ARRAY_SIZE;
}
pos = Arrays.copyOf(pos, cap);
pos = Arrays.copyOf(pos, ArraysSupport.newLength(p, 1, p >> 1));
}
pos[p] = j;
i = j + targLen;

20
src/java.base/share/classes/java/lang/StringUTF16.java
View File

@ -33,6 +33,7 @@ import java.util.function.IntConsumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.HotSpotIntrinsicCandidate;
import jdk.internal.util.ArraysSupport;
import jdk.internal.vm.annotation.ForceInline;
import jdk.internal.vm.annotation.DontInline;
@ -649,15 +650,7 @@ final class StringUTF16 {
: indexOf(value, valLen, targ, targLen, i))) > 0)
{
if (++p == pos.length) {
int cap = p + (p >> 1);
// overflow-conscious code
if (cap - MAX_ARRAY_SIZE > 0) {
if (p == MAX_ARRAY_SIZE) {
throw new OutOfMemoryError();
}
cap = MAX_ARRAY_SIZE;
}
pos = Arrays.copyOf(pos, cap);
pos = Arrays.copyOf(pos, ArraysSupport.newLength(p, 1, p >> 1));
}
pos[p] = j;
i = j + targLen;
@ -1554,15 +1547,6 @@ final class StringUTF16 {
static final int MAX_LENGTH = Integer.MAX_VALUE >> 1;
/**
* The maximum size of array to allocate (unless necessary).
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
// Used by trusted callers. Assumes all necessary bounds checks have
// been done by the caller.

22
src/java.base/share/classes/java/nio/file/Files.java
View File

@ -77,6 +77,7 @@ import java.util.function.BiPredicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.util.ArraysSupport;
import sun.nio.ch.FileChannelImpl;
import sun.nio.fs.AbstractFileSystemProvider;
@ -3196,14 +3197,6 @@ public final class Files {
}
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;
private static final jdk.internal.access.JavaLangAccess JLA =
jdk.internal.access.SharedSecrets.getJavaLangAccess();
@ -3240,13 +3233,10 @@ public final class Files {
break;
// one more byte was read; need to allocate a larger buffer
if (capacity <= MAX_BUFFER_SIZE - capacity) {
capacity = Math.max(capacity << 1, BUFFER_SIZE);
} else {
if (capacity == MAX_BUFFER_SIZE)
throw new OutOfMemoryError("Required array size too large");
capacity = MAX_BUFFER_SIZE;
}
capacity = Math.max(ArraysSupport.newLength(capacity,
1, /* minimum growth */
capacity /* preferred growth */),
BUFFER_SIZE);
buf = Arrays.copyOf(buf, capacity);
buf[nread++] = (byte)n;
}
@ -3283,7 +3273,7 @@ public final class Files {
if (sbc instanceof FileChannelImpl)
((FileChannelImpl) sbc).setUninterruptible();
long size = sbc.size();
if (size > (long) MAX_BUFFER_SIZE)
if (size > (long) Integer.MAX_VALUE)
throw new OutOfMemoryError("Required array size too large");
return read(in, (int)size);
}

38
src/java.base/share/classes/java/util/AbstractCollection.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -25,6 +25,8 @@
package java.util;
import jdk.internal.util.ArraysSupport;
/**
* This class provides a skeletal implementation of the {@code Collection}
* interface, to minimize the effort required to implement this interface. <p>
@ -203,14 +205,6 @@ public abstract class AbstractCollection<E> implements Collection<E> {
return it.hasNext() ? finishToArray(r, it) : r;
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* Reallocates the array being used within toArray when the iterator
* returned more elements than expected, and finishes filling it from
@ -223,29 +217,19 @@ public abstract class AbstractCollection<E> implements Collection<E> {
*/
@SuppressWarnings("unchecked")
private static <T> T[] finishToArray(T[] r, Iterator<?> it) {
int i = r.length;
int len = r.length;
int i = len;
while (it.hasNext()) {
int cap = r.length;
if (i == cap) {
int newCap = cap + (cap >> 1) + 1;
// overflow-conscious code
if (newCap - MAX_ARRAY_SIZE > 0)
newCap = hugeCapacity(cap + 1);
r = Arrays.copyOf(r, newCap);
if (i == len) {
len = ArraysSupport.newLength(len,
1, /* minimum growth */
(len >> 1) + 1 /* preferred growth */);
r = Arrays.copyOf(r, len);
}
r[i++] = (T)it.next();
}
// trim if overallocated
return (i == r.length) ? r : Arrays.copyOf(r, i);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError
("Required array size too large");
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
return (i == len) ? r : Arrays.copyOf(r, i);
}
// Modification Operations

55
src/java.base/share/classes/java/util/ArrayList.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -29,6 +29,7 @@ import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
import jdk.internal.access.SharedSecrets;
import jdk.internal.util.ArraysSupport;
/**
* Resizable-array implementation of the {@code List} interface. Implements
@ -218,14 +219,6 @@ public class ArrayList<E> extends AbstractList<E>
}
}
/**
* The maximum size of array to allocate (unless necessary).
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
@ -234,47 +227,21 @@ public class ArrayList<E> extends AbstractList<E>
* @throws OutOfMemoryError if minCapacity is less than zero
*/
private Object[] grow(int minCapacity) {
return elementData = Arrays.copyOf(elementData,
newCapacity(minCapacity));
int oldCapacity = elementData.length;
if (oldCapacity > 0 || elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
int newCapacity = ArraysSupport.newLength(oldCapacity,
minCapacity - oldCapacity, /* minimum growth */
oldCapacity >> 1 /* preferred growth */);
return elementData = Arrays.copyOf(elementData, newCapacity);
} else {
return elementData = new Object[Math.max(DEFAULT_CAPACITY, minCapacity)];
}
}
private Object[] grow() {
return grow(size + 1);
}
/**
* Returns a capacity at least as large as the given minimum capacity.
* Returns the current capacity increased by 50% if that suffices.
* Will not return a capacity greater than MAX_ARRAY_SIZE unless
* the given minimum capacity is greater than MAX_ARRAY_SIZE.
*
* @param minCapacity the desired minimum capacity
* @throws OutOfMemoryError if minCapacity is less than zero
*/
private int newCapacity(int minCapacity) {
// overflow-conscious code
int oldCapacity = elementData.length;
int newCapacity = oldCapacity + (oldCapacity >> 1);
if (newCapacity - minCapacity <= 0) {
if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
return Math.max(DEFAULT_CAPACITY, minCapacity);
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return minCapacity;
}
return (newCapacity - MAX_ARRAY_SIZE <= 0)
? newCapacity
: hugeCapacity(minCapacity);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE)
? Integer.MAX_VALUE
: MAX_ARRAY_SIZE;
}
/**
* Returns the number of elements in this list.
*

29
src/java.base/share/classes/java/util/PriorityQueue.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -28,6 +28,7 @@ package java.util;
import java.util.function.Consumer;
import java.util.function.Predicate;
import jdk.internal.access.SharedSecrets;
import jdk.internal.util.ArraysSupport;
/**
* An unbounded priority {@linkplain Queue queue} based on a priority heap.
@ -281,14 +282,6 @@ public class PriorityQueue<E> extends AbstractQueue<E>
heapify();
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* Increases the capacity of the array.
*
@ -297,23 +290,13 @@ public class PriorityQueue<E> extends AbstractQueue<E>
private void grow(int minCapacity) {
int oldCapacity = queue.length;
// Double size if small; else grow by 50%
int newCapacity = oldCapacity + ((oldCapacity < 64) ?
(oldCapacity + 2) :
(oldCapacity >> 1));
// overflow-conscious code
if (newCapacity - MAX_ARRAY_SIZE > 0)
newCapacity = hugeCapacity(minCapacity);
int newCapacity = ArraysSupport.newLength(oldCapacity,
minCapacity - oldCapacity, /* minimum growth */
oldCapacity < 64 ? oldCapacity + 2 : oldCapacity >> 1
/* preferred growth */);
queue = Arrays.copyOf(queue, newCapacity);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}
/**
* Inserts the specified element into this priority queue.
*

51
src/java.base/share/classes/java/util/Vector.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -32,6 +32,8 @@ import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
import jdk.internal.util.ArraysSupport;
/**
* The {@code Vector} class implements a growable array of
* objects. Like an array, it contains components that can be
@ -241,14 +243,6 @@ public class Vector<E>
}
}
/**
* The maximum size of array to allocate (unless necessary).
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
@ -257,45 +251,18 @@ public class Vector<E>
* @throws OutOfMemoryError if minCapacity is less than zero
*/
private Object[] grow(int minCapacity) {
return elementData = Arrays.copyOf(elementData,
newCapacity(minCapacity));
int oldCapacity = elementData.length;
int newCapacity = ArraysSupport.newLength(oldCapacity,
minCapacity - oldCapacity, /* minimum growth */
capacityIncrement > 0 ? capacityIncrement : oldCapacity
/* preferred growth */);
return elementData = Arrays.copyOf(elementData, newCapacity);
}
private Object[] grow() {
return grow(elementCount + 1);
}
/**
* Returns a capacity at least as large as the given minimum capacity.
* Will not return a capacity greater than MAX_ARRAY_SIZE unless
* the given minimum capacity is greater than MAX_ARRAY_SIZE.
*
* @param minCapacity the desired minimum capacity
* @throws OutOfMemoryError if minCapacity is less than zero
*/
private int newCapacity(int minCapacity) {
// overflow-conscious code
int oldCapacity = elementData.length;
int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
capacityIncrement : oldCapacity);
if (newCapacity - minCapacity <= 0) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return minCapacity;
}
return (newCapacity - MAX_ARRAY_SIZE <= 0)
? newCapacity
: hugeCapacity(minCapacity);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}
/**
* Sets the size of this vector. If the new size is greater than the
* current size, new {@code null} items are added to the end of

15
src/java.base/share/classes/java/util/regex/Pattern.java
View File

@ -43,6 +43,7 @@ import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.util.ArraysSupport;
/**
* A compiled representation of a regular expression.
@ -2315,13 +2316,15 @@ loop: for(int x=0, offset=0; x<nCodePoints; x++, offset+=len) {
}
}
private void append(int ch, int len) {
if (len >= buffer.length) {
int[] tmp = new int[len+len];
System.arraycopy(buffer, 0, tmp, 0, len);
buffer = tmp;
private void append(int ch, int index) {
int len = buffer.length;
if (index - len >= 0) {
len = ArraysSupport.newLength(len,
1 + index - len, /* minimum growth */
len /* preferred growth */);
buffer = Arrays.copyOf(buffer, len);
}
buffer[len] = ch;
buffer[index] = ch;
}
/**

56
src/java.base/share/classes/jdk/internal/util/ArraysSupport.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -28,7 +28,9 @@ import jdk.internal.HotSpotIntrinsicCandidate;
import jdk.internal.misc.Unsafe;
/**
* Utility methods to find a mismatch between two primitive arrays.
* Utility methods to work with arrays. This includes a set of methods
* to find a mismatch between two primitive arrays. Also included is
* a method to calculate the new length of an array to be reallocated.
*
* <p>Array equality and lexicographical comparison can be built on top of
* array mismatch functionality.
@ -571,4 +573,54 @@ public class ArraysSupport {
return -1;
}
/**
* The maximum length of array to allocate (unless necessary).
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* {@code OutOfMemoryError: Requested array size exceeds VM limit}
*/
public static final int MAX_ARRAY_LENGTH = Integer.MAX_VALUE - 8;
/**
* Calculates a new array length given an array's current length, a preferred
* growth value, and a minimum growth value. If the preferred growth value
* is less than the minimum growth value, the minimum growth value is used in
* its place. If the sum of the current length and the preferred growth
* value does not exceed {@link #MAX_ARRAY_LENGTH}, that sum is returned.
* If the sum of the current length and the minimum growth value does not
* exceed {@code MAX_ARRAY_LENGTH}, then {@code MAX_ARRAY_LENGTH} is returned.
* If the sum does not overflow an int, then {@code Integer.MAX_VALUE} is
* returned. Otherwise, {@code OutOfMemoryError} is thrown.
*
* @param oldLength current length of the array (must be non negative)
* @param minGrowth minimum required growth of the array length (must be
* positive)
* @param prefGrowth preferred growth of the array length (ignored, if less
* then {@code minGrowth})
* @return the new length of the array
* @throws OutOfMemoryError if increasing {@code oldLength} by
* {@code minGrowth} overflows.
*/
public static int newLength(int oldLength, int minGrowth, int prefGrowth) {
// assert oldLength >= 0
// assert minGrowth > 0
int newLength = Math.max(minGrowth, prefGrowth) + oldLength;
if (newLength - MAX_ARRAY_LENGTH <= 0) {
return newLength;
}
return hugeLength(oldLength, minGrowth);
}
private static int hugeLength(int oldLength, int minGrowth) {
int minLength = oldLength + minGrowth;
if (minLength < 0) { // overflow
throw new OutOfMemoryError("Required array length too large");
}
if (minLength <= MAX_ARRAY_LENGTH) {
return MAX_ARRAY_LENGTH;
}
return Integer.MAX_VALUE;
}
}