archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-08-27 06:45:07 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8270416: Enhance construction of Identity maps

Browse source 
Reviewed-by: dfuchs, chegar, rhalade, ahgross, smarks, robm
This commit is contained in:
Julia Boes 2021-08-25 11:41:26 +00:00 • committed by Henry Jen
parent 6b6f829b46
commit 5832a34404
3 changed files with 41 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

37
src/java.base/share/classes/java/util/Hashtable.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2021, 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
@ -1254,7 +1254,7 @@ public class Hashtable<K,V>
* Reconstitute the Hashtable from a stream (i.e., deserialize it).
*/
@java.io.Serial
private void readObject(java.io.ObjectInputStream s)
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException {
readHashtable(s);
}
@ -1263,14 +1263,16 @@ public class Hashtable<K,V>
* Perform deserialization of the Hashtable from an ObjectInputStream.
* The Properties class overrides this method.
*/
void readHashtable(java.io.ObjectInputStream s)
void readHashtable(ObjectInputStream s)
throws IOException, ClassNotFoundException {
// Read in the threshold and loadFactor
s.defaultReadObject();
// Validate loadFactor (ignore threshold - it will be re-computed)
if (loadFactor <= 0 || Float.isNaN(loadFactor))
throw new StreamCorruptedException("Illegal Load: " + loadFactor);
ObjectInputStream.GetField fields = s.readFields();
// Read and validate loadFactor (ignore threshold - it will be re-computed)
float lf = fields.get("loadFactor", 0.75f);
if (lf <= 0 || Float.isNaN(lf))
throw new StreamCorruptedException("Illegal load factor: " + lf);
lf = Math.min(Math.max(0.25f, lf), 4.0f);
// Read the original length of the array and number of elements
int origlength = s.readInt();
@ -1282,13 +1284,13 @@ public class Hashtable<K,V>
// Clamp original length to be more than elements / loadFactor
// (this is the invariant enforced with auto-growth)
origlength = Math.max(origlength, (int)(elements / loadFactor) + 1);
origlength = Math.max(origlength, (int)(elements / lf) + 1);
// Compute new length with a bit of room 5% + 3 to grow but
// no larger than the clamped original length. Make the length
// odd if it's large enough, this helps distribute the entries.
// Guard against the length ending up zero, that's not valid.
int length = (int)((elements + elements / 20) / loadFactor) + 3;
int length = (int)((elements + elements / 20) / lf) + 3;
if (length > elements && (length & 1) == 0)
length--;
length = Math.min(length, origlength);
@ -1300,8 +1302,9 @@ public class Hashtable<K,V>
// Check Map.Entry[].class since it's the nearest public type to
// what we're actually creating.
SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Map.Entry[].class, length);
Hashtable.UnsafeHolder.putLoadFactor(this, lf);
table = new Entry<?,?>[length];
threshold = (int)Math.min(length * loadFactor, MAX_ARRAY_SIZE + 1);
threshold = (int)Math.min(length * lf, MAX_ARRAY_SIZE + 1);
count = 0;
// Read the number of elements and then all the key/value objects
@ -1315,6 +1318,18 @@ public class Hashtable<K,V>
}
}
// Support for resetting final field during deserializing
private static final class UnsafeHolder {
private UnsafeHolder() { throw new InternalError(); }
private static final jdk.internal.misc.Unsafe unsafe
= jdk.internal.misc.Unsafe.getUnsafe();
private static final long LF_OFFSET
= unsafe.objectFieldOffset(Hashtable.class, "loadFactor");
static void putLoadFactor(Hashtable<?, ?> table, float lf) {
unsafe.putFloat(table, LF_OFFSET, lf);
}
}
/**
* The put method used by readObject. This is provided because put
* is overridable and should not be called in readObject since the