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8292983: ModuleReferenceImpl.computeHash should record algorithm for cache checks

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Reviewed-by: alanb, mchung, jpai
This commit is contained in:
Aleksey Shipilev 2022-08-29 05:58:41 +00:00
parent 99cab6a68e
commit a476ec5c81
1 changed files with 16 additions and 9 deletions
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25
src/java.base/share/classes/jdk/internal/module/ModuleReferenceImpl.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2016, 2022, 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
@ -62,8 +62,11 @@ public class ModuleReferenceImpl extends ModuleReference {
// ModuleResolution flags
private final ModuleResolution moduleResolution;
// cached hash of this module to avoid needing to compute it many times
private byte[] cachedHash;
// Single-slot cache of this module's hash to avoid needing to compute
// it many times. For correctness under concurrent updates, we need to
// wrap the fields updated at the same time with a record.
private record CachedHash(byte[] hash, String algorithm) {}
private CachedHash cachedHash;
/**
* Constructs a new instance of this class.
@ -139,13 +142,17 @@ public class ModuleReferenceImpl extends ModuleReference {
* @throws java.io.UncheckedIOException if an I/O error occurs
*/
public byte[] computeHash(String algorithm) {
byte[] result = cachedHash;
if (result != null)
return result;
if (hasher == null)
CachedHash ch = cachedHash;
if (ch != null && ch.algorithm().equals(algorithm)) {
return ch.hash();
}
if (hasher == null) {
return null;
cachedHash = result = hasher.generate(algorithm);
return result;
}
byte[] hash = hasher.generate(algorithm);
cachedHash = new CachedHash(hash, algorithm);
return hash;
}
@Override