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8383172: Create AbstractLRUReferencePolicy base class

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Reviewed-by: ayang, jsikstro
This commit is contained in:
Axel Boldt-Christmas 2026-05-07 13:05:42 +00:00
parent 253df3a580
commit a6d763ac87
2 changed files with 27 additions and 48 deletions
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43
src/hotspot/share/gc/shared/referencePolicy.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2026, 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
@ -28,21 +28,17 @@
#include "gc/shared/referencePolicy.hpp"
#include "memory/universe.hpp"
#include "runtime/globals.hpp"
#include "utilities/integerCast.hpp"
LRUCurrentHeapPolicy::LRUCurrentHeapPolicy() {
setup();
}
// Capture state (of-the-VM) information needed to evaluate the policy
void LRUCurrentHeapPolicy::setup() {
_max_interval = (Universe::heap()->free_at_last_gc() / M) * SoftRefLRUPolicyMSPerMB;
assert(_max_interval >= 0,"Sanity check");
void AbstractLRUReferencePolicy::set_max_interval(jlong max_interval) {
assert(max_interval >= 0, "Sanity check");
_max_interval = max_interval;
}
// The oop passed in is the SoftReference object, and not
// the object the SoftReference points to.
bool LRUCurrentHeapPolicy::should_clear_reference(oop p,
jlong timestamp_clock) {
bool AbstractLRUReferencePolicy::should_clear_reference(oop p, jlong timestamp_clock) {
assert(_max_interval >= 0, "Forgot to call setup");
jlong interval = timestamp_clock - java_lang_ref_SoftReference::timestamp(p);
assert(interval >= 0, "Sanity check");
@ -54,10 +50,9 @@ bool LRUCurrentHeapPolicy::should_clear_reference(oop p,
return true;
}
/////////////////////// MaxHeap //////////////////////
LRUMaxHeapPolicy::LRUMaxHeapPolicy() {
setup();
// Capture state (of-the-VM) information needed to evaluate the policy
void LRUCurrentHeapPolicy::setup() {
set_max_interval(integer_cast<jlong>(Universe::heap()->free_at_last_gc() / M) * SoftRefLRUPolicyMSPerMB);
}
// Capture state (of-the-VM) information needed to evaluate the policy
@ -66,21 +61,5 @@ void LRUMaxHeapPolicy::setup() {
max_heap -= Universe::heap()->used_at_last_gc();
max_heap /= M;
_max_interval = max_heap * SoftRefLRUPolicyMSPerMB;
assert(_max_interval >= 0,"Sanity check");
}
// The oop passed in is the SoftReference object, and not
// the object the SoftReference points to.
bool LRUMaxHeapPolicy::should_clear_reference(oop p,
jlong timestamp_clock) {
jlong interval = timestamp_clock - java_lang_ref_SoftReference::timestamp(p);
assert(interval >= 0, "Sanity check");
// The interval will be zero if the ref was accessed since the last scavenge/gc.
if(interval <= _max_interval) {
return false;
}
return true;
set_max_interval(integer_cast<jlong>(max_heap) * SoftRefLRUPolicyMSPerMB);
}

32
src/hotspot/share/gc/shared/referencePolicy.hpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2026, 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
@ -56,28 +56,28 @@ class AlwaysClearPolicy : public ReferencePolicy {
}
};
class LRUCurrentHeapPolicy : public ReferencePolicy {
class AbstractLRUReferencePolicy : public ReferencePolicy {
private:
jlong _max_interval;
jlong _max_interval = -1;
protected:
void set_max_interval(jlong max_interval);
public:
LRUCurrentHeapPolicy();
// Capture state (of-the-VM) information needed to evaluate the policy
void setup();
virtual bool should_clear_reference(oop p, jlong timestamp_clock);
bool should_clear_reference(oop p, jlong timestamp_clock) final;
void setup() override = 0;
};
class LRUMaxHeapPolicy : public ReferencePolicy {
private:
jlong _max_interval;
class LRUCurrentHeapPolicy : public AbstractLRUReferencePolicy {
public:
LRUMaxHeapPolicy();
// Capture state (of-the-VM) information needed to evaluate the policy
void setup();
virtual bool should_clear_reference(oop p, jlong timestamp_clock);
void setup() final;
};
class LRUMaxHeapPolicy : public AbstractLRUReferencePolicy {
public:
// Capture state (of-the-VM) information needed to evaluate the policy
void setup() final;
};
#endif // SHARE_GC_SHARED_REFERENCEPOLICY_HPP