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提交 33a080ef authored 作者: Andrei Tokar's avatar Andrei Tokar
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CacheLongKeyLIRS: some re-factoring, 

make high water mark for non-resident queue size configurable
上级 dc6b54b1
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正在显示 包含 75 行增加 和 99 行删除
h2/src/main/org/h2/mvstore/cache/CacheLongKeyLIRS.java
浏览文件 @ 33a080ef
......@@ -57,6 +57,7 @@ public class CacheLongKeyLIRS<V> {
private final int segmentMask;
private final int stackMoveDistance;
private final int nonResidentQueueSize;
private final int nonResidentQueueSizeHigh;
/**
* Create a new cache with the given memory size.
......@@ -67,6 +68,7 @@ public class CacheLongKeyLIRS<V> {
public CacheLongKeyLIRS(Config config) {
setMaxMemory(config.maxMemory);
this.nonResidentQueueSize = config.nonResidentQueueSize;
this.nonResidentQueueSizeHigh = config.nonResidentQueueSizeHigh;
DataUtils.checkArgument(
Integer.bitCount(config.segmentCount) == 1,
"The segment count must be a power of 2, is {0}", config.segmentCount);
......@@ -85,8 +87,8 @@ public class CacheLongKeyLIRS<V> {
public void clear() {
long max = getMaxItemSize();
for (int i = 0; i < segmentCount; i++) {
segments[i] = new Segment<>(
max, stackMoveDistance, 8, nonResidentQueueSize);
segments[i] = new Segment<>(max, stackMoveDistance, 8, nonResidentQueueSize,
nonResidentQueueSizeHigh);
}
}
......@@ -111,8 +113,8 @@ public class CacheLongKeyLIRS<V> {
* @return true if there is a resident entry
*/
public boolean containsKey(long key) {
int hash = getHash(key);
return getSegment(hash).containsKey(key, hash);
Entry<V> e = find(key);
return e != null && e.value != null;
}
/**
......@@ -149,6 +151,10 @@ public class CacheLongKeyLIRS<V> {
* @return the old value, or null if there was no resident entry
*/
public V put(long key, V value, int memory) {
if (value == null) {
throw DataUtils.newIllegalArgumentException(
"The value may not be null");
}
int hash = getHash(key);
int segmentIndex = getSegmentIndex(hash);
Segment<V> s = segments[segmentIndex];
......@@ -215,8 +221,8 @@ public class CacheLongKeyLIRS<V> {
* @return the memory, or 0 if there is no resident entry
*/
public int getMemory(long key) {
int hash = getHash(key);
return getSegment(hash).getMemory(key, hash);
Entry<V> e = find(key);
return e == null ? 0 : e.getMemory();
}
/**
......@@ -229,7 +235,9 @@ public class CacheLongKeyLIRS<V> {
*/
public V get(long key) {
int hash = getHash(key);
return getSegment(hash).get(key, hash);
Segment<V> s = getSegment(hash);
Entry<V> e = s.find(key, hash);
return s.get(e);
}
private Segment<V> getSegment(int hash) {
......@@ -553,11 +561,17 @@ public class CacheLongKeyLIRS<V> {
private final int mask;
/**
* The number of entries in the non-resident queue, as a factor of the
* number of entries in the map.
* Low watermark for the number of entries in the non-resident queue,
* as a factor of the number of entries in the map.
*/
private final int nonResidentQueueSize;
/**
* High watermark for the number of entries in the non-resident queue,
* as a factor of the number of entries in the map.
*/
private final int nonResidentQueueSizeHigh;
/**
* The stack of recently referenced elements. This includes all hot
* entries, and the recently referenced cold entries. Resident cold
......@@ -594,18 +608,19 @@ public class CacheLongKeyLIRS<V> {
/**
* Create a new cache segment.
*
* @param maxMemory the maximum memory to use
* @param maxMemory the maximum memory to use
* @param stackMoveDistance the number of other entries to be moved to
* the top of the stack before moving an entry to the top
* @param len the number of hash table buckets (must be a power of 2)
* @param nonResidentQueueSize the non-resident queue size factor
* @param nonResidentQueueSize the non-resident queue size low watermark factor
* @param nonResidentQueueSizeHigh the non-resident queue size high watermark factor
*/
Segment(long maxMemory, int stackMoveDistance, int len,
int nonResidentQueueSize) {
int nonResidentQueueSize, int nonResidentQueueSizeHigh) {
setMaxMemory(maxMemory);
this.stackMoveDistance = stackMoveDistance;
this.nonResidentQueueSize = nonResidentQueueSize;
this.nonResidentQueueSizeHigh = nonResidentQueueSizeHigh;
// the bit mask has all bits set
mask = len - 1;
......@@ -632,12 +647,13 @@ public class CacheLongKeyLIRS<V> {
* @param len the number of hash table buckets (must be a power of 2)
*/
Segment(Segment<V> old, int len) {
this(old.maxMemory, old.stackMoveDistance, len, old.nonResidentQueueSize);
this(old.maxMemory, old.stackMoveDistance, len,
old.nonResidentQueueSize, old.nonResidentQueueSizeHigh);
hits = old.hits;
misses = old.misses;
Entry<V> s = old.stack.stackPrev;
while (s != old.stack) {
Entry<V> e = copy(s);
Entry<V> e = new Entry<>(s);
addToMap(e);
addToStack(e);
s = s.stackPrev;
......@@ -646,7 +662,7 @@ public class CacheLongKeyLIRS<V> {
while (s != old.queue) {
Entry<V> e = find(s.key, getHash(s.key));
if (e == null) {
e = copy(s);
e = new Entry<>(s);
addToMap(e);
}
addToQueue(queue, e);
......@@ -656,7 +672,7 @@ public class CacheLongKeyLIRS<V> {
while (s != old.queue2) {
Entry<V> e = find(s.key, getHash(s.key));
if (e == null) {
e = copy(s);
e = new Entry<>(s);
addToMap(e);
}
addToQueue(queue2, e);
......@@ -690,54 +706,25 @@ public class CacheLongKeyLIRS<V> {
mapSize++;
}
private static <V> Entry<V> copy(Entry<V> old) {
Entry<V> e = new Entry<>(old.memory);
e.key = old.key;
e.value = old.value;
e.reference = old.reference;
e.topMove = old.topMove;
return e;
}
/**
* Get the memory used for the given key.
* Get the value from the given entry.
* This method adjusts the internal state of the cache sometimes,
* to ensure commonly used entries stay in the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @return the memory, or 0 if there is no resident entry
*/
int getMemory(long key, int hash) {
Entry<V> e = find(key, hash);
return e == null ? 0 : e.getMemory();
}
/**
* Get the value for the given key if the entry is cached. This method
* adjusts the internal state of the cache sometimes, to ensure commonly
* used entries stay in the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @param e the entry
* @return the value, or null if there is no resident entry
*/
V get(long key, int hash) {
Entry<V> e = find(key, hash);
synchronized (this) {
if (e == null) {
// the entry was not found
misses++;
return null;
}
V value = e.getValue();
if (value == null) {
// it was a non-resident entry
misses++;
return null;
}
synchronized V get(Entry<V> e) {
V value = e == null ? null : e.getValue();
if (value == null) {
// the entry was not found
// or it was a non-resident entry
misses++;
} else {
access(e);
hits++;
return value;
}
return value;
}
/**
......@@ -749,8 +736,7 @@ public class CacheLongKeyLIRS<V> {
private void access(Entry<V> e) {
if (e.isHot()) {
if (e != stack.stackNext && e.stackNext != null) {
if (stackMoveDistance == 0 ||
stackMoveCounter - e.topMove > stackMoveDistance) {
if (stackMoveCounter - e.topMove > stackMoveDistance) {
// move a hot entry to the top of the stack
// unless it is already there
boolean wasEnd = e == stack.stackPrev;
......@@ -806,10 +792,6 @@ public class CacheLongKeyLIRS<V> {
* @return the old value, or null if there was no resident entry
*/
synchronized V put(long key, int hash, V value, int memory) {
if (value == null) {
throw DataUtils.newIllegalArgumentException(
"The value may not be null");
}
Entry<V> e = find(key, hash);
boolean existed = e != null;
V old = null;
......@@ -821,9 +803,7 @@ public class CacheLongKeyLIRS<V> {
// the new entry is too big to fit
return old;
}
e = new Entry<>(memory);
e.key = key;
e.value = value;
e = new Entry<>(key, value, memory);
int index = hash & mask;
e.mapNext = entries[index];
entries[index] = e;
......@@ -930,19 +910,16 @@ public class CacheLongKeyLIRS<V> {
}
void trimNonResidentQueue() {
Entry<V> e;
int maxQueue2Size = 4 * nonResidentQueueSize * (mapSize - queue2Size);
int residentCount = mapSize - queue2Size;
int maxQueue2SizeHigh = nonResidentQueueSizeHigh * residentCount;
int maxQueue2Size = nonResidentQueueSize * residentCount;
while (queue2Size > maxQueue2Size) {
e = queue2.queuePrev;
int hash = getHash(e.key);
remove(e.key, hash);
}
maxQueue2Size >>= 2;
while (queue2Size > maxQueue2Size) {
e = queue2.queuePrev;
WeakReference<V> reference = e.reference;
if (reference != null && reference.get() != null) {
break; // stop trimming if entry holds a value
Entry<V> e = queue2.queuePrev;
if (queue2Size <= maxQueue2SizeHigh) {
WeakReference<V> reference = e.reference;
if (reference != null && reference.get() != null) {
break; // stop trimming if entry holds a value
}
}
int hash = getHash(e.key);
remove(e.key, hash);
......@@ -1075,19 +1052,6 @@ public class CacheLongKeyLIRS<V> {
return keys;
}
/**
* Check whether there is a resident entry for the given key. This
* method does not adjust the internal state of the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @return true if there is a resident entry
*/
boolean containsKey(long key, int hash) {
Entry<V> e = find(key, hash);
return e != null && e.value != null;
}
/**
* Get the set of keys for resident entries.
*
......@@ -1131,7 +1095,7 @@ public class CacheLongKeyLIRS<V> {
/**
* The key.
*/
long key;
final long key;
/**
* The value. Set to null for non-resident-cold entries.
......@@ -1180,12 +1144,20 @@ public class CacheLongKeyLIRS<V> {
Entry<V> mapNext;
public Entry() {
this(0);
Entry() {
this(0L, null, 0);
}
public Entry(int memory) {
Entry(long key, V value, int memory) {
this.key = key;
this.memory = memory;
this.value = value;
}
Entry(Entry<V> old) {
this(old.key, old.value, old.memory);
this.reference = old.reference;
this.topMove = old.topMove;
}
/**
......@@ -1228,11 +1200,15 @@ public class CacheLongKeyLIRS<V> {
public int stackMoveDistance = 32;
/**
* The number of entries in the non-resident queue, as a factor of the
* number of all other entries in the map.
* Low water mark for the number of entries in the non-resident queue,
* as a factor of the number of all other entries in the map.
*/
public final int nonResidentQueueSize = 3;
/**
* High watermark for the number of entries in the non-resident queue,
* as a factor of the number of all other entries in the map
*/
public final int nonResidentQueueSizeHigh = 12;
}
}
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