tmf: Implement a cache of TmfStateValue
This patch provides a caching implementation in the TmfStateValue factory.
TmfStateValue are immutable and can be shared.
By changing the size of the cache, we observed this cache ratio.
size hit total ratio
2 count: 7369956/15551000 [0.4739216770625683]
4 count: 11742495/15530000 [0.7561168705730843]
8 count: 14622383/15545000 [0.9406486330009649]
16 count: 15007948/15552000 [0.965017232510288]
32 count: 15372868/15543000 [0.9890541079585665]
64 count: 15432506/15523000 [0.9941703279005347]
128 count: 15488720/15534000 [0.9970851036436205]
Which seems to be an excellent ratio for a really small cache.
The same idea is used with Integer.valueOf(...).
Change-Id: I3701b900035d83b19531101ab60e7292899d8cef
Signed-off-by: Etienne Bergeron <etienne.bergeron@gmail.com>
Reviewed-on: https://git.eclipse.org/r/19030
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
IP-Clean: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
diff --git a/lttng/org.eclipse.linuxtools.tmf.core/src/org/eclipse/linuxtools/tmf/core/statevalue/TmfStateValue.java b/lttng/org.eclipse.linuxtools.tmf.core/src/org/eclipse/linuxtools/tmf/core/statevalue/TmfStateValue.java
index 6330cae..acb17df 100644
--- a/lttng/org.eclipse.linuxtools.tmf.core/src/org/eclipse/linuxtools/tmf/core/statevalue/TmfStateValue.java
+++ b/lttng/org.eclipse.linuxtools.tmf.core/src/org/eclipse/linuxtools/tmf/core/statevalue/TmfStateValue.java
@@ -29,6 +29,19 @@
* @author Alexandre Montplaisir
*/
public abstract class TmfStateValue implements ITmfStateValue {
+
+ // ------------------------------------------------------------------------
+ // State value caches (sizes must be powers of 2)
+ // ------------------------------------------------------------------------
+
+ private static final int INT_CACHE_SIZE = 128;
+ private static final int LONG_CACHE_SIZE = 128;
+ private static final int DOUBLE_CACHE_SIZE = 128;
+
+ private static final IntegerStateValue intCache[] = new IntegerStateValue[INT_CACHE_SIZE];
+ private static final LongStateValue longCache[] = new LongStateValue[LONG_CACHE_SIZE];
+ private static final DoubleStateValue doubleCache[] = new DoubleStateValue[DOUBLE_CACHE_SIZE];
+
// ------------------------------------------------------------------------
// Factory methods to instantiate new state values
// ------------------------------------------------------------------------
@@ -56,7 +69,17 @@
* @return The newly-created TmfStateValue object
*/
public static TmfStateValue newValueInt(int intValue) {
- return new IntegerStateValue(intValue);
+ /* Lookup in cache for the existence of the same value. */
+ int offset = intValue & (INT_CACHE_SIZE - 1);
+ IntegerStateValue cached = intCache[offset];
+ if (cached != null && cached.unboxInt() == intValue) {
+ return cached;
+ }
+
+ /* Not in cache, create a new value and cache it. */
+ IntegerStateValue newValue = new IntegerStateValue(intValue);
+ intCache[offset] = newValue;
+ return newValue;
}
/**
@@ -68,7 +91,17 @@
* @since 2.0
*/
public static TmfStateValue newValueLong(long longValue) {
- return new LongStateValue(longValue);
+ /* Lookup in cache for the existence of the same value. */
+ int offset = (int) longValue & (LONG_CACHE_SIZE - 1);
+ LongStateValue cached = longCache[offset];
+ if (cached != null && cached.unboxLong() == longValue) {
+ return cached;
+ }
+
+ /* Not in cache, create a new value and cache it. */
+ LongStateValue newValue = new LongStateValue(longValue);
+ longCache[offset] = newValue;
+ return newValue;
}
/**
@@ -79,7 +112,22 @@
* @return The newly-created TmfStateValue object
*/
public static TmfStateValue newValueDouble(double value) {
- return new DoubleStateValue(value);
+ /* Lookup in cache for the existence of the same value. */
+ int offset = (int) Double.doubleToLongBits(value) & (DOUBLE_CACHE_SIZE - 1);
+ DoubleStateValue cached = doubleCache[offset];
+
+ /*
+ * We're using Double.compare() instead of .equals(), because .compare()
+ * works when both values are Double.NaN.
+ */
+ if (cached != null && Double.compare(cached.unboxDouble(), value) == 0) {
+ return cached;
+ }
+
+ /* Not in cache, create a new value and cache it. */
+ DoubleStateValue newValue = new DoubleStateValue(value);
+ doubleCache[offset] = newValue;
+ return newValue;
}
/**
