LogDistribution.java revision 91cfa10a8e55050a5103c4b2e83b0bf8d783a7cb
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91cfa10a8e55050a5103c4b2e83b0bf8d783a7cbtomee * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Use is subject to license terms.
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * ident "%Z%%M% %I% %E% SMI"
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * A power-of-two logarithmic frequency distribution aggregated by the
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * DTrace {@code quantize()} action. Aggregated values fall into
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * consecutive ranges, each twice as large as the previous range. Each
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * range, known as a bucket, begins at two to the power of <i>n</i> and
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * ends at one less than the beginning of the next bucket, two to the
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * power of <i>n + 1</i>. The zero bucket is the degenerate case and
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * holds the frequency of the base value zero. For example, the first
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * bucket after 0 starts at 1 (2 to the power of 0) and ends at 1 (one
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * less than 2 to the power of 1). The next bucket starts at 2 (2 to
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * the power of 1) and ends at 3 (one less than 2 to the power of 2).
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Each bucket frequency is incremented for each aggregated value that
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * falls into its range. Buckets are typically identified by their
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * lower bound: 1, 2, 4, 8, etc. Mirroring these are buckets with
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * negative ranges: -1, -2, -4, -8, etc. The range of an entire {@code
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * LogDistribution} is (<code>-2<sup>63</sup> ..
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * 2<sup>63</sup></code>).
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Immutable. Supports persistence using {@link java.beans.XMLEncoder}.
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * @see LinearDistribution
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * @see Aggregation
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * @author Tom Erickson
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomeepublic final class LogDistribution extends Distribution
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee static final long serialVersionUID = -1279719751212721961L;
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee BeanInfo info = Introspector.getBeanInfo(LogDistribution.class);
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee d.setValue("persistenceDelegate", persistenceDelegate);
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Called by native C code
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee super(0, 2, buckets); // initializes using base 0, power of 2
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Creates a logarithmic distribution with the given frequencies.
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Supports XML persistence.
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * @param frequencies list of frequencies in bucket ranges bounded
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * by consucutive powers of two
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * @throws NullPointerException if {@code frequencies} is {@code
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * @throws IllegalArgumentException if any bucket does not have the
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * expected range (bounded by consecutive powers of two)
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Gets a two element array: the first elelemt is the range minimum
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * (inclusive), the second element is the range maximum (inclusive).
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee getBucketRange(int i, int len, long base, long constant)
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee long max = (LocalConsumer._quantizeBucket(i + 1) - 1);
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee total += ((double)bucket.getFrequency() * (double)bucket.getMin());
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee private long
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * Compares the {@code double} values of {@link #getValue()} for
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * overall magnitude, and if those are equal, compares the
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * frequencies at the zero bucket (the bucket whose range has a
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee * minimum and maximum value of zero).
fb3fb4f3d76d55b64440afd0af72775dfad3bd1dtomee private void
91cfa10a8e55050a5103c4b2e83b0bf8d783a7cbtomee } catch (Exception e) {