Mercurial > jdk8-mips64-public > hotspot / file revision
src/share/vm/utilities/intHisto.hpp@c96030fff130
src/share/vm/utilities/intHisto.hpp
Thu, 20 Nov 2008 16:56:09 -0800
- author
- ysr
- date
- Thu, 20 Nov 2008 16:56:09 -0800
- changeset 888
- c96030fff130
- parent 777
- 37f87013dfd8
- child 1907
- c18cbe5936b8
- permissions
- -rw-r--r--
6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa
1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 // This class implements a simple histogram.
27 // A histogram summarizes a series of "measurements", each of which is
28 // assumed (required in this implementation) to have an outcome that is a
29 // non-negative integer. The histogram efficiently maps measurement outcomes
30 // to the number of measurements had that outcome.
32 // To print the results, invoke print() on your Histogram*.
34 // Note: there is already an existing "Histogram" class, in file
35 // histogram.{hpp,cpp}, but to my mind that's not a histogram, it's a table
36 // mapping strings to counts. To be a histogram (IMHO) it needs to map
37 // numbers (in fact, integers) to number of occurrences of that number.
39 // ysr: (i am not sure i agree with the above note.) i suspect we want to have a
40 // histogram template that will map an arbitrary type (with a defined order
41 // relation) to a count.
44 class IntHistogram : public CHeapObj {
45 protected:
46 int _max;
47 int _tot;
48 GrowableArray<int>* _elements;
50 public:
51 // Create a new, empty table. "est" is an estimate of the maximum outcome
52 // that will be added, and "max" is an outcome such that all outcomes at
53 // least that large will be bundled with it.
54 IntHistogram(int est, int max);
55 // Add a measurement with the given outcome to the sequence.
56 void add_entry(int outcome);
57 // Return the number of entries recorded so far with the given outcome.
58 int entries_for_outcome(int outcome);
59 // Return the total number of entries recorded so far.
60 int total_entries() { return _tot; }
61 // Return the number of entries recorded so far with the given outcome as
62 // a fraction of the total number recorded so far.
63 double fraction_for_outcome(int outcome) {
64 return
65 (double)entries_for_outcome(outcome)/
66 (double)total_entries();
67 }
68 // Print the histogram on the given output stream.
69 void print_on(outputStream* st) const;
70 };
