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LUCENE-6292: seed StringHelper better 

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1662141 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Robert Muir 2015-02-25 00:10:21 +00:00
parent d59b1e944a
commit 5a409e6ed4
2 changed files with 28 additions and 11 deletions
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2
lucene/CHANGES.txt
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@ -170,6 +170,8 @@ Other
* LUCENE-6239: Removed RAMUsageEstimator's sun.misc.Unsafe calls.
(Robert Muir, Dawid Weiss, Uwe Schindler)
* LUCENE-6292: Seed StringHelper better. (Robert Muir)
Changes in Runtime Behavior
* LUCENE-6255: PhraseQuery now ignores leading holes and requires that

37
lucene/core/src/java/org/apache/lucene/util/StringHelper.java
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@ -17,7 +17,10 @@ package org.apache.lucene.util;
* limitations under the License.
*/
import java.io.DataInputStream;
import java.math.BigInteger;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.Properties;
@ -253,18 +256,30 @@ public abstract class StringHelper {
x0 = Long.parseLong(prop, 16);
x1 = x0;
} else {
// Randomess from 3 different sources:
x0 = System.nanoTime();
x1 = StringHelper.class.hashCode() << 32;
StringBuilder sb = new StringBuilder();
// Properties can vary across JVM instances:
Properties p = System.getProperties();
for (String s: p.stringPropertyNames()) {
sb.append(s);
sb.append(p.getProperty(s));
// seed from /dev/urandom, if its available
try (DataInputStream is = new DataInputStream(Files.newInputStream(Paths.get("/dev/urandom")))) {
x0 = is.readLong();
x1 = is.readLong();
} catch (Exception unavailable) {
// may not be available on this platform
// fall back to lower quality randomness from 3 different sources:
x0 = System.nanoTime();
x1 = StringHelper.class.hashCode() << 32;
StringBuilder sb = new StringBuilder();
// Properties can vary across JVM instances:
try {
Properties p = System.getProperties();
for (String s: p.stringPropertyNames()) {
sb.append(s);
sb.append(p.getProperty(s));
}
x1 |= sb.toString().hashCode();
} catch (SecurityException notallowed) {
// getting Properties requires wildcard read-write: may not be allowed
x1 |= StringBuffer.class.hashCode();
}
}
x1 |= sb.toString().hashCode();
// TODO: maybe read from /dev/urandom when it's available?
}
// Use a few iterations of xorshift128 to scatter the seed