Hello Rob,
On 27/11/24 12:52 am, Rob Spoor wrote:
The comment provided in `store(Writer, String)` is added in addition
to the date comment:
if (comments != null) {
writeComments(bw, comments);
}
writeDateComment(bw);
The system property can be used to replace the date with a constant,
but a) it's not possible to omit it because an empty property value
still leads to the date being written,
The caller of Properties.store(Writer, String), if they pass null to the
comments parameter, then an attempt will be made to write out a comment.
The value for that comment will come from a system property named
java.properties.date. The value can be any free form text
https://docs.oracle.com/en/java/javase/23/docs/api/java.base/java/util/Properties.html#java.properties.date.
A blank (not empty) value can be set for that system property and that
will write out just whitespace as the comment line. Here's a test which
shows that usage
https://github.com/openjdk/jdk/blob/master/test/jdk/java/util/Properties/StoreReproducibilityTest.java#L106.
b) it's a global setting, not something to apply to a single
Properties instance, and c) you need to set it when starting the JVM
because its value is cached (tested in jshell).
Perhaps adding an enum Properties.StoreProperties with single constant
OMIT_DATE can be used:
The change to support reproducibility for Properties.store() went
through several rounds of discussions, including proposed overloads to
methods, before we settled on the current implementation. Some of those
discussions are here:
https://mail.openjdk.org/pipermail/core-libs-dev/2021-August/080758.html
https://mail.openjdk.org/pipermail/core-libs-dev/2021-September/081113.html
https://github.com/openjdk/jdk/pull/5372
-Jaikiran
// overload, not replacement; similar for OutputStream
public void store(Writer writer, String comments,
StoreProperties... properties)
This can then be called as props.store(writer, null,
Properties.StoreProperties.OMIT_DATE).
Rob
On 26/11/2024 00:23, Roger Riggs wrote:
Hi Rafael,
You might have missed the update added by JDK-8231640 <https://
bugs.openjdk.org/browse/JDK-8231640> Canonical property storage
The comment string can be provided either by a separate method
`store(Writer, String)` or by a system property.
Regards, Roger
On 11/25/24 4:53 PM, Rafael Winterhalter wrote:
Hello,
I find the java.util.Properties class to be quite convenient when
writing minor collections of key-values. One unfortunate implication
of the store method is that it always contains a comment line with
the current date. The comment is never deserialized when loading the
file, but the file hash is of course always changed, even if the
content is identical at a later time. This can have unfortunate
implications when the file hash is relevant to some form of cashing
or validation mechanism.
Would it be a good idea to add an overload that allows disabling the
date comment? This would only require minimal code changes and the
storage format would become reproducible. The key-values are already
sorted by their key. The date can be fixed by a system property, but
this is not always possible to define if the writer is not in
control of the command line. Right now I have to reimplement the
Properties::store method only to exclude this line.
Thanks for your consideration and opinion,
Rafael
