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https://issues.apache.org/jira/browse/LUCENE-9395?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tony Xu updated LUCENE-9395:
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Description:
At my day job, we use ConstantValuesSource to represent default values or a
constant query-level feature by calling *_DoubleValuesSource.constant_*. I
realized under the hood the _*ConstantValuesSource.getDoubleValues*_ creates a
new _*DoubleValues*_ which simply return the specified value each time it is
called.
Unless I missed something, I don't see a risk of creating one _*DoubleValues*_
as use it as the return value of all _*getDoubleValues**()*_ calls given that
the constant _*DoubleValues*_ doesn't maintain any state.
We can also offer the user flexibilities of how to initialize it.
1) _*DoubleValuesSource.constant(double constant)*_ – we can eagerly initialize
an `DoubleValues` that returns the constant and make it the return value of all
_*getDoubleValues()*_ calls.
2) _*DoubleValuesSource.constant(DoubleSupplier doubleSupplier)*_ – For lazy
evaluation if the constant takes some time to compute and user expects the
returned DVS will not be used in all code path.
was:
At day job, we use ConstantValuesSource to represent default values or a
constant query-level feature by calling *_DoubleValuesSource.constant_*. I
realized under the hood the _*ConstantValuesSource.getDoubleValues*_ creates a
new _*DoubleValues*_ which simply return the specified value each time it is
called.
Unless I missed something, I don't see a risk of creating one _*DoubleValues*_
as use it as the return value of all _*getDoubleValues**()*_ calls given that
the constant _*DoubleValues*_ doesn't maintain any state.
We can also offer the user flexibilities of how to initialize it.
1) _*DoubleValuesSource.constant(double constant)*_ – we can eagerly initialize
an `DoubleValues` that returns the constant and make it the return value of all
_*getDoubleValues()*_ calls.
2) _*DoubleValuesSource.constant(DoubleSupplier doubleSupplier)*_ – For lazy
evaluation if the constant takes some time to compute and user expects the
returned DVS will not be used in all code path.
> ConstantValuesSource creates more than one DoubleValues unnecessarily
> ----------------------------------------------------------------------
>
> Key: LUCENE-9395
> URL: https://issues.apache.org/jira/browse/LUCENE-9395
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/search
> Affects Versions: 8.5.2
> Reporter: Tony Xu
> Priority: Minor
>
> At my day job, we use ConstantValuesSource to represent default values or a
> constant query-level feature by calling *_DoubleValuesSource.constant_*. I
> realized under the hood the _*ConstantValuesSource.getDoubleValues*_ creates
> a new _*DoubleValues*_ which simply return the specified value each time it
> is called.
> Unless I missed something, I don't see a risk of creating one
> _*DoubleValues*_ as use it as the return value of all _*getDoubleValues**()*_
> calls given that the constant _*DoubleValues*_ doesn't maintain any state.
> We can also offer the user flexibilities of how to initialize it.
> 1) _*DoubleValuesSource.constant(double constant)*_ – we can eagerly
> initialize an `DoubleValues` that returns the constant and make it the return
> value of all _*getDoubleValues()*_ calls.
> 2) _*DoubleValuesSource.constant(DoubleSupplier doubleSupplier)*_ – For lazy
> evaluation if the constant takes some time to compute and user expects the
> returned DVS will not be used in all code path.
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