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From "Shad Storhaug (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENENET-602) Error using Lucene.Net.Facet 4.8.0-beta00005 with Xamarin.iOS
Date Thu, 08 Aug 2019 01:08:00 GMT

    [ https://issues.apache.org/jira/browse/LUCENENET-602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16902578#comment-16902578
] 

Shad Storhaug commented on LUCENENET-602:
-----------------------------------------

Come to think of it, the primary reason why LurchTable was chosen was not for thread safety,
but for performance (it's all coming back to me now)....[https://apache.markmail.org/search/?q=lucenenet+lurchtable#query:lucenenet%20lurchtable+page:1+mid:wtuyqd3sfre6532s+state:results|https://apache.markmail.org/search/?q=lucenenet+lurchtable#query:lucenenet%20lurchtable+page:1+mid:wtuyqd3sfre6532s+state:results].
We had another implementation previously that looks a lot like the one you linked to (with
lots of lock statements) and we had some complaints about how it performed. I would rather
try to fix it so it works with Xamarin.iOS than to replace it, if possible. 


{quote}At the link [https://docs.microsoft.com/it-it/xamarin/ios/internals/limitations] ,
I found the problem cause (I suppose...):
{quote}
{quote}Value types as Dictionary Keys Using a value type as a Dictionary<TKey, TValue>
key is problematic, as the default Dictionary constructor attempts to use EqualityComparer<TKey>.Default.
EqualityComparer<TKey>.Default, in turn, attempts to use Reflection to instantiate a
new type which implements the IEqualityComparer<TKey> interface. This works for reference
types (as the reflection+create a new type step is skipped), but for value types it crashes
and burns rather quickly once you attempt to use it on the device. Workaround: Manually implement
the IEqualityComparer<TKey> interface in a new type and provide an instance of that
type to the Dictionary<TKey, TValue> (IEqualityComparer<TKey>) constructor.
{quote}
 

Just out of curiosity, what happens if you provide a custom EqualityComparer instead of falling
back to {{EqualityComparer<TKey>.Default}}? Do note that LurchTable seems to have many
hard coded references to {{EqualityComparer<TKey>.Default}}, it doesn't consistently
use the passed in comparer argument everywhere.

I tried that before, but without any way to see how/why it is failing, it is like shooting
in the dark. It would be helpful if you could provide a fix that works.

One other possibility is to wrap your value type keys inside of reference types and use those
in the declaration of LurchTable. For example:

{code:c#}
// This is pseudo-code - you will probably need to fix it up to compile
private class ValueTypeRef<TKey> //where TKey: struct
{
	public TKey Value { get; set }
	
	public override int GetHashCode()
	{
	    return Value?.GetHashCode();
	}
	
	public override bool Equals(object other)
	{
	    return Value?.Equals(other);
	}
}

cache = new LurchTable<ValueTypeRef<TKey>, TValue>(LurchTableOrder.Access, limit,
comparer);

// and change the rest of the class so it gets/sets the value from/to ValueTypeRef and only
exposes the value type externally...
{code}




> Error using Lucene.Net.Facet 4.8.0-beta00005  with Xamarin.iOS
> --------------------------------------------------------------
>
>                 Key: LUCENENET-602
>                 URL: https://issues.apache.org/jira/browse/LUCENENET-602
>             Project: Lucene.Net
>          Issue Type: Bug
>          Components: Lucene.Net.Facet
>    Affects Versions: Lucene.Net 4.8.0
>         Environment: Xamarin Forms 3.0.0.561731
> Ios 10.3.3 and Higher
> Lucene.Net.Facet 4.8.0-beta00005
>            Reporter: Enrico Caltran
>            Priority: Blocker
>              Labels: AOT, Xamarin.iOS, lucene.net.facet
>             Fix For: Lucene.Net 4.8.0
>
>         Attachments: AppTestLucene.zip, image-2019-08-08-02-26-40-582.png
>
>   Original Estimate: 120h
>  Remaining Estimate: 120h
>
> I'm using Lucene.Net.Facet 4.8.0-beta00005 in a big Xamarin project.
> +With Xamarin.Android and Xamarin.UWP it's all right.+
> *+But With Xamarin.iOS on device (Ipad)+*, i'm receiving this error:
>  _Attempting to JIT compile method 'Lucene.Net.Support.LurchTable2&lt;Lucene.Net.Facet.Taxonomy.FacetLabel,
Lucene.Net.Facet.Taxonomy.Directory.DirectoryTaxonomyReader/Int32Class&gt;:InternalInsert&lt;Lucene.Net.Support.LurchTable2/Add2Info<Lucene.Net.Facet.Taxonomy.FacetLabel,
Lucene.Net.Facet.Taxonomy.Directory.DirectoryTaxonomyReader/Int32Class>> (int,Lucene.Net.Facet.Taxonomy.FacetLabel,int&,Lucene.Net.Support.LurchTable`2/Add2Info<Lucene.Net.Facet.Taxonomy.FacetLabel,
Lucene.Net.Facet.Taxonomy.Directory.DirectoryTaxonomyReader/Int32Class>&)' while running
in aot-only mode. See [https://developer.xamarin.com/guides/ios/advanced_topics/limitations/]
for more information._
> _{color:#d04437}at Lucene.Net.Support.LurchTable2[TKey,TValue].Insert[T] (TKey key, T&amp;
value) &lt;0x2570f48 + 0x000e0&gt; in &lt;063e095c95d945a4ace32ab83d1227eb#2ae0fea9ea4eacaef83bf2e9713bb8ea&gt;:0
at (wrapper unknown) System.Object.gsharedvt_in() at Lucene.Net.Support.LurchTable2[TKey,TValue].AddOrUpdate
(TKey key, TValue addValue, Lucene.Net.Support.KeyValueUpdate2[TKey,TValue] fnUpdate) &lt;0x232824c
+ 0x0013b&gt; in &lt;063e095c95d945a4ace32ab83d1227eb#2ae0fea9ea4eacaef83bf2e9713bb8ea&gt;:0
at Lucene.Net.Facet.Taxonomy.LRUHashMap2[TKey,TValue].Put (TKey key, TValue value) <0x2c487f8
+ 0x0015b> in <79d3a7b905954d0993025c09c5d087ce#2ae0fea9ea4eacaef83bf2e9713bb8ea>:0
at Lucene.Net.Facet.Taxonomy.Directory.DirectoryTaxonomyReader.GetOrdinal (Lucene.Net.Facet.Taxonomy.FacetLabel
cp) <0x2c51970 + 0x0019b> in <79d3a7b905954d0993025c09c5d087ce#2ae0fea9ea4eacaef83bf2e9713bb8ea>:0
at Lucene.Net.Facet.Taxonomy.Int32TaxonomyFacets.GetTopChildren{color} (System.Int32 topN,
System.String dim, System.String[] path) <0x2c481dc + 0x0008f> in <79d3a7b905954d0993025c09c5d087ce#2ae0fea9ea4eacaef83bf2e9713bb8ea>:0
at Login.MyMB.Lucene.Client.LuceneArticoliSearcher.GetListaArticoloXRicercaAvanzataConRicercaSemplice
(System.Collections.Generic.List1[T] listParametri) &lt;0x224add0 + 0x001bb&gt; in
&lt;8f49891e0f0546e185aba7424d294ef7#2ae0fea9ea4eacaef83bf2e9713bb8ea&gt;:0 at Login.MyMB.Lucene.Client.LuceneArticoliSearcher.GetListaArticoloConRicercaSemplice
(System.Collections.Generic.List1[T] listParametri) <0x224afbc + 0x0009f> in <8f49891e0f0546e185aba7424d294ef7#2ae0fea9ea4eacaef83bf2e9713bb8ea>:0
at MyMB.Forms.RicercaLucene.RicercaArticoloLucene.GetListaArticoliXRicercaSemplice (Login.MyMB.Interface.IAmbiente
ambiente, Login.MyMB.Lucene.Client.LuceneArticoliSearcher las, System.Collections.Generic.List`1[T]
ListParametri, System.Boolean isAbilitataRicercaBarcode) <0xe47fc0 + 0x000e7> in <f1bb3149abe145459612794f1a096634#2ae0fea9ea4eacaef83bf2e9713bb8ea>:0
..............................._
> At the link [https://docs.microsoft.com/it-it/xamarin/ios/internals/limitations] , I
found the problem cause (I suppose...):
> _Value types as Dictionary Keys Using a value type as a Dictionary<TKey, TValue>
key is problematic, as the default Dictionary constructor attempts to use EqualityComparer<TKey>.Default.
EqualityComparer<TKey>.Default, in turn, attempts to use Reflection to instantiate a
new type which implements the IEqualityComparer<TKey> interface. This works for reference
types (as the reflection+create a new type step is skipped), but for value types it crashes
and burns rather quickly once you attempt to use it on the device. Workaround: Manually implement
the IEqualityComparer<TKey> interface in a new type and provide an instance of that
type to the Dictionary<TKey, TValue> (IEqualityComparer<TKey>) constructor._
> So, what can I do? Thank you in advance, Enrico Caltran +393357485560 [enrico.caltran@timegroup.it|mailto:enrico.caltran@timegroup.it]



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