ChrisHegarty commented on code in PR #14482:
URL: https://github.com/apache/lucene/pull/14482#discussion_r2057896977
##########
lucene/core/src/java/org/apache/lucene/store/Directory.java:
##########
@@ -79,6 +83,31 @@ public abstract class Directory implements Closeable {
*/
public abstract long fileLength(String name) throws IOException;
+ protected void validateIOContext(IOContext context) {
+ Map<Class<? extends IOContext.FileOpenHint>, List<IOContext.FileOpenHint>>
hintClasses =
+
context.hints().stream().collect(Collectors.groupingBy(IOContext.FileOpenHint::getClass));
+
+ // there should only be one of FileType, FileData, DataAccess
+ List<IOContext.FileOpenHint> fileTypes =
+ hintClasses.getOrDefault(FileTypeHint.class, List.of());
+ if (fileTypes.size() > 1) {
+ throw new IllegalArgumentException("Multiple file type hints specified:
" + fileTypes);
+ }
+ List<IOContext.FileOpenHint> fileData =
hintClasses.getOrDefault(FileDataHint.class, List.of());
+ if (fileData.size() > 1) {
+ throw new IllegalArgumentException("Multiple file data hints specified:
" + fileData);
+ }
+ List<IOContext.FileOpenHint> dataAccess =
+ hintClasses.getOrDefault(DataAccessHint.class, List.of());
+ if (dataAccess.size() > 1) {
+ throw new IllegalArgumentException("Multiple data access hints
specified: " + dataAccess);
+ }
+ }
+
+ protected ReadAdvice toReadAdvice(IOContext context) {
Review Comment:
The final api position as I understand it, `IOContext` has no knowledge of
`ReadAdvice` ( `IOConext::withReadAdvice` and `IOContext::readAdvice` will be
removed ).
`ReadAdvice` is rather determined by the directory when given the
higher-level hints from the IOContext. For example, the `MMapDirectory`
implementation of openInput would do something like.
```java
public IndexInput openInput(String name, IOContext context) throws
IOException {
...
return PROVIDER.openInput(..., toReadAdvice(context), preload.test(name,
context),...);
}
```
... so it's somewhat akin to the the current preLoad model.
For a custom filter wrapper one would do:
```java
Directory dir = new FilterDirectory(mmapDirectory) {
@Override
public ReadAdvice toReadAdvice(IOContext context) {
if (someCondition) {
// enforce specific read advice instead of relying on hints
return ReadAdvice.NORMAL;
}
// hints to readAdvice
}
}
```
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