Change CacheAccessor::remove to take &self rather than &mut self (#18726)

## Which issue does this PR close?

<!--
We generally require a GitHub issue to be filed for all bug fixes and
enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax. For example
`Closes #123` indicates that this PR will close issue #123.
-->

- Closes #18725 

## Rationale for this change

The change make the cache accessor remove API interface inline with
other APIs
<!--
Why are you proposing this change? If this is already explained clearly
in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand
your changes and offer better suggestions for fixes.
-->

## What changes are included in this PR?

Change the remove API for non mut type

<!--
There is no need to duplicate the description in the issue here but it
is sometimes worth providing a summary of the individual changes in this
PR.
-->

## Are these changes tested?

Covered in existing changes
<!--
We typically require tests for all PRs in order to:
1. Prevent the code from being accidentally broken by subsequent changes
2. Serve as another way to document the expected behavior of the code

If tests are not included in your PR, please explain why (for example,
are they covered by existing tests)?
-->

## Are there any user-facing changes?

The CacheAccessor trait will be slightly different now.
<!--
If there are user-facing changes then we may require documentation to be
updated before approving the PR.
-->

<!--
If there are any breaking changes to public APIs, please add the `api
change` label.
-->

---------

Signed-off-by: Arpit Bandejiya <abandeji@amazon.com>
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

Author: alchemist51

datafusion/execution/src/cache/cache_unit.rs

@@ -87,7 +87,7 @@ impl CacheAccessor<Path, Arc<Statistics>> for DefaultFileStatisticsCache {
             .map(|x| x.1)
     }
 
-    fn remove(&mut self, k: &Path) -> Option<Arc<Statistics>> {
+    fn remove(&self, k: &Path) -> Option<Arc<Statistics>> {
         self.statistics.remove(k).map(|x| x.1 .1)
     }
 
@@ -151,7 +151,7 @@ impl CacheAccessor<Path, Arc<Vec<ObjectMeta>>> for DefaultListFilesCache {
         panic!("Not supported DefaultListFilesCache put_with_extra")
     }
 
-    fn remove(&mut self, k: &Path) -> Option<Arc<Vec<ObjectMeta>>> {
+    fn remove(&self, k: &Path) -> Option<Arc<Vec<ObjectMeta>>> {
         self.statistics.remove(k).map(|x| x.1)
     }
 
@@ -399,7 +399,7 @@ impl CacheAccessor<ObjectMeta, Arc<dyn FileMetadata>> for DefaultFilesMetadataCa
         self.put(key, value)
     }
 
-    fn remove(&mut self, k: &ObjectMeta) -> Option<Arc<dyn FileMetadata>> {
+    fn remove(&self, k: &ObjectMeta) -> Option<Arc<dyn FileMetadata>> {
         let mut state = self.state.lock().unwrap();
         state.remove(k)
     }
@@ -542,7 +542,7 @@ mod tests {
             metadata: "retrieved_metadata".to_owned(),
         });
 
-        let mut cache = DefaultFilesMetadataCache::new(1024 * 1024);
+        let cache = DefaultFilesMetadataCache::new(1024 * 1024);
         assert!(cache.get(&object_meta).is_none());
 
         // put
@@ -610,7 +610,7 @@ mod tests {
 
     #[test]
     fn test_default_file_metadata_cache_with_limit() {
-        let mut cache = DefaultFilesMetadataCache::new(1000);
+        let cache = DefaultFilesMetadataCache::new(1000);
         let (object_meta1, metadata1) = generate_test_metadata_with_size("1", 100);
         let (object_meta2, metadata2) = generate_test_metadata_with_size("2", 500);
         let (object_meta3, metadata3) = generate_test_metadata_with_size("3", 300);
@@ -726,7 +726,7 @@ mod tests {
 
     #[test]
     fn test_default_file_metadata_cache_entries_info() {
-        let mut cache = DefaultFilesMetadataCache::new(1000);
+        let cache = DefaultFilesMetadataCache::new(1000);
         let (object_meta1, metadata1) = generate_test_metadata_with_size("1", 100);
         let (object_meta2, metadata2) = generate_test_metadata_with_size("2", 200);
         let (object_meta3, metadata3) = generate_test_metadata_with_size("3", 300);

datafusion/execution/src/cache/mod.rs

@@ -36,7 +36,7 @@ pub trait CacheAccessor<K, V>: Send + Sync {
     /// Put value into cache. Returns the old value associated with the key if there was one.
     fn put_with_extra(&self, key: &K, value: V, e: &Self::Extra) -> Option<V>;
     /// Remove an entry from the cache, returning value if they existed in the map.
-    fn remove(&mut self, k: &K) -> Option<V>;
+    fn remove(&self, k: &K) -> Option<V>;
     /// Check if the cache contains a specific key.
     fn contains_key(&self, k: &K) -> bool;
     /// Fetch the total number of cache entries.

docs/source/library-user-guide/upgrading.md

@@ -67,6 +67,10 @@ SELECT median(c1) IGNORE NULLS FROM table
 
 Instead of silently succeeding.
 
+### API change for `CacheAccessor` trait
+
+The remove API no longer requires a mutable instance
+
 ## DataFusion `51.0.0`
 
 ### `arrow` / `parquet` updated to 57.0.0