Minor refactor

crates/polars-core/src/chunked_array/logical/categorical/string_cache.rs

@@ -25,7 +25,7 @@ static STRING_CACHE_UUID_CTR: AtomicU32 = AtomicU32::new(0);
 /// ```
 /// use polars_core::StringCacheHolder;
 ///
-/// let handle = StringCacheHolder::hold();
+/// let _sc = StringCacheHolder::hold();
 /// ```
 ///
 /// The string cache is enabled until `handle` is dropped.

crates/polars-io/src/parquet/read_impl.rs

@@ -251,7 +251,7 @@ pub fn read_parquet<R: MmapBytesReader>(
     // if there are multiple row groups and categorical data
     // we need a string cache
     // we keep it alive until the end of the function
-    let _string_cache = if n_row_groups > 1 {
+    let _sc = if n_row_groups > 1 {
         #[cfg(feature = "dtype-categorical")]
         {
             Some(polars_core::StringCacheHolder::hold())

crates/polars-plan/src/logical_plan/functions/mod.rs

@@ -332,7 +332,7 @@ impl FunctionNode {
                 // we use a global string cache here as streaming chunks all have different rev maps
                 #[cfg(feature = "dtype-categorical")]
                 {
-                    let _hold = StringCacheHolder::hold();
+                    let _sc = StringCacheHolder::hold();
                     Arc::get_mut(function).unwrap().call_udf(df)
                 }
 

crates/polars/tests/it/core/joins.rs

@@ -1,6 +1,6 @@
 use polars_core::utils::{accumulate_dataframes_vertical, split_df};
 #[cfg(feature = "dtype-categorical")]
-use polars_core::{disable_string_cache, StringCacheHolder};
+use polars_core::{disable_string_cache, StringCacheHolder, SINGLE_LOCK};
 
 use super::*;
 

py-polars/polars/string_cache.py

@@ -154,18 +154,16 @@ def disable_string_cache() -> bool:
     """
     Disable and clear the global string cache.
 
-    Warnings
-    --------
-    Disabling the string cache this way may cause errors if there are other threads
-    that rely the global string cache being enabled.
-    Consider using the :class:`StringCache` context manager for a more reliable way of
-    enabling and disabling the string cache.
-
     See Also
     --------
     enable_string_cache : Function to enable the string cache.
     StringCache : Context manager for enabling and disabling the string cache.
 
+    Notes
+    -----
+    Consider using the :class:`StringCache` context manager for a more reliable way of
+    enabling and disabling the string cache.
+
     Examples
     --------
     Construct two Series using the same global string cache.