tustvold commented on code in PR #2906:
URL: https://github.com/apache/arrow-datafusion/pull/2906#discussion_r923327000
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datafusion/core/src/datasource/object_store.rs:
##########
@@ -132,19 +149,41 @@ impl ObjectStoreRegistry {
///
/// - URL with scheme `file:///` or no schema will return the default
LocalFS store
/// - URL with scheme `s3://bucket/` will return the S3 store if it's
registered
+ /// - URL with scheme `hdfs://hostname:port/` will return the hdfs store
if it's registered
///
pub fn get_by_url(&self, url: impl AsRef<Url>) -> Result<Arc<dyn
ObjectStore>> {
let url = url.as_ref();
- let s = &url[url::Position::BeforeScheme..url::Position::AfterHost];
- let stores = self.object_stores.read();
- let store = stores.get(s).ok_or_else(|| {
- DataFusionError::Internal(format!(
- "No suitable object store found for {}",
- url
- ))
- })?;
-
- Ok(store.clone())
+ // First check whether can get object store from registry
+ let store = {
+ let stores = self.object_stores.read();
+ let s =
&url[url::Position::BeforeScheme..url::Position::BeforePath];
+ stores.get(s).cloned()
+ };
+
+ // If not, then try to detector based on its url.
+ let store = store
Review Comment:
In the uncontended case, which is extremely likely given how short the
critical section is, they will perform exactly the same - if anything the Mutex
might be marginally faster. It was more an observation that the complexity of
using a RWLock is probably not actually yielding any return.
A simple Mutex would allow you to use `get_or_insert_with`, and avoid what
is currently a thread race
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