refactor(content_hash): remove keys_being_calculated

This parameter won't be useful once we parallelize content hashing, because the keys being calculated won't be helpful to find the dependency cycle when other tasks are also calculating keys.

focus/internals/src/lib/index/content_hash.rs

@@ -2,8 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use std::cell::RefCell;
-use std::collections::HashMap;
-use std::collections::{BTreeSet, HashSet};
+use std::collections::{BTreeSet, HashMap};
 use std::fmt::{Display, Write};
 use std::hash::Hash;
 use std::path::Path;
@@ -107,31 +106,19 @@ impl std::fmt::Debug for HashContext<'_> {
 /// Compute a content-addressable hash for the provided [`DependencyKey`] using
 /// the context in `ctx`.
 pub fn content_hash(ctx: &HashContext, key: &DependencyKey) -> anyhow::Result<ContentHash> {
-    content_hash_dependency_key(ctx, key, &mut HashSet::new())
+    content_hash_dependency_key(ctx, key)
 }
 
 fn content_hash_dependency_key(
     ctx: &HashContext,
     key: &DependencyKey,
-    keys_being_calculated: &mut HashSet<DependencyKey>,
 ) -> anyhow::Result<ContentHash> {
     debug!(?key, "Hashing dependency key");
 
     {
         let cache = &mut ctx.caches.borrow_mut().dependency_key_cache;
-        match cache.get(key) {
-            Some(hash) => return Ok(hash.to_owned()),
-            None => {
-                if !keys_being_calculated.insert(key.clone()) {
-                    anyhow::bail!(
-                        "\
-Circular dependency when hashing: {:?}
-These are the keys currently being hashed: {:?}",
-                        key,
-                        keys_being_calculated.iter().collect::<BTreeSet<_>>(),
-                    );
-                }
-            }
+        if let Some(hash) = cache.get(key) {
+            return Ok(hash.to_owned());
         }
     }
 
@@ -259,9 +246,7 @@ These are the keys currently being hashed: {:?}",
     let hashes = values_to_hash
         .into_iter()
         .map(|key_or_hash| match key_or_hash {
-            KeyOrPath::Key(dep_key) => {
-                content_hash_dependency_key(ctx, &dep_key, keys_being_calculated)
-            }
+            KeyOrPath::Key(dep_key) => content_hash_dependency_key(ctx, &dep_key),
             KeyOrPath::Path(path) => content_hash_tree_path(ctx, path),
         })
         .collect::<Result<Vec<_>, _>>()?;