Use displacement instead of initial bucket in HashMap code #38022
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r? @sfackler (rust_highfive has picked a reviewer for you, use r? to override) |
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I botched the patch porting.. as always, will fix in the morning. |
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| @@ -431,12 +431,12 @@ fn pop_internal<K, V>(starting_bucket: FullBucketMut<K, V>) -> (K, V) { | |||
| } | |||
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| /// Perform robin hood bucket stealing at the given `bucket`. You must | |||
| /// also pass the position of that bucket's initial bucket so we don't have | |||
| /// also pass the position of that bucket's displacement so we don't have | |||
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it's no longer passing a “position”
| @@ -522,11 +523,11 @@ impl<K, V, S> HashMap<K, V, S> | |||
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| // The caller should ensure that invariants by Robin Hood Hashing hold. | |||
| fn insert_hashed_ordered(&mut self, hash: SafeHash, k: K, v: V) { | |||
| let raw_cap = self.raw_capacity(); | |||
| let capacity = self.table.capacity(); | |||
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this is still the raw capacity (change is equivalent, so seems unnecessary to change).
| @@ -537,8 +538,8 @@ impl<K, V, S> HashMap<K, V, S> | |||
| Full(b) => b.into_bucket(), | |||
| }; | |||
| buckets.next(); | |||
| debug_assert!(buckets.index() < limit_bucket); | |||
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This is an infinite loop if there is no free bucket, but that there is, is a requirement already in the caller (resize), so it seems ok.
(Note to other readers: buckets.index() keeps increasing even if the pointer it corresponds to wraps back to the first bucket.)
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Thanks for the review. Commit amended with fixed/new comments. |
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@bors r+ Thanks |
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📌 Commit 178e29d has been approved by |
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⌛ Testing commit 178e29d with merge 03bdaad... |
Use displacement instead of initial bucket in HashMap code Use displacement instead of initial bucket in HashMap code. It makes the code a bit cleaner and also saves a few instructions (handy since it'll be using some to do some sort of adaptive behavior soon).
Use displacement instead of initial bucket in HashMap code. It makes the code a bit cleaner and also saves a few instructions (handy since it'll be using some to do some sort of adaptive behavior soon).