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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
namespace search::bmcluster {
/*
* Map from document index to bucket to ensure even spread between buckets
* while ensuring that each bucket used belong to a specific thread.
*/
class BucketSelector
{
uint32_t _thread_id;
uint32_t _threads;
uint32_t _num_buckets;
public:
BucketSelector(uint32_t thread_id_in, uint32_t threads_in, uint32_t num_buckets_in)
: _thread_id(thread_id_in),
_threads(threads_in),
_num_buckets((num_buckets_in / _threads) * _threads)
{
}
uint64_t operator()(uint32_t i) const {
return (static_cast<uint64_t>(i) * _threads + _thread_id) % _num_buckets;
}
};
}
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