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e4c643880a
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2ebc2107ba
@ -10,34 +10,17 @@ private:
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std::unordered_map<char, WordRefList> directory_;
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public:
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/// Inserts references to all words from word_list between first_index and
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/// last_index, including first_index, excluding last_index.
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void insert(const WordList &word_list, size_t first_index, size_t last_index);
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/// Find all words that start with search_term
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/// @return A list with references to the results.
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WordRefList find_prefix(std::string_view search_term) const;
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};
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/** This class provides efficient, parallel search over a list of strings.
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*
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* References to all input strings are stored in a tree-like structure that
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* provides fast and lock-free parallel insertion and parallel (with minimal
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* synchronization) search for all words that start with a given term.
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*/
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class BucketFinder : public Finder {
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private:
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std::vector<Bucket> buckets_;
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public:
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/// Creates a BucketFinder over all words in word_list.
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BucketFinder(const WordList &word_list);
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/// Find all words that start with search_term
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/// @return A list with references to the results.
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WordRefList find_prefix(std::string_view search_term) const override;
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private:
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/// Inserts references to all words from word_list.
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void insert(const WordList &word_list);
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};
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@ -1,9 +1,12 @@
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#pragma once
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#include <filesystem>
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#include <mutex>
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#include <string>
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#include <vector>
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class WordRefList;
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class WordList : public std::vector<std::string> {
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public:
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WordList &multiply(size_t factor);
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@ -12,10 +15,22 @@ public:
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static WordList oneCap();
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static WordList fourCaps();
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static WordList fromFile(const std::filesystem::path &path);
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static void find_prefix_in_range(const WordList &word_list,
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const std::string_view &search_prefix,
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size_t start_index, size_t end_index,
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WordRefList &result,
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std::mutex &result_mutex);
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};
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class WordRefList : public std::vector<const std::string *> {
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public:
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WordRefList() = default;
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WordRefList(const WordList &source);
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static void find_prefix_in_range(const WordRefList &word_list,
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const std::string_view &search_prefix,
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size_t start_index, size_t end_index,
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WordRefList &result,
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std::mutex &result_mutex);
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};
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@ -1,11 +1,8 @@
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#include "bucket_finder.h"
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#include <algorithm>
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#include <iterator>
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#include <mutex>
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#include <string>
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#include <strings.h>
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#include <thread>
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#include <vector>
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void Bucket::insert(const WordList &word_list, size_t first_index,
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size_t last_index) {
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@ -31,35 +28,34 @@ WordRefList Bucket::find_prefix(std::string_view search_term) const {
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return result;
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}
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BucketFinder::BucketFinder(const WordList &word_list) { insert(word_list); }
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void BucketFinder::insert(const WordList &word_list) {
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BucketFinder::BucketFinder(const WordList &word_list) {
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if (word_list.empty()) {
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return;
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}
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const size_t max_threads = std::thread::hardware_concurrency();
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const size_t word_list_size = word_list.size();
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const size_t bucket_count = std::min<size_t>(max_threads, word_list_size);
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const size_t bucket_count =
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std::min<size_t>(std::thread::hardware_concurrency(), word_list_size);
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const size_t bucket_size = word_list_size / bucket_count;
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buckets_.resize(bucket_count);
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std::vector<std::thread> insert_threads;
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std::vector<std::thread> threads;
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for (auto bucket_index = 0; bucket_index < bucket_count; ++bucket_index) {
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auto &bucket = buckets_[bucket_index];
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const bool is_last_bucket = bucket_index == bucket_count - 1;
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const size_t first_word_index = bucket_index * bucket_size;
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const size_t last_word_index =
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is_last_bucket ? word_list_size : first_word_index + bucket_size;
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bool is_last_bucket = bucket_index == bucket_count - 1;
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insert_threads.emplace_back([&, first_word_index, last_word_index] {
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bucket.insert(word_list, first_word_index, last_word_index);
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const size_t first_index = bucket_index * bucket_size;
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const size_t last_index =
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is_last_bucket ? word_list_size : first_index + bucket_size;
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threads.emplace_back([&, first_index, last_index] {
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bucket.insert(word_list, first_index, last_index);
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});
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}
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for (auto &thread : insert_threads) {
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for (auto &thread : threads) {
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thread.join();
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}
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}
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@ -73,7 +69,7 @@ WordRefList BucketFinder::find_prefix(std::string_view search_term) const {
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threads.emplace_back([&] {
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auto thread_search_results = bucket.find_prefix(search_term);
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if (!thread_search_results.empty()) {
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const std::lock_guard result_lock(search_results_mutex);
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std::lock_guard result_lock(search_results_mutex);
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std::move(thread_search_results.begin(), thread_search_results.end(),
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std::back_inserter(search_results));
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}
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@ -19,43 +19,31 @@ WordRefList GroupedFinder::find_prefix(string_view search_prefix) const {
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}
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const auto word_list = group->second;
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const size_t word_list_size = word_list.size();
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const size_t thread_count =
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std::min<size_t>(std::thread::hardware_concurrency(), word_list_size);
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const size_t words_per_thread = word_list_size / thread_count;
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const auto word_list_size = word_list.size();
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WordRefList search_results;
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mutex search_results_mutex;
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const auto thread_count =
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std::min<size_t>(std::thread::hardware_concurrency(), word_list_size);
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WordRefList result;
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mutex result_mutex;
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vector<thread> search_threads;
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for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
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const bool is_last_thread = thread_index == thread_count - 1;
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const size_t start_index = thread_index * words_per_thread;
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const size_t end_index =
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is_last_thread ? word_list_size : start_index + words_per_thread;
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const size_t first_index = thread_index * (word_list_size / thread_count);
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search_threads.emplace_back([&, start_index, end_index] {
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WordRefList local_results;
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const size_t last_index =
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(thread_index == thread_count - 1)
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? word_list_size
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: (thread_index + 1) * (word_list_size / thread_count);
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for (size_t word_index = start_index; word_index < end_index;
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++word_index) {
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const auto *current_word = word_list[word_index];
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if (current_word->starts_with(search_prefix)) {
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local_results.push_back(current_word);
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}
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}
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if (!local_results.empty()) {
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const std::lock_guard lock(search_results_mutex);
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std::move(local_results.begin(), local_results.end(),
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std::back_inserter(search_results));
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}
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});
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search_threads.emplace_back(
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WordRefList::find_prefix_in_range, cref(word_list), cref(search_prefix),
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first_index, last_index, ref(result), ref(result_mutex));
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}
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for (auto &thread : search_threads) {
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thread.join();
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}
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return search_results;
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return result;
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}
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@ -9,43 +9,30 @@ ParallelFinder::ParallelFinder(const WordList &word_list)
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: word_list_(word_list) {}
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WordRefList ParallelFinder::find_prefix(string_view search_prefix) const {
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WordRefList search_results;
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mutex search_results_mutex;
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WordRefList result;
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mutex result_mutex;
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const size_t word_list_size = word_list_.size();
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const size_t thread_count =
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std::min<size_t>(thread::hardware_concurrency(), word_list_size);
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const size_t words_per_thread = word_list_size / thread_count;
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vector<thread> search_threads;
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for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
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const bool is_last_thread = thread_index == thread_count - 1;
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const size_t start_index = thread_index * words_per_thread;
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const size_t end_index =
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is_last_thread ? word_list_size : start_index + words_per_thread;
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const size_t first_index = thread_index * (word_list_size / thread_count);
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search_threads.emplace_back([&, start_index, end_index] {
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WordRefList local_results;
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const size_t last_index =
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(thread_index == thread_count - 1)
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? word_list_size
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: (thread_index + 1) * (word_list_size / thread_count);
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for (size_t word_index = start_index; word_index < end_index;
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++word_index) {
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const auto ¤t_word = word_list_[word_index];
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if (current_word.starts_with(search_prefix)) {
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local_results.push_back(¤t_word);
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}
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}
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if (!local_results.empty()) {
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const std::lock_guard lock(search_results_mutex);
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std::move(local_results.begin(), local_results.end(),
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std::back_inserter(search_results));
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}
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});
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search_threads.emplace_back(
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WordList::find_prefix_in_range, cref(word_list_), cref(search_prefix),
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first_index, last_index, ref(result), ref(result_mutex));
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}
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for (auto &thread : search_threads) {
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thread.join();
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}
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return search_results;
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return result;
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}
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@ -71,8 +71,50 @@ WordList WordList::fromFile(const std::filesystem::path &path) {
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return word_list;
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}
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void WordList::find_prefix_in_range(const WordList &word_list,
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const std::string_view &search_prefix,
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size_t start_index, size_t end_index,
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WordRefList &result,
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std::mutex &result_mutex) {
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WordRefList local_results;
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for (size_t index = start_index; index < end_index; ++index) {
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const auto ¤t_word = word_list[index];
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if (current_word.starts_with(search_prefix)) {
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local_results.push_back(¤t_word);
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}
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}
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if (!local_results.empty()) {
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const std::lock_guard<std::mutex> lock(result_mutex);
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std::move(local_results.begin(), local_results.end(),
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std::back_inserter(result));
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}
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};
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WordRefList::WordRefList(const WordList &source) {
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for (const auto &word : source) {
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push_back(&word);
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}
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}
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void WordRefList::find_prefix_in_range(const WordRefList &word_list,
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const std::string_view &search_prefix,
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size_t start_index, size_t end_index,
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WordRefList &result,
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std::mutex &result_mutex) {
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WordRefList local_results;
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for (size_t index = start_index; index < end_index; ++index) {
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const auto *current_word = word_list[index];
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if (current_word->starts_with(search_prefix)) {
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local_results.push_back(current_word);
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}
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}
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if (!local_results.empty()) {
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const std::lock_guard<std::mutex> lock(result_mutex);
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std::move(local_results.begin(), local_results.end(),
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std::back_inserter(result));
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}
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};
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