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// Pool of Client instances, implemented with LruCache.

#include "unix/emacs/client_pool.h"

#include <memory>

namespace mozc {
namespace emacs {
namespace {

constexpr int kMaxClients = 64;  // max number of parallel clients

}  // namespace

ClientPool::ClientPool() : lru_cache_(kMaxClients), next_id_(1) {}

int ClientPool::CreateClient() {
  // Emacs supports at-least 28-bit integer.
  constexpr int k28BitIntMax = 134217727;
  while (lru_cache_.HasKey(next_id_)) {
    if (++next_id_ <= 0 || k28BitIntMax < next_id_) {
      next_id_ = 1;  // Keep next_id_ to be a positive 28-bit integer.
    }
  }
  lru_cache_.Insert(next_id_, std::make_shared<Client>());
  return next_id_++;
}

void ClientPool::DeleteClient(int id) { lru_cache_.Erase(id); }

std::shared_ptr<ClientPool::Client> ClientPool::GetClient(int id) {
  const std::shared_ptr<Client> *value = lru_cache_.Lookup(id);
  if (value) {
    lru_cache_.Insert(id, *value);  // Put id at the head of LRU.
    return *value;
  } else {
    auto client_ptr = std::make_shared<Client>();
    lru_cache_.Insert(id, client_ptr);
    return client_ptr;
  }
}

}  // namespace emacs
}  // namespace mozc
