src/unix/emacs/client_pool.cc

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// Pool of Client instances, implemented with LRUCache.

#include "unix/emacs/client_pool.h"

namespace mozc {
namespace emacs {

static const int kMaxClients = 64;  // max number of parallel clients

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

int ClientPool::CreateClient() {
  // Emacs supports at-least 28-bit integer.
  const 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_, linked_ptr<Client>(new Client()));
  return next_id_++;
}

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

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

}  // namespace emacs
}  // namespace mozc