Ершов Вадим, Магистратура ИТМО "Распределенные веб-сервисы", hw 5 #291
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| public class ThreadSafeDaoImpl implements Dao<MemorySegment, Entry<MemorySegment>> { | ||
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| private final Comparator<MemorySegment> comparator = ThreadSafeDaoImpl::compare; | ||
| private NavigableMap<MemorySegment, Entry<MemorySegment>> storage = new ConcurrentSkipListMap<>(comparator); |
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Поле storage читается/пишется из разных потоков. Чтения не защищены.
| public void flush() { | ||
| w.lock(); | ||
| try { | ||
| DiskStorage.save(path, storage.values()); |
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Почему мы не очищаем storage (MemTable) после flush и не переоткрываем флашнутую таблицу?
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| iterators.add(firstIterator); | ||
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| return new MergeIterator<>(iterators, Comparator.comparing(Entry::key, ThreadSafeDaoImpl::compare)); |
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Мы обращаемся к полю ThreadSafeDaoImpl? Текут абстракции...
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| // private final ExecutorService executorService = Executors.newSingleThreadExecutor(); | ||
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| private long currentBytes = 0; |
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Поле модифицируется из разных потоков под гонкой.
| if (currentBytes > flushThresholdBytes) { | ||
| flush(); | ||
| } | ||
| currentBytes += entry.key().byteSize(); |
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Операции инкремента currentBytes в таком виде не атомарны.
| DiskStorage.save(path, storage.values()); | ||
| currentBytes = 0; | ||
| } catch (IOException e) { | ||
| throw new RuntimeException(e); |
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| throw new RuntimeException(e); | |
| throw new UncheckedIOException(e); |
| } | ||
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| @Override | ||
| public void flush() { |
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Операция блокирующая и не соответствует спецификации, верно?
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| @Override | ||
| public void compact() throws IOException { |
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Операция блокирующая и не соответствует спецификации, верно?
| try { | ||
| Files.createDirectories(compactPath); | ||
| DiskStorage.save(compactPath, this::all); | ||
| DiskStorage.deleteFiles(path); |
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Почему мы не переключаемся на результат compaction, а продолжаем использовать удалённые файлы?
| private final Path compactPath; | ||
| private final long flushThresholdBytes; | ||
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| private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock(); |
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| private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock(); | |
| private final ReadWriteLock rwl = new ReentrantReadWriteLock(); |
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