Method getAt

output/java_guava/1.4.19/Striped.java:391–413

(int index)

    }

    @Override
    public L getAt(int index) {
      if (size != Integer.MAX_VALUE) {
        Preconditions.checkElementIndex(index, size());
      } // else no check necessary, all index values are valid
      ArrayReference<? extends L> existingRef = locks.get(index);
      L existing = existingRef == null ? null : existingRef.get();
      if (existing != null) {
        return existing;
      }
      L created = supplier.get();
      ArrayReference<L> newRef = new ArrayReference<L>(created, index, queue);
      while (!locks.compareAndSet(index, existingRef, newRef)) {
        // we raced, we need to re-read and try again
        existingRef = locks.get(index);
        existing = existingRef == null ? null : existingRef.get();
        if (existing != null) {
          return existing;
        }
      }
      drainQueue();
      return created;
    }

    // N.B. Draining the queue is only necessary to ensure that we don't accumulate empty references
    // in the array. We could skip this if we decide we don't care about holding on to Reference