# Copyright 2018 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Tests for the CacheDataset serialization."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import os

from absl.testing import parameterized

from tensorflow.python.data.experimental.kernel_tests.serialization import dataset_serialization_test_base
from tensorflow.python.data.ops import dataset_ops
from tensorflow.python.framework import errors
from tensorflow.python.platform import test


class CacheDatasetSerializationTest(
    dataset_serialization_test_base.DatasetSerializationTestBase,
    parameterized.TestCase):

  def setUp(self):
    self.range_size = 10
    self.num_repeats = 3
    self.num_outputs = self.range_size * self.num_repeats
    self.cache_file_prefix = 'test'

  def make_dataset_fn(self, is_memory):
    if is_memory:
      filename = ''
    else:
      filename = os.path.join(self.get_temp_dir(), self.cache_file_prefix)

    def ds_fn():
      return dataset_ops.Dataset.range(self.range_size).cache(filename).repeat(
          self.num_repeats)

    return ds_fn

  def expected_outputs(self):
    return list(range(self.range_size)) * self.num_repeats

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointBeforeOneEpoch(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Generate 5 entries from iterator and save checkpoint.
    outputs = self.gen_outputs(ds_fn, [], 5, verify_exhausted=False)
    self.assertSequenceEqual(outputs, range(5))

    # Restore from checkpoint and produce the rest of the elements from the
    # iterator.
    outputs.extend(
        self.gen_outputs(
            ds_fn, [],
            self.num_outputs - 5,
            ckpt_saved=True,
            verify_exhausted=False))
    self.assertSequenceEqual(outputs, self.expected_outputs())

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointBeforeOneEpochThenRunFewSteps(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Generate 8 entries from iterator but save checkpoint after producing 5.
    outputs = self.gen_outputs(
        ds_fn, [5], 8, verify_exhausted=False, save_checkpoint_at_end=False)
    self.assertSequenceEqual(outputs, range(8))

    outputs = outputs[:5]
    outputs.extend(
        self.gen_outputs(
            ds_fn, [],
            self.num_outputs - 5,
            ckpt_saved=True,
            verify_exhausted=False))
    self.assertSequenceEqual(outputs, self.expected_outputs())

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointAfterOneEpoch(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Generate 15 entries from iterator and save checkpoint.
    outputs = self.gen_outputs(ds_fn, [], 15, verify_exhausted=False)
    self.assertSequenceEqual(outputs, list(range(10)) + list(range(5)))

    # Restore from checkpoint and produce the rest of the elements from the
    # iterator.
    outputs.extend(
        self.gen_outputs(
            ds_fn, [],
            self.num_outputs - 15,
            ckpt_saved=True,
            verify_exhausted=False))
    self.assertSequenceEqual(outputs, self.expected_outputs())

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointAfterOneEpochThenRunFewSteps(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Generate 18 entries from iterator but save checkpoint after producing 15.
    outputs = self.gen_outputs(
        ds_fn, [15], 18, verify_exhausted=False, save_checkpoint_at_end=False)
    self.assertSequenceEqual(outputs, list(range(10)) + list(range(8)))

    outputs = list(range(10)) + list(range(5)) + self.gen_outputs(
        ds_fn, [],
        self.num_outputs - 15,
        ckpt_saved=True,
        verify_exhausted=False)
    self.assertSequenceEqual(outputs, list(range(10)) * 3)

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointBeforeOneEpochButRunCompleteEpoch(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Generate 13 entries from iterator but save checkpoint after producing 5.
    outputs = self.gen_outputs(
        ds_fn, [5], 13, verify_exhausted=False, save_checkpoint_at_end=False)
    self.assertSequenceEqual(outputs, list(range(10)) + list(range(3)))

    # Since we ran for more than one epoch, the cache was completely written.
    # The ckpt was saved when the iterator was in cache-write mode. Test that
    # the iterator falls back to read mode after restoring if the cache has
    # been completely written.

    outputs = list(range(5)) + self.gen_outputs(
        ds_fn, [],
        self.num_outputs - 5,
        ckpt_saved=True,
        verify_exhausted=False)
    self.assertSequenceEqual(outputs, list(range(10)) * 3)

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointUnusedWriterIterator(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Checkpoint before get_next is called even once.
    outputs = self.gen_outputs(ds_fn, [], 0, verify_exhausted=False)
    self.assertSequenceEqual(outputs, [])

    outputs = self.gen_outputs(
        ds_fn, [], self.num_outputs, ckpt_saved=True, verify_exhausted=False)
    self.assertSequenceEqual(outputs, list(range(10)) * 3)

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testCheckpointUnusedMidwayWriterIterator(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Produce 5 elements and checkpoint.
    outputs = self.gen_outputs(ds_fn, [], 5, verify_exhausted=False)
    self.assertSequenceEqual(outputs, range(5))

    # Restore from checkpoint, then produce no elements and checkpoint.
    outputs.extend(
        self.gen_outputs(ds_fn, [], 0, ckpt_saved=True, verify_exhausted=False))
    self.assertSequenceEqual(outputs, range(5))

    # Restore from checkpoint and produce rest of the elements.
    outputs.extend(
        self.gen_outputs(
            ds_fn, [],
            self.num_outputs - 5,
            ckpt_saved=True,
            verify_exhausted=False))
    self.assertSequenceEqual(outputs, list(range(10)) * 3)

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testUnusedCheckpointError(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Produce 5 elements and save ckpt.
    outputs = self.gen_outputs(ds_fn, [], 5, verify_exhausted=False)
    self.assertSequenceEqual(outputs, range(5))

    if is_memory:
      outputs = self.gen_outputs(
          ds_fn, [], self.num_outputs, verify_exhausted=False)
      self.assertSequenceEqual(outputs, self.expected_outputs())
    else:
      # Since the complete cache has not been written, a new iterator which does
      # not restore the checkpoint will throw an error since there is a partial
      # cache shard.
      with self.assertRaises(errors.AlreadyExistsError):
        outputs = self.gen_outputs(
            ds_fn, [], self.num_outputs, verify_exhausted=False)

  @parameterized.named_parameters(
      ('Memory', True),
      ('File', False),
  )
  def testIgnoreCheckpointIfCacheWritten(self, is_memory):
    ds_fn = self.make_dataset_fn(is_memory)

    # Produce 15 elements and save ckpt. This will write the complete cache.
    outputs = self.gen_outputs(ds_fn, [], 15, verify_exhausted=False)
    self.assertSequenceEqual(outputs, list(range(10)) + list(range(5)))

    # Build the iterator again but do not restore from ckpt. Since the cache
    # has already been written we should be able to use it.
    outputs = self.gen_outputs(
        ds_fn, [], self.num_outputs, verify_exhausted=False)
    self.assertSequenceEqual(outputs, list(range(10)) * 3)


if __name__ == '__main__':
  test.main()
