[&env]() { return env->NowSeconds(); });
  // Execute the first read to load the block.
  TF_EXPECT_OK(ReadCache(&cache2, "", 0, 1, &out));
  EXPECT_EQ(calls, 1);
  // Advance the clock by a huge amount and verify that the cached block is
  // used to satisfy the read.
  env->SetNowSeconds(365 * 24 * 60 * 60);  // ~1 year, just for fun.
  TF_EXPECT_OK(ReadCache(&cache2, "", 0, 1, &out));
  EXPECT_EQ(calls, 1);
}

// setting the same key will lead to errors.
//
// Note that the key-values are only expected to be used for cluster
// configuration data, and should not be used for storing a large amount of data
// or being accessed very frequently.
TF_CAPI_EXPORT extern void TFE_InsertConfigKeyValue(TFE_Context* ctx,
                                                    const char* key,