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# KIND, either express or implied.  See the License for the
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import pytest
import re
from random import randint

from tests.common.impala_test_suite import ImpalaTestSuite
from tests.common.test_dimensions import create_exec_option_dimension
from tests.common.test_dimensions import create_uncompressed_text_dimension
from tests.common.test_vector import ImpalaTestDimension
from tests.util.test_file_parser import QueryTestSectionReader

class TestExprs(ImpalaTestSuite):
  @classmethod
  def get_workload(cls):
    return 'functional-query'

  @classmethod
  def add_test_dimensions(cls):
    super(TestExprs, cls).add_test_dimensions()
    # Test with and without expr rewrites to cover regular expr evaluations
    # as well as constant folding, in particular, timestamp literals.
    cls.ImpalaTestMatrix.add_dimension(
        ImpalaTestDimension('enable_expr_rewrites', *[0,1]))
    if cls.exploration_strategy() == 'core':
      # Test with file format that supports codegen
      cls.ImpalaTestMatrix.add_constraint(lambda v:\
          v.get_value('table_format').file_format == 'text' and\
          v.get_value('table_format').compression_codec == 'none')

  def test_exprs(self, vector):
    vector.get_value('exec_option')['enable_expr_rewrites'] = \
        vector.get_value('enable_expr_rewrites')
    # TODO: Enable some of these tests for Avro if possible
    # Don't attempt to evaluate timestamp expressions with Avro tables (which don't
    # support a timestamp type)"
    table_format = vector.get_value('table_format')
    if table_format.file_format == 'avro':
      pytest.skip()
    if table_format.file_format == 'hbase':
      pytest.xfail("A lot of queries check for NULLs, which hbase does not recognize")
    if table_format.file_format == 'kudu':
      # Can't load LikeTbl without KUDU-1570.
      pytest.xfail("Need support for Kudu tables with nullable PKs (KUDU-1570)")
    self.run_test_case('QueryTest/exprs', vector)

    # This will change the current database to matching table format and then execute
    # select current_database(). An error will be thrown if multiple values are returned.
    current_db = self.execute_scalar('select current_database()', vector=vector)
    assert current_db == QueryTestSectionReader.get_db_name(table_format)

  def test_special_strings(self, vector):
    """Test handling of expressions with "special" strings."""
    vector.get_value('exec_option')['enable_expr_rewrites'] = \
        vector.get_value('enable_expr_rewrites')
    self.run_test_case('QueryTest/special-strings', vector)

# Tests very deep expression trees and expressions with many children. Impala defines
# a 'safe' upper bound on the expr depth and the number of expr children in the
# FE Expr.java and any changes to those limits should be reflected in this test.
# The expr limits primarily guard against stack overflows or similar problems
# causing crashes. Therefore, this tests succeeds if no Impalads crash.
class TestExprLimits(ImpalaTestSuite):
  # Keep these in sync with Expr.java
  EXPR_CHILDREN_LIMIT = 10000
  EXPR_DEPTH_LIMIT = 1000

  @classmethod
  def get_workload(self):
    return 'functional-query'

  @classmethod
  def add_test_dimensions(cls):
    super(TestExprLimits, cls).add_test_dimensions()
    if cls.exploration_strategy() != 'exhaustive':
      # Ensure the test runs with codegen enabled and disabled, even when the
      # exploration strategy is not exhaustive.
      cls.ImpalaTestMatrix.clear_dimension('exec_option')
      cls.ImpalaTestMatrix.add_dimension(create_exec_option_dimension(
          cluster_sizes=[0], disable_codegen_options=[False, True], batch_sizes=[0]))

    # There is no reason to run these tests using all dimensions.
    cls.ImpalaTestMatrix.add_dimension(
        create_uncompressed_text_dimension(cls.get_workload()))

  def test_expr_child_limit(self, vector):
    # IN predicate
    in_query = "select 1 IN("
    for i in xrange(0, self.EXPR_CHILDREN_LIMIT - 1):
      in_query += str(i)
      if (i + 1 != self.EXPR_CHILDREN_LIMIT - 1):
        in_query += ","
    in_query += ")"
    self.__exec_query(in_query)

    # CASE expr
    case_query = "select case "
    for i in xrange(0, self.EXPR_CHILDREN_LIMIT/2):
      case_query += " when true then 1"
    case_query += " end"
    self.__exec_query(case_query)

  def test_expr_depth_limit(self, vector):
    # Compound predicates
    and_query = "select " + self.__gen_deep_infix_expr("true", " and false")
    self.__exec_query(and_query)
    or_query = "select " + self.__gen_deep_infix_expr("true", " or false")
    self.__exec_query(or_query)

    # Arithmetic expr
    arith_query = "select " + self.__gen_deep_infix_expr("1", " + 1")
    self.__exec_query(arith_query)

    func_query = "select " + self.__gen_deep_func_expr("lower(", "'abc'", ")")
    self.__exec_query(func_query)

    # Casts.
    cast_query = "select " + self.__gen_deep_func_expr("cast(", "1", " as int)")
    self.__exec_query(cast_query)

  def test_under_statement_expression_limit(self):
    """Generate a huge case statement that barely fits within the statement expression
       limit and verify that it runs."""
    # This takes 20+ minutes, so only run it on exhaustive.
    # TODO: Determine whether this needs to run serially. It use >5 GB of memory.
    if self.exploration_strategy() != 'exhaustive':
      pytest.skip("Only test limit of codegen on exhaustive")
    case = self.__gen_huge_case("int_col", 32, 2, "  ")
    query = "select {0} as huge_case from functional_parquet.alltypes".format(case)
    self.__exec_query(query)

  def test_max_statement_size(self):
    """Generate a huge case statement that exceeds the default 16MB limit and verify
       that it gets rejected."""

    expected_err_tmpl = ("Statement length of {0} bytes exceeds the maximum "
        "statement length \({1} bytes\)")
    size_16mb = 16 * 1024 * 1024

    # Case 1: a valid SQL that would parse correctly
    case = self.__gen_huge_case("int_col", 75, 2, "  ")
    query = "select {0} as huge_case from functional.alltypes".format(case)
    err = self.execute_query_expect_failure(self.client, query)
    assert re.search(expected_err_tmpl.format(len(query), size_16mb), str(err))

    # Case 2: a string of 'a' characters that does not parse. This will still fail
    # with the same message, because the check is before parsing.
    invalid_sql = 'a' * (size_16mb + 1)
    err = self.execute_query_expect_failure(self.client, invalid_sql)
    assert re.search(expected_err_tmpl.format(len(invalid_sql), size_16mb), str(err))

  def test_statement_expression_limit(self):
    """Generate a huge case statement that barely fits within the 16MB limit but exceeds
       the statement expression limit. Verify that it fails."""
    case = self.__gen_huge_case("int_col", 66, 2, "  ")
    query = "select {0} as huge_case from functional.alltypes".format(case)
    assert len(query) < 16 * 1024 * 1024
    expected_err_re = ("Exceeded the statement expression limit \({0}\)\n"
        "Statement has .* expressions.").format(250000)
    err = self.execute_query_expect_failure(self.client, query)
    assert re.search(expected_err_re, str(err))

  def __gen_huge_case(self, col_name, fanout, depth, indent):
    toks = ["case\n"]
    for i in xrange(fanout):
      add = randint(1, 1000000)
      divisor = randint(1, 10000000)
      mod = randint(0, divisor)
      # Generate a mathematical expr that can't be easily optimised out.
      when_expr = "{0} + {1} % {2} = {3}".format(col_name, add, divisor, mod)
      if depth == 0:
        then_expr = "{0}".format(i)
      else:
        then_expr = "({0})".format(
            self.__gen_huge_case(col_name, fanout, depth - 1, indent + "  "))
      toks.append(indent)
      toks.append("when {0} then {1}\n".format(when_expr, then_expr))
    toks.append(indent)
    toks.append("end")
    return ''.join(toks)

  def __gen_deep_infix_expr(self, prefix, repeat_suffix):
    expr = prefix
    for i in xrange(self.EXPR_DEPTH_LIMIT - 1):
      expr += repeat_suffix
    return expr

  def __gen_deep_func_expr(self, open_func, base_arg, close_func):
    expr = ""
    for i in xrange(self.EXPR_DEPTH_LIMIT - 1):
      expr += open_func
    expr += base_arg
    for i in xrange(self.EXPR_DEPTH_LIMIT - 1):
      expr += close_func
    return expr

  def __exec_query(self, sql_str):
    try:
      impala_ret = self.execute_query(sql_str)
      assert impala_ret.success, "Failed to execute query %s" % (sql_str)
    except Exception as e:  # consider any exception a failure
      assert False, "Failed to execute query %s: %s" % (sql_str, e)

class TestUtcTimestampFunctions(ImpalaTestSuite):
  """Tests for UTC timestamp functions, i.e. functions that do not depend on the behavior
     of the flag --use_local_tz_for_unix_timestamp_conversions. Tests added here should
     also be run in the custom cluster test test_local_tz_conversion.py to ensure they
     have the same behavior when the conversion flag is set to true."""

  @classmethod
  def add_test_dimensions(cls):
    super(TestUtcTimestampFunctions, cls).add_test_dimensions()
    # Test with and without expr rewrites to cover regular expr evaluations
    # as well as constant folding, in particular, timestamp literals.
    cls.ImpalaTestMatrix.add_dimension(
        ImpalaTestDimension('enable_expr_rewrites', *[0,1]))
    if cls.exploration_strategy() == 'core':
      # Test with file format that supports codegen
      cls.ImpalaTestMatrix.add_constraint(lambda v:\
          v.get_value('table_format').file_format == 'text' and\
          v.get_value('table_format').compression_codec == 'none')

  @classmethod
  def get_workload(cls):
    return 'functional-query'

  def test_utc_functions(self, vector):
    vector.get_value('exec_option')['enable_expr_rewrites'] = \
        vector.get_value('enable_expr_rewrites')
    self.run_test_case('QueryTest/utc-timestamp-functions', vector)