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# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you 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.

# Talk to an impalad through beeswax.
# Usage:
#   * impalad is a string with the host and port of the impalad
#     with which the connection should be established.
#     The format is "<hostname>:<port>"
#   * query_string is the query to be executed, as a string.
#   client = ImpalaBeeswaxClient(impalad)
#   client.connect()
#   result = client.execute(query_string)
#   where result is an object of the class ImpalaBeeswaxResult.
import time
import shlex
import getpass
import re

from beeswaxd import BeeswaxService
from beeswaxd.BeeswaxService import QueryState
from datetime import datetime
try:
  # If Exec Summary is not implemented in Impala, this cannot be imported
  from ExecStats.ttypes import TExecStats
except ImportError:
  pass
from ImpalaService import ImpalaService
from tests.util.thrift_util import create_transport
from thrift.transport.TTransport import TTransportException
from thrift.protocol import TBinaryProtocol
from thrift.Thrift import TApplicationException

# Custom exception wrapper.
# All exceptions coming from thrift/beeswax etc. go through this wrapper.
# __str__ preserves the exception type.
# TODO: Add the ability to print some of the stack.
class ImpalaBeeswaxException(Exception):
  __name__ = "ImpalaBeeswaxException"
  def __init__(self, message, inner_exception):
    self.__message = message
    self.inner_exception = inner_exception

  def __str__(self):
    return "%s:\n %s" % (self.__name__, self.__message)

class ImpalaBeeswaxResult(object):
  def __init__(self, **kwargs):
    self.query = kwargs.get('query', None)
    self.success = kwargs.get('success', False)
    # Insert returns an int, convert into list to have a uniform data type.
    # TODO: We should revisit this if we have more datatypes to deal with.
    self.data = kwargs.get('data', None)
    if not isinstance(self.data, list):
      self.data = str(self.data)
      self.data = [self.data]
    self.log = None
    self.time_taken = kwargs.get('time_taken', 0)
    self.summary = kwargs.get('summary', str())
    self.schema = kwargs.get('schema', None)
    self.runtime_profile = kwargs.get('runtime_profile', str())
    self.exec_summary = kwargs.get('exec_summary', None)

  def get_data(self):
    return self.__format_data()

  def __format_data(self):
    if self.data:
      return '\n'.join(self.data)
    return ''

  def __str__(self):
    message = ('Summary: %s\n'
               'Success: %s\n'
               'Took: %s(s)\n'
               'Data:\n%s\n'
               % (self.summary, self.success, self.time_taken,
                  self.__format_data())
              )
    return message

# Interface to beeswax. Responsible for executing queries, fetching results.
class ImpalaBeeswaxClient(object):
  # Regex applied to all tokens of a query to detect the query type.
  INSERT_REGEX = re.compile("^insert$", re.I)

  def __init__(self, impalad, use_kerberos=False, user=None, password=None,
               use_ssl=False):
    self.connected = False
    self.impalad = impalad
    self.imp_service = None
    self.transport = None
    self.use_kerberos = use_kerberos
    self.use_ssl = use_ssl
    self.user, self.password = user, password
    self.use_ldap = (self.user is not None)
    self.__query_options = {}
    self.query_states = QueryState._NAMES_TO_VALUES

  def __options_to_string_list(self):
    return ["%s=%s" % (k,v) for (k,v) in self.__query_options.iteritems()]

  def get_query_options(self):
    return self.__query_options

  def set_query_option(self, name, value):
    self.__query_options[name.upper()] = value

  def set_query_options(self, query_option_dict):
    if query_option_dict is None:
      raise ValueError, 'Cannot pass None value for query options'
    self.clear_query_options()
    for name, value in query_option_dict.iteritems():
      self.set_query_option(name, value)

  def get_query_option(self, name):
    return self.__query_options.get(name.upper())

  def clear_query_options(self):
    self.__query_options.clear()

  def connect(self):
    """Connect to impalad specified in intializing this object

    Raises an exception if the connection is unsuccesful.
    """
    try:
      self.impalad = self.impalad.split(':')
      self.transport = self.__get_transport()
      self.transport.open()
      protocol = TBinaryProtocol.TBinaryProtocol(self.transport)
      self.imp_service = ImpalaService.Client(protocol)
      self.connected = True
    except Exception, e:
      raise ImpalaBeeswaxException(self.__build_error_message(e), e)

  def close_connection(self):
    """Close the transport if it's still open"""
    if self.transport:
      self.transport.close()
    self.connected = False

  def __get_transport(self):
    """Creates the proper transport type based environment (secure vs unsecure)"""
    trans_type = 'buffered'
    if self.use_kerberos:
      trans_type = 'kerberos'
    elif self.use_ldap:
      trans_type = 'plain_sasl'
    return create_transport(host=self.impalad[0], port=int(self.impalad[1]),
                            service='impala', transport_type=trans_type, user=self.user,
                            password=self.password, use_ssl=self.use_ssl)

  def execute(self, query_string, user=None):
    """Re-directs the query to its appropriate handler, returns ImpalaBeeswaxResult"""
    # Take care of leading/trailing whitespaces.
    query_string = query_string.strip()
    start = time.time()
    start_time = datetime.now()
    handle = self.__execute_query(query_string.strip(), user=user)
    if self.__get_query_type(query_string) == 'insert':
      # DML queries are finished by this point.
      time_taken = time.time() - start

      # fetch_results() will close the query after which there is no guarantee that
      # profile and log will be available so fetch them first.
      runtime_profile = self.get_runtime_profile(handle)
      exec_summary = self.get_exec_summary_and_parse(handle)
      log = self.get_log(handle.log_context)

      result = self.fetch_results(query_string, handle)
      result.time_taken, result.start_time, result.runtime_profile, result.log = \
          time_taken, start_time, runtime_profile, log
      result.exec_summary = exec_summary
    else:
      # For SELECT queries, execution might still be ongoing. fetch_results() will block
      # until the query is completed.
      result = self.fetch_results(query_string, handle)
      result.time_taken = time.time() - start
      result.start_time = start_time
      result.exec_summary = self.get_exec_summary_and_parse(handle)
      result.log = self.get_log(handle.log_context)
      result.runtime_profile = self.get_runtime_profile(handle)
      self.close_query(handle)
    return result

  def get_exec_summary(self, handle):
    return self.__do_rpc(lambda: self.imp_service.GetExecSummary(handle))

  def get_exec_summary_and_parse(self, handle):
    """Calls GetExecSummary() for the last query handle, parses it and returns a summary
    table. Returns None in case of an error or an empty result"""
    try:
      summary = self.get_exec_summary(handle)
    except ImpalaBeeswaxException:
      summary = None

    if summary is None or summary.nodes is None:
      return None
      # If exec summary is not implemented in Impala, this function returns, so we do not
      # get the function __build_summary_table which requires TExecStats to be imported.

    output = []
    self.__build_summary_table(summary, 0, False, 0, False, output)
    return output

  def __build_summary_table(self, summary, idx, is_fragment_root, indent_level,
      new_indent_level, output):
    """NOTE: This was taken from impala_shell.py. Changes made here must be made there as
    well. TODO: This method will be a placed in a library that is shared between
    impala_shell and this file. (IMPALA-5792)

    Direct translation of Coordinator::PrintExecSummary() to recursively build a list
    of rows of summary statistics, one per exec node

    summary: the TExecSummary object that contains all the summary data

    idx: the index of the node to print

    is_fragment_root: true if the node to print is the root of a fragment (and therefore
    feeds into an exchange)

    indent_level: the number of spaces to print before writing the node's label, to give
    the appearance of a tree. The 0th child of a node has the same indent_level as its
    parent. All other children have an indent_level of one greater than their parent.

    new_indent_level: If true, this indent level is different from the previous row's.

    output: the list of rows into which to append the rows produced for this node and its
    children.

    Returns the index of the next exec node in summary.exec_nodes that should be
    processed, used internally to this method only.
    """
    attrs = ["latency_ns", "cpu_time_ns", "cardinality", "memory_used"]

    # Initialise aggregate and maximum stats
    agg_stats, max_stats = TExecStats(), TExecStats()
    for attr in attrs:
      setattr(agg_stats, attr, 0)
      setattr(max_stats, attr, 0)

    row = {}
    node = summary.nodes[idx]
    # exec_stats may not be set even if the query is FINISHED if there are fragments that
    # are still executing or that were cancelled before sending a status report.
    if node.exec_stats is not None:
      for stats in node.exec_stats:
        for attr in attrs:
          val = getattr(stats, attr)
          if val is not None:
            setattr(agg_stats, attr, getattr(agg_stats, attr) + val)
            setattr(max_stats, attr, max(getattr(max_stats, attr), val))

      if len(node.exec_stats) > 0:
        avg_time = agg_stats.latency_ns / len(node.exec_stats)
      else:
        avg_time = 0

      row["num_hosts"] = len(node.exec_stats)
      row["avg_time"] = avg_time

    # If the node is a broadcast-receiving exchange node, the cardinality of rows produced
    # is the max over all instances (which should all have received the same number of
    # rows). Otherwise, the cardinality is the sum over all instances which process
    # disjoint partitions.
    if node.is_broadcast:
      cardinality = max_stats.cardinality
    else:
      cardinality = agg_stats.cardinality

    est_stats = node.estimated_stats

    label_prefix = ""
    if indent_level > 0:
      label_prefix = "|"
      label_prefix += "  |" * (indent_level - 1)
      if new_indent_level:
        label_prefix += "--"
      else:
        label_prefix += "  "

    row["prefix"] = label_prefix
    row["operator"] = node.label
    row["max_time"] = max_stats.latency_ns
    row["num_rows"] = cardinality
    row["est_num_rows"] = est_stats.cardinality
    row["peak_mem"] = max_stats.memory_used
    row["est_peak_mem"] = est_stats.memory_used
    row["detail"] = node.label_detail
    output.append(row)

    if summary.exch_to_sender_map is not None and idx in summary.exch_to_sender_map:
      sender_idx = summary.exch_to_sender_map[idx]
      # This is an exchange node, so the sender is a fragment root, and should be printed
      # next.
      self.__build_summary_table(summary, sender_idx, True, indent_level, False, output)

    idx += 1
    if node.num_children > 0:
      first_child_output = []
      idx = \
        self.__build_summary_table(
            summary, idx, False, indent_level, False, first_child_output)
      for child_idx in xrange(1, node.num_children):
        # All other children are indented (we only have 0, 1 or 2 children for every exec
        # node at the moment)
        idx = self.__build_summary_table(
            summary, idx, False, indent_level + 1, True, output)
      output += first_child_output
    return idx

  def get_runtime_profile(self, handle):
    return self.__do_rpc(lambda: self.imp_service.GetRuntimeProfile(handle))

  def execute_query_async(self, query_string, user=None):
    """
    Executes a query asynchronously

    Issues a query and returns the query handle to the caller for processing.
    """
    query = BeeswaxService.Query()
    query.query = query_string
    query.hadoop_user = user if user is not None else getpass.getuser()
    query.configuration = self.__options_to_string_list()
    return self.__do_rpc(lambda: self.imp_service.query(query,))

  def __execute_query(self, query_string, user=None):
    """Executes a query and waits for completion"""
    handle = self.execute_query_async(query_string, user=user)
    # Wait for the query to finish execution.
    self.wait_for_completion(handle)
    return handle

  def cancel_query(self, query_id):
    return self.__do_rpc(lambda: self.imp_service.Cancel(query_id))

  def close_query(self, handle):
    self.__do_rpc(lambda: self.imp_service.close(handle))

  def wait_for_completion(self, query_handle):
    """Given a query handle, polls the coordinator waiting for the query to complete"""
    while True:
      query_state = self.get_state(query_handle)
      # if the rpc succeeded, the output is the query state
      if query_state == self.query_states["FINISHED"]:
        break
      elif query_state == self.query_states["EXCEPTION"]:
        try:
          error_log = self.__do_rpc(
            lambda: self.imp_service.get_log(query_handle.log_context))
          raise ImpalaBeeswaxException("Query aborted:" + error_log, None)
        finally:
          self.close_query(query_handle)
      time.sleep(0.05)

  def wait_for_admission_control(self, query_handle):
    """Given a query handle, polls the coordinator waiting for it to complete
      admission control processing of the query"""
    while True:
      query_state = self.get_state(query_handle)
      if query_state > self.query_states["COMPILED"]:
        break
      time.sleep(0.05)

  def get_admission_result(self, query_handle):
    """Given a query handle, returns the admission result from the query profile"""
    query_state = self.get_state(query_handle)
    if query_state > self.query_states["COMPILED"]:
      query_profile = self.get_runtime_profile(query_handle)
      admit_result = re.search(r"Admission result: (.*)", query_profile)
      if admit_result:
        return admit_result.group(1)
    return ""

  def get_default_configuration(self):
    return self.__do_rpc(lambda: self.imp_service.get_default_configuration(False))

  def get_state(self, query_handle):
    return self.__do_rpc(lambda: self.imp_service.get_state(query_handle))

  def get_log(self, query_handle):
    return self.__do_rpc(lambda: self.imp_service.get_log(query_handle))

  def refresh(self):
    """Invalidate the Impalad catalog"""
    return self.execute("invalidate metadata")

  def refresh_table(self, db_name, table_name):
    """Refresh a specific table from the catalog"""
    return self.execute("refresh %s.%s" % (db_name, table_name))

  def fetch_results(self, query_string, query_handle, max_rows = -1):
    """Fetches query results given a handle and query type (insert, use, other)"""
    query_type = self.__get_query_type(query_string)
    if query_type == 'use':
      # TODO: "use <database>" does not currently throw an error. Need to update this
      # to handle the error case once that behavior has been changed.
      return ImpalaBeeswaxResult(query=query_string, success=True, data=[])

    # Result fetching for insert is different from other queries.
    exec_result = None
    if query_type == 'insert':
      exec_result = self.__fetch_insert_results(query_handle)
    else:
      exec_result = self.__fetch_results(query_handle, max_rows)
    exec_result.query = query_string
    return exec_result

  def __fetch_results(self, handle, max_rows = -1):
    """Handles query results, returns a ImpalaBeeswaxResult object"""
    schema = self.__do_rpc(lambda: self.imp_service.get_results_metadata(handle)).schema
    # The query has finished, we can fetch the results
    result_rows = []
    while len(result_rows) < max_rows or max_rows < 0:
      fetch_rows = -1 if max_rows < 0 else max_rows - len(result_rows)
      results = self.__do_rpc(lambda: self.imp_service.fetch(handle, False, fetch_rows))
      result_rows.extend(results.data)
      if not results.has_more:
        break

    # The query executed successfully and all the data was fetched.
    exec_result = ImpalaBeeswaxResult(success=True, data=result_rows, schema=schema)
    exec_result.summary = 'Returned %d rows' % (len(result_rows))
    return exec_result

  def __fetch_insert_results(self, handle):
    """Executes an insert query"""
    result = self.__do_rpc(lambda: self.imp_service.CloseInsert(handle))
    # The insert was successful
    num_rows = sum(map(int, result.rows_modified.values()))
    data = ["%s: %s" % row for row in result.rows_modified.iteritems()]
    exec_result = ImpalaBeeswaxResult(success=True, data=data)
    exec_result.summary = "Inserted %d rows" % (num_rows,)
    return exec_result

  def __get_query_type(self, query_string):
    # Set posix=True and add "'" to escaped quotes
    # to deal with escaped quotes in string literals
    lexer = shlex.shlex(query_string.lstrip(), posix=True)
    lexer.escapedquotes += "'"
    tokens = list(lexer)
    # Do not classify explain queries as 'insert'
    if (tokens[0].lower() == "explain"):
      return tokens[0].lower()
    # Because the WITH clause may precede INSERT or SELECT queries,
    # just checking the first token is insufficient.
    if filter(self.INSERT_REGEX.match, tokens):
      return "insert"
    return tokens[0].lower()

  def __build_error_message(self, exception):
    """Construct a meaningful exception string"""
    message = str(exception)
    if isinstance(exception, BeeswaxService.BeeswaxException):
      message = exception.message
    return 'INNER EXCEPTION: %s\n MESSAGE: %s' % (exception.__class__, message)

  def __do_rpc(self, rpc):
    """Executes the RPC lambda provided with some error checking.

    Catches all the relevant exceptions and re throws them wrapped
    in a custom exception [ImpalaBeeswaxException].
    """
    if not self.connected:
      raise ImpalaBeeswaxException("Not connected", None)
    try:
      return rpc()
    except BeeswaxService.BeeswaxException, b:
      raise ImpalaBeeswaxException(self.__build_error_message(b), b)
    except TTransportException, e:
      self.connected = False
      raise ImpalaBeeswaxException(self.__build_error_message(e), e)
    except TApplicationException, t:
      raise ImpalaBeeswaxException(self.__build_error_message(t), t)
    except Exception, u:
      raise ImpalaBeeswaxException(self.__build_error_message(u), u)