Class: Presto::Client::StatementClient

Inherits:
Object
  • Object
show all
Defined in:
lib/presto/client/statement_client.rb

Constant Summary collapse

JSON_OPTIONS =

Presto can return too deep nested JSON

{
    :max_nesting => false
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(faraday, query, options, next_uri = nil) ⇒ StatementClient

Returns a new instance of StatementClient.



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# File 'lib/presto/client/statement_client.rb', line 29

def initialize(faraday, query, options, next_uri=nil)
  @faraday = faraday

  @options = options
  @query = query
  @closed = false
  @exception = nil
  @retry_timeout = options[:retry_timeout] || 120
  if model_version = @options[:model_version]
    @models = ModelVersions.const_get("V#{model_version.gsub(".", "_")}")
  else
    @models = Models
  end

  @plan_timeout = options[:plan_timeout]
  @query_timeout = options[:query_timeout]

  if @plan_timeout || @query_timeout
    # this is set before the first call of faraday_get_with_retry so that
    # resuming StatementClient with next_uri is also under timeout control.
    @started_at = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  end

  if next_uri
    response = faraday_get_with_retry(next_uri)
    @results_headers = response.headers
    @results = @models::QueryResults.decode(parse_body(response))
  else
    post_query_request!
  end
end

Instance Attribute Details

#exception ⇒ Object (readonly)

Returns the value of attribute exception.



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# File 'lib/presto/client/statement_client.rb', line 98

def exception
  @exception
end

#query ⇒ Object (readonly)

Returns the value of attribute query.



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# File 'lib/presto/client/statement_client.rb', line 88

def query
  @query
end

Instance Method Details

#advance ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 124

def advance
  if closed? || !has_next?
    return false
  end

  uri = @results.next_uri
  response = faraday_get_with_retry(uri)
  @results_headers = response.headers
  @results = decode_model(uri, parse_body(response), @models::QueryResults)

  raise_if_timeout!

  return true
end

#cancel_leaf_stage ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 243

def cancel_leaf_stage
  if uri = @results.partial_cancel_uri
    @faraday.delete do |req|
      req.url uri
    end
  end
end

#close ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 251

def close
  return if @closed

  begin
    if uri = @results.next_uri
      @faraday.delete do |req|
        req.url uri
      end
    end
  rescue => e
  end

  @closed = true
  nil
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 94

def closed?
  @closed
end

#current_results ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 112

def current_results
  @results
end

#current_results_headers ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 116

def current_results_headers
  @results_headers
end

#debug? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 90

def debug?
  !!@options[:debug]
end

#exception? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 100

def exception?
  @exception
end

#faraday_get_with_retry(uri, &block) ⇒ Object

Raises:



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# File 'lib/presto/client/statement_client.rb', line 176

def faraday_get_with_retry(uri, &block)
  start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  attempts = 0

  begin
    begin
      response = @faraday.get(uri)
    rescue Faraday::Error::TimeoutError, Faraday::Error::ConnectionFailed
      # temporally error to retry
      response = nil
    rescue => e
      @exception = e
      raise @exception
    end

    if response
      if response.status == 200 && !response.body.to_s.empty?
        return response
      end

      if response.status != 503  # retry only if 503 Service Unavailable
        # deterministic error
        @exception = PrestoHttpError.new(response.status, "Presto API error at #{uri} returned #{response.status}: #{response.body}")
        raise @exception
      end
    end

    raise_if_timeout!

    attempts += 1
    sleep attempts * 0.1
  end while (Process.clock_gettime(Process::CLOCK_MONOTONIC) - start) < @retry_timeout && !@closed

  @exception = PrestoHttpError.new(408, "Presto API error due to timeout")
  raise @exception
end

#has_next? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 120

def has_next?
  !!@results.next_uri
end

#query_failed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 104

def query_failed?
  @results.error != nil
end

#query_info ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 139

def query_info
  uri = "/v1/query/#{@results.id}"
  response = faraday_get_with_retry(uri)
  decode_model(uri, parse_body(response), @models::QueryInfo)
end

#query_succeeded? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 108

def query_succeeded?
  @results.error == nil && !@exception && !@closed
end

#raise_if_timeout! ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 213

def raise_if_timeout!
  if @started_at
    if @results && @results.next_uri == nil
      # query is already done
      return
    end

    elapsed = Process.clock_gettime(Process::CLOCK_MONOTONIC) - @started_at

    if @query_timeout && elapsed > @query_timeout
      raise_timeout_error!
    end

    if @plan_timeout && (@results == nil || @results.columns == nil) &&
        elapsed > @plan_timeout
      # @results is not set (even first faraday_get_with_retry isn't called yet) or
      # result from Presto doesn't include result schema. Query planning isn't done yet.
      raise_timeout_error!
    end
  end
end

#raise_timeout_error! ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 235

def raise_timeout_error!
  if query_id = @results && @results.id
    raise PrestoQueryTimeoutError, "Query #{query_id} timed out"
  else
    raise PrestoQueryTimeoutError, "Query timed out"
  end
end