Class: Presto::Client::StatementClient

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

Constant Summary collapse

HEADERS = 
{
  "User-Agent" => "presto-ruby/#{VERSION}"
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(faraday, session, query) ⇒ StatementClient

Returns a new instance of StatementClient.



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# File 'lib/presto/client/statement_client.rb', line 38

def initialize(faraday, session, query)
  @faraday = faraday
  @faraday.headers.merge!(HEADERS)

  @session = session
  @query = query
  @closed = false
  @exception = nil
  post_query_request!
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 91

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 81

def query
  @query
end

Instance Method Details

#advance ⇒ Object

Raises:



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# File 'lib/presto/client/statement_client.rb', line 113

def advance
  if closed? || !has_next?
    return false
  end
  uri = @results.next_uri

  start = Time.now
  attempts = 0

  begin
    begin
      response = @faraday.get do |req|
        req.url uri
      end
    rescue => e
      @exception = e
      raise @exception
    end

    if response.status == 200 && !response.body.to_s.empty?
      @results = QueryResults.decode_hash(MultiJson.load(response.body))
      return true
    end

    if response.status != 503  # retry on 503 Service Unavailable
      # deterministic error
      @exception = StandardError.new("Error fetching next at #{uri} returned #{response.status}: #{response.body}")  # TODO error class
      raise @exception
    end

    attempts += 1
    sleep attempts * 0.1
  end while (Time.now - start) < 2*60*60 && !@closed

  @exception = StandardError.new("Error fetching next")  # TODO error class
  raise @exception
end

#close ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 151

def close
  return if @closed

  # cancel running statement
  if uri = @results.next_uri
    # TODO error handling
    # TODO make async reqeust and ignore response
    @faraday.delete do |req|
      req.url uri
    end
  end

  @closed = true
  nil
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 87

def closed?
  @closed
end

#current_results ⇒ Object 



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# File 'lib/presto/client/statement_client.rb', line 105

def current_results
  @results
end

#debug? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 83

def debug?
  @session.debug?
end

#exception? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 93

def exception?
  @exception
end

#has_next? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 109

def has_next?
  !!@results.next_uri
end

#query_failed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 97

def query_failed?
  @results.error != nil
end

#query_succeeded? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/presto/client/statement_client.rb', line 101

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