Class: Refile::Postgres::Backend::Reader

Inherits:
Object
  • Object
show all
Includes:
SmartTransaction
Defined in:
lib/refile/postgres/backend/reader.rb

Constant Summary collapse

STREAM_CHUNK_SIZE = 
16384

Constants included from SmartTransaction

SmartTransaction::INIT_CONNECTION_ARG_ERROR_MSG, SmartTransaction::PQTRANS_INTRANS

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from SmartTransaction

#ensure_in_transaction, #smart_transaction, #with_connection

Constructor Details

#initialize(connection_or_proc, oid) ⇒ Reader

Returns a new instance of Reader.



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# File 'lib/refile/postgres/backend/reader.rb', line 8

def initialize(connection_or_proc, oid)
  @connection_or_proc = connection_or_proc
  @oid = oid.to_s.to_i
  @closed = false
  @pos = 0
end

Instance Attribute Details

#oid ⇒ Object (readonly)

Returns the value of attribute oid.



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# File 'lib/refile/postgres/backend/reader.rb', line 15

def oid
  @oid
end

#pos ⇒ Object (readonly)

Returns the value of attribute pos.



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# File 'lib/refile/postgres/backend/reader.rb', line 15

def pos
  @pos
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/refile/postgres/backend/reader.rb', line 61

def close
  @closed = true
end

#each ⇒ Object 



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# File 'lib/refile/postgres/backend/reader.rb', line 47

def each
  if block_given?
    until eof?
      yield(read(STREAM_CHUNK_SIZE))
    end
  else
    to_enum
  end
end

#eof? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/refile/postgres/backend/reader.rb', line 39

def eof?
  with_connection do |connection|
    smart_transaction(connection) do |descriptor|
      @pos == size
    end
  end
end

#read(length = nil, buffer = nil) ⇒ Object 



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# File 'lib/refile/postgres/backend/reader.rb', line 17

def read(length = nil, buffer = nil)
  result = if length
    raise "closed" if @closed
    with_connection do |connection|
      smart_transaction(connection) do |descriptor|
        connection.lo_lseek(descriptor, @pos, PG::SEEK_SET)
        data = connection.lo_read(descriptor, length)
        @pos = connection.lo_tell(descriptor)
        data
      end
    end
  else
    with_connection do |connection|
      smart_transaction(connection) do |descriptor|
        connection.lo_read(descriptor, size)
      end
    end
  end
  buffer.replace(result) if buffer and result
  result
end

#size ⇒ Object 



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# File 'lib/refile/postgres/backend/reader.rb', line 57

def size
  @size ||= fetch_size
end