Class: QueueLite::Queue

Inherits:
Object
  • Object
show all
Defined in:
lib/queue_lite/queue.rb

Constant Summary collapse

READY_STATUS = 
"ready"
LOCKED_STATUS = 
"locked"
FAILED_STATUS = 
"failed"
Task = 
Data.define(:id, :data) do
  def initialize(data: nil, **)
    super
  end
end

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(db) ⇒ Queue

Returns a new instance of Queue.



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# File 'lib/queue_lite/queue.rb', line 25

def initialize(db)
  @db = db
end

Class Method Details

.build(connection_string) ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 17

def self.build(connection_string)
  db = SQLite3::Database.new(connection_string)

  new(db).tap do |instance|
    instance.prepare
  end
end

Instance Method Details

#done(id) ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 68

def done(id)
  row = db.get_first_row(<<~SQL, [LOCKED_STATUS, id])
    UPDATE queue
    SET status = ?
    WHERE id = ?
    RETURNING id, data
  SQL

  Task.new(*row)
end

#failed(id) ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 79

def failed(id)
  row = db.get_first_row(<<~SQL, [FAILED_STATUS, id])
    UPDATE queue
    SET status = ?
    WHERE id = ?
    RETURNING id, data
  SQL

  Task.new(*row)
end

#get(id) ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 90

def get(id)
  row = db.get_first_row(<<~SQL, [id])
    SELECT id, data
    FROM queue
    WHERE id = ?
    LIMIT 1
  SQL

  Task.new(*row)
end

#pop ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 51

def pop
  row = db.get_first_row(<<~SQL, [LOCKED_STATUS, READY_STATUS])
    UPDATE queue
    SET status = ?
    WHERE rowid = (SELECT rowid
                   FROM queue
                   WHERE status = ?
                   ORDER BY id
                   LIMIT 1)
    RETURNING id, data
  SQL

  return if row.nil?

  Task.new(*row)
end

#prepare ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 29

def prepare
  db.execute("PRAGMA journal_mode = 'WAL';")

  db.execute(<<~SQL)
    CREATE TABLE IF NOT EXISTS queue
    (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      data TEXT,
      status TEXT
    )
  SQL
end

#put(data) ⇒ Object 



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# File 'lib/queue_lite/queue.rb', line 42

def put(data)
  row = db.get_first_row(<<~SQL, [data, READY_STATUS])
    INSERT INTO queue(data, status) VALUES(?, ?)
    RETURNING id, data
  SQL

  Task.new(*row)
end