Class: PerfectQueue::Backend::RDBCompatBackend

Inherits:
Object
  • Object
show all
Includes:
PerfectQueue::BackendHelper
Defined in:
lib/perfectqueue/backend/rdb_compat.rb

Defined Under Namespace

Classes: Token

Constant Summary collapse

MAX_RETRY =

KEEPALIVE = 10

10
DEFAULT_DELETE_INTERVAL = 
20

Instance Attribute Summary collapse

Attributes included from PerfectQueue::BackendHelper

#client

Instance Method Summary collapse

Methods included from PerfectQueue::BackendHelper

#close

Constructor Details

#initialize(client, config) ⇒ RDBCompatBackend

Returns a new instance of RDBCompatBackend.



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 27

def initialize(client, config)
  super

  require 'sequel'
  url = config[:url]
  @table = config[:table]
  unless @table
    raise ConfigError, ":table option is required"
  end

  #password = config[:password]
  #user = config[:user]
  @db = Sequel.connect(url, :max_connections=>1)
  @mutex = Mutex.new

  connect {
    # connection test
  }

  if config[:disable_resource_limit]
    @sql = "SELECT id, timeout, data, created_at, resource\nFROM `\#{@table}`\nWHERE timeout <= ? AND timeout <= ? AND created_at IS NOT NULL\nORDER BY timeout ASC\nLIMIT ?\n"
  else
    @sql = "SELECT id, timeout, data, created_at, resource, max_running, max_running/running AS weight\nFROM `\#{@table}`\nLEFT JOIN (\n  SELECT resource AS res, COUNT(1) AS running\n  FROM `\#{@table}` AS T\n  WHERE timeout > ? AND created_at IS NOT NULL AND resource IS NOT NULL\n  GROUP BY resource\n) AS R ON resource = res\nWHERE timeout <= ? AND created_at IS NOT NULL AND (max_running-running IS NULL OR max_running-running > 0)\nORDER BY weight IS NOT NULL, weight DESC, timeout ASC\nLIMIT ?\n"
  end

  case url.split('//',2)[0].to_s
  when /sqlite/i
    # sqlite always locks tables on BEGIN
    @table_lock = nil
  when /mysql/i
    if config[:disable_resource_limit]
      @table_lock = "LOCK TABLES `#{@table}` WRITE"
    else
      @table_lock = "LOCK TABLES `#{@table}` WRITE, `#{@table}` AS T WRITE"
    end
  else
    @table_lock = "LOCK TABLE `#{@table}`"
  end

  @prefetch_break_types = config[:prefetch_break_types] || []

  @cleanup_interval = config[:cleanup_interval] || DEFAULT_DELETE_INTERVAL
  @cleanup_interval_count = 0
end

Instance Attribute Details

#db ⇒ Object (readonly)

Returns the value of attribute db.



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 90

def db
  @db
end

Instance Method Details

#acquire(alive_time, max_acquire, options) ⇒ Object

> [AcquiredTask]



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 187

def acquire(alive_time, max_acquire, options)
  now = (options[:now] || Time.now).to_i
  next_timeout = now + alive_time

  tasks = []

  connect {
    if @cleanup_interval_count <= 0
      @db["DELETE FROM `#{@table}` WHERE timeout <= ? AND created_at IS NULL", now].delete
      @cleanup_interval_count = @cleanup_interval
    end

    @db.transaction do
      if @table_lock
        @db[@table_lock].update
      end

      tasks = []
      @db.fetch(@sql, now, now, max_acquire) {|row|
        attributes = create_attributes(nil, row)
        task_token = Token.new(row[:id])
        task = AcquiredTask.new(@client, row[:id], attributes, task_token)
        tasks.push task

        if @prefetch_break_types.include?(attributes[:type])
          break
        end
      }

      if tasks.empty?
        return nil
      end

      sql = "UPDATE `#{@table}` SET timeout=? WHERE id IN ("
      params = [sql, next_timeout]
      tasks.each {|t| params << t.key }
      sql << (1..tasks.size).map { '?' }.join(',')
      sql << ") AND created_at IS NOT NULL"

      n = @db[*params].update
      if n != tasks.size
        # TODO table lock doesn't work. error?
      end

      @cleanup_interval_count -= 1
    end
    return tasks
  }
end

#cancel_request(key, options) ⇒ Object

> nil



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 238

def cancel_request(key, options)
  now = (options[:now] || Time.now).to_i

  # created_at=0 means cancel_requested
  connect {
    n = @db["UPDATE `#{@table}` SET created_at=0 WHERE id=? AND created_at IS NOT NULL", key].update
    if n <= 0
      raise AlreadyFinishedError, "task key=#{key} does not exist or already finished."
    end
  }
  nil
end

#finish(task_token, retention_time, options) ⇒ Object

> nil



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 256

def finish(task_token, retention_time, options)
  now = (options[:now] || Time.now).to_i
  delete_timeout = now + retention_time
  key = task_token.key

  connect {
    n = @db["UPDATE `#{@table}` SET timeout=?, created_at=NULL, resource=NULL WHERE id=? AND created_at IS NOT NULL", delete_timeout, key].update
    if n <= 0
      raise IdempotentAlreadyFinishedError, "task key=#{key} does not exist or already finished."
    end
  }
  nil
end

#force_finish(key, retention_time, options) ⇒ Object 



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 251

def force_finish(key, retention_time, options)
  finish(Token.new(key), retention_time, options)
end

#get_task_metadata(key, options) ⇒ Object

> TaskStatus



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 113

def get_task_metadata(key, options)
  now = (options[:now] || Time.now).to_i

  connect {
    row = @db.fetch("SELECT timeout, data, created_at, resource, max_running FROM `#{@table}` WHERE id=? LIMIT 1", key).first
    unless row
      raise NotFoundError, "task key=#{key} does no exist"
    end
    attributes = create_attributes(now, row)
    return TaskMetadata.new(@client, key, attributes)
  }
end

#heartbeat(task_token, alive_time, options) ⇒ Object

> nil



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 271

def heartbeat(task_token, alive_time, options)
  now = (options[:now] || Time.now).to_i
  next_timeout = now + alive_time
  key = task_token.key
  data = options[:data]

  sql = "UPDATE `#{@table}` SET timeout=?"
  params = [sql, next_timeout]
  if data
    sql << ", data=?"
    params << data.to_json
  end
  sql << " WHERE id=? AND created_at IS NOT NULL"
  params << key

  connect {
    n = @db[*params].update
    if n <= 0
      row = @db.fetch("SELECT id, timeout, created_at FROM `#{@table}` WHERE id=? LIMIT 1", key).first
      if row == nil
        raise PreemptedError, "task key=#{key} does not exist or preempted."
      elsif row[:created_at] == nil
        raise PreemptedError, "task key=#{key} preempted."
      elsif row[:created_at] <= 0
        raise CancelRequestedError, "task key=#{key} is cancel requested."
      else # row[:timeout] == next_timeout
        # ok
      end
    end
  }
  nil
end

#init_database(options) ⇒ Object 



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 96

def init_database(options)
  sql = %[
      CREATE TABLE IF NOT EXISTS `#{@table}` (
        id VARCHAR(256) NOT NULL,
        timeout INT NOT NULL,
        data BLOB NOT NULL,
        created_at INT,
        resource VARCHAR(256),
        max_running INT,
        PRIMARY KEY (id)
      );]
  connect {
    @db.run sql
  }
end

#list(options, &block) ⇒ Object

yield [TaskWithMetadata]



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 132

def list(options, &block)
  now = (options[:now] || Time.now).to_i

  connect {
    #@db.fetch("SELECT id, timeout, data, created_at, resource FROM `#{@table}` WHERE !(created_at IS NULL AND timeout <= ?) ORDER BY timeout ASC;", now) {|row|
    @db.fetch("SELECT id, timeout, data, created_at, resource, max_running FROM `#{@table}` ORDER BY timeout ASC", now) {|row|
      attributes = create_attributes(now, row)
      task = TaskWithMetadata.new(@client, row[:id], attributes)
      yield task
    }
  }
end

#preempt(key, alive_time, options) ⇒ Object

> AcquiredTask

Raises:



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 127

def preempt(key, alive_time, options)
  raise NotSupportedError.new("preempt is not supported by rdb_compat backend")
end

#release(task_token, alive_time, options) ⇒ Object 



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 304

def release(task_token, alive_time, options)
  heartbeat(task_token, alive_time, options)
end

#submit(key, type, data, options) ⇒ Object

> Task



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# File 'lib/perfectqueue/backend/rdb_compat.rb', line 146

def submit(key, type, data, options)
  now = (options[:now] || Time.now).to_i
  now = 1 if now < 1  # 0 means cancel requested
  run_at = (options[:run_at] || now).to_i
  user = options[:user]
  user = user.to_s if user
  max_running = options[:max_running]
  data = data ? data.dup : {}
  data['type'] = type

  d = data.to_json

  if options[:compression] == 'gzip'
    require 'zlib'
    require 'stringio'
    io = StringIO.new
    gz = Zlib::GzipWriter.new(io)
    begin
      gz.write(d)
    ensure
      gz.close
    end
    d = io.string
    d.force_encoding('ASCII-8BIT') if d.respond_to?(:force_encoding)
    d = Sequel::SQL::Blob.new(d)
  end

  connect {
    begin
      n = @db[
        "INSERT INTO `#{@table}` (id, timeout, data, created_at, resource, max_running) VALUES (?, ?, ?, ?, ?, ?)",
        key, run_at, d, now, user, max_running
      ].insert
      return Task.new(@client, key)
    rescue Sequel::DatabaseError
      raise IdempotentAlreadyExistsError, "task key=#{key} already exists"
    end
  }
end