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

DELETE_OFFSET =

timeout model

0 —- now-1Bs —- retention —|—– now – alive ——- FUTURE

~~~~~~~^  to be deleted ^      |~~~^~~~       ^ running or in-queue
 DELETE          13_0000_0000->|   to be acquired

NOTE: this architecture introduces Year 2042 problem.

10_0000_0000
EVENT_HORIZON =

2011-03-13 07:06:40 UTC

13_0000_0000
LOCK_RETRY_INITIAL_INTERVAL = 
0.5
LOCK_RETRY_MAX_INTERVAL = 
30
KEEPALIVE = 
10
MAX_RETRY = 
10
LOCK_WAIT_TIMEOUT = 
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.



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 42

def initialize(client, config)
  super

  @pq_connect_timeout = config.fetch(:pq_connect_timeout, 20)
  url = config[:url]
  @table = config[:table]
  unless @table
    raise ConfigError, ":table option is required"
  end

  if /\Amysql2:/i =~ url
    options = {max_connections: 1, sslca: config[:sslca]}
    options[:connect_timeout] = config.fetch(:connect_timeout, 3)
    @db = Sequel.connect(url, options)
    if config.fetch(:use_connection_pooling, nil) != nil
      @use_connection_pooling = !!config[:use_connection_pooling]
    else
      @use_connection_pooling = !!config[:sslca]
    end
    @table_lock = lambda {
      locked = nil
      interval = LOCK_RETRY_INITIAL_INTERVAL
      loop do
        @db.fetch("SELECT GET_LOCK('#{@table}', #{LOCK_WAIT_TIMEOUT}) locked") do |row|
          locked = true if row[:locked] == 1
        end
        break if locked
        sleep interval
        interval = [interval * 2, LOCK_RETRY_MAX_INTERVAL].min
      end
    }
    @table_unlock = lambda {
      @db.run("DO RELEASE_LOCK('#{@table}')")
    }
  else
    raise ConfigError, "only 'mysql' is supported"
  end

  @last_time = Time.now.to_i
  @mutex = Mutex.new

  connect {
    # connection test
  }

  @disable_resource_limit = config[:disable_resource_limit]
  @cleanup_interval = config[:cleanup_interval] || DEFAULT_DELETE_INTERVAL
  # If cleanup_interval > max_request_per_child / max_acquire,
  # some processes won't run DELETE query.
  # (it's not an issue when there are enough workers)
  @cleanup_interval_count = @cleanup_interval > 0 ? rand(@cleanup_interval) : 0
end

Instance Attribute Details

#db ⇒ Object (readonly)

Returns the value of attribute db.



95
96
97
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 95

def db
  @db
end

Instance Method Details

#acquire(alive_time, max_acquire, options) ⇒ Object

> [AcquiredTask]



198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 198

def acquire(alive_time, max_acquire, options)
  now = (options[:now] || Time.now).to_i
  next_timeout = now + alive_time
  t0 = nil

  if @cleanup_interval_count <= 0
    connect {
      t0=Process.clock_gettime(Process::CLOCK_MONOTONIC)
      @db["DELETE FROM `#{@table}` WHERE timeout <= ?", now-DELETE_OFFSET].delete
      @cleanup_interval_count = @cleanup_interval
      STDERR.puts"PQ:delete from #{@table}:%6f sec" % [Process.clock_gettime(Process::CLOCK_MONOTONIC)-t0]
    }
  end

  if @disable_resource_limit
    return acquire_without_resource(next_timeout, now, max_acquire)
  else
    return acquire_with_resource(next_timeout, now, max_acquire)
  end
end

#compress_data(data, compression) ⇒ Object 



156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 156

def compress_data(data, compression)
  if compression == 'gzip'
    io = StringIO.new
    io.set_encoding(Encoding::ASCII_8BIT)
    gz = Zlib::GzipWriter.new(io)
    begin
      gz.write(data)
    ensure
      gz.close
    end
    data = io.string
    data = Sequel::SQL::Blob.new(data)
  end
  data
end

#finish(task_token, retention_time, options) ⇒ Object

> nil



224
225
226
227
228
229
230
231
232
233
234
235
236
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 224

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



219
220
221
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 219

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

#get_task_metadata(key, options) ⇒ Object

> TaskStatus



125
126
127
128
129
130
131
132
133
134
135
136
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 125

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



239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 239

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 << compress_data(data.to_json, options[:compression])
  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."
      else # row[:timeout] == next_timeout
        # ok
      end
    end
  }
  nil
end

#init_database(options) ⇒ Object 



102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 102

def init_database(options)
  sql = []
  sql << "DROP TABLE IF EXISTS `#{@table}`" if options[:force]
  sql << <<-SQL
    CREATE TABLE IF NOT EXISTS `#{@table}` (
      id VARCHAR(255) NOT NULL,
      timeout INT NOT NULL,
      data LONGBLOB NOT NULL,
      created_at INT,
      resource VARCHAR(255),
      max_running INT,
      /* CONNECTION_ID() can be 64bit: https://bugs.mysql.com/bug.php?id=19806 */
      owner BIGINT(21) UNSIGNED NOT NULL DEFAULT 0,
      PRIMARY KEY (id)
    )
    SQL
  sql << "CREATE INDEX `index_#{@table}_on_timeout` ON `#{@table}` (`timeout`)"
  connect {
    sql.each(&@db.method(:run))
  }
end

#list(options, &block) ⇒ Object

yield [TaskWithMetadata]



144
145
146
147
148
149
150
151
152
153
154
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 144

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

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

#preempt(key, alive_time, options) ⇒ Object

> AcquiredTask

Raises:



139
140
141
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 139

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 



270
271
272
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 270

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

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

> Task



173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 173

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 = compress_data(data.to_json, options[:compression])

  connect {
    begin
      @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::UniqueConstraintViolation
      raise IdempotentAlreadyExistsError, "task key=#{key} already exists"
    end
  }
end