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
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 42

def initialize(client, config)
  super

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

  if /\Amysql2:/i =~ url
    @db = Sequel.connect(url, {max_connections: 1, sslca: config[:sslca]})
    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
  }

  if config[:disable_resource_limit]
    @sql = <<SQL
SELECT id, timeout, data, created_at, resource
FROM `#{@table}`
WHERE #{EVENT_HORIZON} < timeout AND timeout <= ? AND timeout <= ?
AND created_at IS NOT NULL
ORDER BY timeout ASC
LIMIT ?
SQL
  else
    @sql = <<SQL
SELECT id, timeout, data, created_at, resource, max_running, IFNULL(max_running, 1) / (IFNULL(running, 0) + 1) AS weight
FROM `#{@table}`
LEFT JOIN (
  SELECT resource AS res, COUNT(1) AS running
  FROM `#{@table}` AS T
  WHERE timeout > ? AND created_at IS NOT NULL AND resource IS NOT NULL
  GROUP BY resource
) AS R ON resource = res
WHERE #{EVENT_HORIZON} < timeout AND timeout <= ?
AND created_at IS NOT NULL
AND (max_running-running IS NULL OR max_running-running > 0)
ORDER BY weight DESC, timeout ASC
LIMIT ?
SQL
  end

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

  @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.



120
121
122
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 120

def db
  @db
end

Instance Method Details

#acquire(alive_time, max_acquire, options) ⇒ Object

> [AcquiredTask]



221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
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
269
270
271
272
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 221

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

  if @cleanup_interval_count <= 0
    connect { # TODO: HERE should be still connect_locked ?
      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

  connect_locked {
    t0=Process.clock_gettime(Process::CLOCK_MONOTONIC)
    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}` FORCE INDEX (PRIMARY) SET timeout=? WHERE timeout <= ? AND id IN ("
    params = [sql, next_timeout, now]
    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
      # NOTE table lock doesn't work. error!
      return nil
    end

    @cleanup_interval_count -= 1

    return tasks
  }
ensure
  STDERR.puts "PQ:acquire from #{@table}:%6f sec (%d tasks)" % [Process.clock_gettime(Process::CLOCK_MONOTONIC)-t0,tasks.size] if tasks
end

#cancel_request(key, options) ⇒ Object

> nil



275
276
277
278
279
280
281
282
283
284
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 275

def cancel_request(key, options)
  # 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

#compress_data(data, compression) ⇒ Object 



179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 179

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



291
292
293
294
295
296
297
298
299
300
301
302
303
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 291

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 



286
287
288
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 286

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

#get_task_metadata(key, options) ⇒ Object

> TaskStatus



148
149
150
151
152
153
154
155
156
157
158
159
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 148

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



306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 306

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 



127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 127

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,
      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]



167
168
169
170
171
172
173
174
175
176
177
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 167

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:



162
163
164
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 162

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 



337
338
339
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 337

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

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

> Task



196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
 
# File 'lib/perfectqueue/backend/rdb_compat.rb', line 196

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