Class: Fluent::Plugin::Buffer

Inherits:
Base
  • Object
show all
Includes:
OwnedByMixin, Fluent::PluginHelper::Mixin, Fluent::PluginId, UniqueId::Mixin, MonitorMixin
Defined in:
lib/fluent/plugin/buffer/chunk.rb,
lib/fluent/plugin/buffer.rb,
lib/fluent/plugin/buffer/file_chunk.rb,
lib/fluent/plugin/buffer/memory_chunk.rb,
lib/fluent/plugin/buffer/file_single_chunk.rb

Overview

fluent/plugin/buffer is already loaded

Direct Known Subclasses

FileBuffer, FileSingleBuffer, MemoryBuffer

Defined Under Namespace

Classes: BufferChunkOverflowError, BufferError, BufferOverflowError, Chunk, FileChunk, FileSingleChunk, MemoryChunk, Metadata, ShouldRetry

Constant Summary collapse

MINIMUM_APPEND_ATTEMPT_RECORDS = 
10
DEFAULT_CHUNK_LIMIT_SIZE =

8MB

8 * 1024 * 1024
DEFAULT_TOTAL_LIMIT_SIZE =

512MB, same with v0.12 (BufferedOutput + buf_memory: 64 x 8MB)

512 * 1024 * 1024
DEFAULT_CHUNK_FULL_THRESHOLD = 
0.95
STATS_KEYS = 
[
  'stage_length',
  'stage_byte_size',
  'queue_length',
  'queue_byte_size',
  'available_buffer_space_ratios',
  'total_queued_size',
  'oldest_timekey',
  'newest_timekey'
]

Constants included from Configurable

Configurable::CONFIG_TYPE_REGISTRY

Instance Attribute Summary collapse

Attributes inherited from Base

#under_plugin_development

Instance Method Summary collapse

Methods included from Fluent::PluginHelper::Mixin

included

Methods included from Fluent::PluginId

#plugin_id, #plugin_id_configured?, #plugin_id_for_test?, #plugin_root_dir, #stop

Methods included from UniqueId::Mixin

#dump_unique_id_hex, #generate_unique_id

Methods included from OwnedByMixin

#log, #owner, #owner=

Methods inherited from Base

#acquire_worker_lock, #after_shutdown, #after_shutdown?, #after_start, #after_started?, #before_shutdown, #before_shutdown?, #called_in_test?, #closed?, #configured?, #context_router, #context_router=, #fluentd_worker_id, #get_lock_path, #has_router?, #inspect, #multi_workers_ready?, #plugin_root_dir, #reloadable_plugin?, #shutdown, #shutdown?, #started?, #stop, #stopped?, #string_safe_encoding, #terminated?

Methods included from SystemConfig::Mixin

#system_config, #system_config_override

Methods included from Configurable

#config, #configure_proxy_generate, #configured_section_create, included, lookup_type, register_type

Constructor Details

#initialize ⇒ Buffer

Returns a new instance of Buffer.



172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
 
# File 'lib/fluent/plugin/buffer.rb', line 172

def initialize
  super

  @chunk_limit_size = nil
  @total_limit_size = nil
  @queue_limit_length = nil
  @chunk_limit_records = nil

  @stage = {}    #=> Hash (metadata -> chunk) : not flushed yet
  @queue = []    #=> Array (chunks)           : already flushed (not written)
  @dequeued = {} #=> Hash (unique_id -> chunk): already written (not purged)
  @queued_num = {} # metadata => int (number of queued chunks)
  @dequeued_num = {} # metadata => int (number of dequeued chunks)

  @stage_length_metrics = nil
  @stage_size_metrics = nil
  @queue_length_metrics = nil
  @queue_size_metrics = nil
  @available_buffer_space_ratios_metrics = nil
  @total_queued_size_metrics = nil
  @newest_timekey_metrics = nil
  @oldest_timekey_metrics = nil
  @timekeys = Hash.new(0)
  @enable_update_timekeys = false
  @mutex = Mutex.new
end

Instance Attribute Details

#available_buffer_space_ratios_metrics ⇒ Object (readonly)

Returns the value of attribute available_buffer_space_ratios_metrics.



167
168
169
 
# File 'lib/fluent/plugin/buffer.rb', line 167

def available_buffer_space_ratios_metrics
  @available_buffer_space_ratios_metrics
end

#dequeued ⇒ Object (readonly)

for tests



170
171
172
 
# File 'lib/fluent/plugin/buffer.rb', line 170

def dequeued
  @dequeued
end

#newest_timekey_metrics ⇒ Object (readonly)

Returns the value of attribute newest_timekey_metrics.



168
169
170
 
# File 'lib/fluent/plugin/buffer.rb', line 168

def newest_timekey_metrics
  @newest_timekey_metrics
end

#oldest_timekey_metrics ⇒ Object (readonly)

Returns the value of attribute oldest_timekey_metrics.



168
169
170
 
# File 'lib/fluent/plugin/buffer.rb', line 168

def oldest_timekey_metrics
  @oldest_timekey_metrics
end

#queue ⇒ Object (readonly)

for tests



170
171
172
 
# File 'lib/fluent/plugin/buffer.rb', line 170

def queue
  @queue
end

#queue_length_metrics ⇒ Object (readonly)

for metrics



166
167
168
 
# File 'lib/fluent/plugin/buffer.rb', line 166

def queue_length_metrics
  @queue_length_metrics
end

#queue_size_metrics ⇒ Object (readonly)

for metrics



166
167
168
 
# File 'lib/fluent/plugin/buffer.rb', line 166

def queue_size_metrics
  @queue_size_metrics
end

#queued_num ⇒ Object (readonly)

for tests



170
171
172
 
# File 'lib/fluent/plugin/buffer.rb', line 170

def queued_num
  @queued_num
end

#stage ⇒ Object (readonly)

for tests



170
171
172
 
# File 'lib/fluent/plugin/buffer.rb', line 170

def stage
  @stage
end

#stage_length_metrics ⇒ Object (readonly)

for metrics



166
167
168
 
# File 'lib/fluent/plugin/buffer.rb', line 166

def stage_length_metrics
  @stage_length_metrics
end

#stage_size_metrics ⇒ Object (readonly)

for metrics



166
167
168
 
# File 'lib/fluent/plugin/buffer.rb', line 166

def stage_size_metrics
  @stage_size_metrics
end

#total_queued_size_metrics ⇒ Object (readonly)

Returns the value of attribute total_queued_size_metrics.



167
168
169
 
# File 'lib/fluent/plugin/buffer.rb', line 167

def total_queued_size_metrics
  @total_queued_size_metrics
end

Instance Method Details

#backup(chunk_unique_id) ⇒ Object 



918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
 
# File 'lib/fluent/plugin/buffer.rb', line 918

def backup(chunk_unique_id)
  unique_id = dump_unique_id_hex(chunk_unique_id)

  if @disable_chunk_backup
    log.warn "disable_chunk_backup is true. #{unique_id} chunk is not backed up."
    return
  end

  safe_owner_id = owner.plugin_id.gsub(/[ "\/\\:;|*<>?]/, '_')
  backup_base_dir = system_config.root_dir || DEFAULT_BACKUP_DIR
  backup_file = File.join(backup_base_dir, 'backup', "worker#{fluentd_worker_id}", safe_owner_id, "#{unique_id}.log")
  backup_dir = File.dirname(backup_file)

  log.warn "bad chunk is moved to #{backup_file}"
  FileUtils.mkdir_p(backup_dir, mode: system_config.dir_permission || Fluent::DEFAULT_DIR_PERMISSION) unless Dir.exist?(backup_dir)
  File.open(backup_file, 'ab', system_config.file_permission || Fluent::DEFAULT_FILE_PERMISSION) { |f| yield f }
end

#chunk_size_full?(chunk) ⇒ Boolean

Returns:

  • (Boolean) 


641
642
643
 
# File 'lib/fluent/plugin/buffer.rb', line 641

def chunk_size_full?(chunk)
  chunk.bytesize >= @chunk_limit_size * @chunk_full_threshold || (@chunk_limit_records && chunk.size >= @chunk_limit_records * @chunk_full_threshold)
end

#chunk_size_over?(chunk) ⇒ Boolean

Returns:

  • (Boolean) 


637
638
639
 
# File 'lib/fluent/plugin/buffer.rb', line 637

def chunk_size_over?(chunk)
  chunk.bytesize > @chunk_limit_size || (@chunk_limit_records && chunk.size > @chunk_limit_records)
end

#clear_queue! ⇒ Object 



619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
 
# File 'lib/fluent/plugin/buffer.rb', line 619

def clear_queue!
  log.on_trace { log.trace "clearing queue", instance: self.object_id }

  synchronize do
    until @queue.empty?
      begin
        q = @queue.shift
        log.trace("purging a chunk in queue"){ {id: dump_unique_id_hex(chunk.unique_id), bytesize: chunk.bytesize, size: chunk.size} }
        q.purge
      rescue => e
        log.error "unexpected error while clearing buffer queue", error_class: e.class, error: e
        log.error_backtrace
      end
    end
    @queue_size_metrics.set(0)
  end
end

#close ⇒ Object 



269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
 
# File 'lib/fluent/plugin/buffer.rb', line 269

def close
  super
  synchronize do
    log.debug "closing buffer", instance: self.object_id
    @dequeued.each_pair do |chunk_id, chunk|
      chunk.close
    end
    until @queue.empty?
      @queue.shift.close
    end
    @stage.each_pair do |metadata, chunk|
      chunk.close
    end
  end
end

#configure(conf) ⇒ Object 



219
220
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
 
# File 'lib/fluent/plugin/buffer.rb', line 219

def configure(conf)
  super

  unless @queue_limit_length.nil?
    @total_limit_size = @chunk_limit_size * @queue_limit_length
  end
  @stage_length_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "stage_length",
                                         help_text: 'Length of stage buffers', prefer_gauge: true)
  @stage_length_metrics.set(0)
  @stage_size_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "stage_byte_size",
                                       help_text: 'Total size of stage buffers', prefer_gauge: true)
  @stage_size_metrics.set(0) # Ensure zero.
  @queue_length_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "queue_length",
                                         help_text: 'Length of queue buffers', prefer_gauge: true)
  @queue_length_metrics.set(0)
  @queue_size_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "queue_byte_size",
                                       help_text: 'Total size of queue buffers', prefer_gauge: true)
  @queue_size_metrics.set(0) # Ensure zero.
  @available_buffer_space_ratios_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "available_buffer_space_ratios",
                                                          help_text: 'Ratio of available space in buffer', prefer_gauge: true)
  @available_buffer_space_ratios_metrics.set(100) # Default is 100%.
  @total_queued_size_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "total_queued_size",
                                              help_text: 'Total size of stage and queue buffers', prefer_gauge: true)
  @total_queued_size_metrics.set(0)
  @newest_timekey_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "newest_timekey",
                                           help_text: 'Newest timekey in buffer', prefer_gauge: true)
  @oldest_timekey_metrics = metrics_create(namespace: "fluentd", subsystem: "buffer", name: "oldest_timekey",
                                           help_text: 'Oldest timekey in buffer', prefer_gauge: true)
end

#dequeue_chunk ⇒ Object 



557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
 
# File 'lib/fluent/plugin/buffer.rb', line 557

def dequeue_chunk
  return nil if @queue.empty?
  log.on_trace { log.trace "dequeueing a chunk", instance: self.object_id }

  synchronize do
    chunk = @queue.shift

    # this buffer is dequeued by other thread just before "synchronize" in this thread
    return nil unless chunk

    @dequeued[chunk.unique_id] = chunk
    @queued_num[chunk.metadata] -= 1 # BUG if nil, 0 or subzero
    @dequeued_num[chunk.metadata] ||= 0
    @dequeued_num[chunk.metadata] += 1
    log.trace "chunk dequeued", instance: self.object_id, metadata: chunk.metadata
    chunk
  end
end

#enable_update_timekeys ⇒ Object 



249
250
251
 
# File 'lib/fluent/plugin/buffer.rb', line 249

def enable_update_timekeys
  @enable_update_timekeys = true
end

#enqueue_all(force_enqueue = false) ⇒ Object

At flush_at_shutdown, all staged chunks should be enqueued for buffer flush. Set true to force_enqueue for it.



535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
 
# File 'lib/fluent/plugin/buffer.rb', line 535

def enqueue_all(force_enqueue = false)
  log.on_trace { log.trace "enqueueing all chunks in buffer", instance: self.object_id }
  update_timekeys if @enable_update_timekeys

  if block_given?
    synchronize{ @stage.keys }.each do |metadata|
      return if !force_enqueue && queue_full?
      # NOTE: The following line might cause data race depending on Ruby implementations except CRuby
      # cf. https://github.com/fluent/fluentd/pull/1721#discussion_r146170251
      chunk = @stage[metadata]
      next unless chunk
      v = yield metadata, chunk
      enqueue_chunk(metadata) if v
    end
  else
    synchronize{ @stage.keys }.each do |metadata|
      return if !force_enqueue && queue_full?
      enqueue_chunk(metadata)
    end
  end
end

#enqueue_chunk(metadata) ⇒ Object 



480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
 
# File 'lib/fluent/plugin/buffer.rb', line 480

def enqueue_chunk(metadata)
  log.on_trace { log.trace "enqueueing chunk", instance: self.object_id, metadata: metadata }

  chunk = synchronize do
    @stage.delete(metadata)
  end
  return nil unless chunk

  chunk.synchronize do
    synchronize do
      if chunk.empty?
        chunk.close
      else
        chunk.metadata.seq = 0 # metadata.seq should be 0 for counting @queued_num
        @queue << chunk
        @queued_num[metadata] = @queued_num.fetch(metadata, 0) + 1
        chunk.enqueued!
      end
      bytesize = chunk.bytesize
      @stage_size_metrics.sub(bytesize)
      @queue_size_metrics.add(bytesize)
    end
  end
  nil
end

#enqueue_unstaged_chunk(chunk) ⇒ Object 



506
507
508
509
510
511
512
513
514
515
516
517
518
519
 
# File 'lib/fluent/plugin/buffer.rb', line 506

def enqueue_unstaged_chunk(chunk)
  log.on_trace { log.trace "enqueueing unstaged chunk", instance: self.object_id, metadata: chunk.metadata }

  synchronize do
    chunk.synchronize do
      metadata = chunk.metadata
      metadata.seq = 0 # metadata.seq should be 0 for counting @queued_num
      @queue << chunk
      @queued_num[metadata] = @queued_num.fetch(metadata, 0) + 1
      chunk.enqueued!
    end
    @queue_size_metrics.add(chunk.bytesize)
  end
end

#generate_chunk(metadata) ⇒ Object

Raises:

  • (NotImplementedError) 


308
309
310
 
# File 'lib/fluent/plugin/buffer.rb', line 308

def generate_chunk(metadata)
  raise NotImplementedError, "Implement this method in child class"
end

#metadata(timekey: nil, tag: nil, variables: nil) ⇒ Object

Keep this method for existing code



317
318
319
 
# File 'lib/fluent/plugin/buffer.rb', line 317

def metadata(timekey: nil, tag: nil, variables: nil)
  Metadata.new(timekey, tag, variables)
end

#new_metadata(timekey: nil, tag: nil, variables: nil) ⇒ Object 



312
313
314
 
# File 'lib/fluent/plugin/buffer.rb', line 312

def new_metadata(timekey: nil, tag: nil, variables: nil)
  Metadata.new(timekey, tag, variables)
end

#persistent? ⇒ Boolean

Returns:

  • (Boolean) 


215
216
217
 
# File 'lib/fluent/plugin/buffer.rb', line 215

def persistent?
  false
end

#purge_chunk(chunk_id) ⇒ Object 



590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
 
# File 'lib/fluent/plugin/buffer.rb', line 590

def purge_chunk(chunk_id)
  metadata = nil
  synchronize do
    chunk = @dequeued.delete(chunk_id)
    return nil unless chunk # purged by other threads

    metadata = chunk.metadata
    log.on_trace { log.trace "purging a chunk", instance: self.object_id, chunk_id: dump_unique_id_hex(chunk_id), metadata: metadata }

    begin
      bytesize = chunk.bytesize
      chunk.purge
      @queue_size_metrics.sub(bytesize)
    rescue => e
      log.error "failed to purge buffer chunk", chunk_id: dump_unique_id_hex(chunk_id), error_class: e.class, error: e
      log.error_backtrace
    end

    @dequeued_num[chunk.metadata] -= 1
    if metadata && !@stage[metadata] && (!@queued_num[metadata] || @queued_num[metadata] < 1) && @dequeued_num[metadata].zero?
      @queued_num.delete(metadata)
      @dequeued_num.delete(metadata)
    end
    log.on_trace { log.trace "chunk purged", instance: self.object_id, chunk_id: dump_unique_id_hex(chunk_id), metadata: metadata }
  end

  nil
end

#queue_full? ⇒ Boolean

Returns:

  • (Boolean) 


462
463
464
 
# File 'lib/fluent/plugin/buffer.rb', line 462

def queue_full?
  synchronize { @queue.size } >= @queued_chunks_limit_size
end

#queue_size ⇒ Object 



207
208
209
 
# File 'lib/fluent/plugin/buffer.rb', line 207

def queue_size
  @queue_size_metrics.get
end

#queue_size=(value) ⇒ Object 



211
212
213
 
# File 'lib/fluent/plugin/buffer.rb', line 211

def queue_size=(value)
  @queue_size_metrics.set(value)
end

#queued?(metadata = nil, optimistic: false) ⇒ Boolean

Returns:

  • (Boolean) 


470
471
472
473
474
475
476
477
478
 
# File 'lib/fluent/plugin/buffer.rb', line 470

def queued?(metadata = nil, optimistic: false)
  if optimistic
    optimistic_queued?(metadata)
  else
    synchronize do
      optimistic_queued?(metadata)
    end
  end
end

#queued_records ⇒ Object 



466
467
468
 
# File 'lib/fluent/plugin/buffer.rb', line 466

def queued_records
  synchronize { @queue.reduce(0){|r, chunk| r + chunk.size } }
end

#resume ⇒ Object

TODO: for back pressure feature def used?(ratio)

@total_limit_size * ratio > @stage_size_metrics.get + @queue_size_metrics.get

end

Raises:

  • (NotImplementedError) 


303
304
305
306
 
# File 'lib/fluent/plugin/buffer.rb', line 303

def resume
  # return {}, []
  raise NotImplementedError, "Implement this method in child class"
end

#stage_size ⇒ Object 



199
200
201
 
# File 'lib/fluent/plugin/buffer.rb', line 199

def stage_size
  @stage_size_metrics.get
end

#stage_size=(value) ⇒ Object 



203
204
205
 
# File 'lib/fluent/plugin/buffer.rb', line 203

def stage_size=(value)
  @stage_size_metrics.set(value)
end

#start ⇒ Object 



253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
 
# File 'lib/fluent/plugin/buffer.rb', line 253

def start
  super

  @stage, @queue = resume
  @stage.each_pair do |metadata, chunk|
    @stage_size_metrics.add(chunk.bytesize)
  end
  @queue.each do |chunk|
    @queued_num[chunk.metadata] ||= 0
    @queued_num[chunk.metadata] += 1
    @queue_size_metrics.add(chunk.bytesize)
  end
  update_timekeys
  log.debug "buffer started", instance: self.object_id, stage_size: @stage_size_metrics.get, queue_size: @queue_size_metrics.get
end

#statistics ⇒ Object 



889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
 
# File 'lib/fluent/plugin/buffer.rb', line 889

def statistics
  stage_size, queue_size = @stage_size_metrics.get, @queue_size_metrics.get
  buffer_space = 1.0 - ((stage_size + queue_size * 1.0) / @total_limit_size)
  @stage_length_metrics.set(@stage.size)
  @queue_length_metrics.set(@queue.size)
  @available_buffer_space_ratios_metrics.set(buffer_space * 100)
  @total_queued_size_metrics.set(stage_size + queue_size)
  stats = {
    'stage_length' => @stage_length_metrics.get,
    'stage_byte_size' => stage_size,
    'queue_length' => @queue_length_metrics.get,
    'queue_byte_size' => queue_size,
    'available_buffer_space_ratios' => @available_buffer_space_ratios_metrics.get.round(1),
    'total_queued_size' => @total_queued_size_metrics.get,
  }

  tkeys = timekeys
  if (m = tkeys.min)
    @oldest_timekey_metrics.set(m)
    stats['oldest_timekey'] = @oldest_timekey_metrics.get
  end
  if (m = tkeys.max)
    @newest_timekey_metrics.set(m)
    stats['newest_timekey'] = @newest_timekey_metrics.get
  end

  { 'buffer' => stats }
end

#storable? ⇒ Boolean

Returns:

  • (Boolean) 


294
295
296
 
# File 'lib/fluent/plugin/buffer.rb', line 294

def storable?
  @total_limit_size > @stage_size_metrics.get + @queue_size_metrics.get
end

#takeback_chunk(chunk_id) ⇒ Object 



576
577
578
579
580
581
582
583
584
585
586
587
588
 
# File 'lib/fluent/plugin/buffer.rb', line 576

def takeback_chunk(chunk_id)
  log.on_trace { log.trace "taking back a chunk", instance: self.object_id, chunk_id: dump_unique_id_hex(chunk_id) }

  synchronize do
    chunk = @dequeued.delete(chunk_id)
    return false unless chunk # already purged by other thread
    @queue.unshift(chunk)
    log.on_trace { log.trace "chunk taken back", instance: self.object_id, chunk_id: dump_unique_id_hex(chunk_id), metadata: chunk.metadata }
    @queued_num[chunk.metadata] += 1 # BUG if nil
    @dequeued_num[chunk.metadata] -= 1
  end
  true
end

#terminate ⇒ Object 



285
286
287
288
289
290
291
292
 
# File 'lib/fluent/plugin/buffer.rb', line 285

def terminate
  super
  @dequeued = @stage = @queue = @queued_num = nil
  @stage_length_metrics = @stage_size_metrics = @queue_length_metrics = @queue_size_metrics = nil
  @available_buffer_space_ratios_metrics = @total_queued_size_metrics = nil
  @newest_timekey_metrics = @oldest_timekey_metrics = nil
  @timekeys.clear
end

#timekeys ⇒ Object 



321
322
323
 
# File 'lib/fluent/plugin/buffer.rb', line 321

def timekeys
  @timekeys.keys
end

#update_timekeys ⇒ Object 



521
522
523
524
525
526
527
528
529
530
531
532
 
# File 'lib/fluent/plugin/buffer.rb', line 521

def update_timekeys
  synchronize do
    chunks = @stage.values
    chunks.concat(@queue)
    @timekeys = chunks.each_with_object({}) do |chunk, keys|
      if chunk.metadata && chunk.metadata.timekey
        t = chunk.metadata.timekey
        keys[t] = keys.fetch(t, 0) + 1
      end
    end
  end
end

#write(metadata_and_data, format: nil, size: nil, enqueue: false) ⇒ Object

metadata MUST have consistent object_id for each variation data MUST be Array of serialized events, or EventStream metadata_and_data MUST be a hash of { metadata => data }

Raises:



328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
 
# File 'lib/fluent/plugin/buffer.rb', line 328

def write(metadata_and_data, format: nil, size: nil, enqueue: false)
  return if metadata_and_data.size < 1
  raise BufferOverflowError, "buffer space has too many data" unless storable?

  log.on_trace { log.trace "writing events into buffer", instance: self.object_id, metadata_size: metadata_and_data.size }

  operated_chunks = []
  unstaged_chunks = {} # metadata => [chunk, chunk, ...]
  chunks_to_enqueue = []
  staged_bytesizes_by_chunk = {}
  # track internal BufferChunkOverflowError in write_step_by_step
  buffer_chunk_overflow_errors = []

  begin
    # sort metadata to get lock of chunks in same order with other threads
    metadata_and_data.keys.sort.each do |metadata|
      data = metadata_and_data[metadata]
      write_once(metadata, data, format: format, size: size) do |chunk, adding_bytesize, error|
        chunk.mon_enter # add lock to prevent to be committed/rollbacked from other threads
        operated_chunks << chunk
        if chunk.staged?
          #
          # https://github.com/fluent/fluentd/issues/2712
          # write_once is supposed to write to a chunk only once
          # but this block **may** run multiple times from write_step_by_step and previous write may be rollbacked
          # So we should be counting the stage_size only for the last successful write
          #
          staged_bytesizes_by_chunk[chunk] = adding_bytesize
        elsif chunk.unstaged?
          unstaged_chunks[metadata] ||= []
          unstaged_chunks[metadata] << chunk
        end
        if error && !error.empty?
          buffer_chunk_overflow_errors << error
        end
      end
    end

    return if operated_chunks.empty?

    # Now, this thread acquires many locks of chunks... getting buffer-global lock causes dead lock.
    # Any operations needs buffer-global lock (including enqueueing) should be done after releasing locks.

    first_chunk = operated_chunks.shift
    # Following commits for other chunks also can finish successfully if the first commit operation
    # finishes without any exceptions.
    # In most cases, #commit just requires very small disk spaces, so major failure reason are
    # permission errors, disk failures and other permanent(fatal) errors.
    begin
      first_chunk.commit
      if enqueue || first_chunk.unstaged? || chunk_size_full?(first_chunk)
        chunks_to_enqueue << first_chunk
      end
      first_chunk.mon_exit
    rescue
      operated_chunks.unshift(first_chunk)
      raise
    end

    errors = []
    # Buffer plugin estimates there's no serious error cause: will commit for all chunks eigher way
    operated_chunks.each do |chunk|
      begin
        chunk.commit
        if enqueue || chunk.unstaged? || chunk_size_full?(chunk)
          chunks_to_enqueue << chunk
        end
        chunk.mon_exit
      rescue => e
        chunk.rollback
        chunk.mon_exit
        errors << e
      end
    end

    # All locks about chunks are released.

    #
    # Now update the stage, stage_size with proper locking
    # FIX FOR stage_size miscomputation - https://github.com/fluent/fluentd/issues/2712
    #
    staged_bytesizes_by_chunk.each do |chunk, bytesize|
      chunk.synchronize do
        synchronize { @stage_size_metrics.add(bytesize) }
        log.on_trace { log.trace { "chunk #{chunk.path} size_added: #{bytesize} new_size: #{chunk.bytesize}" } }
      end
    end

    chunks_to_enqueue.each do |c|
      if c.staged? && (enqueue || chunk_size_full?(c))
        m = c.metadata
        enqueue_chunk(m)
        if unstaged_chunks[m] && !unstaged_chunks[m].empty?
          u = unstaged_chunks[m].pop
          u.synchronize do
            if u.unstaged? && !chunk_size_full?(u)
              # `u.metadata.seq` and `m.seq` can be different but Buffer#enqueue_chunk expect them to be the same value
              u.metadata.seq = 0
              synchronize {
                @stage[m] = u.staged!
                @stage_size_metrics.add(u.bytesize)
              }
            end
          end
        end
      elsif c.unstaged?
        enqueue_unstaged_chunk(c)
      else
        # previously staged chunk is already enqueued, closed or purged.
        # no problem.
      end
    end

    operated_chunks.clear if errors.empty?

    if errors.size > 0
      log.warn "error occurs in committing chunks: only first one raised", errors: errors.map(&:class)
      raise errors.first
    end
  ensure
    operated_chunks.each do |chunk|
      chunk.rollback rescue nil # nothing possible to do for #rollback failure
      if chunk.unstaged?
        chunk.purge rescue nil # to prevent leakage of unstaged chunks
      end
      chunk.mon_exit rescue nil # this may raise ThreadError for chunks already committed
    end
    unless buffer_chunk_overflow_errors.empty?
      # Notify delayed BufferChunkOverflowError here
      raise BufferChunkOverflowError, buffer_chunk_overflow_errors.join(", ")
    end
  end
end

#write_once(metadata, data, format: nil, size: nil, &block) ⇒ Object

write once into a chunk

  1. append whole data into existing chunk

  2. commit it & return unless chunk_size_over?

  3. enqueue existing chunk & retry whole method if chunk was not empty

  4. go to step_by_step writing



653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
 
# File 'lib/fluent/plugin/buffer.rb', line 653

def write_once(metadata, data, format: nil, size: nil, &block)
  return if data.empty?

  stored = false
  adding_bytesize = nil

  chunk = synchronize { @stage[metadata] ||= generate_chunk(metadata).staged! }
  enqueue_chunk_before_retry = false
  chunk.synchronize do
    # retry this method if chunk is already queued (between getting chunk and entering critical section)
    raise ShouldRetry unless chunk.staged?

    empty_chunk = chunk.empty?

    original_bytesize = chunk.bytesize
    begin
      if format
        serialized = format.call(data)
        chunk.concat(serialized, size ? size.call : data.size)
      else
        chunk.append(data, compress: @compress)
      end
      adding_bytesize = chunk.bytesize - original_bytesize

      if chunk_size_over?(chunk)
        if format && empty_chunk
          if chunk.bytesize > @chunk_limit_size
            log.warn "chunk bytes limit exceeds for an emitted event stream: #{adding_bytesize}bytes"
          else
            log.warn "chunk size limit exceeds for an emitted event stream: #{chunk.size}records"
          end
        end
        chunk.rollback

        if format && !empty_chunk
          # Event streams should be appended into a chunk at once
          # as far as possible, to improve performance of formatting.
          # Event stream may be a MessagePackEventStream. We don't want to split it into
          # 2 or more chunks (except for a case that the event stream is larger than chunk limit).
          enqueue_chunk_before_retry = true
          raise ShouldRetry
        end
      else
        stored = true
      end
    rescue
      chunk.rollback
      raise
    end

    if stored
      block.call(chunk, adding_bytesize)
    end
  end

  unless stored
    # try step-by-step appending if data can't be stored into existing a chunk in non-bulk mode
    #
    # 1/10 size of original event stream (splits_count == 10) seems enough small
    # to try emitting events into existing chunk.
    # it does not matter to split event stream into very small splits, because chunks have less
    # overhead to write data many times (even about file buffer chunks).
    write_step_by_step(metadata, data, format, 10, &block)
  end
rescue ShouldRetry
  enqueue_chunk(metadata) if enqueue_chunk_before_retry
  retry
end

#write_step_by_step(metadata, data, format, splits_count, &block) ⇒ Object

  1. split event streams into many (10 -> 100 -> 1000 -> …) chunks

  2. append splits into the staged chunks as much as possible

  3. create unstaged chunk and append rest splits -> repeat it for all splits



729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
 
# File 'lib/fluent/plugin/buffer.rb', line 729

def write_step_by_step(metadata, data, format, splits_count, &block)
  splits = []
  if splits_count > data.size
    splits_count = data.size
  end
  slice_size = if data.size % splits_count == 0
                 data.size / splits_count
               else
                 data.size / (splits_count - 1)
               end
  slice_origin = 0
  while slice_origin < data.size
    splits << data.slice(slice_origin, slice_size)
    slice_origin += slice_size
  end

  # This method will append events into the staged chunk at first.
  # Then, will generate chunks not staged (not queued) to append rest data.
  staged_chunk_used = false
  modified_chunks = []
  modified_metadata = metadata
  get_next_chunk = ->(){
    if staged_chunk_used
      # Staging new chunk here is bad idea:
      # Recovering whole state including newly staged chunks is much harder than current implementation.
      modified_metadata = modified_metadata.dup_next
      generate_chunk(modified_metadata)
    else
      synchronize { @stage[modified_metadata] ||= generate_chunk(modified_metadata).staged! }
    end
  }

  writing_splits_index = 0
  enqueue_chunk_before_retry = false

  while writing_splits_index < splits.size
    chunk = get_next_chunk.call
    errors = []
    # The chunk must be locked until being passed to &block.
    chunk.mon_enter
    modified_chunks << {chunk: chunk, adding_bytesize: 0, errors: errors}

    raise ShouldRetry unless chunk.writable?
    staged_chunk_used = true if chunk.staged?

    original_bytesize = committed_bytesize = chunk.bytesize
    begin
      while writing_splits_index < splits.size
        split = splits[writing_splits_index]
        formatted_split = format ? format.call(split) : nil

        if split.size == 1 # Check BufferChunkOverflowError
          determined_bytesize = nil
          if @compress != :text
            determined_bytesize = nil
          elsif formatted_split
            determined_bytesize = formatted_split.bytesize
          elsif split.first.respond_to?(:bytesize)
            determined_bytesize = split.first.bytesize
          end

          if determined_bytesize && determined_bytesize > @chunk_limit_size
            # It is a obvious case that BufferChunkOverflowError should be raised here.
            # But if it raises here, already processed 'split' or
            # the proceeding 'split' will be lost completely.
            # So it is a last resort to delay raising such a exception
            errors << "a #{determined_bytesize} bytes record (nth: #{writing_splits_index}) is larger than buffer chunk limit size (#{@chunk_limit_size})"
            writing_splits_index += 1
            next
          end

          if determined_bytesize.nil? || chunk.bytesize + determined_bytesize > @chunk_limit_size
            # The split will (might) cause size over so keep already processed
            # 'split' content here (allow performance regression a bit).
            chunk.commit
            committed_bytesize = chunk.bytesize
          end
        end

        if format
          chunk.concat(formatted_split, split.size)
        else
          chunk.append(split, compress: @compress)
        end
        adding_bytes = chunk.bytesize - committed_bytesize

        if chunk_size_over?(chunk) # split size is larger than difference between size_full? and size_over?
          chunk.rollback
          committed_bytesize = chunk.bytesize

          if split.size == 1 # Check BufferChunkOverflowError again
            if adding_bytes > @chunk_limit_size
              errors << "concatenated/appended a #{adding_bytes} bytes record (nth: #{writing_splits_index}) is larger than buffer chunk limit size (#{@chunk_limit_size})"
              writing_splits_index += 1
              next
            else
              # As already processed content is kept after rollback, then unstaged chunk should be queued.
              # After that, re-process current split again.
              # New chunk should be allocated, to do it, modify @stage and so on.
              synchronize { @stage.delete(modified_metadata) }
              staged_chunk_used = false
              chunk.unstaged!
              break
            end
          end

          if chunk_size_full?(chunk) || split.size == 1
            enqueue_chunk_before_retry = true
          else
            splits_count *= 10
          end

          raise ShouldRetry
        end

        writing_splits_index += 1

        if chunk_size_full?(chunk)
          break
        end
      end
    rescue
      chunk.purge if chunk.unstaged? # unstaged chunk will leak unless purge it
      raise
    end

    modified_chunks.last[:adding_bytesize] = chunk.bytesize - original_bytesize
  end
  modified_chunks.each do |data|
    block.call(data[:chunk], data[:adding_bytesize], data[:errors])
  end
rescue ShouldRetry
  modified_chunks.each do |data|
    chunk = data[:chunk]
    chunk.rollback rescue nil
    if chunk.unstaged?
      chunk.purge rescue nil
    end
    chunk.mon_exit rescue nil
  end
  enqueue_chunk(metadata) if enqueue_chunk_before_retry
  retry
ensure
  modified_chunks.each do |data|
    chunk = data[:chunk]
    chunk.mon_exit
  end
end