Class: MoSQL::Streamer

Inherits:
Object
  • Object
show all
Includes:
Logging
Defined in:
lib/mosql/streamer.rb

Constant Summary collapse

BATCH = 
1000
NEW_KEYS = 
[:options, :tailer, :mongo, :sql, :schema]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Logging

#log

Constructor Details

#initialize(opts) ⇒ Streamer

Returns a new instance of Streamer.



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# File 'lib/mosql/streamer.rb', line 11

def initialize(opts)
  NEW_KEYS.each do |parm|
    unless opts.key?(parm)
      raise ArgumentError.new("Required argument `#{parm}' not provided to #{self.class.name}#new.")
    end
    instance_variable_set(:"@#{parm.to_s}", opts[parm])
  end

  @done    = false
end

Instance Attribute Details

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/mosql/streamer.rb', line 7

def options
  @options
end

#tailer ⇒ Object (readonly)

Returns the value of attribute tailer.



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# File 'lib/mosql/streamer.rb', line 7

def tailer
  @tailer
end

Instance Method Details

#bulk_upsert(table, ns, items) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 51

def bulk_upsert(table, ns, items)
  begin
    @schema.copy_data(table.db, ns, items)
  rescue Sequel::DatabaseError => e
    log.debug("Bulk insert error (#{e}), attempting invidual upserts...")
    cols = @schema.all_columns(@schema.find_ns(ns))
    items.each do |it|
      h = {}
      cols.zip(it).each { |k,v| h[k] = v }
      unsafe_handle_exceptions(ns, h) do
        @sql.upsert!(table, @schema.primary_sql_key_for_ns(ns), h)
      end
    end
  end
end

#collection_for_ns(ns) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 32

def collection_for_ns(ns)
  dbname, collection = ns.split(".", 2)
  @mongo.db(dbname).collection(collection)
end

#did_truncate ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 110

def did_truncate; @did_truncate ||= {}; end

#handle_op(op) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 172

def handle_op(op)
  log.debug("processing op: #{op.inspect}")
  unless op['ns'] && op['op']
    log.warn("Weird op: #{op.inspect}")
    return
  end

  unless @schema.find_ns(op['ns'])
    log.debug("Skipping op for unknown ns #{op['ns']}...")
    return
  end

  ns = op['ns']
  dbname, collection_name = ns.split(".", 2)

  case op['op']
  when 'n'
    log.debug("Skipping no-op #{op.inspect}")
  when 'i'
    if collection_name == 'system.indexes'
      log.info("Skipping index update: #{op.inspect}")
    else
      unsafe_handle_exceptions(ns, op['o'])  do
        @sql.upsert_ns(ns, op['o'])
      end
    end
  when 'u'
    selector = op['o2']
    update   = op['o']
    if update.keys.any? { |k| k.start_with? '$' }
      log.debug("resync #{ns}: #{selector['_id']} (update was: #{update.inspect})")
      sync_object(ns, selector['_id'])
    else
      log.debug("upsert #{ns}: _id=#{selector['_id']}")

      # The update operation replaces the existing object, but
      # preserves its _id field, so grab the _id off of the
      # 'query' field -- it's not guaranteed to be present on the
      # update.
      update = { '_id' => selector['_id'] }.merge(update)
      unsafe_handle_exceptions(ns, update) do
        @sql.upsert_ns(ns, update)
      end
    end
  when 'd'
    if options[:ignore_delete]
      log.debug("Ignoring delete op on #{ns} as instructed.")
    else
      @sql.delete_ns(ns, op['o'])
    end
  else
    log.info("Skipping unknown op #{op.inspect}")
  end
end

#import ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 26

def import
  if options[:reimport] || tailer.read_timestamp.seconds == 0
    initial_import
  end
end

#import_collection(ns, collection) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 112

def import_collection(ns, collection)
  log.info("Importing for #{ns}...")
  count = 0
  batch = []
  table = @sql.table_for_ns(ns)
  unless options[:no_drop_tables] || did_truncate[table.first_source]
    table.truncate
    did_truncate[table.first_source] = true
  end

  start    = Time.now
  sql_time = 0
  collection.find(nil, :batch_size => BATCH) do |cursor|
    with_retries do
      cursor.each do |obj|
        batch << @schema.transform(ns, obj)
        count += 1

        if batch.length >= BATCH
          sql_time += track_time do
            bulk_upsert(table, ns, batch)
          end
          elapsed = Time.now - start
          log.info("Imported #{count} rows (#{elapsed}s, #{sql_time}s SQL)...")
          batch.clear
          exit(0) if @done
        end
      end
    end
  end

  unless batch.empty?
    bulk_upsert(table, ns, batch)
  end
end

#initial_import ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 89

def initial_import
  @schema.create_schema(@sql.db, !options[:no_drop_tables])

  unless options[:skip_tail]
    start_ts = @mongo['local']['oplog.rs'].find_one({}, {:sort => [['$natural', -1]]})['ts']
  end

  @mongo.database_names.each do |dbname|
    next unless spec = @schema.find_db(dbname)
    log.info("Importing for Mongo DB #{dbname}...")
    db = @mongo.db(dbname)
    db.collections.select { |c| spec.key?(c.name) }.each do |collection|
      ns = "#{dbname}.#{collection.name}"
      import_collection(ns, collection)
      exit(0) if @done
    end
  end

  tailer.write_timestamp(start_ts) unless options[:skip_tail]
end

#optail ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 148

def optail
  tailer.tail_from(options[:tail_from] ?
                   BSON::Timestamp.new(options[:tail_from].to_i, 0) :
                   nil)
  until @done
    tailer.stream(1000) do |op|
      handle_op(op)
    end
  end
end

#stop ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 22

def stop
  @done = true
end

#sync_object(ns, _id) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 159

def sync_object(ns, _id)
  primary_sql_key = @schema.primary_sql_key_for_ns(ns)
  sqlid           = @sql.transform_one_ns(ns, { '_id' => _id })[primary_sql_key]
  obj             = collection_for_ns(ns).find_one({:_id => _id})
  if obj
    unsafe_handle_exceptions(ns, obj) do
      @sql.upsert_ns(ns, obj)
    end
  else
    @sql.table_for_ns(ns).where(primary_sql_key.to_sym => sqlid).delete()
  end
end

#track_time ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 83

def track_time
  start = Time.now
  yield
  Time.now - start
end

#unsafe_handle_exceptions(ns, obj) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 37

def unsafe_handle_exceptions(ns, obj)
  begin
    yield
  rescue Sequel::DatabaseError => e
    wrapped = e.wrapped_exception
    if wrapped.result && options[:unsafe]
      log.warn("Ignoring row (#{obj.inspect}): #{e}")
    else
      log.error("Error processing #{obj.inspect} for #{ns}.")
      raise e
    end
  end
end

#with_retries(tries = 10) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 67

def with_retries(tries=10)
  tries.times do |try|
    begin
      yield
    rescue Mongo::ConnectionError, Mongo::ConnectionFailure, Mongo::OperationFailure => e
      # Duplicate key error
      raise if e.kind_of?(Mongo::OperationFailure) && [11000, 11001].include?(e.error_code)
      # Cursor timeout
      raise if e.kind_of?(Mongo::OperationFailure) && e.message =~ /^Query response returned CURSOR_NOT_FOUND/
      delay = 0.5 * (1.5 ** try)
      log.warn("Mongo exception: #{e}, sleeping #{delay}s...")
      sleep(delay)
    end
  end
end