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 130

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

#handle_op(op) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 192

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

  # First, check if this was an operation performed via applyOps. If so, call handle_op with
  # for each op that was applied.
  # The oplog format of applyOps commands can be viewed here:
  # https://groups.google.com/forum/#!topic/mongodb-user/dTf5VEJJWvY
  if op['op'] == 'c' && (ops = op['o']['applyOps'])
    ops.each { |op| handle_op(op) }
    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)
    else

      # 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.
      primary_sql_keys = @schema.primary_sql_key_for_ns(ns)
      schema = @schema.find_ns!(ns)
      keys = {}
      primary_sql_keys.each do |key|
        source =  schema[:columns].find {|c| c[:name] == key }[:source]
        keys[source] = selector[source]
      end

      log.debug("upsert #{ns}: #{keys}")

      update = keys.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_position.nil?
    initial_import
  end
end

#import_collection(ns, collection, filter) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 132

def import_collection(ns, collection, filter)
  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(filter, :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_state = {
      'time' => nil,
      'position' => @tailer.most_recent_position
    }
  end

  dbnames = []

  if options[:dbname]
    log.info "Skipping DB scan and using db: #{options[:dbname]}"
    dbnames = [ options[:dbname] ]
  else
    dbnames = @mongo.database_names
  end

  dbnames.each do |dbname|
    spec = @schema.find_db(dbname)

    if(spec.nil?)
      log.info("Mongd DB '#{dbname}' not found in config file. Skipping.")
      next
    end

    log.info("Importing for Mongo DB #{dbname}...")
    db = @mongo.db(dbname)
    collections = db.collections.select { |c| spec.key?(c.name) }

    collections.each do |collection|
      ns = "#{dbname}.#{collection.name}"
      import_collection(ns, collection, spec[collection.name][:meta][:filter])
      exit(0) if @done
    end
  end

  tailer.save_state(start_state) unless options[:skip_tail]
end

#optail ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 168

def optail
  tail_from = options[:tail_from]
  if tail_from.is_a? Time
    tail_from = tailer.most_recent_position(tail_from)
  end
  tailer.tail(:from => tail_from, :filter => options[:oplog_filter])
  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, selector) ⇒ Object 



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# File 'lib/mosql/streamer.rb', line 181

def sync_object(ns, selector)
  obj = collection_for_ns(ns).find_one(selector)
  if obj
    unsafe_handle_exceptions(ns, obj) do
      @sql.upsert_ns(ns, obj)
    end
  else
    @sql.delete_ns(ns, selector)
  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