class Riffer::Rig::Runtime::JobLog

# File lib/riffer/rig/runtime/job_log.rb, line 21
def initialize(output, path)
  @output = output
  @path = path
  @mutex = Mutex.new
  @dropped = 0
  file = File.new(path, 'a+b', 0o600)
  file.sync = true
  @copier = Thread.new { copy(file) }
end

# File lib/riffer/rig/runtime/job_log.rb, line 61
def close
  # Closing the pipe raises IOError in a copier blocked reading it.
  @output.close
  @copier.join
end

# File lib/riffer/rig/runtime/job_log.rb, line 56
def drain(timeout)
  @copier.join(timeout)
end

# File lib/riffer/rig/runtime/job_log.rb, line 34
def read(offset, limit)
  @mutex.synchronize do
    marker = marker_bytes
    # Offsets count the bytes the job has written rather than a place in the
    # file, so they stay valid when the head of the file is dropped.
    position = offset < @dropped ? 0 : marker + offset - @dropped
    size = File.size?(@path).to_i
    output = slice(limit, position)
    # The inner max covers a file that grew between the size and the read,
    # the outer one a removed file, which must not move the offset back.
    [output, [@dropped - marker + [position + output.bytesize, size].max, offset].max]
  end
end

# File lib/riffer/rig/runtime/job_log.rb, line 50
def tail(limit)
  @mutex.synchronize { slice(limit, [File.size?(@path).to_i - limit, 0].max) }
end