// positionLogFile will update the internal read position of the logFile to be
// at the end of the file or somewhere in the middle if backlog has been specified.
func (stream *logStream) positionLogFile(logFile io.ReadSeeker) error {
// Seek to the end, or lines back from the end if we need to.
if !stream.fromTheStart {
return tailer.SeekLastLines(logFile, stream.backlog, stream.filterLine)
}
return nil
}
func (s *tailerSuite) TestTailer(c *gc.C) {
for i, test := range tests {
c.Logf("Test #%d) %s", i, test.description)
bufferSize := test.bufferSize
if bufferSize == 0 {
// Default value.
bufferSize = 4096
}
s.PatchValue(tailer.BufferSize, bufferSize)
reader, writer := io.Pipe()
sigc := make(chan struct{}, 1)
rs := startReadSeeker(c, test.data, test.initialLinesWritten, sigc)
if !test.fromStart {
err := tailer.SeekLastLines(rs, test.initialLinesRequested, test.filter)
c.Assert(err, gc.IsNil)
}
tailer := tailer.NewTestTailer(rs, writer, test.filter, 2*time.Millisecond)
linec := startReading(c, tailer, reader, writer)
// Collect initial data.
assertCollected(c, linec, test.initialCollectedData, nil)
sigc <- struct{}{}
// Collect remaining data, possibly with injection to stop
// earlier or generate an error.
var injection func([]string)
if test.injector != nil {
injection = test.injector(tailer, rs)
}
assertCollected(c, linec, test.appendedCollectedData, injection)
if test.err == "" {
c.Assert(tailer.Stop(), gc.IsNil)
} else {
c.Assert(tailer.Err(), gc.ErrorMatches, test.err)
}
}
}