diff options
Diffstat (limited to 'libpod')
| -rw-r--r-- | libpod/logs/log.go | 88 | ||||
| -rw-r--r-- | libpod/logs/reversereader/reversereader.go | 66 |
2 files changed, 132 insertions, 22 deletions
diff --git a/libpod/logs/log.go b/libpod/logs/log.go index 9a7bcb5be..bd918abae 100644 --- a/libpod/logs/log.go +++ b/libpod/logs/log.go @@ -2,13 +2,16 @@ package logs import ( "fmt" - "io/ioutil" + "io" + "os" "strings" "sync" "time" + "github.com/containers/libpod/libpod/logs/reversereader" "github.com/hpcloud/tail" "github.com/pkg/errors" + "github.com/sirupsen/logrus" ) const ( @@ -74,43 +77,84 @@ func GetLogFile(path string, options *LogOptions) (*tail.Tail, []*LogLine, error func getTailLog(path string, tail int) ([]*LogLine, error) { var ( - tailLog []*LogLine - nlls []*LogLine - tailCounter int - partial string + nlls []*LogLine + nllCounter int + leftover string + partial string + tailLog []*LogLine ) - content, err := ioutil.ReadFile(path) + f, err := os.Open(path) if err != nil { return nil, err } - splitContent := strings.Split(string(content), "\n") - // We read the content in reverse and add each nll until we have the same - // number of F type messages as the desired tail - for i := len(splitContent) - 1; i >= 0; i-- { - if len(splitContent[i]) == 0 { - continue - } - nll, err := NewLogLine(splitContent[i]) - if err != nil { - return nil, err + rr, err := reversereader.NewReverseReader(f) + if err != nil { + return nil, err + } + + inputs := make(chan []string) + go func() { + for { + s, err := rr.Read() + if err != nil { + if errors.Cause(err) == io.EOF { + inputs <- []string{leftover} + close(inputs) + break + } + logrus.Error(err) + close(inputs) + } + line := strings.Split(s+leftover, "\n") + if len(line) > 1 { + inputs <- line[1:] + } + leftover = line[0] } - nlls = append(nlls, nll) - if !nll.Partial() { - tailCounter++ + }() + + for i := range inputs { + // the incoming array is FIFO; we want FIFO so + // reverse the slice read order + for j := len(i) - 1; j >= 0; j-- { + // lines that are "" are junk + if len(i[j]) < 1 { + continue + } + // read the content in reverse and add each nll until we have the same + // number of F type messages as the desired tail + nll, err := NewLogLine(i[j]) + if err != nil { + return nil, err + } + nlls = append(nlls, nll) + if !nll.Partial() { + nllCounter++ + } } - if tailCounter == tail { + // if we have enough loglines, we can hangup + if nllCounter >= tail { + if err := f.Close(); err != nil { + logrus.Error(err) + } break } } - // Now we iterate the results and assemble partial messages to become full messages + + // re-assemble the log lines and trim (if needed) to the + // tail length for _, nll := range nlls { if nll.Partial() { partial += nll.Msg } else { nll.Msg += partial - tailLog = append(tailLog, nll) + // prepend because we need to reverse the order again to FIFO + tailLog = append([]*LogLine{nll}, tailLog...) partial = "" } + if len(tailLog) == tail { + break + } } return tailLog, nil } diff --git a/libpod/logs/reversereader/reversereader.go b/libpod/logs/reversereader/reversereader.go new file mode 100644 index 000000000..72d9ad975 --- /dev/null +++ b/libpod/logs/reversereader/reversereader.go @@ -0,0 +1,66 @@ +package reversereader + +import ( + "io" + "os" + + "github.com/pkg/errors" +) + +// ReverseReader structure for reading a file backwards +type ReverseReader struct { + reader *os.File + offset int64 + readSize int64 +} + +// NewReverseReader returns a reader that reads from the end of a file +// rather than the beginning. It sets the readsize to pagesize and determines +// the first offset using using modulus. +func NewReverseReader(reader *os.File) (*ReverseReader, error) { + // pagesize should be safe for memory use and file reads should be on page + // boundaries as well + pageSize := int64(os.Getpagesize()) + stat, err := reader.Stat() + if err != nil { + return nil, err + } + // figure out the last page boundary + remainder := stat.Size() % pageSize + end, err := reader.Seek(0, 2) + if err != nil { + return nil, err + } + // set offset (starting position) to the last page boundary or + // zero if fits in one page + startOffset := end - remainder + if startOffset < 0 { + startOffset = 0 + } + rr := ReverseReader{ + reader: reader, + offset: startOffset, + readSize: pageSize, + } + return &rr, nil +} + +// ReverseReader reads from a given offset to the previous offset and +// then sets the newoff set one pagesize less than the previous read. +func (r *ReverseReader) Read() (string, error) { + if r.offset < 0 { + return "", errors.Wrap(io.EOF, "at beginning of file") + } + // Read from given offset + b := make([]byte, r.readSize) + n, err := r.reader.ReadAt(b, r.offset) + if err != nil && errors.Cause(err) != io.EOF { + return "", err + } + if int64(n) < r.readSize { + b = b[0:n] + } + // Set to the next page boundary + r.offset = -r.readSize + return string(b), nil +} |