Struct LogLine

logline.go:32–74

LogLine represents a CSV text line using ASCII 30 as field separator. It implement Record.. In memory, it is kept in a format optimized for very fast parsing and low memory-consumption. The vast majority of fields are never accessed during the lifetime of an object, as a filter usually reads or wri

// Modifications can be done through the Set() method, and can be done to any
// field, both those that had a parsed value, and those that were empty.
type LogLine struct {
	// These next few fields handle the read-only fields that were parsed from a
	// text logline. data is the original line in memory, while idx is the index
	// into the original line to the separator that lies before the beginning of
	// each field (idx[0] is always -1).  meta is the metadata associated with
	// the original input.
	// Note that data is never modified, because it would be very slow to do it
	// in-place, enlarging / shrinking fields as necessary; if the user code
	// wants to modify a field through Set(), it is stored in a parallel
	// data-structure (see wmask/wdata/wcnt below).
	idx  [LogLineNumFields + 1]int32
	data []byte

	// meta values can be filled in by the input to add informations on the
	// datasource of the Logline, like timestamps, originating S3 file,
	// debugging info or other metadata.  Values can be accessed by filters or
	// output to perform checks, transformations, etc.
	meta Metadata

	// This triplet handles in-memory modifications to LogLines (through
	// LogLine.Set()).
	// wcnt is the 1-based counter of how many fields were modified;
	// wdata is the dense storage for those modifications (so we allow for a
	// total of 254 different fields being written to).
	// wmask is a table indexed by each possible field index, that contains:
	//   * 0 if the field was not modified (so the current value can be fetched
	//     by idx/data)
	//   * the index into wdata were the new value for the field is stored (if
	//     the field was modified)
	//
	// NOTE: wdata[0] is never written to, because the index "0" in wmask is the
	// special value to signal "no modifications". We keep it like this because
	// we like that the zero-initialization of wmask does the right thing
	// (i.e. indicates that no fields have been written to).
	wmask [LogLineNumFields + NumFieldsBaker]uint8
	wdata [256][]byte
	wcnt  uint8

	cache Cache

	// FieldSeparator is the byte used to separate fields value.
	FieldSeparator byte
}

// Get the value of a field (either standard or custom).
func (l *LogLine) Get(f FieldIndex) []byte {