diff options
Diffstat (limited to 'vendor/github.com/pierrec/lz4/v4/options.go')
| -rw-r--r-- | vendor/github.com/pierrec/lz4/v4/options.go | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/vendor/github.com/pierrec/lz4/v4/options.go b/vendor/github.com/pierrec/lz4/v4/options.go new file mode 100644 index 0000000000..4e1b6703b5 --- /dev/null +++ b/vendor/github.com/pierrec/lz4/v4/options.go @@ -0,0 +1,213 @@ +package lz4 + +import ( + "fmt" + "github.com/pierrec/lz4/v4/internal/lz4block" + "github.com/pierrec/lz4/v4/internal/lz4errors" + "reflect" + "runtime" +) + +//go:generate go run golang.org/x/tools/cmd/stringer -type=BlockSize,CompressionLevel -output options_gen.go + +type ( + applier interface { + Apply(...Option) error + private() + } + // Option defines the parameters to setup an LZ4 Writer or Reader. + Option func(applier) error +) + +// String returns a string representation of the option with its parameter(s). +func (o Option) String() string { + return o(nil).Error() +} + +// Default options. +var ( + DefaultBlockSizeOption = BlockSizeOption(Block4Mb) + DefaultChecksumOption = ChecksumOption(true) + DefaultConcurrency = ConcurrencyOption(1) + defaultOnBlockDone = OnBlockDoneOption(nil) +) + +const ( + Block64Kb BlockSize = 1 << (16 + iota*2) + Block256Kb + Block1Mb + Block4Mb +) + +// BlockSizeIndex defines the size of the blocks to be compressed. +type BlockSize uint32 + +// BlockSizeOption defines the maximum size of compressed blocks (default=Block4Mb). +func BlockSizeOption(size BlockSize) Option { + return func(a applier) error { + switch w := a.(type) { + case nil: + s := fmt.Sprintf("BlockSizeOption(%s)", size) + return lz4errors.Error(s) + case *Writer: + size := uint32(size) + if !lz4block.IsValid(size) { + return fmt.Errorf("%w: %d", lz4errors.ErrOptionInvalidBlockSize, size) + } + w.frame.Descriptor.Flags.BlockSizeIndexSet(lz4block.Index(size)) + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +// BlockChecksumOption enables or disables block checksum (default=false). +func BlockChecksumOption(flag bool) Option { + return func(a applier) error { + switch w := a.(type) { + case nil: + s := fmt.Sprintf("BlockChecksumOption(%v)", flag) + return lz4errors.Error(s) + case *Writer: + w.frame.Descriptor.Flags.BlockChecksumSet(flag) + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +// ChecksumOption enables/disables all blocks or content checksum (default=true). +func ChecksumOption(flag bool) Option { + return func(a applier) error { + switch w := a.(type) { + case nil: + s := fmt.Sprintf("ChecksumOption(%v)", flag) + return lz4errors.Error(s) + case *Writer: + w.frame.Descriptor.Flags.ContentChecksumSet(flag) + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +// SizeOption sets the size of the original uncompressed data (default=0). It is useful to know the size of the +// whole uncompressed data stream. +func SizeOption(size uint64) Option { + return func(a applier) error { + switch w := a.(type) { + case nil: + s := fmt.Sprintf("SizeOption(%d)", size) + return lz4errors.Error(s) + case *Writer: + w.frame.Descriptor.Flags.SizeSet(size > 0) + w.frame.Descriptor.ContentSize = size + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +// ConcurrencyOption sets the number of go routines used for compression. +// If n <= 0, then the output of runtime.GOMAXPROCS(0) is used. +func ConcurrencyOption(n int) Option { + if n <= 0 { + n = runtime.GOMAXPROCS(0) + } + return func(a applier) error { + switch rw := a.(type) { + case nil: + s := fmt.Sprintf("ConcurrencyOption(%d)", n) + return lz4errors.Error(s) + case *Writer: + rw.num = n + return nil + case *Reader: + rw.num = n + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +// CompressionLevel defines the level of compression to use. The higher the better, but slower, compression. +type CompressionLevel uint32 + +const ( + Fast CompressionLevel = 0 + Level1 CompressionLevel = 1 << (8 + iota) + Level2 + Level3 + Level4 + Level5 + Level6 + Level7 + Level8 + Level9 +) + +// CompressionLevelOption defines the compression level (default=Fast). +func CompressionLevelOption(level CompressionLevel) Option { + return func(a applier) error { + switch w := a.(type) { + case nil: + s := fmt.Sprintf("CompressionLevelOption(%s)", level) + return lz4errors.Error(s) + case *Writer: + switch level { + case Fast, Level1, Level2, Level3, Level4, Level5, Level6, Level7, Level8, Level9: + default: + return fmt.Errorf("%w: %d", lz4errors.ErrOptionInvalidCompressionLevel, level) + } + w.level = lz4block.CompressionLevel(level) + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +func onBlockDone(int) {} + +// OnBlockDoneOption is triggered when a block has been processed. For a Writer, it is when is has been compressed, +// for a Reader, it is when it has been uncompressed. +func OnBlockDoneOption(handler func(size int)) Option { + if handler == nil { + handler = onBlockDone + } + return func(a applier) error { + switch rw := a.(type) { + case nil: + s := fmt.Sprintf("OnBlockDoneOption(%s)", reflect.TypeOf(handler).String()) + return lz4errors.Error(s) + case *Writer: + rw.handler = handler + return nil + case *Reader: + rw.handler = handler + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} + +// LegacyOption provides support for writing LZ4 frames in the legacy format. +// +// See https://github.com/lz4/lz4/blob/dev/doc/lz4_Frame_format.md#legacy-frame. +// +// NB. compressed Linux kernel images use a tweaked LZ4 legacy format where +// the compressed stream is followed by the original (uncompressed) size of +// the kernel (https://events.static.linuxfound.org/sites/events/files/lcjpcojp13_klee.pdf). +// This is also supported as a special case. +func LegacyOption(legacy bool) Option { + return func(a applier) error { + switch rw := a.(type) { + case nil: + s := fmt.Sprintf("LegacyOption(%v)", legacy) + return lz4errors.Error(s) + case *Writer: + rw.legacy = legacy + return nil + } + return lz4errors.ErrOptionNotApplicable + } +} |