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- // Copyright 2019+ Klaus Post. All rights reserved.
- // License information can be found in the LICENSE file.
- // Based on work by Yann Collet, released under BSD License.
- package zstd
- import (
- "errors"
- "fmt"
- "runtime"
- )
- // DOption is an option for creating a decoder.
- type DOption func(*decoderOptions) error
- // options retains accumulated state of multiple options.
- type decoderOptions struct {
- lowMem bool
- concurrent int
- maxDecodedSize uint64
- }
- func (o *decoderOptions) setDefault() {
- *o = decoderOptions{
- // use less ram: true for now, but may change.
- lowMem: true,
- concurrent: runtime.GOMAXPROCS(0),
- }
- o.maxDecodedSize = 1 << 63
- }
- // WithDecoderLowmem will set whether to use a lower amount of memory,
- // but possibly have to allocate more while running.
- func WithDecoderLowmem(b bool) DOption {
- return func(o *decoderOptions) error { o.lowMem = b; return nil }
- }
- // WithDecoderConcurrency will set the concurrency,
- // meaning the maximum number of decoders to run concurrently.
- // The value supplied must be at least 1.
- // By default this will be set to GOMAXPROCS.
- func WithDecoderConcurrency(n int) DOption {
- return func(o *decoderOptions) error {
- if n <= 0 {
- return fmt.Errorf("Concurrency must be at least 1")
- }
- o.concurrent = n
- return nil
- }
- }
- // WithDecoderMaxMemory allows to set a maximum decoded size for in-memory
- // non-streaming operations or maximum window size for streaming operations.
- // This can be used to control memory usage of potentially hostile content.
- // For streaming operations, the maximum window size is capped at 1<<30 bytes.
- // Maximum and default is 1 << 63 bytes.
- func WithDecoderMaxMemory(n uint64) DOption {
- return func(o *decoderOptions) error {
- if n == 0 {
- return errors.New("WithDecoderMaxMemory must be at least 1")
- }
- if n > 1<<63 {
- return fmt.Errorf("WithDecoderMaxmemory must be less than 1 << 63")
- }
- o.maxDecodedSize = n
- return nil
- }
- }
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