zstd: Add ResetWithOptions to encoder/decoder by klauspost · Pull Request #1122 · klauspost/compress

klauspost · 2026-01-13T21:24:21Z

New API Methods

  func (*Encoder) ResetWithOptions(w io.Writer, opts ...EOption) error
  func (*Decoder) ResetWithOptions(r io.Reader, opts ...DOption) error

New Options

  // Encoder - clears dictionary
  `WithEncoderDictDelete() EOption`

  // Decoder - removes dicts by ID; no args clears all
  `WithDecoderDictDelete(ids ...uint32) DOption`

Option Reset Compatibility

Can be changed with ResetWithOptions:

Encoder: WithEncoderCRC, WithEncoderPadding, WithZeroFrames, WithAllLitEntropyCompression, WithNoEntropyCompression, WithSingleSegment, WithEncoderDict, WithEncoderDictRaw, WithEncoderDictDelete
Decoder: WithDecoderMaxMemory, WithDecoderMaxWindow, WithDecoderDicts, WithDecoderDictRaw, WithDecoderDictDelete, WithDecodeAllCapLimit, IgnoreChecksum

Cannot be changed with ResetWithOptions:

Encoder: WithEncoderConcurrency, WithWindowSize, WithEncoderLevel, WithLowerEncoderMem
Decoder: WithDecoderLowmem, WithDecoderConcurrency, WithDecodeBuffersBelow

Summary by CodeRabbit

New Features
- Added ResetWithOptions for decoders and encoders to apply option changes when reinitializing streams.
- Added ability to delete specific or all dictionaries during reset.
Chores
- Tightened option mutability rules so some settings cannot be changed during reset to preserve stability.
- Switched dictionary storage to ID-keyed maps for more direct lookup.
Tests
- Added tests covering reset-with-options behavior and dictionary deletion scenarios.

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## New API Methods ``` func (*Encoder) ResetWithOptions(w io.Writer, opts ...EOption) error func (*Decoder) ResetWithOptions(r io.Reader, opts ...DOption) error ``` New Options // Encoder - clears dictionary `WithEncoderDictDelete() EOption` // Decoder - removes dicts by ID; no args clears all `WithDecoderDictDelete(ids ...uint32) DOption` Option Reset Compatibility Can be changed with ResetWithOptions: - Encoder: WithEncoderCRC, WithEncoderPadding, WithZeroFrames, WithAllLitEntropyCompression, WithNoEntropyCompression, WithSingleSegment, WithEncoderDict, WithEncoderDictRaw, WithEncoderDictDelete - Decoder: WithDecoderMaxMemory, WithDecoderMaxWindow, WithDecoderDicts, WithDecoderDictRaw, WithDecoderDictDelete, WithDecodeAllCapLimit, IgnoreChecksum Cannot be changed with ResetWithOptions: - Encoder: WithEncoderConcurrency, WithWindowSize, WithEncoderLevel, WithLowerEncoderMem - Decoder: WithDecoderLowmem, WithDecoderConcurrency, WithDecodeBuffersBelow

coderabbitai · 2026-01-13T21:24:34Z

📝 Walkthrough

Walkthrough

Added ResetWithOptions to Encoder and Decoder to apply option changes during stream resets, moved decoder dictionary storage from per-decoder field to options-layer map, introduced resetOpt to restrict certain option changes during resets, and added dictionary deletion options and tests.

Changes

Cohort / File(s)	Summary
Core Reset Methods `zstd/decoder.go`, `zstd/encoder.go`	Added `ResetWithOptions(r io.Reader, opts ...DOption) error` and `ResetWithOptions(w io.Writer, opts ...EOption) error`. Decoder now reads dictionaries from options (`d.o.dicts`) instead of a per-decoder field.
Options & Dict Storage `zstd/decoder_options.go`, `zstd/encoder_options.go`	Introduced `resetOpt` flag in options to mark reset context and prevent changing certain options during reset. Switched decoder dict storage to `map[uint32]*dict`. Added public options `WithDecoderDictDelete(ids ...uint32)` and `WithEncoderDictDelete()` to remove dictionaries. Several option setters now reject changes when reset is active.
Tests `zstd/decoder_test.go`, `zstd/encoder_options_test.go`	Added tests: `TestDecoderResetWithOptions`, `TestDecoderDictDelete`, `TestDecoderDictDeleteMultiple`, `TestEncoderResetWithOptions`, and `TestEncoderDictDelete` to validate reset semantics and dict lifecycle operations.

Sequence Diagram(s)

mermaid
sequenceDiagram
participant Client
participant Decoder
participant Options
participant Reader
Client->>Decoder: Call ResetWithOptions(reader, opts...)
Decoder->>Options: set resetOpt = true
Options-->>Decoder: apply each DOption (may mutate o.dicts or other fields)
Decoder->>Decoder: call Reset(reader) (reinitialize stream using o)
Decoder->>Options: set resetOpt = false
Decoder-->>Client: return result

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 77.42% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'zstd: Add ResetWithOptions to encoder/decoder' directly and accurately summarizes the main change—introducing ResetWithOptions methods to both Encoder and Decoder types.

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✨ Finishing touches

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klauspost · 2026-01-13T21:25:26Z

@dsnet As per #1110

# Conflicts: # zstd/encoder_options.go

coderabbitai

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

zstd/decoder_options.go (1)
95-96: Typo in error message.

The error message uses WithDecoderMaxmemory but the function is WithDecoderMaxMemory (capital M).
Proposed fix
-		return errors.New("WithDecoderMaxmemory must be less than 1 << 63")
+		return errors.New("WithDecoderMaxMemory must be less than 1 << 63")

klauspost added 2 commits January 14, 2026 12:46

Merge branch 'master' into add-reset-opts

9aeed46

Merge branch 'master' into add-reset-opts

f425c3c

# Conflicts: # zstd/encoder_options.go

coderabbitai bot reviewed Jan 22, 2026

View reviewed changes

klauspost added 2 commits January 28, 2026 09:54

Merge branch 'master' into add-reset-opts

7160eda

Merge branch 'master' into add-reset-opts

9200d68

klauspost merged commit c03560f into master Feb 5, 2026
22 checks passed

klauspost deleted the add-reset-opts branch February 5, 2026 15:29

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zstd: Add ResetWithOptions to encoder/decoder#1122

zstd: Add ResetWithOptions to encoder/decoder#1122
klauspost merged 5 commits intomasterfrom
add-reset-opts

klauspost commented Jan 13, 2026 •

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Walkthrough

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klauspost commented Jan 13, 2026 • edited by coderabbitai bot Loading Uh oh! There was an error while loading. Please reload this page.

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New API Methods

New Options

Option Reset Compatibility

Summary by CodeRabbit

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Walkthrough

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klauspost commented Jan 13, 2026 •

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