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[kjdev]

Summary by CodeRabbit

• New Features

  • Added support for decompression using dictionaries, improving compatibility with dictionary-compressed data.

• Improvements

  • Enhanced compression and decompression performance by switching to dynamic streaming buffers instead of fixed-size allocations.
  • Improved error handling and warnings for more consistent user feedback.

• Bug Fixes

  • Resolved issues related to buffer management and dictionary handling in compression and decompression operations.

[coderabbitai]

Walkthrough

This update refactors the internal Zstd context management in the PHP extension by introducing centralized context initialization and helper functions for compression and decompression. It adds support for decompression dictionaries, replaces fixed-size output buffers with dynamic streaming buffers, and standardizes error handling and dictionary management throughout the codebase.

Changes

File(s) / Area	Change Summary
zstd.c	Added centralized context init/free helpers, new compress/decompress context creation functions, added ddict field, rewrote one-shot and streaming APIs to use new helpers and dynamic buffers, standardized dictionary and error handling, updated stream wrapper and output handler logic.
Internal functions, macros, struct definitions	Introduced php_zstd_context_init, php_zstd_context_create_compress, php_zstd_context_create_decompress, new error checking macros, modified php_zstd_stream_data struct to embed context, updated function signatures for context and dictionary handling.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant PHP_Extension
    participant Zstd_Lib

    User->>PHP_Extension: Call zstd_compress/uncompress
    PHP_Extension->>PHP_Extension: php_zstd_context_init()
    PHP_Extension->>PHP_Extension: php_zstd_context_create_compress/decompress()
    PHP_Extension->>Zstd_Lib: Create CCtx/DCtx, load dictionary if needed
    PHP_Extension->>PHP_Extension: Use streaming API with smart_string buffer
    PHP_Extension->>Zstd_Lib: Compress/Decompress via ZSTD_compressStream2/ZSTD_decompressStream
    PHP_Extension->>User: Return result

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Possibly related PRs

• change: error message #83: Introduces new macros for error checking and error message improvements, directly related to the standardized error handling in this PR.
• Add incremental zstd_(un)compress_init() and zstd_(un)compress_add() #79: Refactors incremental compression/decompression functions and context management, which this PR further centralizes and extends.
• Fix/streaming uncompress dict #81: Refactors dictionary-based decompression and streaming logic, closely related to the new centralized context and dictionary handling in this PR.

Poem

In the warren of code, a context anew,
With helpers and buffers, the logic grew.
Dictionaries now hop in with ease,
And error checks bring rabbits peace.
With streaming and macros, the patch is complete—
Zstd extension now skips to a modern beat!
🐇✨

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📜 Recent review details

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Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 8afadfc and 1a92e55.

📒 Files selected for processing (1)

• zstd.c (26 hunks)

🧰 Additional context used

🧠 Learnings (2)

📓 Common learnings

Learnt from: thekid
PR: kjdev/php-ext-zstd#77
File: zstd.stub.php:13-22
Timestamp: 2025-04-20T19:39:56.258Z
Learning: The php-ext-zstd library aims to maintain compatibility with PHP 7, so PHP 8-specific syntax features like union types should be avoided in favor of PHPDoc annotations.

zstd.c (1)

Learnt from: thekid
PR: kjdev/php-ext-zstd#77
File: zstd.stub.php:13-22
Timestamp: 2025-04-20T19:39:56.258Z
Learning: The php-ext-zstd library aims to maintain compatibility with PHP 7, so PHP 8-specific syntax features like union types should be avoided in favor of PHPDoc annotations.

🧬 Code Graph Analysis (1)

zstd.c (1)

zstd.stub.php (6)

• zstd_uncompress (7-7)
• zstd_compress_dict (9-9)
• zstd_uncompress_dict (11-11)
• zstd_compress_add (15-15)
• zstd_uncompress_add (19-19)
• compress (25-25)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (19)

• GitHub Check: ci (8.1, x86, nts, vs16, true, apcu)
• GitHub Check: ci (8.1, x64, ts, vs16, true)
• GitHub Check: ci (8.1, x64, nts, vs16, true, apcu)
• GitHub Check: ci (8.1, x64, ts, vs16, true, apcu)
• GitHub Check: ci (8.1, x64, ts, vs16, false)
• GitHub Check: ci (8.2, x86, ts, vs16, true)
• GitHub Check: ci (8.2, x86, nts, vs16, true, apcu)
• GitHub Check: ci (8.2, x86, nts, vs16, false)
• GitHub Check: ci (8.2, x64, ts, vs16, true)
• GitHub Check: ci (8.2, x64, nts, vs16, true, apcu)
• GitHub Check: ci (8.3, x86, ts, vs16, true)
• GitHub Check: ci (8.3, x86, nts, vs16, true, apcu)
• GitHub Check: ci (8.3, x64, ts, vs16, true, apcu)
• GitHub Check: ci (8.2-zts, system, apcu, php)
• GitHub Check: ci (8.2-zts, system, php)
• GitHub Check: ci (8.3, system, php)
• GitHub Check: ci (8.3, apcu, php)
• GitHub Check: ci (8.4, system, apcu, php)
• GitHub Check: ci (8.4, php)

🔇 Additional comments (19)

zstd.c (19)

63-68: LGTM! Good addition of error handling macros.

The introduction of ZSTD_WARNING and ZSTD_IS_ERROR macros standardizes error handling throughout the codebase and improves code readability.

---

78-78: LGTM! Proper addition of decompression dictionary support.

Adding the ddict field to the context structure enables symmetric dictionary support for both compression and decompression operations.

---

91-108: LGTM! Proper context initialization implementation.

The centralized php_zstd_context_init function ensures all context fields are properly initialized, preventing potential undefined behavior from uninitialized memory.

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124-127: LGTM! Proper cleanup of decompression dictionary.

The php_zstd_context_free function correctly frees the decompression dictionary resource, preventing memory leaks.

---

160-189: LGTM! Well-structured compression context creation.

The helper function properly encapsulates context creation with good error handling. It correctly manages resources and returns appropriate status codes.

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191-217: LGTM! Symmetric decompression context creation.

The decompression helper function follows the same pattern as the compression helper, ensuring consistency in the API design and error handling.

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383-428: LGTM! Excellent refactoring to streaming compression.

The refactoring improves the function by:

• Using zend_string for better PHP string integration
• Replacing fixed-size buffers with dynamic smart_string for memory efficiency
• Implementing streaming compression which handles arbitrary input sizes
• Maintaining proper error handling and resource cleanup

---

430-492: LGTM! Robust streaming decompression implementation.

The refactoring handles edge cases well:

• Properly manages unknown content sizes with dynamic buffer expansion
• Uses streaming API for efficient memory usage
• Maintains consistency with the compression function structure

---

494-540: LGTM! Consistent dictionary compression implementation.

The function properly uses the new helper function with dictionary support and maintains the same streaming pattern as the non-dictionary variant.

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542-607: LGTM! Proper dictionary decompression implementation.

The decompression function correctly handles dictionaries and follows the same robust pattern with dynamic buffer management.

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624-627: LGTM! Proper use of compression context helper.

The function correctly delegates context creation to the new helper function.

---

630-680: LGTM! Consistent incremental compression API.

The function properly accepts zend_string input and maintains the streaming compression pattern.

---

686-689: LGTM! Proper decompression context initialization.

Uses the new helper function consistently.

---

692-746: LGTM! Consistent incremental decompression API.

The function properly handles zend_string input and maintains proper error handling.

---

748-753: LGTM! Cleaner stream data structure.

Embedding the context directly simplifies the structure and reduces indirection.

---

776-777: LGTM! Proper context cleanup in stream close functions.

Both decompression and compression close functions correctly use the centralized context cleanup.

Also applies to: 834-835

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973-1070: LGTM! Improved dictionary handling in stream opener.

The stream opener properly:

• Loads dictionaries as zend_string
• Uses the new context creation helpers
• Ensures proper cleanup of dictionary strings in all code paths

---

1204-1236: LGTM! Cleaner dictionary loading implementation.

The function now properly returns a zend_string* for the dictionary data, which integrates better with the new context creation helpers.

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1246-1250: LGTM! Proper integration with context creation helper.

The function correctly uses the loaded dictionary string with the new context creation helper.

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[kjdev]

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