Retain the dyld_shared_cache to which one belongs #238
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Pull Request Overview
Adds retention of dyld cache objects to avoid repeatedly re-mapping the same files and propagates parent FullDyldCache / main-cache references through created DyldCache and MachOFile instances.
- Passes DyldCache references into MachOFile initializers to retain and reuse mapped caches.
- Introduces internal linkage (_fullCache / _mainCache) plus helper APIs (cache(for:), subcache init) to navigate between main, sub, and full caches.
- Updates ObjC optimization helpers and subcache resolution to propagate cache references.
Reviewed Changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| ObjCHeaderInfoRO.swift | Adds cache parameter when constructing MachOFile to retain associated DyldCache. |
| DyldSubCacheEntry.swift | Uses new subcache initializer and propagates _fullCache. |
| MachOFile.swift | Adds cache/fullCache retention fields, new convenience init, and makes cache/fullCache properties public with lazy caching logic. |
| FullDyldCache.swift | Ensures created DyldCache instances point back to FullDyldCache; adds cache(for:) lookup. |
| DyldCache.swift | Adds retention of parent/full caches, new subcache init variant, and passes self when creating MachOFile instances. |
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| public var cache: DyldCache? { | ||
| if let _cache { return _cache } | ||
| if let fullCache { | ||
| return fullCache.cache(for: url) |
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The result of fullCache.cache(for:) is not stored back into _cache, causing a new DyldCache instance to be produced on every access despite the stated goal of retaining caches. Assign the looked-up cache to _cache before returning to ensure reuse.
| return fullCache.cache(for: url) | |
| _cache = fullCache.cache(for: url) | |
| return _cache |
Sources/MachOKit/MachOFile.swift
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| if let _fullCache { return _fullCache } | ||
| if let _cache, | ||
| let _fullCache = _cache._fullCache { | ||
| return _cache._fullCache |
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This early return does not persist the discovered FullDyldCache into self._fullCache, so subsequent calls will recompute (or re-traverse) instead of using a cached reference. Set self._fullCache = _fullCache before returning to retain it.
| return _cache._fullCache | |
| self._fullCache = _fullCache | |
| return _fullCache |
…ence - Ensure _fullCache is set in _cache when initializing - Return _fullCache directly if available
DyldCacheorFullDyldCacheevery time to access the cache is inefficient.Foundation.FileHandlewas used for reading files, resulting in a structure that repeatedly performed seek and read operations.