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245b5e0766
This is better than the `alternativePaths` mechanism because it means that a client of the `Runtime` module can do its own thing, which might even mean fetching things from a remote server or decompressing files or any other thing we might find useful. rdar://170642627
115 lines
3.2 KiB
Swift
115 lines
3.2 KiB
Swift
//===--- ElfImageCache.swift - ELF support for Swift ----------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2024 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Provides a per-thread Elf image cache that improves efficiency when
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// taking multiple backtraces by avoiding loading ELF images multiple times.
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//
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//===----------------------------------------------------------------------===//
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import Swift
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#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
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internal import Darwin
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#elseif os(Windows)
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internal import WinSDK
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#elseif canImport(Glibc)
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internal import Glibc
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#elseif canImport(Musl)
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internal import Musl
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#endif
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/// Provides a per-thread image cache for ELF image processing. This means
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/// if you take multiple backtraces from a thread, you won't load the same
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/// image multiple times.
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@available(Backtracing 6.2, *)
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final class ElfImageCache {
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var elf32: [String: Elf32Image] = [:]
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var elf64: [String: Elf64Image] = [:]
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func purge() {
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elf32 = [:]
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elf64 = [:]
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}
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enum Result {
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case elf32Image(Elf32Image)
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case elf64Image(Elf64Image)
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}
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func lookup(path: String?) -> Result? {
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guard let path = path else {
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return nil
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}
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if let image = elf32[path] {
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return .elf32Image(image)
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}
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if let image = elf64[path] {
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return .elf64Image(image)
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}
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if let source = try? ImageSource(path: path) {
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if let elfImage = try? Elf32Image(source: source) {
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elf32[path] = elfImage
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return .elf32Image(elfImage)
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}
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if let elfImage = try? Elf64Image(source: source) {
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elf64[path] = elfImage
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return .elf64Image(elfImage)
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}
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}
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return nil
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}
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#if os(Windows)
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private static var dwTlsIndex: DWORD = {
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let dwNdx = TlsAlloc()
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if dwNdx == TLS_OUT_OF_INDEXES {
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fatalError("Unable to allocate TSD for ElfImageCache")
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}
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return dwNdx
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}()
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#else
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private static var key: pthread_key_t = {
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var theKey = pthread_key_t()
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let err = pthread_key_create(
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&theKey,
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{ rawPtr in
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let ptr = Unmanaged<ElfImageCache>.fromOpaque(
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notMutable(notOptional(rawPtr))
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)
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ptr.release()
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}
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)
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if err != 0 {
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fatalError("Unable to create TSD key for ElfImageCache")
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}
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return theKey
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}()
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#endif
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static var threadLocal: ElfImageCache {
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#if os(Windows)
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guard let rawPtr = TlsGetValue(dwTlsIndex) else {
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let cache = Unmanaged<ElfImageCache>.passRetained(ElfImageCache())
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TlsSetValue(dwTlsIndex, cache.toOpaque())
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return cache.takeUnretainedValue()
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}
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#else
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guard let rawPtr = pthread_getspecific(key) else {
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let cache = Unmanaged<ElfImageCache>.passRetained(ElfImageCache())
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pthread_setspecific(key, cache.toOpaque())
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return cache.takeUnretainedValue()
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}
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#endif
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let cache = Unmanaged<ElfImageCache>.fromOpaque(rawPtr)
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return cache.takeUnretainedValue()
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}
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}
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