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perf: cache debug images #1965

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perf: cache debug images #1965

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0492cc1
perf: cache debug images
kevinrenskers Jul 13, 2022
93c1658
Add a test
kevinrenskers Jul 18, 2022
3e6ca07
Merge branch 'master' into perf/1096-cache-debug-images
kevinrenskers Jul 18, 2022
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5 changes: 5 additions & 0 deletions Sources/Sentry/Public/SentryDebugImageProvider.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,11 @@ NS_ASSUME_NONNULL_BEGIN
*/
- (NSArray<SentryDebugMeta *> *)getDebugImages;

/**
* Clears the cached debug images.
*/
- (void)clearCachedDebugImages;

@end

NS_ASSUME_NONNULL_END
23 changes: 23 additions & 0 deletions Sources/Sentry/SentryDebugImageProvider.m
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Expand Up @@ -9,6 +9,7 @@
#import "SentryStacktrace.h"
#import "SentryThread.h"
#import <Foundation/Foundation.h>
#include <mach-o/dyld.h>

@interface
SentryDebugImageProvider ()
Expand All @@ -19,6 +20,8 @@

@implementation SentryDebugImageProvider

static NSArray<SentryDebugMeta *> *_Nullable cachedDebugImages;

- (instancetype)init
{

Expand All @@ -36,9 +39,24 @@ - (instancetype)initWithBinaryImageProvider:(id<SentryCrashBinaryImageProvider>)
if (self = [super init]) {
self.binaryImageProvider = binaryImageProvider;
}

_dyld_register_func_for_add_image(clearCachedDebugImages);
_dyld_register_func_for_remove_image(clearCachedDebugImages);

Comment on lines +43 to +45
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In some cases your callback function may be called on a different thread (namely the thread that is loading the library), see here: https://twitter.com/gparker/status/1266572192126386176?s=20&t=jXOtWHAPuZ8oUrlUj788jQ

In this scenario the callback functions are accessing cachedDebugImages in a non-thread safe way, so you would need to use a lock to guard all reads/writes to cachedDebugImages.

return self;
}

void
clearCachedDebugImages(const struct mach_header *header, intptr_t slide)
{
cachedDebugImages = nil;
}

- (void)clearCachedDebugImages
{
cachedDebugImages = nil;
}

- (NSArray<SentryDebugMeta *> *)getDebugImagesForThreads:(NSArray<SentryThread *> *)threads
{
NSMutableSet<NSString *> *imageAdresses = [[NSMutableSet alloc] init];
Expand Down Expand Up @@ -66,6 +84,10 @@ - (instancetype)initWithBinaryImageProvider:(id<SentryCrashBinaryImageProvider>)

- (NSArray<SentryDebugMeta *> *)getDebugImages
{
if (cachedDebugImages != nil) {
return cachedDebugImages;
}

NSMutableArray<SentryDebugMeta *> *debugMetaArray = [NSMutableArray new];

NSInteger imageCount = [self.binaryImageProvider getImageCount];
Expand All @@ -75,6 +97,7 @@ - (instancetype)initWithBinaryImageProvider:(id<SentryCrashBinaryImageProvider>)
[debugMetaArray addObject:debugMeta];
}

cachedDebugImages = debugMetaArray;
return debugMetaArray;
}

Expand Down
26 changes: 24 additions & 2 deletions Tests/SentryTests/SentryCrash/SentryDebugImageProviderTests.swift
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Expand Up @@ -8,8 +8,9 @@ import XCTest
class SentryDebugImageProviderTests: XCTestCase {

private class Fixture {
let imageProvider = TestSentryCrashBinaryImageProvider()

func getSut(images: [SentryCrashBinaryImage] = []) -> SentryDebugImageProvider {
let imageProvider = TestSentryCrashBinaryImageProvider()
imageProvider.imageCount = images.count
imageProvider.binaryImage = images
return SentryDebugImageProvider(binaryImageProvider: imageProvider)
Expand Down Expand Up @@ -72,6 +73,27 @@ class SentryDebugImageProviderTests: XCTestCase {
XCTAssertEqual("apple", debugMeta.type)
XCTAssertEqual(352_256, debugMeta.imageSize)
}

func test_DebugImageCache() {
let twoImages = Array(fixture.getTestImages().dropLast())
let sut = fixture.getSut(images: twoImages)

var actual = sut.getDebugImages()
XCTAssertEqual(2, actual.count)

// We update the debug images under the hood
fixture.imageProvider.binaryImage = fixture.getTestImages()
fixture.imageProvider.imageCount = fixture.imageProvider.binaryImage.count

// It's still using the cached value
actual = sut.getDebugImages()
XCTAssertEqual(2, actual.count)

// Clear the cache and get the new value
sut.clearCachedDebugImages()
actual = sut.getDebugImages()
XCTAssertEqual(3, actual.count)
}

func testImageVmAddressIsZero() {
let image = SentryDebugImageProviderTests.createSentryCrashBinaryImage(vmAddress: 0)
Expand Down Expand Up @@ -156,7 +178,7 @@ class SentryDebugImageProviderTests: XCTestCase {

XCTAssertEqual(actual.count, 0)
}

private static func createSentryCrashBinaryImage(
address: UInt64 = 0,
vmAddress: UInt64 = 0,
Expand Down