APM – iOS 内存泄漏监控 MLeaksFinder代码解析

iOS 2周前 0 12

简介

MLeaksFinder是微信开源的能够在iOS开发阶段用来检测内存走漏的库，能够主动的在UIView和UIViewController中发现走漏，经过弹出框显示在View-ViewController中的走漏目标。除了发现UIView和UIViewController的走漏目标，开发者也能够扩展到其他类型的目标。

并且能够经过FBRetainCycleDetector找到引证环。

内存分类

Leaked memory 不被应用引证的内存，无法再次运用或者开释（能够运用Leaks Instrument东西检测到）
Abandoned memory 没有用途的，仍被应用引证的内存
Cached memory 仍然被应用引证，能够被再次运用然后得到更好的功能

原理

除了单例及其持有它的强引证，当一个UIViewController被pop或dismiss后，对应的View，View的subViews等目标将很快被开释。

Hook

Hook所有页面退出的状况作为检测机遇

UIViewController
- -dismiss
- -viewDidDisappear
UINavigationController
- -pop
- -popToRoot
- -popToViewController

视图层级

页面生命周期

UINavigationController -push/pop

-[MyUINavigationController pushViewController:animated:] -[ParentViewController viewWillDisappear:] -[ChildViewController viewWillAppear:] -[ParentViewController viewDidDisappear:] -[ChildViewController viewDidAppear:]
-[MyUINavigationController popViewControllerAnimated:] -[ChildViewController viewWillDisappear:] -[ParentViewController viewWillAppear:] -[ChildViewController viewDidDisappear:] -[ParentViewController viewDidAppear:] -[ChildViewController dealloc]

从上述的页面生命周期能够看到，viewDidDisappear在页面做push的时分也会触发，所以不能独自以viewDidDisappear作为检测机遇，需要以先有popViewControllerAnimated，后有viewDidDisappear为特征，才干作为页面出栈的判别。

Left-edge swipe

UINavigationController -pop有一种特殊状况是左滑手势

先左滑-后松开

-[MyUINavigationController popViewControllerAnimated:]
-[ChildViewController viewWillDisappear:]
-[ParentViewController viewWillAppear:]
-[ParentViewController viewWillDisappear:]
-[ParentViewController viewDidDisappear:]
-[ChildViewController viewWillAppear:]
-[ChildViewController viewDidAppear:]

先左滑-后完成

-[MyUINavigationController popViewControllerAnimated:]
-[ChildViewController viewWillDisappear:]
-[ParentViewController viewWillAppear:]
-[ChildViewController viewDidDisappear:]
-[ParentViewController viewDidAppear:]
-[ChildViewController dealloc]

因为左滑开端的时分，popViewControllerAnimated已经触发，并且时长由用户决定。因为检测需要运用延迟履行，查看页面等目标是否开释，所以不能独自以

popViewControllerAnimated为检测机遇，需要以先有popViewControllerAnimated，后有viewDidDisappear为特征，才干作为页面出栈的判别。

popToRoot/popToViewController

-[MyUINavigationController pushViewController:animated:]
-[MyUINavigationController pushViewController:animated:]
-[ParentViewController viewWillDisappear:]
-[OtherViewController viewWillAppear:]
-[ParentViewController viewDidDisappear:]
-[OtherViewController viewDidAppear:]
-[OtherViewController viewWillDisappear:]
-[ChildViewController viewWillAppear:]
-[OtherViewController viewDidDisappear:]
-[ChildViewController viewDidAppear:]
-[MyUINavigationController popToRootViewControllerAnimated:]
-[ChildViewController viewWillDisappear:]
-[ParentViewController viewWillAppear:]
-[OtherViewController dealloc]
-[ChildViewController viewDidDisappear:]
-[ParentViewController viewDidAppear:]
-[ChildViewController dealloc]

从页面生命周期能够看到，除了TopViewController和RootViewController/ToViewController，其他处于中心的ViewController在弹出页面栈的时分不会有生命周期的调用，能够获取中心的ViewController开端检测。

UIViewController -present/dismiss

Modal

Modal是指模态，形式状况，模态是人机交互过程中的一种状况，表现为用户相同的操作下能够发生不同的成果。例如使翻开文件夹时，点击和右击会触发不同的作用。弹框也有对应的对话框，弹出框，全屏框等作用。

根据Modal的不同，ParentViewController的Appear状况会不同，当ParentViewController完全被遮挡的时分，会有Appear相关的页面生命周期改变。

不同模态下的页面生命周期不同，能够分为3类。

半掩盖

UIModalPresentationPageSheet
UIModalPresentationFormSheet
UIModalPresentationAutomatic
UIModalPresentationCustom
UIModalPresentationPopover

-[ParentViewController presentViewController:animated:completion:] -[ChildViewController viewWillAppear:] -[ChildViewController viewDidAppear:]
-[ChildViewController dismissViewControllerAnimated:completion:] -[ChildViewController viewWillDisappear:] -[ChildViewController viewDidDisappear:] -[ChildViewController dealloc]

全掩盖

UIModalPresentationCurrentContext
UIModalPresentationFullScreen

-[ParentViewController presentViewController:animated:completion:] -[ParentViewController viewWillDisappear:] -[ChildViewController viewWillAppear:] -[ChildViewController viewDidAppear:] -[ParentViewController viewDidDisappear:]
-[ChildViewController dismissViewControllerAnimated:completion:] -[ChildViewController viewWillDisappear:] -[ParentViewController viewWillAppear:] -[ParentViewController viewDidAppear:] -[ChildViewController viewDidDisappear:] -[ChildViewController dealloc]

报错

UIModalPresentationOverFullScreen
UIModalPresentationNone

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'The specified modal presentation style doesn't have a corresponding presentation controller.'

这两种模态，会导致报OC语言层面反常，模态展现方式和对应controller不匹配

代码解析

运用了Method Swizzle对页面的生命周期进行了Hook

Method Swizzle

NSObject (MemoryLeak)中对swizzle做了封装

+ (void)swizzleSEL:(SEL)originalSEL withSEL:(SEL)swizzledSEL {
#if _INTERNAL_MLF_ENABLED
    Class class = [self class];
    Method originalMethod = class_getInstanceMethod(class, originalSEL);
    Method swizzledMethod = class_getInstanceMethod(class, swizzledSEL);
    BOOL didAddMethod =
    class_addMethod(class,
                    originalSEL,
                    method_getImplementation(swizzledMethod),
                    method_getTypeEncoding(swizzledMethod));
    if (didAddMethod) {
        class_replaceMethod(class,
                            swizzledSEL,
                            method_getImplementation(originalMethod),
                            method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
#endif
}

运用宏作为功能开关，DEBUG的状况下翻开，或者手动设置MEMORY_LEAKS_FINDER_ENABLED为1翻开

//#define MEMORY_LEAKS_FINDER_ENABLED 0
#ifdef MEMORY_LEAKS_FINDER_ENABLED
#define _INTERNAL_MLF_ENABLED MEMORY_LEAKS_FINDER_ENABLED
#else
#define _INTERNAL_MLF_ENABLED DEBUG
#endif

UINavigationController (MemoryLeak)

popViewControllerAnimated

在该生命周期中符号kHasBeenPoppedKey为YES

- (UIViewController *)swizzled_popViewControllerAnimated:(BOOL)animated {
    UIViewController *poppedViewController = [self swizzled_popViewControllerAnimated:animated];
    if (!poppedViewController) {
        return nil;
    }
    // Detail VC in UISplitViewController is not dealloced until another detail VC is shown
    if (self.splitViewController &&
        self.splitViewController.viewControllers.firstObject == self &&
        self.splitViewController == poppedViewController.splitViewController) {
        objc_setAssociatedObject(self, kPoppedDetailVCKey, poppedViewController, OBJC_ASSOCIATION_RETAIN);
        return poppedViewController;
    }
    // VC is not dealloced until disappear when popped using a left-edge swipe gesture
    extern const void *const kHasBeenPoppedKey;
    objc_setAssociatedObject(poppedViewController, kHasBeenPoppedKey, @(YES), OBJC_ASSOCIATION_RETAIN);
    return poppedViewController;
}

在UIViewController的viewWillAppear中，符号kHasBeenPoppedKey为NO

- (void)swizzled_viewWillAppear:(BOOL)animated {
    [self swizzled_viewWillAppear:animated];
    objc_setAssociatedObject(self, kHasBeenPoppedKey, @(NO), OBJC_ASSOCIATION_RETAIN);
}

popToViewController

获取中心的ViewController开端检测

- (NSArray<UIViewController *> *)swizzled_popToViewController:(UIViewController *)viewController animated:(BOOL)animated {
    NSArray<UIViewController *> *poppedViewControllers = [self swizzled_popToViewController:viewController animated:animated];
    for (UIViewController *viewController in poppedViewControllers) {
        [viewController willDealloc];
    }
    return poppedViewControllers;
}

popToRootViewControllerAnimated

获取中心的ViewController开端检测

- (NSArray<UIViewController *> *)swizzled_popToRootViewControllerAnimated:(BOOL)animated {
    NSArray<UIViewController *> *poppedViewControllers = [self swizzled_popToRootViewControllerAnimated:animated];
    for (UIViewController *viewController in poppedViewControllers) {
        [viewController willDealloc];
    }
    return poppedViewControllers;
}

UIViewController (MemoryLeak)

viewDidDisappear

判别kHasBeenPoppedKey为YES，然后开端检测

- (void)swizzled_viewDidDisappear:(BOOL)animated {
    [self swizzled_viewDidDisappear:animated];
    if ([objc_getAssociatedObject(self, kHasBeenPoppedKey) boolValue]) {
        [self willDealloc];
    }
}

dismissViewControllerAnimated

- (void)swizzled_dismissViewControllerAnimated:(BOOL)flag completion:(void (^)(void))completion {
    [self swizzled_dismissViewControllerAnimated:flag completion:completion];
    UIViewController *dismissedViewController = self.presentedViewController;
    if (!dismissedViewController && self.presentingViewController) {
        dismissedViewController = self;
    }
    if (!dismissedViewController) return;
    [dismissedViewController willDealloc];
}

对应的presentedViewController，presentingViewController，self对应如下，获取到dismissedViewController并履行检测。因为dismissedViewController并没有边缘手势的影响，不需要运用dimiss和viewDidDisappear叠加的方式来判别检测的机遇。

-[ChildViewController dismissViewControllerAnimated:completion:]
self.presentedViewController (null)
self.presentingViewController <MyUINavigationController: 0x10181d600>
self <ChildViewController: 0x102d043e0>
-[ChildViewController viewWillDisappear:]
-[ChildViewController viewDidDisappear:]
-[ChildViewController dealloc]

Action

获取对应类的weakSelf，延迟2秒在主行列履行，调用weakSelf中的assertNotDealloc办法，办法还能呼应的话就记载相关信息

类结构

NSObject

UIViewController
- UINavigationController
- UIPageViewController
- UISplitViewController
- UITabBarController
UIView

检测目标中存在承继联系，检测办法也运用了承继联系

代码解析

NSObject (MemoryLeak)

willDealloc

如果在白名单中，不进行检测
如果走漏目标是最近一次UIControl事件的触发者，不进行检测（按照修改记载来看，当运用Button来pop ViewController的时分，VC不能及时开释）

- (BOOL)willDealloc {
    NSString *className = NSStringFromClass([self class]);
    if ([[NSObject classNamesWhitelist] containsObject:className])
        return NO;
    NSNumber *senderPtr = objc_getAssociatedObject([UIApplication sharedApplication], kLatestSenderKey);
    if ([senderPtr isEqualToNumber:@((uintptr_t)self)])
        return NO;
    __weak id weakSelf = self;
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        __strong id strongSelf = weakSelf;
        [strongSelf assertNotDealloc];
    });
    return YES;
}

UIApplication (MemoryLeak)

获取和更新LatestSender

- (BOOL)swizzled_sendAction:(SEL)action to:(id)target from:(id)sender forEvent:(UIEvent *)event {
    objc_setAssociatedObject(self, kLatestSenderKey, @((uintptr_t)sender), OBJC_ASSOCIATION_RETAIN);
    return [self swizzled_sendAction:action to:target from:sender forEvent:event];
}

UITouch (MemoryLeak)

获取和更新LatestSender

- (void)swizzled_setView:(UIView *)view {
    [self swizzled_setView:view];
    if (view) {
        objc_setAssociatedObject([UIApplication sharedApplication],
                                 kLatestSenderKey,
                                 @((uintptr_t)view),
                                 OBJC_ASSOCIATION_RETAIN);
    }
}

assertNotDealloc

判别该目标是否已经在走漏目标的调集里
添加到走漏目标的调集里
内存走漏提示

- (void)assertNotDealloc {
    if ([MLeakedObjectProxy isAnyObjectLeakedAtPtrs:[self parentPtrs]]) {
        return;
    }
    [MLeakedObjectProxy addLeakedObject:self];
    NSString *className = NSStringFromClass([self class]);
    NSLog(@"Possibly Memory Leak.\nIn case that %@ should not be dealloced, override -willDealloc in %@ by returning NO.\nView-ViewController stack: %@", className, className, [self viewStack]);
}

willReleaseChildren

遍历视图树，构建视图堆栈ViewStack
记载父节点

- (void)willReleaseChildren:(NSArray *)children {
    NSArray *viewStack = [self viewStack];
    NSSet *parentPtrs = [self parentPtrs];
    for (id child in children) {
        NSString *className = NSStringFromClass([child class]);
        [child setViewStack:[viewStack arrayByAddingObject:className]];
        [child setParentPtrs:[parentPtrs setByAddingObject:@((uintptr_t)child)]];
        [child willDealloc];
    }
}

UINavigationController (MemoryLeak)

willDealloc

检测self.viewControllers

- (BOOL)willDealloc {
    if (![super willDealloc]) {
        return NO;
    }
    [self willReleaseChildren:self.viewControllers];
    return YES;
}

UIPageViewController (MemoryLeak)

willDealloc

检测self.viewControllers

- (BOOL)willDealloc {
    if (![super willDealloc]) {
        return NO;
    }
    [self willReleaseChildren:self.viewControllers];
    return YES;
}

UISplitViewController (MemoryLeak)

willDealloc

检测self.viewControllers

- (BOOL)willDealloc {
    if (![super willDealloc]) {
        return NO;
    }
    [self willReleaseChildren:self.viewControllers];
    return YES;
}

UITabBarController (MemoryLeak)

willDealloc

检测self.viewControllers

- (BOOL)willDealloc {
    if (![super willDealloc]) {
        return NO;
    }
    [self willReleaseChildren:self.viewControllers];
    return YES;
}

UIViewController (MemoryLeak)

willDealloc

检测self.childViewControllers
检测self.presentedViewController
viewDidLoad的状况下从self.view开端遍历subviews

- (BOOL)willDealloc {
    if (![super willDealloc]) {
        return NO;
    }
    [self willReleaseChildren:self.childViewControllers];
    [self willReleaseChild:self.presentedViewController];
    if (self.isViewLoaded) {
        [self willReleaseChild:self.view];
    }
    return YES;
}

UIView (MemoryLeak)

willDealloc

遍历view的subviews

UIView (MemoryLeak)
- (BOOL)willDealloc {
    if (![super willDealloc]) {
        return NO;
    }
    [self willReleaseChildren:self.subviews];
    return YES;
}

引证

MLeaksFinder Github

MLeaksFinder 新特性

MLeaksFinder：精准 iOS 内存走漏检测东西

APP Git GitHub Go iOS Python 内存泄漏微信手势监控

简介

内存分类

原理

Hook

页面生命周期

UINavigationController -push/pop

Left-edge swipe

popToRoot/popToViewController

UIViewController -present/dismiss

Modal

半掩盖

全掩盖

报错

代码解析

Method Swizzle

UINavigationController (MemoryLeak)

popViewControllerAnimated

popToViewController

popToRootViewControllerAnimated

UIViewController (MemoryLeak)

viewDidDisappear

dismissViewControllerAnimated

Action

类结构

代码解析

NSObject (MemoryLeak)

willDealloc

assertNotDealloc

willReleaseChildren

UINavigationController (MemoryLeak)

willDealloc

UIPageViewController (MemoryLeak)

willDealloc

UISplitViewController (MemoryLeak)

willDealloc

UITabBarController (MemoryLeak)

willDealloc

UIViewController (MemoryLeak)

willDealloc

UIView (MemoryLeak)

willDealloc

引证

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