iOS性能优化 — 一、crash监控及防崩溃处理

{"type":"doc","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"大家好，欢迎来到 iOS性能优化"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"本篇文章将为大家讲解下crash监控及防崩溃处理。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如何收集crash利用bugly、友盟等第三方收集监控crash原理"}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"防崩溃处理常见崩溃类型防崩溃处理方案hook方案安全接口"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"如何收集crash"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在平常开发过程中，由于代码的不严谨比如不对入参做校验，使用C++野指针等会造成程序crash。crash应该算是最严重的bug了，尤其是线上crash，如果App用户量大的话可能造成很大的影响，所以需要有一套机制来收集项目中的crash并及时解决。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"利用bugly、友盟等第三方收集"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"大部分公司都是采用第三方平台来收集crash。业内用的比较多有bugly、友盟、talkingdata。笔者比较推荐bugly，腾讯研发，比较轻量，用来监控crash和卡顿还是很方便的。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"监控crash原理"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"一线大厂，大部分都会自研crash捕获框架。这个时候了解crash捕获原理就很有必要了，大家可以阅读开源库"},{"type":"link","attrs":{"href":"https://github.com/kstenerud/KSCrash","title":null},"content":[{"type":"text","text":"kscrash"}]},{"type":"text","text":"或者"},{"type":"link","attrs":{"href":"https://github.com/microsoft/plcrashreporter","title":null},"content":[{"type":"text","text":"plcrashreporter"}]},{"type":"text","text":"其实捕获crash原理很简单。主要需要处理两种情况："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1、OC类异常。NSException异常是OC代码导致的crash。我们可以先通过NSGetUncaughtExceptionHandler保存先前注册的异常处理器，然后通过NSSetUncaughtExceptionHandler设置我们自己的异常处理器，我们不监控了，"},{"type":"text","marks":[{"type":"strong"}],"text":"需要再设置回原理的异常处理器"},{"type":"text","text":"，在我们自己的uncaughtHandleException处理器里面，"},{"type":"text","marks":[{"type":"strong"}],"text":"需要手动调用下原来的处理器"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"static NSUncaughtExceptionHandler* g_previousUncaughtExceptionHandler;\n\nvoid installUncaughtExceptionHandler(void){\n g_previousUncaughtExceptionHandler = NSGetUncaughtExceptionHandler();\n NSSetUncaughtExceptionHandler(&uncaughtHandleException);\n\n}\n\nvoid uninstallUncaughtExceptionHandler(void){\n if(g_previousUncaughtExceptionHandler){\n NSSetUncaughtExceptionHandler(g_previousUncaughtExceptionHandler);\n }\n\n}\n\nvoid uncaughtHandleException(NSException *exception)\n{\n // 异常的堆栈信息\n NSArray *stackArray = [exception callStackSymbols];\n\n // 出现异常的原因\n NSString *reason = [exception reason];\n\n // 异常名称\n NSString *name = [exception name];\n\n NSString *exceptionInfo = [NSString stringWithFormat:@\"Exception reason：%@\\nException name：%@\\nException stack：%@\",name, reason, stackArray];\n NSLog(exceptionInfo);\n\n if (g_previousUncaughtExceptionHandler != NULL)\n {\n g_previousUncaughtExceptionHandler(exception);\n }\n\n}\n\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2、Signal信号捕获。Signal信号是由iOS底层mach信号异常转换后以signal信号抛出的异常。既然是兼容posix标准的异常，我们同样可以通过sigaction函数注册对应的信号。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"static struct sigaction* g_previousSignalHandlers = NULL; //旧的信号处理函数结构体数组\nstatic int g_fatalSignals[] = {\n SIGHUP,\n SIGINT,\n SIGQUIT,\n SIGABRT,\n SIGILL,\n SIGSEGV,\n SIGFPE,\n SIGBUS,\n SIGPIPE\n};\nstatic int g_fatalSignalsCount = (sizeof(g_fatalSignals) / sizeof(g_fatalSignals[0]));\n\nconst int* kssignal_fatalSignals(void){\n return g_fatalSignals;\n}\n\nint kssignal_numFatalSignals(void){\n return g_fatalSignalsCount;\n}\n\nvoid signalExceptionHandler(int signo, siginfo_t *info, void *uapVoid){\n\n void *frames[128];\n int i, len = backtrace(frames, 128);\n //堆栈信息\n char **symbols = backtrace_symbols(frames, len);\n NSMutableString *exceptionContent = [[NSMutableString alloc] init];\n [exceptionContent appendFormat:@\"signal name：%d \\n signal stack：\\n\",signo];\n for (i = 0; i < len; ++i)\n {\n [exceptionContent appendFormat:@\"%s\\r\\n\", symbols[i]];\n }\n //释放缓存\n free(symbols);\n\n raise(signo);\n}\n\nvoid installSignalHandler(void){\n const int* fatalSignals = kssignal_fatalSignals();\n\n int fatalSignalsCount = kssignal_numFatalSignals();\n\n if(g_previousSignalHandlers == NULL){\n g_previousSignalHandlers = (struct sigaction *)malloc(sizeof(*g_previousSignalHandlers)\n * (unsigned)fatalSignalsCount);\n }\n //初始化处理函数结构体\n struct sigaction action = {{0}};\n\n action.sa_flags = SA_SIGINFO | SA_ONSTACK;\n sigemptyset(&action.sa_mask);\n action.sa_sigaction = &signalExceptionHandler;\n\n for(int i = 0; i < fatalSignalsCount; i++)\n {\n if(sigaction(fatalSignals[i], &action, &g_previousSignalHandlers[i]) != 0)\n {\n // 取消已监听的handler\n for(i--;i >= 0; i--)\n {\n sigaction(fatalSignals[i], &g_previousSignalHandlers[i], NULL);\n }\n break;\n }\n }\n}\n\nvoid uninstallSignalHandler(void){\n\n const int* fatalSignals = kssignal_fatalSignals();\n int fatalSignalsCount = kssignal_numFatalSignals();\n\n for(int i = 0; i < fatalSignalsCount; i++)\n {\n sigaction(fatalSignals[i], &g_previousSignalHandlers[i], NULL);\n }\n}\n\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"防崩溃处理"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"常见崩溃类型"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"根据笔者经验来看，oc中大部分崩溃都是源于没有对调用方法进行入参判断，比如数组添加object没有判空，访问数组元素越界等；还有一些C++崩溃，比如使用野指针。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"防崩溃处理方案"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"由于oc中大部分崩溃都是来源于未对入参进行判断，所以调用方法对入参进行判断就能解决崩溃。如何统一地解决这类崩溃，有两种方案：hook方案和安全接口"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"hook方案"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"该方案对系统常见类的方法进行hook，进行入参判断。比如对hook NSMutableArray的addObject方法，进行判空操作。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"@implementation NSMutableArray (akSafe)\n\n+ (void)load {\n [self swizzMethodOriginalSelector:@selector(addObject:)\n swizzledSelector:@selector(akSafe_addObject:)];\n}\n\n+ (void)swizzMethodOriginalSelector:(SEL)originalSelector swizzledSelector:(SEL)swizzledSelector {\n Method originalMethod = class_getInstanceMethod(self.class, originalSelector);\n Method swizzledMethod = class_getInstanceMethod(self.class, swizzledSelector);\n BOOL didAddMethod = class_addMethod(self.class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));\n if (didAddMethod) {\n class_replaceMethod(self.class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));\n } else {\n method_exchangeImplementations(originalMethod, swizzledMethod);\n }\n}\n\n- (void)aksafe_AddObject:(id)anObject {\n\n if (anObject) {\n [self aksafe_AddObject:anObject];\n }\n}\n\n@end\n\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"安全接口"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"该方案对系统常见类的方法进行一层封装，进行入参判断。大家统一调用安全接口，比如封装NSMutableArray的addObject方法为aksafe_AddObject，大家统一调用aksafe_AddObject添加对象。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"@implementation NSMutableArray (aksafe)\n\n- (void)aksafe_AddObject:(id)anObject {\n\n if (anObject) {\n [self addObject:anObject];\n }\n}\n@end\n\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"两种方案各有优缺点，hook方案优点是业务方直接调用系统方法就行，缺点是由于要进行hook，有损性能；安全接口方案是业务方要统一调用安全接口，优点则是轻量。"},{"type":"text","marks":[{"type":"strong"}],"text":"笔者推荐方案二，轻量并且可以作为编码规范。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"资料推荐"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果你正在跳槽或者正准备跳槽不妨动动小手，添加一下咱们的交流群"},{"type":"link","attrs":{"href":"https://links.jianshu.com/go?to=https%3A%2F%2Fjq.qq.com%2F%3F_wv%3D1027%26k%3D5JFjujE","title":null},"content":[{"type":"text","text":"1012951431"}]},{"type":"text","text":"来获取一份详细的大厂面试资料为你的跳槽多添一份保障。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/92/92394154a3e96888899d492b73de1e69.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}}]}