1# Subscribing to Freeze Events (C/C++) 2 3## Available APIs 4 5For details about how to use the APIs (such as parameter usage restrictions and value ranges), see [HiAppEvent](../reference/apis-performance-analysis-kit/_hi_app_event.md#hiappevent). 6 7**Subscription APIs** 8 9| API | Description | 10| ------------------------------------------------------------ | -------------------------------------------- | 11| int OH_HiAppEvent_AddWatcher (HiAppEvent_Watcher \*watcher) | Adds a watcher to listen for application events.| 12| int OH_HiAppEvent_RemoveWatcher (HiAppEvent_Watcher *watcher) | Removes a watcher to unsubscribe from application events.| 13 14## How to Develop 15 16The following describes how to subscribe to the freeze event triggered by a button click. 17 181. Create a native C++ project and import the **jsoncpp** file to the project. The directory structure is as follows: 19 20 ```yml 21 entry: 22 src: 23 main: 24 cpp: 25 - json: 26 - json.h 27 - json-forwards.h 28 - types: 29 libentry: 30 - index.d.ts 31 - CMakeLists.txt 32 - napi_init.cpp 33 - jsoncpp.cpp 34 ets: 35 - entryability: 36 - EntryAbility.ets 37 - pages: 38 - Index.ets 39 ``` 40 412. In the **CMakeLists.txt** file, add the source file and dynamic libraries. 42 43 ```cmake 44 # Add the jsoncpp.cpp file, which is used to parse the JSON strings in the subscription events. 45 add_library(entry SHARED napi_init.cpp jsoncpp.cpp) 46 # Add libhiappevent_ndk.z.so and libhilog_ndk.z.so (log output). 47 target_link_libraries(entry PUBLIC libace_napi.z.so libhilog_ndk.z.so libhiappevent_ndk.z.so) 48 ``` 49 503. Import the dependency files to the **napi_init.cpp** file, and define **LOG_TAG**. 51 52 ```c++ 53 # include "json/json.h" 54 # include "hilog/log.h" 55 # include "hiappevent/hiappevent.h" 56 57 # undef LOG_TAG 58 # define LOG_TAG "testTag" 59 ``` 60 614. Subscribe to application events. 62 63 - Watcher of the onReceive type: 64 65 In the **napi_init.cpp** file, define the methods related to the watcher of the onReceive type. 66 67 ```c++ 68 // Define a variable to cache the pointer to the created watcher. 69 static HiAppEvent_Watcher *systemEventWatcher; 70 71 static void OnReceive(const char *domain, const struct HiAppEvent_AppEventGroup *appEventGroups, uint32_t groupLen) { 72 for (int i = 0; i < groupLen; ++i) { 73 for (int j = 0; j < appEventGroups[i].infoLen; ++j) { 74 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.domain=%{public}s", appEventGroups[i].appEventInfos[j].domain); 75 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.name=%{public}s", appEventGroups[i].appEventInfos[j].name); 76 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.eventType=%{public}d", appEventGroups[i].appEventInfos[j].type); 77 if (strcmp(appEventGroups[i].appEventInfos[j].domain, DOMAIN_OS) == 0 && 78 strcmp(appEventGroups[i].appEventInfos[j].name, EVENT_APP_FREEZE) == 0) { 79 Json::Value params; 80 Json::Reader reader(Json::Features::strictMode()); 81 Json::FastWriter writer; 82 if (reader.parse(appEventGroups[i].appEventInfos[j].params, params)) { 83 auto time = params["time"].asInt64(); 84 auto foreground = params["foreground"].asBool(); 85 auto bundleVersion = params["bundle_version"].asString(); 86 auto bundleName = params["bundle_name"].asString(); 87 auto processName = params["process_name"].asString(); 88 auto pid = params["pid"].asInt(); 89 auto uid = params["uid"].asInt(); 90 auto uuid = params["uuid"].asString(); 91 auto exception = writer.write(params["exception"]); 92 auto hilogSize = params["hilog"].size(); 93 auto handleSize = params["event_handler"].size(); 94 auto handleSize3s = params["event_handler_size_3s"].asString(); 95 auto handleSize6s = params["event_handler_size_6s"].asString(); 96 auto peerBindSize = params["peer_binder"].size(); 97 auto threadSize = params["threads"].size(); 98 auto memory = writer.write(params["memory"]); 99 auto externalLog = writer.write(params["external_log"]); 100 auto logOverLimit = params["log_over_limit"].asBool(); 101 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.time=%{public}lld", time); 102 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.foreground=%{public}d", foreground); 103 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_version=%{public}s", bundleVersion.c_str()); 104 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_name=%{public}s", bundleName.c_str()); 105 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.process_name=%{public}s", processName.c_str()); 106 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.pid=%{public}d", pid); 107 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.uid=%{public}d", uid); 108 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.uuid=%{public}s", uuid.c_str()); 109 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.exception=%{public}s", exception.c_str()); 110 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.hilog.size=%{public}d", hilogSize); 111 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.event_handler.size=%{public}d", handleSize); 112 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.event_handler_3s.size=%{public}s", handleSize3s.c_str()); 113 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.event_handler_6s.size=%{public}s", handleSize6s.c_str()); 114 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.peer_binder.size=%{public}d", peerBindSize); 115 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.threads.size=%{public}d", threadSize); 116 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.memory=%{public}s", memory.c_str()); 117 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.external_log=%{public}s", externalLog.c_str()); 118 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.log_over_limit=%{public}d", logOverLimit); 119 } 120 } 121 } 122 } 123 } 124 125 static napi_value RegisterWatcher(napi_env env, napi_callback_info info) { 126 // Set the watcher name. The system identifies different watchers based on their names. 127 systemEventWatcher = OH_HiAppEvent_CreateWatcher("onReceiverWatcher"); 128 // Set the event type to EVENT_APP_FREEZE. 129 const char *names[] = {EVENT_APP_FREEZE}; 130 // Add the system events to watch, for example, system events. 131 OH_HiAppEvent_SetAppEventFilter(systemEventWatcher, DOMAIN_OS, 0, names, 1); 132 // Set the implemented callback. After receiving the event, the watcher immediately triggers the OnReceive callback. 133 OH_HiAppEvent_SetWatcherOnReceive(systemEventWatcher, OnReceive); 134 // Add a watcher to listen for the specified event. 135 OH_HiAppEvent_AddWatcher(systemEventWatcher); 136 return {}; 137 } 138 ``` 139 140 - Watcher of the onTrigger type: 141 142 In the **napi_init.cpp** file, define the methods related to the watcher of the OnTrigger type. 143 144 ```c++ 145 // Define a variable to cache the pointer to the created watcher. 146 static HiAppEvent_Watcher *systemEventWatcher; 147 148 // Implement the callback function used to return the listened events. The content pointed to by the events pointer is valid only in this function. 149 static void OnTake(const char *const *events, uint32_t eventLen) { 150 Json::Reader reader(Json::Features::strictMode()); 151 Json::FastWriter writer; 152 for (int i = 0; i < eventLen; ++i) { 153 Json::Value eventInfo; 154 if (reader.parse(events[i], eventInfo)) { 155 auto domain = eventInfo["domain_"].asString(); 156 auto name = eventInfo["name_"].asString(); 157 auto type = eventInfo["type_"].asInt(); 158 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.domain=%{public}s", domain.c_str()); 159 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.name=%{public}s", name.c_str()); 160 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.eventType=%{public}d", type); 161 if (domain == DOMAIN_OS && name == EVENT_APP_FREEZE) { 162 auto time = eventInfo["time"].asInt64(); 163 auto foreground = eventInfo["foreground"].asBool(); 164 auto bundleVersion = eventInfo["bundle_version"].asString(); 165 auto bundleName = eventInfo["bundle_name"].asString(); 166 auto processName = eventInfo["process_name"].asString(); 167 auto pid = eventInfo["pid"].asInt(); 168 auto uid = eventInfo["uid"].asInt(); 169 auto uuid = eventInfo["uuid"].asString(); 170 auto exception = writer.write(eventInfo["exception"]); 171 auto hilogSize = eventInfo["hilog"].size(); 172 auto handleSize = eventInfo["event_handler"].size(); 173 auto handleSize3s = eventInfo["event_handler_size_3s"].asString(); 174 auto handleSize6s = eventInfo["event_handler_size_6s"].asString(); 175 auto peerBindSize = eventInfo["peer_binder"].size(); 176 auto threadSize = eventInfo["threads"].size(); 177 auto memory = writer.write(eventInfo["memory"]); 178 auto externalLog = writer.write(eventInfo["external_log"]); 179 auto logOverLimit = eventInfo["log_over_limit"].asBool(); 180 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.time=%{public}lld", time); 181 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.foreground=%{public}d", foreground); 182 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_version=%{public}s", bundleVersion.c_str()); 183 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_name=%{public}s", bundleName.c_str()); 184 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.process_name=%{public}s", processName.c_str()); 185 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.pid=%{public}d", pid); 186 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.uid=%{public}d", uid); 187 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.uuid=%{public}s", uuid.c_str()); 188 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.exception=%{public}s", exception.c_str()); 189 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.hilog.size=%{public}d", hilogSize); 190 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.event_handler.size=%{public}d", handleSize); 191 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.event_handler_3s.size=%{public}s", handleSize3s.c_str()); 192 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.event_handler_6s.size=%{public}s", handleSize6s.c_str()); 193 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.peer_binder.size=%{public}d", peerBindSize); 194 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.threads.size=%{public}d", threadSize); 195 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.memory=%{public}s", memory.c_str()); 196 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.external_log=%{public}s", externalLog.c_str()); 197 OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.log_over_limit=%{public}d", logOverLimit); 198 } 199 } 200 } 201 } 202 203 // Implement the subscription callback function to apply custom processing to the obtained event logging data. 204 static void OnTrigger(int row, int size) { 205 // After the callback is received, obtain the specified number of received events. 206 OH_HiAppEvent_TakeWatcherData(systemEventWatcher, row, OnTake); 207 } 208 209 static napi_value RegisterWatcher(napi_env env, napi_callback_info info) { 210 // Set the watcher name. The system identifies different watchers based on their names. 211 systemEventWatcher = OH_HiAppEvent_CreateWatcher("onTriggerWatcher"); 212 // Set the event type to EVENT_APP_FREEZE. 213 const char *names[] = {EVENT_APP_FREEZE}; 214 // Add the system events to watch, for example, button onclick events. 215 OH_HiAppEvent_SetAppEventFilter(systemEventWatcher, DOMAIN_OS, 0, names, 1); 216 // Set the implemented callback function. The callback function will be triggered when the conditions set by OH_HiAppEvent_SetTriggerCondition are met. 217 OH_HiAppEvent_SetWatcherOnTrigger(systemEventWatcher, OnTrigger); 218 // Set the conditions for triggering the subscription callback. For example, trigger this onTrigger callback when the number of new event logs is 1. 219 OH_HiAppEvent_SetTriggerCondition(systemEventWatcher, 1, 0, 0); 220 // Add a watcher to listen for the specified event. 221 OH_HiAppEvent_AddWatcher(systemEventWatcher); 222 return {}; 223 } 224 ``` 225 2265. Register **RegisterWatcher** as an ArkTS API. 227 228 In the **napi_init.cpp** file, register **RegisterWatcher** as an ArkTS API. 229 230 ```c++ 231 static napi_value Init(napi_env env, napi_value exports) 232 { 233 napi_property_descriptor desc[] = { 234 { "registerWatcher", nullptr, RegisterWatcher, nullptr, nullptr, nullptr, napi_default, nullptr } 235 }; 236 napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc); 237 return exports; 238 } 239 ``` 240 241 In the **index.d.ts** file, define the ArkTS API. 242 243 ```typescript 244 export const registerWatcher: () => void; 245 ``` 246 2476. In the **EntryAbility.ets** file, add the following interface invocation to **onCreate()**. 248 249 ```typescript 250 // Import the dependent module. 251 import testNapi from 'libentry.so' 252 253 // Add the interface invocation to onCreate(). 254 // Register the system event watcher at startup. 255 testNapi.registerWatcher(); 256 ``` 257 2587. In the **Index.ets** file, add a button to trigger the freeze event. 259 260 ```typescript 261 Button("appFreeze").onClick(() => { 262 setTimeout(()=>{ 263 while(true) {} 264 }, 1000) 265 }) 266 ``` 267 2688. In DevEco Studio, click the **Run** button to run the project. Then, click the **appfreeze** button to trigger a freeze event. 269 2709. The application crashes. After restarting the application, you can view the following event information in the **Log** window. 271 272 ```text 273 HiAppEvent eventInfo.domain=OS 274 HiAppEvent eventInfo.name=APP_FREEZE 275 HiAppEvent eventInfo.eventType=1 276 HiAppEvent eventInfo.params.time=1502049167732 277 HiAppEvent eventInfo.params.foreground=1 278 HiAppEvent eventInfo.params.bundle_version=1.0.0 279 HiAppEvent eventInfo.params.bundle_name=com.example.myapplication 280 HiAppEvent eventInfo.params.process_name=com.example.myapplication 281 HiAppEvent eventInfo.params.pid=1587 282 HiAppEvent eventInfo.params.uid=20010043 283 HiAppEvent eventInfo.params.uuid=a78a23b20f3dd9730f18a5cfa2304deac1104ac4086755c4a59cf7c72d414e2e 284 HiAppEvent eventInfo.params.exception={"message":"App main thread is not response!","name":"THREAD_BLOCK_6S"} 285 HiAppEvent eventInfo.params.hilog.size=6 286 HiAppEvent eventInfo.params.event_handler.size=16 287 HiAppEvent eventInfo.params.event_handler_3s.size=15 288 HiAppEvent eventInfo.params.event_handler_6s.size=16 289 HiAppEvent eventInfo.params.peer_binder.size=0 290 HiAppEvent eventInfo.params.threads.size=28 291 HiAppEvent eventInfo.params.memory={"pss":0,"rss":0,"sys_avail_mem":1326520,"sys_free_mem":940588,"sys_total_mem":1992340,"vss":0} 292 HiAppEvent eventInfo.params.external_log=["/data/storage/el2/log/hiappevent/APP_FREEZE_1502049185239_1587.log"] 293 HiAppEvent eventInfo.params.log_over_limit=0 294 ``` 295 29610. Remove the application event watcher. 297 298 ```c++ 299 static napi_value RemoveWatcher(napi_env env, napi_callback_info info) { 300 // Remove the watcher. 301 OH_HiAppEvent_RemoveWatcher(systemEventWatcher); 302 return {}; 303 } 304 ``` 305 30611. Destroy the application event watcher. 307 308 ```c++ 309 static napi_value DestroyWatcher(napi_env env, napi_callback_info info) { 310 // Destroy the created watcher and set systemEventWatcher to nullptr. 311 OH_HiAppEvent_DestroyWatcher(systemEventWatcher); 312 systemEventWatcher = nullptr; 313 return {}; 314 } 315 ``` 316 317<!--no_check-->