问题背景

我们在适配完展讯T606平台后发现拖拽图标时会卡住，如下图所示，有一个弹出提示：pasting to Launcher，小圆圈一直在打转，桌面不可操作，不过可以点击取消按钮X恢复，OpenHarmony版本是3.2.2 release。

刚开始笔者误以为是gfx图形加速未适配导致，事实上当仔细查看拖拽卡死时的log，能发现如下一些看上去可能和这个pasting有关联的错误：

01-01 09:01:42.311 1467 1466 E C01800/SA_CLIENT: GetSystemAbilityWrapper sa 6001 didn't start. Returning nullptr01-01 09:01:42.312 1466 1466 E C04400/Device_Profile: DistributedDeviceProfileClient::GetDeviceProfileService get service failed01-01 09:01:42.312 1466 1466 E C01c02/PasteboardService: [dev_profile.cpp] GetEnabledStatus# GetDeviceProfile failed, .01-01 09:01:42.312 1466 1466 D C01c02/PasteboardService: [distributed_module_config.cpp] GetEnabledStatus# localEnabledStatus = false.01-01 09:01:42.312 1466 1466 E C01c02/PasteboardService: [pasteboard_service.cpp] HasDistributedData# clipPlugin null.01-01 09:01:42.312 1466 1466 I C01c02/PasteboardService: [pasteboard_service_stub.cpp] OnHasPasteData# end.01-01 09:01:42.312 1813 1813 D C01c01/PasteboardClient: [pasteboard_service_proxy.cpp] HasPasteData# end.[...]01-01 09:01:43.442 1466 1466 E C04400/Device_Profile: DistributedDeviceProfileClient::GetDeviceProfileService get service failed01-01 09:01:43.442 1466 1466 E C01c02/PasteboardService: [dev_profile.cpp] GetEnabledStatus# GetDeviceProfile failed, .01-01 09:01:43.442 1466 1466 D C01c02/PasteboardService: [distributed_module_config.cpp] GetEnabledStatus# localEnabledStatus = false.01-01 09:01:43.442 1466 1466 E C01c02/PasteboardService: [pasteboard_service.cpp] SetDistributedData# clipPlugin null.

这里主要涉及到OpenHarmony的系统能力管理, code位于//foundation/systemabilitymgr，我们先来简单了解下。

SA管理

首先，我们看下启动恢复子系统对samgr的说明：

5.samgr是各个SA的服务注册中心，每个SA启动时，都需要向samgr注册，每个SA会分配一个ID，应用可以通过该ID访问SA。

6.foundation是一个特殊的SA服务进程，提供了用户程序管理框架及基础服务。由该进程负责应用的生命周期管理。

标准系统的systemabilitymgr子系统有两个part(部件or组件)：一个是samgr，一个是safwk。

samgr服务

samgr组件是OpenHarmony的核心组件，提供OpenHarmony系统服务启动、注册、查询等功能。

samgr 服务框架如下图:

samgr服务几个关键接口如下表：

接口名

接口表述

SystemAbilityManager::AddSystemAbility()

接收sa框架发送的注册消息并缓存

SystemAbilityManager::CheckSystemAbility()

接收sa框架发送的获取消息，通过sa id，查找到对应服务的代理对象，然后返回给sa框架

SystemAbilityManager::LoadSystemAbility()

sa非开机启动，按需动态加载，需在配置中指定"ondemand"为true

sa框架

safwk组件定义OpenHarmony中SystemAbility的实现方法，并提供启动、注册等接口实现。

框架图如下：

从层级上看，safwk偏上点，它通过代理samgr_proxy发送消息和samgr服务进行交互。

sa框架主要包含一个可执行程序sa_main以及一个接口库system_ability_fwk:

./services/safwk/BUILD.gn:

ohos_executable("sa_main") { install_enable = true sources = [ "src/main.cpp" ]

./interfaces/innerkits/safwk/BUILD.gn:

ohos_shared_library("system_ability_fwk") { sources = [ "../../../services/safwk/src/local_ability_manager.cpp", "../../../services/safwk/src/local_ability_manager_stub.cpp", "../../../services/safwk/src/system_ability.cpp", ]

sa的实现方式：

SystemAbility实现一般采用XXX.cfg + profile.json + libXXX.z.so的方式由init进程执行对应的XXX.cfg文件拉起相关SystemAbility进程。

其中，profile.json的run-on-create说明：

run-on-create：true表示进程启动后即向samgr组件注册该SystemAbility；false表示按需启动，即在其他模块访问到该SystemAbility时启动，必配项。

示例代码还提到：IXXX是IPC对外接口，XXXProxy是客户端通信代码，XXXStub是服务端通信代码。到这里，我们已经对sa管理有了一些基础的认识。

卡屏分析

客户端分析

在对sa管理有了基本的认识后，接下来我们从PasteboardService的错误看起：

01-01 09:01:42.312 1466 1466 E C01c02/PasteboardService: [dev_profile.cpp] GetEnabledStatus# GetDeviceProfile failed, .

这个剪贴板服务是一个sa，code位于 //foundation/distributeddatamgr/pasteboard/，配置是profile/3701.xml:

<info> <process>pasteboard_service</process> <systemability> <name>3701</name> <libpath>libpasteboard_service.z.so</libpath> <run-on-create>true</run-on-create> <distributed>true</distributed> <dump-level>1</dump-level> </systemability></info>

可以看到run-on-create是true，启动时注册此sa。

出错的code是剪贴板正在操作粘贴数据，如SetPasteData->SetDistributedData:

bool PasteboardService::SetDistributedData(int32_t user, PasteData &data){ std::vector<uint8_t> rawData; auto clipPlugin = GetClipPlugin(); //TJ:here if (clipPlugin == nullptr) { PASTEBOARD_HILOGE(PASTEBOARD_MODULE_SERVICE, "clipPlugin null."); return false; }

笔者在log中发现这个clipPlugin都是null：

01-01 09:01:42.312 1466 1466 E C01c02/PasteboardService: [pasteboard_service.cpp] HasDistributedData# clipPlugin null.01-01 09:01:43.442 1466 1466 E C01c02/PasteboardService: [pasteboard_service.cpp] SetDistributedData# clipPlugin null.01-01 09:01:44.634 1466 2053 E C01c02/PasteboardService: [pasteboard_service.cpp] GetDistributedData# clipPlugin null.

那这个clipPlugin是怎么获取的了：

std::shared_ptr<ClipPlugin> PasteboardService::GetClipPlugin(){ auto isOn = DistributedModuleConfig::IsOn(); //TJ: here std::lock_guard<decltype(mutex)> lockGuard(mutex); if (!isOn || clipPlugin_ != nullptr) { return clipPlugin_; }

//foundation/distributeddatamgr/pasteboard/services/core/src/distributed_module_config.cpp:

bool DistributedModuleConfig::IsOn(){ status_ = GetEnabledStatus(); return status_;}bool DistributedModuleConfig::GetEnabledStatus(){ PASTEBOARD_HILOGD(PASTEBOARD_MODULE_SERVICE, "GetEnabledStatus start."); std::string localEnabledStatus = "false"; DevProfile::GetInstance().GetEnabledStatus("", localEnabledStatus);//TJ:here

//foundation/distributeddatamgr/pasteboard/services/core/src/dev_profile.cpp:

void DevProfile::GetEnabledStatus(const std::string &deviceId, std::string &enabledStatus){ PASTEBOARD_HILOGD(PASTEBOARD_MODULE_SERVICE, "GetEnabledStatus start."); ServiceCharacteristicProfile profile; int32_t ret = DistributedDeviceProfileClient::GetInstance().GetDeviceProfile(deviceId, SERVICE_ID, profile); //TJ: here if (ret != HANDLE_OK) { PASTEBOARD_HILOGE(PASTEBOARD_MODULE_SERVICE, "GetDeviceProfile failed, %{public}.5s.", deviceId.c_str()); return; }

//foundation/deviceprofile/device_info_manager/interfaces/innerkits/core/src/distributed_device_profile_client.cpp:

int32_t DistributedDeviceProfileClient::GetDeviceProfile(const std::string& udid, const std::string& serviceId, ServiceCharacteristicProfile& profile){ auto dps = GetDeviceProfileService();sptr<IDistributedDeviceProfile> DistributedDeviceProfileClient::GetDeviceProfileService(){ std::lock_guard<std::mutex> lock(serviceLock_); if (dpProxy_ != nullptr) { return dpProxy_; } auto samgrProxy = SystemAbilityManagerClient::GetInstance().GetSystemAbilityManager(); if (samgrProxy == nullptr) { HILOGE("get samgr failed"); return nullptr; } auto object = samgrProxy->GetSystemAbility(DISTRIBUTED_DEVICE_PROFILE_SA_ID); //TJ: here if (object == nullptr) { HILOGE("get service failed"); return nullptr; }

//foundation/systemabilitymgr/samgr/frameworks/native/source/system_ability_manager_proxy.cpp：

sptr<IRemoteObject> SystemAbilityManagerProxy::GetSystemAbility(int32_t systemAbilityId){ return GetSystemAbilityWrapper(systemAbilityId);}sptr<IRemoteObject> SystemAbilityManagerProxy::GetSystemAbilityWrapper(int32_t systemAbilityId, const string& deviceId){ [...] bool isExist = false; int32_t timeout = RETRY_TIME_OUT_NUMBER; HILOGD("GetSystemAbilityWrapper:Waiting for sa %{public}d, ", systemAbilityId); do { sptr<IRemoteObject> svc; if (deviceId.empty()) { svc = CheckSystemAbility(systemAbilityId, isExist); //TJ: here if (!isExist) { HILOGW("%{public}s:sa %{public}d is not exist", __func__, systemAbilityId); usleep(SLEEP_ONE_MILLI_SECOND_TIME * SLEEP_INTERVAL_TIME); continue; } } else { svc = CheckSystemAbility(systemAbilityId, deviceId); } [...] } while (timeout--); HILOGE("GetSystemAbilityWrapper sa %{public}d didn't start. Returning nullptr", systemAbilityId); return nullptr;}

deviceId默认是空，走deviceId.empty分支：

sptr<IRemoteObject> SystemAbilityManagerProxy::CheckSystemAbility(int32_t systemAbilityId, bool& isExist){ ... int32_t err = remote->SendRequest(CHECK_SYSTEM_ABILITY_IMMEDIATELY_TRANSACTION, data, reply, option); if (err != ERR_NONE) { return nullptr; } sptr<IRemoteObject> irsp(reply.ReadRemoteObject()); ret = reply.ReadBool(isExist); if (!ret) { HILOGW("CheckSystemAbility Read isExist failed!"); return nullptr; }

pasteboard_service通过代理SystemAbilityManagerProxy发送消息->SendRequest给远端查询sa DISTRIBUTED_DEVICE_PROFILE_SA_ID是否启动正常。

在分析远端处理之前，我们先来看下这个sa(6001)：

//foundation/systemabilitymgr/samgr/interfaces/innerkits/samgr_proxy/include/system_ability_definition.h:271: DISTRIBUTED_DEVICE_PROFILE_SA_ID = 6001,

code位于//foundation/deviceprofile/，配置是sa_profile/6001.xml:

<info> <process>distributedsched</process> <systemability> <name>6001</name> <libpath>libdistributed_device_profile.z.so</libpath> <run-on-create>true</run-on-create> <distributed>false</distributed> <dump-level>1</dump-level> </systemability></info>

可见，这个sa也是开机就注册到系统里(run-on-create是true)。

远端分析

前文已经梳理过sa管理，我们很容易找到接收client请求的远端入口 - //foundation/systemabilitymgr/samgr/services/samgr/native/source/system_ability_manager_stub.cpp：

int32_t SystemAbilityManagerStub::OnRemoteRequest(uint32_t code, MessageParcel& data, MessageParcel& reply, MessageOption &option){ HILOGI("SystemAbilityManagerStub::OnReceived, code = %{public}u, callerPid = %{public}d, flags= %{public}d", code, IPCSkeleton::GetCallingPid(), option.GetFlags()); if (!EnforceInterceToken(data)) { HILOGE("SystemAbilityManagerStub::OnReceived, code = %{public}u, check interfaceToken failed", code); return ERR_PERMISSION_DENIED; } auto itFunc = memberFuncMap_.find(code); //TJ:here if (itFunc != memberFuncMap_.end()) { auto memberFunc = itFunc->second; if (memberFunc != nullptr) { return (this->*memberFunc)(data, reply); } }

在memberFuncMap_里查找CHECK_SYSTEM_ABILITY_IMMEDIATELY_TRANSACTION：

memberFuncMap_[CHECK_SYSTEM_ABILITY_IMMEDIATELY_TRANSACTION] = &SystemAbilityManagerStub::CheckSystemAbilityImmeInner;int32_t SystemAbilityManagerStub::CheckSystemAbilityImmeInner(MessageParcel& data, MessageParcel& reply){ [...] ret = reply.WriteRemoteObject(CheckSystemAbility(systemAbilityId, isExist)); if (!ret) { return ERR_FLATTEN_OBJECT; } [...]}

//foundation/systemabilitymgr/samgr/services/samgr/native/source/system_ability_manager.cpp：

sptr<IRemoteObject> SystemAbilityManager::CheckSystemAbility(int32_t systemAbilityId, bool& isExist){ if (!CheckInputSysAbilityId(systemAbilityId)) { return nullptr; } sptr<IRemoteObject> abilityProxy = CheckSystemAbility(systemAbilityId); //TJ: here if (abilityProxy == nullptr) { lock_guard<recursive_mutex> autoLock(onDemandLock_); auto iter = startingAbilityMap_.find(systemAbilityId); [...]}

startingAbilityMap_应该是给ondemand sa用, 6001 sa配置是开机启动，只看CheckSystemAbility：

sptr<IRemoteObject> SystemAbilityManager::CheckSystemAbility(int32_t systemAbilityId){ HILOGD("%{public}s called, systemAbilityId = %{public}d", __func__, systemAbilityId); [...] shared_lock<shared_mutex> readLock(abilityMapLock_); auto iter = abilityMap_.find(systemAbilityId); if (iter != abilityMap_.end()) { HILOGI("found service : %{public}d.", systemAbilityId); return iter->second.remoteObj; } HILOGW("NOT found service : %{public}d", systemAbilityId); return nullptr;}

在abilityMap_中查找是否有这个sa，辅助相关log：

01-01 09:01:40.179 454 454 W C01800/SAMGR: NOT found service : 6001

而abilityMap_是在AddSystemAbility时才有这个sa：

int32_t SystemAbilityManager::AddSystemAbility(int32_t systemAbilityId, const sptr<IRemoteObject>& ability, const SAExtraProp& extraProp){[...] abilityMap_[systemAbilityId] = std::move(saInfo); HILOGI("insert %{public}d. size : %{public}zu", systemAbilityId, abilityMap_.size());[...]

可见，这个6001 sa就没有添加到系统里，那我们就来追踪下这个sa的添加过程。

sa:6001启动分析

sa 6001的定义:

./foundation/systemabilitymgr/samgr/interfaces/innerkits/samgr_proxy/include/system_ability_definition.h:365: { DISTRIBUTED_DEVICE_PROFILE_SA_ID, "DistributedDeviceProfile" },

顺着这个domain看下启动log，能发现这个服务初始化有错误：

01-01 13:05:05.653 4291 4308 E C04400/Device_Profile: DeviceProfileStorageManager::Init get local udid failed01-01 13:05:05.653 4291 4308 E C04400/Device_Profile: DistributedDeviceProfileService::Init DeviceProfileStorageManager init failed01-01 13:05:05.653 4291 4308 E C04400/Device_Profile: DistributedDeviceProfileService::OnStart init failed

sa启动入口在框架侧：//foundation/systemabilitymgr/safwk/services/safwk/src/system_ability.cpp：

void SystemAbility::Start(){ HILOGD(TAG, "starting system ability..."); if (isRunning_) { return; } HILOGD(TAG, "[PerformanceTest] SAFWK OnStart systemAbilityId:%{public}d", saId_); int64_t begin = GetTickCount(); HITRACE_METER_NAME(HITRACE_TAG_SAMGR, ToString(saId_) + "_OnStart"); OnStart(); //TJ: here// The details should be implemented by subclassvoid SystemAbility::OnStart(){}

//foundation/deviceprofile/device_info_manager/services/core/src/distributed_device_profile_service.cpp：

void DistributedDeviceProfileService::OnStart(){ HILOGI("called"); if (!Init()) { HILOGE("init failed"); //TJ: here return; } if (!Publish(this)) { HILOGE("publish SA failed"); return; }}bool DistributedDeviceProfileService::Init(){ if (!DpDeviceManager::GetInstance().Init()) { HILOGE("DeviceManager init failed"); return false; } if (!DeviceProfileStorageManager::GetInstance().Init()) { HILOGE("DeviceProfileStorageManager init failed"); //TJ: here return false; }

//foundation/deviceprofile/device_info_manager/services/core/src/dbstorage/device_profile_storage_manager.cpp：

bool DeviceProfileStorageManager::Init(){ if (!inited_) { if (!SyncCoordinator::GetInstance().Init()) { HILOGE("SyncCoordinator init failed"); return false; } DpDeviceManager::GetInstance().GetLocalDeviceUdid(localUdid_); if (localUdid_.empty()) { HILOGE("get local udid failed"); //TJ: here return false; }

//foundation/deviceprofile/device_info_manager/services/core/src/devicemanager/dp_device_manager.cpp:

void DpDeviceManager::GetLocalDeviceUdid(std::string& udid){ char localDeviceId[DEVICE_ID_SIZE] = {0}; GetDevUdid(localDeviceId, DEVICE_ID_SIZE); udid = localDeviceId;}

//base/startup/init/interfaces/innerkits/syspara/parameter.c：

int GetDevUdid(char *udid, int size){ return GetDevUdid_(udid, size);}

//base/startup/init/interfaces/innerkits/syspara/param_comm.c：

INIT_LOCAL_API int GetDevUdid_(char *udid, int size){ if (size < UDID_LEN || udid == NULL) { return EC_FAILURE; } uint32_t len = (uint32_t)size; int ret = SystemGetParameter("const.product.udid", udid, &len); BEGET_CHECK(ret != 0, return ret); const char *manufacture = GetManufacture_(); const char *model = GetProductModel_(); const char *sn = GetSerial_(); if (manufacture == NULL || model == NULL || sn == NULL) { return -1; } [...]}

如果获取不到系统参数const.product.udid，那manufacture,model,sn这三个属性必须有。

INIT_LOCAL_API const char *GetProductModel_(void){ static const char *productModel = NULL; return GetProperty("const.product.model", &productModel);}INIT_LOCAL_API const char *GetManufacture_(void){ static const char *productManufacture = NULL; return GetProperty("const.product.manufacturer", &productManufacture);}

manufacture,model都没有问题, 看下sn的获取：

INIT_LOCAL_API const char *GetSerial_(void){ [...] int ret = SystemGetParameter("ohos.boot.sn", ohosSerial, &len); BEGET_CHECK(ret == 0, return NULL); return ohosSerial;}

ohos.boot.sn的配置比较隐蔽，在//base/startup/init/services/param/manager/param_server.c：

INIT_LOCAL_API int LoadParamFromCmdLine(void){ static const cmdLineInfo cmdLines[] = { {OHOS_BOOT"hardware", CommonDealFun }, [...] }, {OHOS_BOOT"sn", SnDealFun //TJ: herebase/startup/init/services/param/include/param_utils.h:#define OHOS_BOOT "ohos.boot."

SnDealFun:

static int SnDealFun(const char *name, const char *value, int res){ const char *snFileList [] = { "/sys/block/mmcblk0/device/cid", "/proc/bootdevice/cid" }; int ret = CheckParamName(name, 0); PARAM_CHECK(ret == 0, return ret, "Invalid name %s", name); if (value != NULL && res == 0 && value[0] != '/') { [...] } if (value != NULL && value[0] == '/') { [...] } for (size_t i = 0; i < ARRAY_LENGTH(snFileList); i++) { ret = ReadSnFromFile(name, snFileList[i]); if (ret == 0) { break; } } return ret;}

就是bootloader传上来的command line如果没有，就从snFileList里去读取，显然这里sn拿的是eMMC的cid，而笔者的存储设备是ufs，它就不吃这一套。

/proc/bootdevice/cid这个路径也没有，笔者的适配参考是Android版本，Android BL当然没有ohos.boot.sn，最简单有效的解决方法就是直接cp对应的Android参数androidboot.serialno。

OK，我们再回到路开始的地方，也就是剪贴板服务的GetClipPluin()：

std::shared_ptr<ClipPlugin> PasteboardService::GetClipPlugin(){ auto isOn = DistributedModuleConfig::IsOn(); std::lock_guard<decltype(mutex)> lockGuard(mutex); if (!isOn || clipPlugin_ != nullptr) { return clipPlugin_; //TJ: here }

!isOn为真，直接返回clipPlugin_，我们从log已经知道这个clipPluin_一直是空，也就是在sn未配置的情况下，clipPlugin_并没有很好的被获取到。

思考总结

在回顾问题时，笔者认为序列号应该是一个与量产有关的参数，让量产因素影响桌面操作的逻辑似乎不合理。

归根结底，这应该还是一个软件设计问题。首先，系统应该为序列号这种关键参数设置适当的默认值，防止因未配置而出现意外行为。其次，在缺失关键参数的情况下，软件应该具备一个优雅降级的处理机制，而不是出现冻住屏幕这类异常行为。另外，文档可以更清晰的注明软件正常运行所需的要求和配置。

如果能确保这几个基本面，笔者认为应该能最大程度减少这类坑的出现，从而增强系统整体的可靠性。

[参考文档]

•https://docs.openharmony.cn/pages/v3.2/zh-cn/device-dev/subsystems/subsys-boot-overview.md/

•https://gitee.com/openharmony/systemabilitymgr_safwk

•https://gitee.com/openharmony/systemabilitymgr_samgr

•https://gitee.com/openharmony/distributeddatamgr_pasteboard

•https://gitee.com/openharmony/deviceprofile_device_info_manager

作者:TJ

来源-微信公众号:酷派技术团队

出处:https://mp.weixin.qq.com/s/K2a0gINe8mAGu6QCXBJYRA