简介
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。
系统架构
图 1 系统服务管理系统架构图
说明
samgr服务接收到sa框架层发送的注册消息,会在本地缓存中存入系统服务相关信息。
int32_t SystemAbilityManager::AddSystemAbility(int32_t systemAbilityId, const sptr< IRemoteObject >& ability, const SAExtraProp& extraProp) { if (!CheckInputSysAbilityId(systemAbilityId) || ability == nullptr) { HILOGE("AddSystemAbilityExtra input params is invalid."); return ERR_INVALID_VALUE; } { unique_lock< shared_mutex > writeLock(abilityMapLock_); auto saSize = abilityMap_.size(); if (saSize >= MAX_SERVICES) { HILOGE("map size error, (Has been greater than %zu)", saSize); return ERR_INVALID_VALUE; } SAInfo saInfo; saInfo.remoteObj = ability; saInfo.isDistributed = extraProp.isDistributed; saInfo.capability = extraProp.capability; saInfo.permission = Str16ToStr8(extraProp.permission); abilityMap_[systemAbilityId] = std::move(saInfo); HILOGI("insert %{public}d. size : %{public}zu", systemAbilityId, abilityMap_.size()); } RemoveCheckLoadedMsg(systemAbilityId); if (abilityDeath_ != nullptr) { ability- >AddDeathRecipient(abilityDeath_); } u16string strName = Str8ToStr16(to_string(systemAbilityId)); if (extraProp.isDistributed && dBinderService_ != nullptr) { dBinderService_- >RegisterRemoteProxy(strName, systemAbilityId); HILOGD("AddSystemAbility RegisterRemoteProxy, serviceId is %{public}d", systemAbilityId); } if (systemAbilityId == SOFTBUS_SERVER_SA_ID && !isDbinderStart_) { if (dBinderService_ != nullptr && rpcCallbackImp_ != nullptr) { bool ret = dBinderService_- >StartDBinderService(rpcCallbackImp_); HILOGI("start result is %{public}s", ret ? "succeed" : "fail"); isDbinderStart_ = true; } } SendSystemAbilityAddedMsg(systemAbilityId, ability); return ERR_OK; }
对于本地服务而言,samgr服务接收到sa框架层发送的获取消息,会通过服务id,查找到对应服务的代理对象,然后返回给sa框架。
sptr< IRemoteObject > SystemAbilityManager::CheckSystemAbility(int32_t systemAbilityId) { if (!CheckInputSysAbilityId(systemAbilityId)) { HILOGW("CheckSystemAbility CheckSystemAbility invalid!"); return nullptr; } 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; } HILOGI("NOT found service : %{public}d", systemAbilityId); return nullptr; }
动态加载系统服务进程及SystemAbility, 系统进程无需开机启动,而是在SystemAbility被访问的时候按需拉起,并加载指定SystemAbility。
3.1 继承SystemAbilityLoadCallbackStub类,并覆写OnLoadSystemAbilitySuccess(int32_t systemAbilityId, const sptr& remoteObject)、OnLoadSystemAbilityFail(int32_t systemAbilityId)方法。class OnDemandLoadCallback : public SystemAbilityLoadCallbackStub { public: void OnLoadSystemAbilitySuccess(int32_t systemAbilityId, const sptr< IRemoteObject >& remoteObject) override; void OnLoadSystemAbilityFail(int32_t systemAbilityId) override; }; void OnDemandLoadCallback::OnLoadSystemAbilitySuccess(int32_t systemAbilityId, const sptr< IRemoteObject >& remoteObject) // systemAbilityId为指定加载的SAID,remoteObject为指定systemAbility的代理对象 { cout < < "OnLoadSystemAbilitySuccess systemAbilityId:" < < systemAbilityId < < " IRemoteObject result:" < < ((remoteObject != nullptr) ? "succeed" : "failed") < < endl; } void OnDemandLoadCallback::OnLoadSystemAbilityFail(int32_t systemAbilityId) // systemAbilityId为指定加载的SAID { cout < < "OnLoadSystemAbilityFail systemAbilityId:" < < systemAbilityId < < endl; }
3.2 调用samgr提供的动态加载接口LoadSystemAbility(int32_t systemAbilityId, const sptr& callback)。
// 构造步骤1的SystemAbilityLoadCallbackStub子类的实例 sptr< OnDemandLoadCallback > loadCallback_ = new OnDemandLoadCallback(); // 调用LoadSystemAbility方法 sptr< ISystemAbilityManager > sm = SystemAbilityManagerClient::GetInstance().GetSystemAbilityManager(); if (sm == nullptr) { cout < < "GetSystemAbilityManager samgr object null!" < < endl; return; } int32_t result = sm- >LoadSystemAbility(systemAbilityId, loadCallback_); if (result != ERR_OK) { cout < < "systemAbilityId:" < < systemAbilityId < < " load failed, result code:" < < result < < endl; return; }
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说明:
1.LoadSystemAbility方法调用成功后,指定SystemAbility加载成功后会触发回调OnLoadSystemAbilitySuccess,加载失败触发回调OnLoadSystemAbilityFail。
2.动态加载的进程cfg文件不能配置为开机启动,需指定"ondemand" : true, 示例如下:
{ "services" : [{ "name" : "listen_test", "path" : ["/system/bin/sa_main", "/system/profile/listen_test.json"], "ondemand" : true, "uid" : "system", "gid" : ["system", "shell"] } ] }
3.LoadSystemAbility方法适用于动态加载场景,其他获取SystemAbility场景建议使用CheckSystemAbility方法。
4.cfg里进程名称需要与SA的配置json文件里进程名保持一致
审核编辑 黄宇
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