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354 lines
12 KiB
354 lines
12 KiB
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "log/log_main.h"
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#define LOG_TAG "AidlLazyServiceRegistrar"
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#include <binder/LazyServiceRegistrar.h>
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#include <binder/IPCThreadState.h>
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#include <binder/IServiceManager.h>
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#include <android/os/BnClientCallback.h>
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#include <android/os/IServiceManager.h>
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#include <utils/Log.h>
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namespace android {
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namespace binder {
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namespace internal {
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using AidlServiceManager = android::os::IServiceManager;
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class ClientCounterCallbackImpl : public ::android::os::BnClientCallback {
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public:
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ClientCounterCallbackImpl() : mNumConnectedServices(0), mForcePersist(false) {}
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bool registerService(const sp<IBinder>& service, const std::string& name,
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bool allowIsolated, int dumpFlags);
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void forcePersist(bool persist);
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void setActiveServicesCallback(const std::function<bool(bool)>& activeServicesCallback);
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bool tryUnregisterLocked();
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void reRegisterLocked();
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protected:
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Status onClients(const sp<IBinder>& service, bool clients) override;
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private:
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struct Service {
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sp<IBinder> service;
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bool allowIsolated;
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int dumpFlags;
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// whether, based on onClients calls, we know we have a client for this
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// service or not
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bool clients = false;
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bool registered = true;
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};
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bool registerServiceLocked(const sp<IBinder>& service, const std::string& name,
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bool allowIsolated, int dumpFlags);
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/**
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* Looks up a service guaranteed to be registered (service from onClients).
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*/
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std::map<std::string, Service>::iterator assertRegisteredService(const sp<IBinder>& service);
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/**
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* Unregisters all services that we can. If we can't unregister all, re-register other
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* services.
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*/
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void tryShutdownLocked();
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/**
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* Try to shutdown the process, unless:
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* - 'forcePersist' is 'true', or
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* - The active services count callback returns 'true', or
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* - Some services have clients.
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*/
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void maybeTryShutdownLocked();
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// for below
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std::mutex mMutex;
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// count of services with clients
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size_t mNumConnectedServices;
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// previous value passed to the active services callback
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std::optional<bool> mPreviousHasClients;
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// map of registered names and services
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std::map<std::string, Service> mRegisteredServices;
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bool mForcePersist;
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// Callback used to report if there are services with clients
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std::function<bool(bool)> mActiveServicesCallback;
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};
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class ClientCounterCallback {
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public:
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ClientCounterCallback();
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bool registerService(const sp<IBinder>& service, const std::string& name,
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bool allowIsolated, int dumpFlags);
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/**
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* Set a flag to prevent services from automatically shutting down
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*/
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void forcePersist(bool persist);
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void setActiveServicesCallback(const std::function<bool(bool)>& activeServicesCallback);
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bool tryUnregister();
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void reRegister();
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private:
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sp<ClientCounterCallbackImpl> mImpl;
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};
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bool ClientCounterCallbackImpl::registerService(const sp<IBinder>& service, const std::string& name,
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bool allowIsolated, int dumpFlags) {
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std::lock_guard<std::mutex> lock(mMutex);
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return registerServiceLocked(service, name, allowIsolated, dumpFlags);
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}
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bool ClientCounterCallbackImpl::registerServiceLocked(const sp<IBinder>& service,
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const std::string& name, bool allowIsolated,
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int dumpFlags) {
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auto manager = interface_cast<AidlServiceManager>(asBinder(defaultServiceManager()));
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bool reRegister = mRegisteredServices.count(name) > 0;
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std::string regStr = (reRegister) ? "Re-registering" : "Registering";
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ALOGI("%s service %s", regStr.c_str(), name.c_str());
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if (Status status = manager->addService(name.c_str(), service, allowIsolated, dumpFlags);
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!status.isOk()) {
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ALOGE("Failed to register service %s (%s)", name.c_str(), status.toString8().c_str());
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return false;
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}
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if (!reRegister) {
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if (Status status =
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manager->registerClientCallback(name, service,
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sp<android::os::IClientCallback>::fromExisting(
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this));
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!status.isOk()) {
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ALOGE("Failed to add client callback for service %s (%s)", name.c_str(),
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status.toString8().c_str());
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return false;
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}
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// Only add this when a service is added for the first time, as it is not removed
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mRegisteredServices[name] = {
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.service = service,
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.allowIsolated = allowIsolated,
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.dumpFlags = dumpFlags
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};
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}
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return true;
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}
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std::map<std::string, ClientCounterCallbackImpl::Service>::iterator ClientCounterCallbackImpl::assertRegisteredService(const sp<IBinder>& service) {
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LOG_ALWAYS_FATAL_IF(service == nullptr, "Got onClients callback for null service");
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for (auto it = mRegisteredServices.begin(); it != mRegisteredServices.end(); ++it) {
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auto const& [name, registered] = *it;
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(void) name;
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if (registered.service != service) continue;
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return it;
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}
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LOG_ALWAYS_FATAL("Got callback on service which we did not register: %s", String8(service->getInterfaceDescriptor()).c_str());
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__builtin_unreachable();
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}
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void ClientCounterCallbackImpl::forcePersist(bool persist) {
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std::lock_guard<std::mutex> lock(mMutex);
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mForcePersist = persist;
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if (!mForcePersist) {
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// Attempt a shutdown in case the number of clients hit 0 while the flag was on
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maybeTryShutdownLocked();
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}
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}
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bool ClientCounterCallbackImpl::tryUnregisterLocked() {
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auto manager = interface_cast<AidlServiceManager>(asBinder(defaultServiceManager()));
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for (auto& [name, entry] : mRegisteredServices) {
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Status status = manager->tryUnregisterService(name, entry.service);
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if (!status.isOk()) {
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ALOGI("Failed to unregister service %s (%s)", name.c_str(), status.toString8().c_str());
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return false;
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}
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entry.registered = false;
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}
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return true;
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}
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void ClientCounterCallbackImpl::reRegisterLocked() {
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for (auto& [name, entry] : mRegisteredServices) {
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// re-register entry if not already registered
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if (entry.registered) {
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continue;
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}
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if (!registerServiceLocked(entry.service, name, entry.allowIsolated, entry.dumpFlags)) {
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// Must restart. Otherwise, clients will never be able to get a hold of this service.
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LOG_ALWAYS_FATAL("Bad state: could not re-register services");
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}
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entry.registered = true;
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}
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}
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void ClientCounterCallbackImpl::maybeTryShutdownLocked() {
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if (mForcePersist) {
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ALOGI("Shutdown prevented by forcePersist override flag.");
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return;
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}
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bool handledInCallback = false;
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if (mActiveServicesCallback != nullptr) {
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bool hasClients = mNumConnectedServices != 0;
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if (hasClients != mPreviousHasClients) {
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handledInCallback = mActiveServicesCallback(hasClients);
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mPreviousHasClients = hasClients;
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}
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}
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// If there is no callback defined or the callback did not handle this
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// client count change event, try to shutdown the process if its services
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// have no clients.
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if (!handledInCallback && mNumConnectedServices == 0) {
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tryShutdownLocked();
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}
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}
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Status ClientCounterCallbackImpl::onClients(const sp<IBinder>& service, bool clients) {
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std::lock_guard<std::mutex> lock(mMutex);
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auto & [name, registered] = *assertRegisteredService(service);
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if (registered.clients == clients) {
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LOG_ALWAYS_FATAL("Process already thought %s had clients: %d but servicemanager has "
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"notified has clients: %d", name.c_str(), registered.clients, clients);
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}
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registered.clients = clients;
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// update cache count of clients
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{
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size_t numWithClients = 0;
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for (const auto& [name, registered] : mRegisteredServices) {
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(void) name;
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if (registered.clients) numWithClients++;
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}
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mNumConnectedServices = numWithClients;
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}
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ALOGI("Process has %zu (of %zu available) client(s) in use after notification %s has clients: %d",
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mNumConnectedServices, mRegisteredServices.size(), name.c_str(), clients);
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maybeTryShutdownLocked();
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return Status::ok();
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}
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void ClientCounterCallbackImpl::tryShutdownLocked() {
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ALOGI("Trying to shut down the service. No clients in use for any service in process.");
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if (tryUnregisterLocked()) {
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ALOGI("Unregistered all clients and exiting");
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exit(EXIT_SUCCESS);
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}
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reRegisterLocked();
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}
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void ClientCounterCallbackImpl::setActiveServicesCallback(const std::function<bool(bool)>&
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activeServicesCallback) {
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std::lock_guard<std::mutex> lock(mMutex);
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mActiveServicesCallback = activeServicesCallback;
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}
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ClientCounterCallback::ClientCounterCallback() {
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mImpl = sp<ClientCounterCallbackImpl>::make();
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}
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bool ClientCounterCallback::registerService(const sp<IBinder>& service, const std::string& name,
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bool allowIsolated, int dumpFlags) {
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return mImpl->registerService(service, name, allowIsolated, dumpFlags);
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}
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void ClientCounterCallback::forcePersist(bool persist) {
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mImpl->forcePersist(persist);
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}
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void ClientCounterCallback::setActiveServicesCallback(const std::function<bool(bool)>&
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activeServicesCallback) {
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mImpl->setActiveServicesCallback(activeServicesCallback);
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}
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bool ClientCounterCallback::tryUnregister() {
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// see comments in header, this should only be called from the active
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// services callback, see also b/191781736
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return mImpl->tryUnregisterLocked();
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}
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void ClientCounterCallback::reRegister() {
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// see comments in header, this should only be called from the active
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// services callback, see also b/191781736
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mImpl->reRegisterLocked();
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}
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} // namespace internal
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LazyServiceRegistrar::LazyServiceRegistrar() {
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mClientCC = std::make_shared<internal::ClientCounterCallback>();
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}
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LazyServiceRegistrar& LazyServiceRegistrar::getInstance() {
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static auto registrarInstance = new LazyServiceRegistrar();
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return *registrarInstance;
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}
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status_t LazyServiceRegistrar::registerService(const sp<IBinder>& service, const std::string& name,
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bool allowIsolated, int dumpFlags) {
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if (!mClientCC->registerService(service, name, allowIsolated, dumpFlags)) {
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return UNKNOWN_ERROR;
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}
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return OK;
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}
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void LazyServiceRegistrar::forcePersist(bool persist) {
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mClientCC->forcePersist(persist);
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}
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void LazyServiceRegistrar::setActiveServicesCallback(const std::function<bool(bool)>&
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activeServicesCallback) {
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mClientCC->setActiveServicesCallback(activeServicesCallback);
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}
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bool LazyServiceRegistrar::tryUnregister() {
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return mClientCC->tryUnregister();
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}
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void LazyServiceRegistrar::reRegister() {
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mClientCC->reRegister();
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}
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} // namespace hardware
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} // namespace android
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