1. Overview
AdapterService.java # onCreate() 调用 initNative() 初始化 Native 层。
2. initNative()
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
@Override
public void onCreate() {
...
initNative(isGuest(), isNiapMode(), configCompareResult, isAtvDevice);
...
}
native boolean initNative(boolean startRestricted, boolean isNiapMode,
int configCompareResult, boolean isAtvDevice);
以上四个参数的值如下（Android R 上新增log，于 Pixel5 平台运行）
parameters log.png
BluetoothAdapterService: kt
guest=false, niapMode=false, configCompareResult=0, isAtvDevice=false
[packages/apps/Bluetooth/jni/com_android_bluetooth_btservice_AdapterService.cpp][com_android_bluetooth_btservice_AdapterService]
static bool initNative(JNIEnv* env, jobject obj, jboolean isGuest,
jboolean isNiapMode, int configCompareResult,
jboolean isAtvDevice) {
android_bluetooth_UidTraffic.clazz =
(jclass)env->NewGlobalRef(env->FindClass("android/bluetooth/UidTraffic"));
sJniAdapterServiceObj = env->NewGlobalRef(obj);
sJniCallbacksObj =
env->NewGlobalRef(env->GetObjectField(obj, sJniCallbacksField));
// 1
int ret = sBluetoothInterface->init(
&sBluetoothCallbacks, isGuest == JNI_TRUE ? 1 : 0,
isNiapMode == JNI_TRUE ? 1 : 0, configCompareResult,
isAtvDevice == JNI_TRUE ? 1 : 0);
// 2
ret = sBluetoothInterface->set_os_callouts(&sBluetoothOsCallouts);
// 3
sBluetoothSocketInterface =
(btsock_interface_t*)sBluetoothInterface->get_profile_interface(
BT_PROFILE_SOCKETS_ID);
return JNI_TRUE;
}
注释 //1 处设置的回调函数列表如下：
static bt_callbacks_t sBluetoothCallbacks = {
sizeof(sBluetoothCallbacks), adapter_state_change_callback,
adapter_properties_callback, remote_device_properties_callback,
device_found_callback, discovery_state_changed_callback,
pin_request_callback, ssp_request_callback,
bond_state_changed_callback, acl_state_changed_callback,
callback_thread_event, dut_mode_recv_callback,
le_test_mode_recv_callback, energy_info_recv_callback};
注释 //2 处设置的回调函数列表如下：
static bt_os_callouts_t sBluetoothOsCallouts = {
sizeof(sBluetoothOsCallouts), set_wake_alarm_callout,
acquire_wake_lock_callout, release_wake_lock_callout,
};
2.1 init bluetooth
分析以下源码实现
int ret = sBluetoothInterface->init(
&sBluetoothCallbacks, isGuest == JNI_TRUE ? 1 : 0,
isNiapMode == JNI_TRUE ? 1 : 0, configCompareResult,
isAtvDevice == JNI_TRUE ? 1 : 0);
参考 3.1 初始化 JNI 可知，执行 sBluetoothInterface->init ，相当于执行
system/bt/btif/src/bluetooth.cc
static int init(bt_callbacks_t* callbacks, bool start_restricted,
bool is_niap_mode, int config_compare_result, bool is_atv) {
// 如果初始化过，则不再初始化。
if (interface_ready()) return BT_STATUS_DONE;
bt_hal_cbacks = callbacks; // 1 缓存 JNI 设置的回调函数列表
restricted_mode = start_restricted;
niap_mode = is_niap_mode;
niap_config_compare_result = config_compare_result;
is_local_device_atv = is_atv;
stack_manager_get_interface()->init_stack(); // 2
btif_debug_init(); // 3
return BT_STATUS_SUCCESS;
}
下面详细分析以上代码注释的 1、2、3 三个部分。
2.1.1 缓存 JNI 设置的回调函数列表
system/bt/btif/src/bluetooth.cc
bt_callbacks_t* bt_hal_cbacks = NULL;
system/bt/include/hardware/bluetooth.h
typedef struct {
/** set to sizeof(bt_callbacks_t) */
size_t size;
adapter_state_changed_callback adapter_state_changed_cb;
adapter_properties_callback adapter_properties_cb;
remote_device_properties_callback remote_device_properties_cb;
device_found_callback device_found_cb;
discovery_state_changed_callback discovery_state_changed_cb;
pin_request_callback pin_request_cb;
ssp_request_callback ssp_request_cb;
bond_state_changed_callback bond_state_changed_cb;
acl_state_changed_callback acl_state_changed_cb;
callback_thread_event thread_evt_cb;
dut_mode_recv_callback dut_mode_recv_cb;
le_test_mode_callback le_test_mode_cb;
energy_info_callback energy_info_cb;
} bt_callbacks_t;
蓝牙协议栈可以通过 bluetooth.h 中定义的结构体成员，来回调 JNI 注册的回调函数。
2.1.2 初始化 stack_manager
2.1.2.1 stack_manager_get_interface()
system/bt/btif/src/stack_manager.cc
static const stack_manager_t interface = {init_stack, start_up_stack_async,
shut_down_stack_async, clean_up_stack,
get_stack_is_running};
const stack_manager_t* stack_manager_get_interface() {
ensure_manager_initialized();
return &interface;
}
static void ensure_manager_initialized() {
// 如果已经初始化，则返回
if (management_thread.IsRunning()) return;
management_thread.StartUp();
}
stack_manager_get_interface() 干了两件事
- 启动了 stack_manager 的工作线程 management_thread；
- 提供了外部访问的入口函数列表。
2.1.2.2 init_stack()
system/bt/btif/src/stack_manager.cc
static void init_stack() {
// This is a synchronous process.
semaphore_t* semaphore = semaphore_new(0);
management_thread.DoInThread(FROM_HERE,
base::Bind(event_init_stack, semaphore));
semaphore_wait(semaphore);
semaphore_free(semaphore);
}
// Synchronous function to initialize the stack
static void event_init_stack(void* context) {
semaphore_t* semaphore = (semaphore_t*)context;
if (stack_is_initialized) {
......
} else {
module_management_start(); // 启动 module_management，实际未执行任何代码
module_init(get_module(OSI_MODULE));
module_init(get_module(BT_UTILS_MODULE));
module_init(get_module(BTIF_CONFIG_MODULE));
btif_init_bluetooth();
stack_is_initialized = true;
}
if (semaphore) semaphore_post(semaphore);
}
2.1.2.2.1 初始化不同的 module
不同 module 初始化，参考 module_init
2.1.2.2.2 初始化蓝牙
system/bt/btif/src/btif_core.cc
bt_status_t btif_init_bluetooth() {
exit_manager = new base::AtExitManager();
bte_main_boot_entry();
jni_thread.StartUp();
jni_thread.DoInThread(FROM_HERE, base::Bind(btif_jni_associate));
return BT_STATUS_SUCCESS;
}
- 创建 chrome 库中的 AtExitManager
- bte_main_boot_entry() ；
- 启动 jni_thread，并在 jni_thread 中执行 btif_jni_associate 。
2.1.2.2.2.1 AtExitManager
创建 AtExitManager 对象
2.1.2.2.2.2 初始化 BTE
void bte_main_boot_entry(void) {
module_init(get_module(INTEROP_MODULE));
hci = hci_layer_get_interface();
hci->set_data_cb(base::Bind(&post_to_main_message_loop));
module_init(get_module(STACK_CONFIG_MODULE));
}
不同 module 初始化，参考 module_init
2.1.2.2.2.3 启动 jni thread，并执行指定函数
static void btif_jni_associate() {
BTIF_TRACE_DEBUG("%s Associating thread to JVM", __func__);
HAL_CBACK(bt_hal_cbacks, thread_evt_cb, ASSOCIATE_JVM);
}
根据前文可知，bt_hal_cbacks 缓存的是 JNI 注册下来的回调函数，因此这里会执行 JNI 中的 callback_thread_event 函数，具体实现如下。
[packages/apps/Bluetooth/jni/com_android_bluetooth_btservice_AdapterService.cpp][com_android_bluetooth_btservice_AdapterService]
static void callback_thread_event(bt_cb_thread_evt event) {
if (event == ASSOCIATE_JVM) {
JavaVMAttachArgs args;
char name[] = "BT Service Callback Thread";
args.version = JNI_VERSION_1_6;
args.name = name;
args.group = NULL;
vm->AttachCurrentThread(&callbackEnv, &args);
sHaveCallbackThread = true;
sCallbackThread = pthread_self();
} else if (event == DISASSOCIATE_JVM) {
......
}
}
2.1.3 btif_debug_init() 实现
system/bt/btif/src/btif_debug.cc
void btif_debug_init(void) {
#if (BTSNOOP_MEM == TRUE)
btif_debug_btsnoop_init();
#endif
}
debug相关的内容，暂不分析。
2.2 set_os_callouts
分析以下源码实现
ret = sBluetoothInterface->set_os_callouts(&sBluetoothOsCallouts)
2.2.1 参数定义 - sBluetoothOsCallouts
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
static bt_os_callouts_t sBluetoothOsCallouts = {
sizeof(sBluetoothOsCallouts), set_wake_alarm_callout,
acquire_wake_lock_callout, release_wake_lock_callout,
};
具体实现暂不贴代码分析，至少是知道具体实现代码 JNI 中。
bt_os_callouts_t 原型定义
system/bt/include/hardware/bluetooth.h
typedef struct {
/* set to sizeof(bt_os_callouts_t) */
size_t size;
set_wake_alarm_callout set_wake_alarm;
acquire_wake_lock_callout acquire_wake_lock;
release_wake_lock_callout release_wake_lock;
} bt_os_callouts_t;
typedef bool (*set_wake_alarm_callout)(uint64_t delay_millis, bool should_wake,
alarm_cb cb, void* data);
typedef int (*acquire_wake_lock_callout)(const char* lock_name);
typedef int (*release_wake_lock_callout)(const char* lock_name);
2.2.2 函数实现 - set_os_callouts
同 2.1，执行 sBluetoothInterface->set_os_callouts 即为执行
system/bt/btif/src/bluetooth.cc
static int set_os_callouts(bt_os_callouts_t* callouts) {
wakelock_os_callouts_saved = callouts; // 1
wakelock_set_os_callouts(&wakelock_os_callouts_jni); // 2
return BT_STATUS_SUCCESS;
}
static bt_os_callouts_t* wakelock_os_callouts_saved = nullptr;
- 注释 // 1 是赋值语句，bluetooth.cc 拿到了 JNI 中具体实现的方法的入口，存在 wakelock_os_callouts_saved 变量中。
- 注释 // 2 是调用蓝牙协议栈中的 wakelock 有关的内容，将 JNI 的 wakelock 实现方法注入到 wakelock模块中。
wakelock_set_os_callouts(&wakelock_os_callouts_jni);
2.2.2.1 参数来源 - wakelock_os_callouts_jni
static bt_os_callouts_t wakelock_os_callouts_jni = {
sizeof(wakelock_os_callouts_jni),
nullptr /* not used */,
acquire_wake_lock_cb,
release_wake_lock_cb,
};
static int acquire_wake_lock_cb(const char* lock_name) {
return do_in_jni_thread(
FROM_HERE, base::Bind(base::IgnoreResult(
wakelock_os_callouts_saved->acquire_wake_lock),
lock_name));
}
static int release_wake_lock_cb(const char* lock_name) {
return do_in_jni_thread(
FROM_HERE, base::Bind(base::IgnoreResult(
wakelock_os_callouts_saved->release_wake_lock),
lock_name));
可以看到这里最终调用的 wakelock_os_callouts_saved 变量的内容，该变量在 2.2.2 中赋值，由 JNI 传递而来。
2.2.2.2 函数实现 - wakelock_set_os_callouts
void wakelock_set_os_callouts(bt_os_callouts_t* callouts) {
wakelock_os_callouts = callouts;
is_native = (wakelock_os_callouts == NULL);
LOG_INFO(LOG_TAG, "%s set to %s", __func__,
(is_native) ? "native" : "non-native");
}
static bt_status_t wakelock_acquire_callout(void) {
return static_cast<bt_status_t>(
wakelock_os_callouts->acquire_wake_lock(WAKE_LOCK_ID));
}
static bt_status_t wakelock_release_callout(void) {
return static_cast<bt_status_t>(
wakelock_os_callouts->release_wake_lock(WAKE_LOCK_ID));
}
2.2.3 小结
经过以上分析可知：
- 具体的 wakelock 实现方法在 JNI 中；
- wakelock 实现方法被传递到 bluetooth.cc 和 wakelock.cc 中供回调使用。
2.3 get_profile_interface
sBluetoothSocketInterface =
(btsock_interface_t*)sBluetoothInterface->get_profile_interface(
BT_PROFILE_SOCKETS_ID);
system/bt/btif/src/bluetooth.cc
static const void* get_profile_interface(const char* profile_id) {
if (is_profile(profile_id, BT_PROFILE_SOCKETS_ID))
return btif_sock_get_interface();
......
}
system/bt/btif/src/btif_sock.cc
const btsock_interface_t* btif_sock_get_interface(void) {
static btsock_interface_t interface = {
sizeof(interface), btsock_listen, /* listen */
btsock_connect, /* connect */
btsock_request_max_tx_data_length /* request_max_tx_data_length */
};
return &interface;
}
由以上代码流程，JNI 获取到 SOCKET profile 的入口函数列表。
传递不同的 profile ID 即可获取到对应的 profile 的入口函数列表。
Android 12 之后增加了一个参数
packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
initNative(isGuest(), isCommonCriteriaMode(), configCompareResult, getInitFlags(),
isAtvDevice);
getInitFlags() 中的 Flag 用于控制 GD 协议栈的 log
根据 device_config 数据库的配置来控制log的开启与否，目前全部开启的命令，开启之后，重启蓝牙。
adb shell device_config put bluetooth INIT_gd_core true
adb shell device_config put bluetooth INIT_gd_advertising true
adb shell device_config put bluetooth INIT_gd_scanning true
adb shell device_config put bluetooth INIT_gd_hci true
adb shell device_config put bluetooth INIT_gd_controller true
adb shell device_config put bluetooth INIT_gd_acl true
adb shell device_config put bluetooth INIT_gd_l2cap true
adb shell device_config put bluetooth INIT_gd_rust true
adb shell device_config put bluetooth INIT_gd_link_policy true
adb shell device_config put bluetooth INIT_btaa_hci true
// 未单独设置的tag，则使用 all 属性
adb shell device_config put bluetooth INIT_logging_debug_enabled_for_all true
// 单独关闭或开启log 的tag，优先级高于 all，低于单独设置
//adb shell device_config put bluetooth INIT_logging_debug_enabled_for_tags tags
//adb shell device_config put bluetooth INIT_logging_debug_disabled_for_tags tags
上面命令中的 bluetooth 是 name space
frameworks/base/core/java/android/provider/DeviceConfig.java
由下面这个类实现 device_config
[com_android_bluetooth_btservice_AdapterService]: https://cs.android.com/android/platform/superproject/+/android-11.0.0_r48:packages/apps/Bluetooth/jni/com_android_bluetooth_btservice_AdapterService.cpp
