adb shell dumpsys [-t timeout] [--help | -l | --skip services | service [arguments] | -c | -h]

adb shell dumpsys input

adb shell dumpsys -l

@frameworks\base\services\core\java\com\android\server\BatteryService.java
private final class BinderService extends Binder {
    @Override protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
            if (args.length > 0 && "--proto".equals(args[0])) {
                dumpProto(fd);
            } else {
                dumpInternal(fd, pw, args);
            }
        }
    ...
}
private void dumpInternal(FileDescriptor fd, PrintWriter pw, String[] args) {
    synchronized (mLock) {
        if (args == null || args.length == 0 || "-a".equals(args[0])) {
            pw.println("Current Battery Service state:");
            if (mUpdatesStopped) {
                pw.println("  (UPDATES STOPPED -- use 'reset' to restart)");
            }
            pw.println("  AC powered: " + mHealthInfo.chargerAcOnline);
            pw.println("  USB powered: " + mHealthInfo.chargerUsbOnline);
            pw.println("  Wireless powered: " + mHealthInfo.chargerWirelessOnline);
            pw.println("  Max charging current: " + mHealthInfo.maxChargingCurrent);
            pw.println("  Max charging voltage: " + mHealthInfo.maxChargingVoltage);
            pw.println("  Charge counter: " + mHealthInfo.batteryChargeCounter);
            pw.println("  status: " + mHealthInfo.batteryStatus);
            pw.println("  health: " + mHealthInfo.batteryHealth);
            pw.println("  present: " + mHealthInfo.batteryPresent);
            pw.println("  level: " + mHealthInfo.batteryLevel);
            pw.println("  scale: " + BATTERY_SCALE);
            pw.println("  voltage: " + mHealthInfo.batteryVoltage);
            pw.println("  temperature: " + mHealthInfo.batteryTemperature);
            pw.println("  technology: " + mHealthInfo.batteryTechnology);
        } else {
            Shell shell = new Shell();
            shell.exec(mBinderService, null, fd, null, args, null, new ResultReceiver(null));
        }
    }
}

@frameworks\native\cmds\dumpsys\android.bp
cc_binary {
    name: "dumpsys",
    defaults: ["dumpsys_defaults"],
    srcs: [
        "main.cpp",
    ],
}

@frameworks\native\cmds\dumpsys\main.cpp
int main(int argc, char* const argv[]) {
    signal(SIGPIPE, SIG_IGN);
    sp<IServiceManager> sm = defaultServiceManager();//獲取SM對(duì)象
    fflush(stdout);
    if (sm == nullptr) {
        ALOGE("Unable to get default service manager!");
        std::cerr << "dumpsys: Unable to get default service manager!" << std::endl;
        return 20;
    }
    Dumpsys dumpsys(sm.get());
    return dumpsys.main(argc, argv);//進(jìn)入dumpsys服務(wù)
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
int Dumpsys::main(int argc, char* const argv[]) {
    ...
    while (1) {
        ...
        c = getopt_long(argc, argv, "+t:T:l", longOptions, &optionIndex);//獲取指令參數(shù)
        ...
        switch (c) {
        case 0://長(zhǎng)參數(shù)
            if (!strcmp(longOptions[optionIndex].name, "skip")) {//跳過(guò)某些服務(wù)打印
                skipServices = true;
            } else if (!strcmp(longOptions[optionIndex].name, "proto")) {
                asProto = true;
            } else if (!strcmp(longOptions[optionIndex].name, "help")) {//指令幫助
                usage();
                return 0;
            } else if (!strcmp(longOptions[optionIndex].name, "priority")) {
                ...
            } else if (!strcmp(longOptions[optionIndex].name, "pid")) {//只顯示服務(wù)的pid
                type = Type::PID;
            } else if (!strcmp(longOptions[optionIndex].name, "thread")) {//僅顯示進(jìn)程使用情況
                type = Type::THREAD;
            }
            break;
        case 't'://超時(shí)時(shí)間設(shè)置，默認(rèn)10秒
            ...
            break;
        case 'T'://超時(shí)時(shí)間設(shè)置，默認(rèn)10秒
            ...
            break;
        case 'l'://顯示支持的服務(wù)列表
            showListOnly = true;
            break;
        default://其他參數(shù)
            fprintf(stderr, "\n");
            usage();
            return -1;
        }
    }
    ...
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
int Dumpsys::main(int argc, char* const argv[]) {
    ...
    for (int i = optind; i < argc; i++) {
    if (skipServices) {
        skippedServices.add(String16(argv[i]));//配置待忽略的服務(wù)
    } else {
        ...
    }
    ...
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
int Dumpsys::main(int argc, char* const argv[]) {
    ...
    if (services.empty() || showListOnly) {
        services = listServices(priorityFlags, asProto);
        setServiceArgs(args, asProto, priorityFlags);
    }
    ...
}
Vector<String16> Dumpsys::listServices(int priorityFilterFlags, bool filterByProto) const {
    Vector<String16> services = sm_->listServices(priorityFilterFlags);//通過(guò)sm獲取服務(wù)集合
    services.sort(sort_func);//集合排序
    ...
    return services;
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
int Dumpsys::main(int argc, char* const argv[]) {
    ...
    const size_t N = services.size();//獲取支持的服務(wù)個(gè)數(shù)
    if (N > 1 || showListOnly) {
        // first print a list of the current services
        std::cout << "Currently running services:" << std::endl;
        for (size_t i=0; i<N; i++) {
            sp<IBinder> service = sm_->checkService(services[i]);//檢查服務(wù)狀態(tài)
            if (service != nullptr) {
                bool skipped = IsSkipped(skippedServices, services[i]);
                std::cout << "  " << services[i] << (skipped ? " (skipped)" : "") << std::endl;//打印服務(wù)名稱
            }
        }
    }
    if (showListOnly) {//如果指令僅需要打印服務(wù)集合，則結(jié)束。
        return 0;
    }
    ...
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
int Dumpsys::main(int argc, char* const argv[]) {
    ...
    for (size_t i = 0; i < N; i++) {
        const String16& serviceName = services[i];
        if (IsSkipped(skippedServices, serviceName)) continue;//跳過(guò)部分服務(wù)
        if (startDumpThread(type, serviceName, args) == OK) {//step 1.創(chuàng)建dump打印的線程
            ...
            std::chrono::duration<double> elapsedDuration;
            size_t bytesWritten = 0;
            status_t status =
                writeDump(STDOUT_FILENO, serviceName, std::chrono::milliseconds(timeoutArgMs),
                          asProto, elapsedDuration, bytesWritten);//step 2.dump執(zhí)行打印操作
            if (status == TIMED_OUT) {//打印超時(shí)
                std::cout << std::endl
                     << "*** SERVICE '" << serviceName << "' DUMP TIMEOUT (" << timeoutArgMs
                     << "ms) EXPIRED ***" << std::endl
                     << std::endl;
            }
            ...
            bool dumpComplete = (status == OK);
            stopDumpThread(dumpComplete);//step 3.結(jié)束dump打印線程
        }
    }
    ...
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
status_t Dumpsys::startDumpThread(Type type, const String16& serviceName,
                                  const Vector<String16>& args) {
    sp<IBinder> service = sm_->checkService(serviceName);//通過(guò)SM獲取service對(duì)象
    int sfd[2];
    if (pipe(sfd) != 0) {//創(chuàng)建管道，用于讀取service端數(shù)據(jù)
        ...
    }
    ...
    redirectFd_ = unique_fd(sfd[0]);
    unique_fd remote_end(sfd[1]);
    sfd[0] = sfd[1] = -1;
    // dump blocks until completion, so spawn a thread..
    activeThread_ = std::thread([=, remote_end{std::move(remote_end)}]() mutable {//創(chuàng)建線程
        status_t err = 0;
        switch (type) {
        case Type::DUMP:
            err = service->dump(remote_end.get(), args);//調(diào)用dump函數(shù)
            break;
        ...
        }
        ...
    });
    return OK;
}

@frameworks\native\cmds\dumpsys\dumpsys.cpp
status_t Dumpsys::writeDump(int fd, const String16& serviceName, std::chrono::milliseconds timeout,
                            bool asProto, std::chrono::duration<double>& elapsedDuration,
                            size_t& bytesWritten) const {
    ...
    int serviceDumpFd = redirectFd_.get();
    struct pollfd pfd = {.fd = serviceDumpFd, .events = POLLIN};
    while (true) {
        ...
        int rc = TEMP_FAILURE_RETRY(poll(&pfd, 1, time_left_ms()));//poll機(jī)制檢測(cè)管道數(shù)據(jù)
        if (rc < 0) {
           ...
        } else if (rc == 0 || time_left_ms() == 0) {
            status = TIMED_OUT;//計(jì)算剩余時(shí)間，來(lái)決定是否超時(shí)
            break;
        }
        char buf[4096];
        rc = TEMP_FAILURE_RETRY(read(redirectFd_.get(), buf, sizeof(buf)));//讀取遠(yuǎn)端的數(shù)據(jù)
        ...
        if (!WriteFully(fd, buf, rc)) {//打印至控制臺(tái)
            ...
            break;
        }
        totalBytes += rc;
    }
    ...
    return status;
}