juce_core/native/juce_android_Threads.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2020 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

/*
    Note that a lot of methods that you'd expect to find in this file actually
    live in juce_posix_SharedCode.h!
*/

#define JNI_CLASS_MEMBERS(METHOD, STATICMETHOD, FIELD, STATICFIELD, CALLBACK) \
 FIELD (activityInfo, "activityInfo", "Landroid/content/pm/ActivityInfo;")

DECLARE_JNI_CLASS (AndroidResolveInfo, "android/content/pm/ResolveInfo")
#undef JNI_CLASS_MEMBERS

//==============================================================================
JavaVM* androidJNIJavaVM = nullptr;
jobject androidApkContext = nullptr;

//==============================================================================
JNIEnv* getEnv() noexcept
{
    if (androidJNIJavaVM != nullptr)
    {
        JNIEnv* env;
        androidJNIJavaVM->AttachCurrentThread (&env, nullptr);

        return env;
    }

    // You did not call Thread::initialiseJUCE which must be called at least once in your apk
    // before using any JUCE APIs. The Projucer will automatically generate java code
    // which will invoke Thread::initialiseJUCE for you.
    jassertfalse;
    return nullptr;
}

void JNICALL juce_JavainitialiseJUCE (JNIEnv* env, jobject /*jclass*/, jobject context)
{
    Thread::initialiseJUCE (env, context);
}

extern "C" jint JNIEXPORT JNI_OnLoad (JavaVM* vm, void*)
{
    // Huh? JNI_OnLoad was called two times!
    jassert (androidJNIJavaVM == nullptr);

    androidJNIJavaVM = vm;

    auto* env = getEnv();

    // register the initialisation function
    auto juceJavaClass = env->FindClass("com/rmsl/juce/Java");

    if (juceJavaClass != nullptr)
    {
        JNINativeMethod method {"initialiseJUCE", "(Landroid/content/Context;)V",
                                reinterpret_cast<void*> (juce_JavainitialiseJUCE)};

        auto status = env->RegisterNatives (juceJavaClass, &method, 1);
        jassert (status == 0);
    }
    else
    {
        // com.rmsl.juce.Java class not found. Apparently this project is a library
        // or was not generated by the Projucer. That's ok, the user will have to
        // call Thread::initialiseJUCE manually
        env->ExceptionClear();
    }

    JNIClassBase::initialiseAllClasses (env);

    return JNI_VERSION_1_2;
}

//==============================================================================
class JuceActivityWatcher   : public ActivityLifecycleCallbacks
{
public:
    JuceActivityWatcher()
    {
        LocalRef<jobject> appContext (getAppContext());

        if (appContext != nullptr)
        {
            auto* env = getEnv();

            myself = GlobalRef (CreateJavaInterface (this, "android/app/Application$ActivityLifecycleCallbacks"));
            env->CallVoidMethod (appContext.get(), AndroidApplication.registerActivityLifecycleCallbacks, myself.get());
        }

        checkActivityIsMain (androidApkContext);
    }

    ~JuceActivityWatcher() override
    {
        LocalRef<jobject> appContext (getAppContext());

        if (appContext != nullptr && myself != nullptr)
        {
            auto* env = getEnv();

            env->CallVoidMethod (appContext.get(), AndroidApplication.unregisterActivityLifecycleCallbacks, myself.get());
            clear();
            myself.clear();
        }
    }

    void onActivityStarted (jobject activity) override
    {
        auto* env = getEnv();

        checkActivityIsMain (activity);

        ScopedLock lock (currentActivityLock);

        if (currentActivity != nullptr)
        {
            // see Clarification June 2001 in JNI reference for why this is
            // necessary
            LocalRef<jobject> localStorage (env->NewLocalRef (currentActivity));

            if (env->IsSameObject (localStorage.get(), activity) != 0)
                return;

            env->DeleteWeakGlobalRef (currentActivity);
            currentActivity = nullptr;
        }

        if (activity != nullptr)
            currentActivity = env->NewWeakGlobalRef (activity);
    }

    void onActivityStopped (jobject activity) override
    {
        auto* env = getEnv();

        ScopedLock lock (currentActivityLock);

        if (currentActivity != nullptr)
        {
            // important that the comparison happens in this order
            // to avoid race condition where the weak reference becomes null
            // just after the first check
            if (env->IsSameObject (currentActivity, activity) != 0
                || env->IsSameObject (currentActivity, nullptr) != 0)
            {
                env->DeleteWeakGlobalRef (currentActivity);
                currentActivity = nullptr;
            }
        }
    }

    LocalRef<jobject> getCurrent()
    {
        ScopedLock lock (currentActivityLock);
        return LocalRef<jobject> (getEnv()->NewLocalRef (currentActivity));
    }

    LocalRef<jobject> getMain()
    {
        ScopedLock lock (currentActivityLock);
        return LocalRef<jobject> (getEnv()->NewLocalRef (mainActivity));
    }

    static JuceActivityWatcher& getInstance()
    {
        static JuceActivityWatcher activityWatcher;
        return activityWatcher;
    }

private:
    void checkActivityIsMain (jobject context)
    {
        auto* env = getEnv();

        ScopedLock lock (currentActivityLock);

        if (mainActivity != nullptr)
        {
            if (env->IsSameObject (mainActivity, nullptr) != 0)
            {
                env->DeleteWeakGlobalRef (mainActivity);
                mainActivity = nullptr;
            }
        }

        if (mainActivity == nullptr)
        {
            LocalRef<jobject> appContext (getAppContext());
            auto mainActivityPath = getMainActivityClassPath();

            if (mainActivityPath.isNotEmpty())
            {
                auto clasz = env->GetObjectClass (context);
                auto activityPath = juceString (LocalRef<jstring> ((jstring) env->CallObjectMethod (clasz, JavaClass.getName)));

                // This may be problematic for apps which use several activities with the same type. We just
                // assume that the very first activity of this type is the main one
                if (activityPath == mainActivityPath)
                    mainActivity = env->NewWeakGlobalRef (context);
            }
        }
    }

    static String getMainActivityClassPath()
    {
        static String mainActivityClassPath;

        if (mainActivityClassPath.isEmpty())
        {
            LocalRef<jobject> appContext (getAppContext());

            if (appContext != nullptr)
            {
                auto* env = getEnv();

                LocalRef<jobject> pkgManager (env->CallObjectMethod (appContext.get(), AndroidContext.getPackageManager));
                LocalRef<jstring> pkgName ((jstring) env->CallObjectMethod (appContext.get(), AndroidContext.getPackageName));

                LocalRef<jobject> intent (env->NewObject (AndroidIntent, AndroidIntent.constructWithString,
                                                          javaString ("android.intent.action.MAIN").get()));

                intent = LocalRef<jobject> (env->CallObjectMethod (intent.get(),
                                                                   AndroidIntent.setPackage,
                                                                   pkgName.get()));

                LocalRef<jobject> resolveInfo (env->CallObjectMethod (pkgManager.get(), AndroidPackageManager.resolveActivity, intent.get(), 0));

                if (resolveInfo != nullptr)
                {
                    LocalRef<jobject> activityInfo (env->GetObjectField (resolveInfo.get(), AndroidResolveInfo.activityInfo));
                    LocalRef<jstring> jName ((jstring) env->GetObjectField (activityInfo.get(), AndroidPackageItemInfo.name));
                    LocalRef<jstring> jPackage ((jstring) env->GetObjectField (activityInfo.get(), AndroidPackageItemInfo.packageName));

                    mainActivityClassPath = juceString (jName);
                }
            }
        }

        return mainActivityClassPath;
    }

    GlobalRef myself;
    CriticalSection currentActivityLock;
    jweak currentActivity = nullptr;
    jweak mainActivity    = nullptr;
};

//==============================================================================
#if JUCE_MODULE_AVAILABLE_juce_events && JUCE_ANDROID
void juce_juceEventsAndroidStartApp();
#endif

void Thread::initialiseJUCE (void* jniEnv, void* context)
{
    static CriticalSection cs;
    ScopedLock lock (cs);

    // jniEnv and context should not be null!
    jassert (jniEnv != nullptr && context != nullptr);

    auto* env = static_cast<JNIEnv*> (jniEnv);

    if (androidJNIJavaVM == nullptr)
    {
        JavaVM* javaVM = nullptr;

        auto status = env->GetJavaVM (&javaVM);
        jassert (status == 0 && javaVM != nullptr);

        androidJNIJavaVM = javaVM;
    }

    static bool firstCall = true;

    if (firstCall)
    {
        firstCall = false;

        // if we ever support unloading then this should probably be a weak reference
        androidApkContext = env->NewGlobalRef (static_cast<jobject> (context));
        JuceActivityWatcher::getInstance();

       #if JUCE_MODULE_AVAILABLE_juce_events && JUCE_ANDROID
        juce_juceEventsAndroidStartApp();
       #endif
    }
}

//==============================================================================
LocalRef<jobject> getAppContext() noexcept
{
    auto* env = getEnv();
    auto context = androidApkContext;

    // You did not call Thread::initialiseJUCE which must be called at least once in your apk
    // before using any JUCE APIs. The Projucer will automatically generate java code
    // which will invoke Thread::initialiseJUCE for you.
    jassert (env != nullptr && context != nullptr);

    if (context == nullptr)
        return LocalRef<jobject>();

    if (env->IsInstanceOf (context, AndroidApplication) != 0)
        return LocalRef<jobject> (env->NewLocalRef (context));

    LocalRef<jobject> applicationContext (env->CallObjectMethod (context, AndroidContext.getApplicationContext));

    if (applicationContext == nullptr)
        return LocalRef<jobject> (env->NewLocalRef (context));

    return applicationContext;
}

LocalRef<jobject> getCurrentActivity() noexcept
{
    return JuceActivityWatcher::getInstance().getCurrent();
}

LocalRef<jobject> getMainActivity() noexcept
{
    return JuceActivityWatcher::getInstance().getMain();
}

//==============================================================================
// sets the process to 0=low priority, 1=normal, 2=high, 3=realtime
JUCE_API void JUCE_CALLTYPE Process::setPriority (ProcessPriority prior)
{
    // TODO

    struct sched_param param;
    int policy, maxp, minp;

    const int p = (int) prior;

    if (p <= 1)
        policy = SCHED_OTHER;
    else
        policy = SCHED_RR;

    minp = sched_get_priority_min (policy);
    maxp = sched_get_priority_max (policy);

    if (p < 2)
        param.sched_priority = 0;
    else if (p == 2 )
        // Set to middle of lower realtime priority range
        param.sched_priority = minp + (maxp - minp) / 4;
    else
        // Set to middle of higher realtime priority range
        param.sched_priority = minp + (3 * (maxp - minp) / 4);

    pthread_setschedparam (pthread_self(), policy, &param);
}

JUCE_API bool JUCE_CALLTYPE juce_isRunningUnderDebugger() noexcept
{
    StringArray lines;
    File ("/proc/self/status").readLines (lines);

    for (int i = lines.size(); --i >= 0;) // (NB - it's important that this runs in reverse order)
        if (lines[i].upToFirstOccurrenceOf (":", false, false).trim().equalsIgnoreCase ("TracerPid"))
            return (lines[i].fromFirstOccurrenceOf (":", false, false).trim().getIntValue() > 0);

    return false;
}

JUCE_API void JUCE_CALLTYPE Process::raisePrivilege() {}
JUCE_API void JUCE_CALLTYPE Process::lowerPrivilege() {}


} // namespace juce