From 749b063af39b2752276cb1268d199ee82abb80cc Mon Sep 17 00:00:00 2001
From: Mathias Agopian <mathias@google.com>
Date: Mon, 3 Jun 2024 10:21:23 -0700
Subject: [PATCH] PerformanceHintManager needs a valid Java thread

FIXES=[343965368, 343550453]
---
 .../backend/platforms/PlatformEGLAndroid.h     |  5 +++++
 filament/backend/src/VirtualMachineEnv.cpp     | 12 +++++++++++-
 .../opengl/platforms/PlatformEGLAndroid.cpp    | 18 +++++++++++++++++-
 .../utils/android/PerformanceHintManager.h     |  6 ++++++
 .../src/android/PerformanceHintManager.cpp     |  7 +++++++
 5 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/filament/backend/include/backend/platforms/PlatformEGLAndroid.h b/filament/backend/include/backend/platforms/PlatformEGLAndroid.h
index d0caeb8c89b..c3cc7da89d8 100644
--- a/filament/backend/include/backend/platforms/PlatformEGLAndroid.h
+++ b/filament/backend/include/backend/platforms/PlatformEGLAndroid.h
@@ -90,8 +90,13 @@ class PlatformEGLAndroid : public PlatformEGL {
     AcquiredImage transformAcquiredImage(AcquiredImage source) noexcept override;
 
 private:
+    struct InitializeJvmForPerformanceManagerIfNeeded {
+        InitializeJvmForPerformanceManagerIfNeeded();
+    };
+
     int mOSVersion;
     ExternalStreamManagerAndroid& mExternalStreamManager;
+    InitializeJvmForPerformanceManagerIfNeeded const mInitializeJvmForPerformanceManagerIfNeeded;
     utils::PerformanceHintManager mPerformanceHintManager;
     utils::PerformanceHintManager::Session mPerformanceHintSession;
 
diff --git a/filament/backend/src/VirtualMachineEnv.cpp b/filament/backend/src/VirtualMachineEnv.cpp
index ba156a8ad48..c7ff7b17906 100644
--- a/filament/backend/src/VirtualMachineEnv.cpp
+++ b/filament/backend/src/VirtualMachineEnv.cpp
@@ -16,13 +16,23 @@
 
 #include "private/backend/VirtualMachineEnv.h"
 
+#include <utils/compiler.h>
 #include <utils/debug.h>
 
+#include <jni.h>
+
 namespace filament {
 
 JavaVM* VirtualMachineEnv::sVirtualMachine = nullptr;
 
-// This is called when the library is loaded. We need this to get a reference to the global VM
+/*
+ * This is typically called by filament_jni.so when it is loaded. If filament_jni.so is not used,
+ * then this must be called manually -- however, this is a problem because VirtualMachineEnv.h
+ * is currently private and part of backend.
+ * For now, we authorize this usage, but we will need to fix it; by making a proper public
+ * API for this.
+ */
+UTILS_PUBLIC
 UTILS_NOINLINE
 jint VirtualMachineEnv::JNI_OnLoad(JavaVM* vm) noexcept {
     JNIEnv* env = nullptr;
diff --git a/filament/backend/src/opengl/platforms/PlatformEGLAndroid.cpp b/filament/backend/src/opengl/platforms/PlatformEGLAndroid.cpp
index 94d602a0ba8..577b66fb315 100644
--- a/filament/backend/src/opengl/platforms/PlatformEGLAndroid.cpp
+++ b/filament/backend/src/opengl/platforms/PlatformEGLAndroid.cpp
@@ -19,6 +19,8 @@
 #include <backend/platforms/PlatformEGL.h>
 #include <backend/platforms/PlatformEGLAndroid.h>
 
+#include <private/backend/VirtualMachineEnv.h>
+
 #include "opengl/GLUtils.h"
 #include "ExternalStreamManagerAndroid.h"
 
@@ -82,9 +84,23 @@ using EGLStream = Platform::Stream;
 
 // ---------------------------------------------------------------------------------------------
 
+PlatformEGLAndroid::InitializeJvmForPerformanceManagerIfNeeded::InitializeJvmForPerformanceManagerIfNeeded() {
+    // PerformanceHintManager() needs the calling thread to be a Java thread; so we need
+    // to attach this thread to the JVM before we initialize PerformanceHintManager.
+    // This should be done in PerformanceHintManager(), but libutils doesn't have access to
+    // VirtualMachineEnv.
+    if (PerformanceHintManager::isSupported()) {
+        (void)VirtualMachineEnv::get().getEnvironment();
+    }
+}
+
+// ---------------------------------------------------------------------------------------------
+
 PlatformEGLAndroid::PlatformEGLAndroid() noexcept
         : PlatformEGL(),
-          mExternalStreamManager(ExternalStreamManagerAndroid::create()) {
+          mExternalStreamManager(ExternalStreamManagerAndroid::create()),
+          mInitializeJvmForPerformanceManagerIfNeeded(),
+          mPerformanceHintManager() {
 
     char scratch[PROP_VALUE_MAX + 1];
     int length = __system_property_get("ro.build.version.release", scratch);
diff --git a/libs/utils/include/utils/android/PerformanceHintManager.h b/libs/utils/include/utils/android/PerformanceHintManager.h
index 9808186475c..40101773157 100644
--- a/libs/utils/include/utils/android/PerformanceHintManager.h
+++ b/libs/utils/include/utils/android/PerformanceHintManager.h
@@ -55,9 +55,15 @@ class UTILS_PUBLIC PerformanceHintManager :
         int reportActualWorkDuration(int64_t actualDurationNanos) noexcept;
     };
 
+    // caveat: This must be called on a Java thread
     PerformanceHintManager() noexcept;
     ~PerformanceHintManager() noexcept;
 
+    // Whether PerformanceHintManager APIs are supported (which doesn't mean PerformanceHintManager
+    // itself is, use isValid()).
+    static bool isSupported() noexcept;
+
+    // Whether PerformanceHintManager can be used.
     bool isValid() const;
 
     int64_t getPreferredUpdateRateNanos() const noexcept;
diff --git a/libs/utils/src/android/PerformanceHintManager.cpp b/libs/utils/src/android/PerformanceHintManager.cpp
index c2c8f8b8f15..4b8dd08d83e 100644
--- a/libs/utils/src/android/PerformanceHintManager.cpp
+++ b/libs/utils/src/android/PerformanceHintManager.cpp
@@ -47,6 +47,13 @@ PerformanceHintManager::PerformanceHintManager() noexcept {
 
 PerformanceHintManager::~PerformanceHintManager() noexcept = default;
 
+bool PerformanceHintManager::isSupported() noexcept {
+    if (__builtin_available(android __ANDROID_API_T__, *)) {
+        return true;
+    }
+    return false;
+}
+
 bool PerformanceHintManager::isValid() const {
     return mImpl->mManager != nullptr;
 }