Merge "Properly manage JniStringCache lifecycle and clear on unload." into main (0be8feb3) · Commits · e / os / android_frameworks_base

core/jni/AndroidRuntime.cpp

+5 −0

Original line number	Diff line number	Diff line
		@@ -35,6 +35,7 @@
		#include <dlfcn.h>
		#include <nativehelper/JNIHelp.h>
		#include <nativehelper/JniInvocation.h>
		#include "com_android_internal_os_JniStringCache.h"
		#include <server_configurable_flags/get_flags.h>
		#include <signal.h>
		#include <stdio.h>
		@@ -109,6 +110,10 @@ extern int register_android_media_ToneGenerator(JNIEnv *env);
		extern int register_android_media_audio_common_AidlConversion(JNIEnv* env);
		extern int register_android_media_midi(JNIEnv *env);

		extern "C" JNIEXPORT void JNICALL JNI_OnUnload(JavaVM* vm, void* reserved) {
		JniStringCache::Unload(vm);
		}

		namespace android {

		/*

core/jni/com_android_internal_os_JniStringCache.cpp

+25 −4

Original line number	Diff line number	Diff line
		@@ -20,10 +20,12 @@
		#include <android_runtime/AndroidRuntime.h>

		#include <atomic>
		#include <mutex>

		namespace android {

		namespace {

		template <typename TChar>
		uint32_t computeHash(const TChar* s, size_t len) {
		uint32_t h = 0;
		@@ -65,11 +67,14 @@ bool StringsAreEqual(JNIEnv* env, jstring jstr, const char* chars, size_t len) {
		return result;
		}

		JniStringCache* gInstance = nullptr;
		std::once_flag gInstanceFlag;

		} // namespace

		JniStringCache& JniStringCache::getInstance() {
		static JniStringCache instance;
		return instance;
		std::call_once(gInstanceFlag, []() { gInstance = new JniStringCache(); });
		return *gInstance;
		}

		JniStringCache::JniStringCache() : mHits(0), mMisses(0), mEvictions(0), mSkips(0) {}
		@@ -261,12 +266,14 @@ size_t JniStringCache::skips() const {
		}

		void JniStringCache::clear() {
		JNIEnv* env = AndroidRuntime::getJNIEnv();
		clear(AndroidRuntime::getJNIEnv());
		}

		void JniStringCache::clear(JNIEnv* env) {
		if (env == nullptr) {
		DCHECK(false) << "JNIEnv is null, can't clear cache";
		return;
		}

		auto clear_cache = [&](std::atomic<CacheEntry>* cache) {
		for (size_t i = 0; i < kCacheSize; ++i) {
		std::atomic<CacheEntry>& slot = cache[i];
		@@ -306,6 +313,20 @@ void JniStringCache::clear() {
		clear_cache(mUtf8Cache);
		}

		void JniStringCache::Unload(JavaVM* vm) {
		if (gInstance == nullptr) {
		return;
		}

		JNIEnv* env = nullptr;
		if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) == JNI_OK) {
		gInstance->clear(env);
		}

		delete gInstance;
		gInstance = nullptr;
		}

		static jlong com_android_internal_os_JniStringCache_nativeHits() {
		return static_cast<jlong>(JniStringCache::getInstance().hits());
		}

core/jni/com_android_internal_os_JniStringCache.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -41,6 +41,9 @@ public:
		// Global instance to use in order to maximize cache hits.
		static JniStringCache& getInstance();

		// Clears all global references held by the cache.
		static void Unload(JavaVM* vm);

		JniStringCache();
		~JniStringCache();

		@@ -67,6 +70,7 @@ public:
		// Under concurrent usage, some entries may not be cleared.
		// Use this for instance to trim memory usage if needed.
		void clear();
		void clear(JNIEnv* env);

		private:
		struct CacheEntry {