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authorIvo van Dongen <info@ivovandongen.nl>2017-11-08 15:28:03 +0200
committerIvo van Dongen <info@ivovandongen.nl>2017-11-08 15:34:28 +0200
commitfe4f2f07b690e01898e3948a73344d926f3c9024 (patch)
tree98a6240ca9e76645b5bfe39d4ebe2141c7a8b424
parent9aac976104f4c6453cf9e79e03a002565720f213 (diff)
downloadqtlocation-mapboxgl-upstream/ivd-fix-weakref-overflow.tar.gz
[android] MapRendererRunnable - avoid weak reference table overflowupstream/ivd-fix-weakref-overflow
Apparently on some devices the weak reference table is limited (numbers around 52000). Even though we don't use that many weak references, when GC is not called for a while they can stack up and a crash will occur before the GC has had the time to clear the references. The C++ peer now holds on to a global ref (strong) which can be obtained to queue the java peer and then release automatically so that the GC can take over after the runnable has been executed.
-rw-r--r--platform/android/src/map_renderer.cpp10
-rw-r--r--platform/android/src/map_renderer_runnable.cpp10
-rw-r--r--platform/android/src/map_renderer_runnable.hpp7
3 files changed, 16 insertions, 11 deletions
diff --git a/platform/android/src/map_renderer.cpp b/platform/android/src/map_renderer.cpp
index 7655455210..36e8142bfa 100644
--- a/platform/android/src/map_renderer.cpp
+++ b/platform/android/src/map_renderer.cpp
@@ -41,15 +41,19 @@ ActorRef<Renderer> MapRenderer::actor() const {
}
void MapRenderer::schedule(std::weak_ptr<Mailbox> scheduled) {
- // Create a runnable and schedule it on the gl thread
+ // Create a runnable
android::UniqueEnv _env = android::AttachEnv();
auto runnable = std::make_unique<MapRendererRunnable>(*_env, std::move(scheduled));
+ // Obtain ownership of the peer (gets transferred to the MapRenderer on the JVM for later GC)
+ auto peer = runnable->peer();
+
+ // Queue the event on the Java Peer
static auto queueEvent = javaClass.GetMethod<void(
jni::Object<MapRendererRunnable>)>(*_env, "queueEvent");
- javaPeer->Call(*_env, queueEvent, runnable->getPeer());
+ javaPeer->Call(*_env, queueEvent, *peer);
- // Release the object as it will be destroyed on GC of the Java Peer
+ // Release the c++ peer as it will be destroyed on GC of the Java Peer
runnable.release();
}
diff --git a/platform/android/src/map_renderer_runnable.cpp b/platform/android/src/map_renderer_runnable.cpp
index df8cba5e55..4dc6611c40 100644
--- a/platform/android/src/map_renderer_runnable.cpp
+++ b/platform/android/src/map_renderer_runnable.cpp
@@ -8,11 +8,13 @@ namespace android {
MapRendererRunnable::MapRendererRunnable(jni::JNIEnv& env, std::weak_ptr<Mailbox> mailbox_)
: mailbox(std::move(mailbox_)) {
- // Create the Java peer
+ // Create the Java peer and hold on to a global reference
+ // Not using a weak reference here as this might oerflow
+ // the weak reference table on some devices
jni::UniqueLocalFrame frame = jni::PushLocalFrame(env, 5);
static auto constructor = javaClass.GetConstructor<jlong>(env);
auto instance = javaClass.New(env, constructor, reinterpret_cast<jlong>(this));
- javaPeer = SeizeGenericWeakRef(env, jni::Object<MapRendererRunnable>(jni::NewWeakGlobalRef(env, instance.Get()).release()));
+ javaPeer = instance.NewGlobalRef(env);
}
MapRendererRunnable::~MapRendererRunnable() = default;
@@ -21,8 +23,8 @@ void MapRendererRunnable::run(jni::JNIEnv&) {
Mailbox::maybeReceive(mailbox);
}
-jni::Object<MapRendererRunnable> MapRendererRunnable::getPeer() {
- return *javaPeer;
+jni::UniqueObject<MapRendererRunnable> MapRendererRunnable::peer() {
+ return std::move(javaPeer);
}
// Static methods //
diff --git a/platform/android/src/map_renderer_runnable.hpp b/platform/android/src/map_renderer_runnable.hpp
index 75646a442d..46fb028d26 100644
--- a/platform/android/src/map_renderer_runnable.hpp
+++ b/platform/android/src/map_renderer_runnable.hpp
@@ -8,8 +8,6 @@
#include <jni/jni.hpp>
-#include "jni/generic_global_ref_deleter.hpp"
-
namespace mbgl {
namespace android {
@@ -39,10 +37,11 @@ public:
void run(jni::JNIEnv&);
- jni::Object<MapRendererRunnable> getPeer();
+ // Transfers ownership of the Peer object to the caller
+ jni::UniqueObject<MapRendererRunnable> peer();
private:
- GenericUniqueWeakObject<MapRendererRunnable> javaPeer;
+ jni::UniqueObject<MapRendererRunnable> javaPeer;
std::weak_ptr<Mailbox> mailbox;
};