From: Matt Corallo <git@bluematt.me>
Date: Thu, 3 Mar 2022 02:32:15 +0000 (+0000)
Subject: [Java] Add a reachabilityFence on underlying trait impl calls
X-Git-Tag: v0.0.105.0~1^2~6
X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=ldk-java;a=commitdiff_plain;h=1f873e8aeb7a8395a7a99d244fba7474a0543278

[Java] Add a reachabilityFence on underlying trait impl calls

Because the implementation instance is implicitly held as a
reference in the `held` field, it seems unlikely this could ever
matter, hwoever, in the simplified implementation in `PeerTest`
(where there is no Human instance to hold a reference to the
underlying bindings instance), we do see the implementation being
free'd while its still in use. Thus, to ensure we can't hit any
such issue in the future, we add one in normal human objects as
well.
---

diff --git a/java_strings.py b/java_strings.py
index cc1a3617..3a8ba6cb 100644
--- a/java_strings.py
+++ b/java_strings.py
@@ -882,7 +882,8 @@ import javax.annotation.Nullable;
                     else:
                         java_trait_constr = java_trait_constr + arg_info.arg_name
 
-                java_trait_constr = java_trait_constr + ");\n"
+                java_trait_constr += ");\n"
+                java_trait_constr += "\t\t\t\tReference.reachabilityFence(arg);\n"
                 if fn_line.ret_ty_info.java_ty != "void":
                     if fn_line.ret_ty_info.from_hu_conv is not None:
                         java_trait_constr = java_trait_constr + "\t\t\t\t" + fn_line.ret_ty_info.java_ty + " result = " + fn_line.ret_ty_info.from_hu_conv[0] + ";\n"
diff --git a/src/test/java/org/ldk/PeerTest.java b/src/test/java/org/ldk/PeerTest.java
index 7dc3f1a3..9b3d2f17 100644
--- a/src/test/java/org/ldk/PeerTest.java
+++ b/src/test/java/org/ldk/PeerTest.java
@@ -7,6 +7,7 @@ import org.ldk.enums.Network;
 import org.ldk.enums.Recipient;
 import org.ldk.impl.bindings;
 
+import java.lang.ref.Reference;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -234,7 +235,8 @@ public class PeerTest {
         deliver_peer_messages(list, peer1.peer_manager, peer2.peer_manager);
 
         ArrayList<Long> events = new ArrayList();
-        long handler = bindings.LDKEventHandler_new(events::add);
+        bindings.LDKEventHandler events_adder = events::add;
+        long handler = bindings.LDKEventHandler_new(events_adder);
 
         bindings.EventsProvider_process_pending_events(peer1.chan_manager_events, handler);
         assert events.size() == 1;
@@ -336,6 +338,7 @@ public class PeerTest {
         bindings.LDKEvent sent_path = bindings.LDKEvent_ref_from_ptr(events.get(0));
         assert sent_path instanceof bindings.LDKEvent.PaymentPathSuccessful;
         bindings.Event_free(events.remove(0));
+        Reference.reachabilityFence(events_adder);
 
         bindings.EventHandler_free(handler);