feat: rework memory allocation to throw when pointers are invalid, fix pointers yielded to java, add pattern for yielding stable pointers to data not owned by Runtime

src/main/java/dev.toad/RefHawk.java

@@ -0,0 +1,89 @@
+package dev.toad;
+
+import java.lang.ref.Cleaner;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * Static class used to track pointers issued by rust code
+ *
+ * When an object instance containing a pointer tracked by RefHawk
+ * is not automatically freed before `RefHawk.ensureReleased` invoked,
+ * an error is thrown indicating incorrect usage of an object containing
+ * a native pointer.
+ */
+public class RefHawk {
+
+  private static final HashSet<Long> addrs = new HashSet<>();
+
+  private RefHawk() {}
+
+  public static class IllegalStorageOfRefError extends Error {
+
+    private static final String fmt =
+      "Instance of %s may not be stored by user code.\n" +
+      "Object was registered by:\n" +
+      ">>>>>>\n" +
+      "%s\n" +
+      "<<<<<<\n";
+
+    IllegalStorageOfRefError(Ptr ptr) {
+      super(String.format(fmt, ptr.clazz, ptr.trace));
+    }
+  }
+
+  public static class Ptr {
+
+    protected final long addr;
+    private final String clazz;
+    private final String trace;
+
+    Ptr(long addr, String clazz, String trace) {
+      this.clazz = clazz;
+      this.addr = addr;
+      this.trace = trace;
+    }
+
+    public long addr() {
+      RefHawk.ensureValid(this);
+      return this.addr;
+    }
+  }
+
+  /**
+   * Associate an object with a raw `long` pointer and a short text
+   * describing the scope in which the object is intended to be valid for
+   * (e.g. "lambda")
+   */
+  public static Ptr register(Class c, long addr) {
+    var trace = Thread.currentThread().getStackTrace();
+    var traceStr = Arrays
+      .asList(trace)
+      .stream()
+      .skip(2)
+      .map(StackTraceElement::toString)
+      .reduce("", (s, tr) -> s == "" ? tr : s + "\n\t" + tr);
+
+    RefHawk.addrs.add(addr);
+    return new Ptr(addr, c.toString(), traceStr);
+  }
+
+  /**
+   * Invokes the cleaning action on the object associated with an address
+   */
+  public static void release(Ptr ptr) {
+    RefHawk.addrs.remove(ptr.addr);
+  }
+
+  /**
+   * Throw `IllegalStorageOfRefError` if object has been leaked
+   * outside of its appropriate context.
+   */
+  public static void ensureValid(Ptr ptr) {
+    if (!RefHawk.addrs.contains(ptr.addr)) {
+      throw new IllegalStorageOfRefError(ptr);
+    }
+  }
+}

src/main/java/dev.toad/msg/MessageOptionRef.java

@@ -1,17 +1,19 @@
 package dev.toad.msg;
 
+import dev.toad.RefHawk;
+import dev.toad.RefHawk.Ptr;
 import java.util.Arrays;
 import java.util.List;
 
-public class MessageOptionRef implements MessageOption {
+public class MessageOptionRef implements MessageOption, AutoCloseable {
 
-  private final long addr;
+  private Ptr ptr;
   private final long number;
 
-  private native MessageOptionValueRef[] values(long addr);
+  private native MessageOptionValueRef[] values(long ptr);
 
   public MessageOptionRef(long addr, long number) {
-    this.addr = addr;
+    this.ptr = RefHawk.register(this.getClass(), addr);
     this.number = number;
   }
 
@@ -20,14 +22,19 @@ public class MessageOptionRef implements MessageOption {
   }
 
   public MessageOptionValueRef[] valueRefs() {
-    return this.values(this.addr);
+    return this.values(this.ptr.addr());
   }
 
   public List<MessageOptionValue> values() {
-    return Arrays.asList(this.values(this.addr));
+    return Arrays.asList(this.values(this.ptr.addr()));
   }
 
   public MessageOption clone() {
     return new MessageOptionOwned(this);
   }
+
+  @Override
+  public void close() {
+    RefHawk.release(this.ptr);
+  }
 }

src/main/java/dev.toad/msg/MessageOptionValueRef.java

@@ -1,24 +1,33 @@
 package dev.toad.msg;
 
-public class MessageOptionValueRef implements MessageOptionValue {
+import dev.toad.RefHawk;
+import dev.toad.RefHawk.Ptr;
 
-  private final long addr;
+public class MessageOptionValueRef
+  implements MessageOptionValue, AutoCloseable {
+
+  private final Ptr ptr;
 
   private native byte[] bytes(long addr);
 
   public MessageOptionValueRef(long addr) {
-    this.addr = addr;
+    this.ptr = RefHawk.register(this.getClass(), addr);
   }
 
   public byte[] asBytes() {
-    return this.bytes(this.addr);
+    return this.bytes(this.ptr.addr());
   }
 
   public String asString() {
-    return new String(this.bytes(this.addr));
+    return new String(this.bytes(this.ptr.addr()));
   }
 
   public MessageOptionValue clone() {
     return this;
   }
+
+  @Override
+  public void close() {
+    RefHawk.release(this.ptr);
+  }
 }

src/main/java/dev.toad/msg/MessageRef.java

@@ -1,5 +1,7 @@
 package dev.toad.msg;
 
+import dev.toad.RefHawk;
+import dev.toad.RefHawk.Ptr;
 import java.util.Arrays;
 import java.util.List;
 
@@ -10,9 +12,9 @@ import java.util.List;
  * control is yielded back to the rust runtime, meaning instances of
  * MessageRef should never be stored in state; invoke `.clone()` first.
  */
-public class MessageRef implements Message {
+public class MessageRef implements Message, AutoCloseable {
 
-  private final long addr;
+  private Ptr ptr;
 
   private static native int id(long addr);
 
@@ -27,7 +29,7 @@ public class MessageRef implements Message {
   private static native MessageOptionRef[] opts(long addr);
 
   public MessageRef(long addr) {
-    this.addr = addr;
+    this.ptr = RefHawk.register(this.getClass(), addr);
   }
 
   public Message clone() {
@@ -35,34 +37,39 @@ public class MessageRef implements Message {
   }
 
   public int id() {
-    return this.id(this.addr);
+    return this.id(this.ptr.addr());
   }
 
   public byte[] token() {
-    return this.token(this.addr);
+    return this.token(this.ptr.addr());
   }
 
   public MessageCode code() {
-    return this.code(this.addr);
+    return this.code(this.ptr.addr());
   }
 
   public MessageType type() {
-    return this.type(this.addr);
+    return this.type(this.ptr.addr());
   }
 
   public MessageOptionRef[] optionRefs() {
-    return this.opts(this.addr);
+    return this.opts(this.ptr.addr());
   }
 
   public List<MessageOption> options() {
-    return Arrays.asList(this.opts(this.addr));
+    return Arrays.asList(this.opts(this.ptr.addr()));
   }
 
   public byte[] payloadBytes() {
-    return this.payload(this.addr);
+    return this.payload(this.ptr.addr());
   }
 
   public String payloadString() {
-    return new String(this.payload(this.addr));
+    return new String(this.payload(this.ptr.addr()));
+  }
+
+  @Override
+  public void close() {
+    RefHawk.release(this.ptr);
   }
 }