[epilogue] Fix lazy logging of mutable arrays (#7665)

epilogue-runtime/src/test/java/edu/wpi/first/epilogue/logging/CustomStruct.java

@@ -0,0 +1,45 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.epilogue.logging;
+
+import edu.wpi.first.util.struct.Struct;
+import edu.wpi.first.util.struct.StructSerializable;
+import java.nio.ByteBuffer;
+
+public record CustomStruct(int x) implements StructSerializable {
+  public static final Serializer struct = new Serializer();
+
+  public static final class Serializer implements Struct<CustomStruct> {
+    @Override
+    public Class<CustomStruct> getTypeClass() {
+      return CustomStruct.class;
+    }
+
+    @Override
+    public String getTypeName() {
+      return "CustomStruct";
+    }
+
+    @Override
+    public int getSize() {
+      return kSizeInt32;
+    }
+
+    @Override
+    public String getSchema() {
+      return "int32 x;";
+    }
+
+    @Override
+    public CustomStruct unpack(ByteBuffer bb) {
+      return new CustomStruct(bb.getInt());
+    }
+
+    @Override
+    public void pack(ByteBuffer bb, CustomStruct value) {
+      bb.putInt(value.x);
+    }
+  }
+}

epilogue-runtime/src/test/java/edu/wpi/first/epilogue/logging/LazyBackendTest.java

@@ -4,6 +4,7 @@
 
 package edu.wpi.first.epilogue.logging;
 
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertSame;
 
@@ -53,4 +54,135 @@ class LazyBackendTest {
           backend.getEntries());
     }
   }
+
+  @Test
+  void inPlaceByteArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    byte[] arr = new byte[] {0};
+    lazy.log("arr", arr);
+
+    arr[0] = 1;
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new byte[] {0}, (byte[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new byte[] {1}, (byte[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceIntArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    int[] arr = new int[] {0};
+    lazy.log("arr", arr);
+
+    arr[0] = 1;
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new int[] {0}, (int[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new int[] {1}, (int[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceLongArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    long[] arr = new long[] {0};
+    lazy.log("arr", arr);
+
+    arr[0] = 1;
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new long[] {0}, (long[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new long[] {1}, (long[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceFloatArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    float[] arr = new float[] {0};
+    lazy.log("arr", arr);
+
+    arr[0] = 1;
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new float[] {0}, (float[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new float[] {1}, (float[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceDoubleArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    double[] arr = new double[] {0};
+    lazy.log("arr", arr);
+
+    arr[0] = 1;
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new double[] {0}, (double[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new double[] {1}, (double[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceBooleanArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    boolean[] arr = new boolean[] {false};
+    lazy.log("arr", arr);
+
+    arr[0] = true;
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new boolean[] {false}, (boolean[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new boolean[] {true}, (boolean[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceStringArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    String[] arr = new String[] {"0"};
+    lazy.log("arr", arr);
+
+    arr[0] = "1";
+    lazy.log("arr", arr);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(new String[] {"0"}, (String[]) backend.getEntries().get(0).value());
+    assertArrayEquals(new String[] {"1"}, (String[]) backend.getEntries().get(1).value());
+  }
+
+  @Test
+  void inPlaceStructArray() {
+    var backend = new TestBackend();
+    var lazy = new LazyBackend(backend);
+
+    CustomStruct[] arr = new CustomStruct[] {new CustomStruct(0)};
+
+    lazy.log("arr", arr, CustomStruct.struct);
+
+    arr[0] = new CustomStruct(1);
+    lazy.log("arr", arr, CustomStruct.struct);
+
+    assertEquals(2, backend.getEntries().size());
+    assertArrayEquals(
+        new byte[] {0x00, 0x00, 0x00, 0x00}, (byte[]) backend.getEntries().get(0).value());
+    assertArrayEquals(
+        new byte[] {0x01, 0x00, 0x00, 0x00}, (byte[]) backend.getEntries().get(1).value());
+  }
 }

epilogue-runtime/src/test/java/edu/wpi/first/epilogue/logging/TestBackend.java

@@ -55,32 +55,32 @@ public class TestBackend implements EpilogueBackend {
 
   @Override
   public void log(String identifier, byte[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
   public void log(String identifier, int[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
   public void log(String identifier, long[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
   public void log(String identifier, float[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
   public void log(String identifier, double[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
   public void log(String identifier, boolean[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
@@ -90,19 +90,27 @@ public class TestBackend implements EpilogueBackend {
 
   @Override
   public void log(String identifier, String[] value) {
-    m_entries.add(new LogEntry<>(identifier, value));
+    m_entries.add(new LogEntry<>(identifier, value.clone()));
   }
 
   @Override
   public <S> void log(String identifier, S value, Struct<S> struct) {
-    var serialized = StructBuffer.create(struct).write(value).array();
+    var buffer = StructBuffer.create(struct).write(value).position(0);
+    var serialized = new byte[buffer.capacity()];
+    for (int i = 0; i < buffer.capacity(); i++) {
+      serialized[i] = buffer.get();
+    }
 
     m_entries.add(new LogEntry<>(identifier, serialized));
   }
 
   @Override
   public <S> void log(String identifier, S[] value, Struct<S> struct) {
-    var serialized = StructBuffer.create(struct).writeArray(value).array();
+    var buffer = StructBuffer.create(struct).writeArray(value).position(0);
+    var serialized = new byte[buffer.capacity()];
+    for (int i = 0; i < buffer.capacity(); i++) {
+      serialized[i] = buffer.get();
+    }
 
     m_entries.add(new LogEntry<>(identifier, serialized));
   }