[hal] Add method to detect if the CAN Stream has overflowed (#6105)

hal/src/main/java/edu/wpi/first/hal/can/CANJNI.java

@@ -31,5 +31,6 @@ public class CANJNI extends JNIWrapper {
   public static native void closeCANStreamSession(int sessionHandle);
 
   public static native int readCANStreamSession(
-      int sessionHandle, CANStreamMessage[] messages, int messagesToRead);
+      int sessionHandle, CANStreamMessage[] messages, int messagesToRead)
+      throws CANStreamOverflowException;
 }

hal/src/main/java/edu/wpi/first/hal/can/CANStreamOverflowException.java

@@ -0,0 +1,35 @@
+// 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.hal.can;
+
+import edu.wpi.first.hal.CANStreamMessage;
+import java.io.IOException;
+
+public class CANStreamOverflowException extends IOException {
+  private final CANStreamMessage[] m_messages;
+  private final int m_messagesRead;
+
+  /**
+   * Constructs a new CANStreamOverflowException.
+   *
+   * @param messages The messages
+   * @param messagesRead The length of messages read
+   */
+  @SuppressWarnings("PMD.ArrayIsStoredDirectly")
+  public CANStreamOverflowException(CANStreamMessage[] messages, int messagesRead) {
+    super("A CAN Stream has overflowed. Data will be missed");
+    this.m_messages = messages;
+    this.m_messagesRead = messagesRead;
+  }
+
+  @SuppressWarnings("PMD.MethodReturnsInternalArray")
+  public CANStreamMessage[] getMessages() {
+    return m_messages;
+  }
+
+  public int getMessagesRead() {
+    return m_messagesRead;
+  }
+}

hal/src/main/native/cpp/jni/CANJNI.cpp

@@ -151,7 +151,8 @@ Java_edu_wpi_first_hal_can_CANJNI_readCANStreamSession
     return 0;
   }
 
-  if (!CheckStatus(env, status)) {
+  if (status != HAL_ERR_CANSessionMux_SessionOverrun &&
+      !CheckStatus(env, status)) {
     return 0;
   }
 
@@ -181,6 +182,12 @@ Java_edu_wpi_first_hal_can_CANJNI_readCANStreamSession
                             reinterpret_cast<jbyte*>(msg->data));
   }
 
+  if (status == HAL_ERR_CANSessionMux_SessionOverrun) {
+    ThrowCANStreamOverflowException(env, messages,
+                                    static_cast<jint>(messagesRead));
+    return 0;
+  }
+
   return static_cast<jint>(messagesRead);
 }
 

hal/src/main/native/cpp/jni/HALUtil.cpp

@@ -56,6 +56,7 @@ static JClass canStreamMessageCls;
 static JClass halValueCls;
 static JClass baseStoreCls;
 static JClass revPHVersionCls;
+static JClass canStreamOverflowExCls;
 
 static const JClassInit classes[] = {
     {"edu/wpi/first/hal/PowerDistributionVersion",
@@ -68,7 +69,9 @@ static const JClassInit classes[] = {
     {"edu/wpi/first/hal/CANStreamMessage", &canStreamMessageCls},
     {"edu/wpi/first/hal/HALValue", &halValueCls},
     {"edu/wpi/first/hal/DMAJNISample$BaseStore", &baseStoreCls},
-    {"edu/wpi/first/hal/REVPHVersion", &revPHVersionCls}};
+    {"edu/wpi/first/hal/REVPHVersion", &revPHVersionCls},
+    {"edu/wpi/first/hal/can/CANStreamOverflowException",
+     &canStreamOverflowExCls}};
 
 static const JExceptionInit exceptions[] = {
     {"java/lang/IllegalArgumentException", &illegalArgExCls},
@@ -209,6 +212,16 @@ void ReportCANError(JNIEnv* env, int32_t status, int message_id) {
   }
 }
 
+void ThrowCANStreamOverflowException(JNIEnv* env, jobjectArray messages,
+                                     jint length) {
+  static jmethodID constructor =
+      env->GetMethodID(canStreamOverflowExCls, "<init>",
+                       "([Ledu/wpi/first/hal/CANStreamMessage;I)V");
+  jobject exception =
+      env->NewObject(canStreamOverflowExCls, constructor, messages, length);
+  env->Throw(static_cast<jthrowable>(exception));
+}
+
 void ThrowIllegalArgumentException(JNIEnv* env, std::string_view msg) {
   illegalArgExCls.Throw(env, msg);
 }

hal/src/main/native/cpp/jni/HALUtil.h

@@ -51,6 +51,8 @@ inline bool CheckCANStatus(JNIEnv* env, int32_t status, int32_t message_id) {
   return status == 0;
 }
 
+void ThrowCANStreamOverflowException(JNIEnv* env, jobjectArray messages,
+                                     jint length);
 void ThrowIllegalArgumentException(JNIEnv* env, std::string_view msg);
 void ThrowBoundaryException(JNIEnv* env, double value, double lower,
                             double upper);