Add external logger interface.

include/cscore_c.h

@@ -54,6 +54,21 @@ enum CS_StatusValue {
   CS_SOURCE_IS_DISCONNECTED = -2005
 };
 
+//
+// Logging levels
+//
+enum CS_LogLevel {
+  CS_LOG_CRITICAL = 50,
+  CS_LOG_ERROR = 40,
+  CS_LOG_WARNING = 30,
+  CS_LOG_INFO = 20,
+  CS_LOG_DEBUG = 10,
+  CS_LOG_DEBUG1 = 9,
+  CS_LOG_DEBUG2 = 8,
+  CS_LOG_DEBUG3 = 7,
+  CS_LOG_DEBUG4 = 6
+};
+
 //
 // Pixel formats
 //
@@ -285,6 +300,13 @@ void CS_RemoveListener(CS_Listener handle, CS_Status* status);
 
 int CS_NotifierDestroyed(void);
 
+//
+// Logging Functions
+//
+typedef void (*CS_LogFunc)(unsigned int level, const char* file,
+                           unsigned int line, const char* msg);
+void CS_SetLogger(CS_LogFunc func, unsigned int min_level);
+
 //
 // Utility Functions
 //

include/cscore_cpp.h

@@ -278,6 +278,14 @@ void RemoveListener(CS_Listener handle, CS_Status* status);
 
 bool NotifierDestroyed();
 
+//
+// Logging Functions
+//
+typedef std::function<void(unsigned int level, const char* file,
+                           unsigned int line, const char* msg)>
+    LogFunc;
+void SetLogger(LogFunc func, unsigned int min_level);
+
 //
 // Utility Functions
 //

java/lib/CameraServerJNI.cpp

@@ -1154,3 +1154,67 @@ JNIEXPORT jobjectArray JNICALL Java_edu_wpi_cscore_CameraServerJNI_getNetworkInt
 }
 
 }  // extern "C"
+
+namespace {
+
+struct LogMessage {
+ public:
+  LogMessage(unsigned int level, const char *file, unsigned int line,
+             const char *msg)
+      : m_level(level), m_file(file), m_line(line), m_msg(msg) {}
+
+  void CallJava(JNIEnv* env, jobject func, jmethodID mid) {
+    JLocal<jstring> file{env, MakeJString(env, m_file)};
+    JLocal<jstring> msg{env, MakeJString(env, m_msg)};
+    env->CallVoidMethod(func, mid, (jint)m_level, file.obj(),
+                        (jint)m_line, msg.obj());
+  }
+
+  static const char* GetName() { return "NTLogger"; }
+  static JavaVM* GetJVM() { return jvm; }
+
+ private:
+  unsigned int m_level;
+  const char* m_file;
+  unsigned int m_line;
+  std::string m_msg;
+};
+
+typedef JSingletonCallbackManager<LogMessage> LoggerJNI;
+
+}  // anonymous namespace
+
+ATOMIC_STATIC_INIT(LoggerJNI)
+
+extern "C" {
+
+/*
+ * Class:     edu_wpi_cscore_CameraServerJNI
+ * Method:    setLogger
+ * Signature: (Ledu/wpi/cscore/CameraServerJNI/LoggerFunction;I)V
+ */
+JNIEXPORT void JNICALL Java_edu_wpi_cscore_CameraServerJNI_setLogger
+  (JNIEnv *env, jclass, jobject func, jint minLevel)
+{
+  // cls is a temporary here; cannot be used within callback functor
+  jclass cls = env->GetObjectClass(func);
+  if (!cls) return;
+
+  // method ids, on the other hand, are safe to retain
+  jmethodID mid = env->GetMethodID(
+      cls, "apply", "(ILjava/lang/String;ILjava/lang/String;)V");
+  if (!mid) return;
+
+  auto& logger = LoggerJNI::GetInstance();
+  logger.Start();
+  logger.SetFunc(env, func, mid);
+
+  cs::SetLogger(
+      [](unsigned int level, const char *file, unsigned int line,
+         const char *msg) {
+        LoggerJNI::GetInstance().Send(level, file, line, msg);
+      },
+      minLevel);
+}
+
+}  // extern "C"

java/src/edu/wpi/cscore/CameraServerJNI.java

@@ -184,6 +184,15 @@ public class CameraServerJNI {
 
   public static native void removeListener(int handle);
 
+  //
+  // Logging Functions
+  //
+  @FunctionalInterface
+  public interface LoggerFunction {
+    void apply(int level, String file, int line, String msg);
+  }
+  public static native void setLogger(LoggerFunction func, int minLevel);
+
   //
   // Utility Functions
   //

src/cscore_c.cpp

@@ -265,6 +265,10 @@ void CS_RemoveListener(CS_Listener handle, CS_Status* status) {
 
 int CS_NotifierDestroyed(void) { return cs::NotifierDestroyed(); }
 
+void CS_SetLogger(CS_LogFunc func, unsigned int min_level) {
+  cs::SetLogger(func, min_level);
+}
+
 CS_Source* CS_EnumerateSources(int* count, CS_Status* status) {
   llvm::SmallVector<CS_Source, 32> buf;
   auto handles = cs::EnumerateSourceHandles(buf, status);

src/cscore_cpp.cpp

@@ -16,6 +16,7 @@
 
 #include "llvm/SmallString.h"
 
+#include "Log.h"
 #include "NetworkListener.h"
 #include "Notifier.h"
 #include "SinkImpl.h"
@@ -511,6 +512,15 @@ void RemoveListener(CS_Listener handle, CS_Status* status) {
 
 bool NotifierDestroyed() { return Notifier::destroyed(); }
 
+//
+// Logging Functions
+//
+void SetLogger(LogFunc func, unsigned int min_level) {
+  Logger& logger = Logger::GetInstance();
+  logger.SetLogger(func);
+  logger.set_min_level(min_level);
+}
+
 //
 // Utility Functions
 //