[wpiutil] Add DataLog and DataLogManager Stop() (#5860)

Restarting a stopped log results in creating a new log file with fresh copies of the same start records and schema data records.

Also check to see if the file has been deleted or if the log file exceeds 1.8 GB, and start a new one.

ntcoreffi/src/main/native/cpp/DataLogManager.cpp

@@ -264,12 +264,18 @@ Thread::~Thread() {
 void Thread::Main() {
   // based on free disk space, scan for "old" FRC_*.wpilog files and remove
   {
-    uintmax_t freeSpace = fs::space(m_logDir).free;
+    std::error_code ec;
+    uintmax_t freeSpace;
+    auto freeSpaceInfo = fs::space(m_logDir, ec);
+    if (!ec) {
+      freeSpace = freeSpaceInfo.available;
+    } else {
+      freeSpace = UINTMAX_MAX;
+    }
     if (freeSpace < kFreeSpaceThreshold) {
       // Delete oldest FRC_*.wpilog files (ignore FRC_TBD_*.wpilog as we just
       // created one)
       std::vector<fs::directory_entry> entries;
-      std::error_code ec;
       for (auto&& entry : fs::directory_iterator{m_logDir, ec}) {
         auto stem = entry.path().stem().string();
         if (wpi::starts_with(stem, "FRC_") &&
@@ -462,6 +468,9 @@ static Instance& GetInstance(std::string_view dir = "",
                              std::string_view filename = "",
                              double period = 0.25) {
   static Instance instance(dir, filename, period);
+  if (!instance.owner) {
+    instance.owner.Start(MakeLogDir(dir), filename, period);
+  }
   return instance;
 }
 
@@ -470,6 +479,12 @@ void DataLogManager::Start(std::string_view dir, std::string_view filename,
   GetInstance(dir, filename, period);
 }
 
+void DataLogManager::Stop() {
+  auto& inst = GetInstance();
+  inst.owner.GetThread()->m_log.Stop();
+  inst.owner.Stop();
+}
+
 void DataLogManager::Log(std::string_view message) {
   GetInstance().owner.GetThread()->m_messageLog.Append(message);
   fmt::print("{}\n", message);
@@ -503,6 +518,10 @@ void DLM_Start(const char* dir, const char* filename, double period) {
   DataLogManager::Start(dir, filename, period);
 }
 
+void DLM_Stop(void) {
+  DataLogManager::Stop();
+}
+
 void DLM_Log(const char* message) {
   DataLogManager::Log(message);
 }

ntcoreffi/src/main/native/include/DataLogManager.h

@@ -52,6 +52,11 @@ class DataLogManager final {
   static void Start(std::string_view dir = "", std::string_view filename = "",
                     double period = 0.25);
 
+  /**
+   * Stop data log manager.
+   */
+  static void Stop();
+
   /**
    * Log a message to the "messages" entry. The message is also printed to
    * standard output (followed by a newline).
@@ -110,6 +115,11 @@ struct WPI_DataLog;
  */
 void DLM_Start(const char* dir, const char* filename, double period);
 
+/**
+ * Stop data log manager.
+ */
+void DLM_Stop(void);
+
 /**
  * Log a message to the "messages" entry. The message is also printed to
  * standard output (followed by a newline).

ntcoreffi/src/main/native/symbols.txt

@@ -4,6 +4,7 @@ DLM_Log
 DLM_LogNetworkTables
 DLM_SignalNewDSDataOccur
 DLM_Start
+DLM_Stop
 NT_AddListener
 NT_AddListenerMultiple
 NT_AddListenerSingle
@@ -245,6 +246,7 @@ WPI_DataLog_Resume
 WPI_DataLog_SetFilename
 WPI_DataLog_SetMetadata
 WPI_DataLog_Start
+WPI_DataLog_Stop
 WPI_DestroyEvent
 WPI_DestroySemaphore
 WPI_DestroySignalObject

wpilibc/src/main/native/cpp/DataLogManager.cpp

@@ -111,12 +111,18 @@ Thread::~Thread() {
 void Thread::Main() {
   // based on free disk space, scan for "old" FRC_*.wpilog files and remove
   {
-    uintmax_t freeSpace = fs::space(m_logDir).available;
+    std::error_code ec;
+    uintmax_t freeSpace;
+    auto freeSpaceInfo = fs::space(m_logDir, ec);
+    if (!ec) {
+      freeSpace = freeSpaceInfo.available;
+    } else {
+      freeSpace = UINTMAX_MAX;
+    }
     if (freeSpace < kFreeSpaceThreshold) {
       // Delete oldest FRC_*.wpilog files (ignore FRC_TBD_*.wpilog as we just
       // created one)
       std::vector<fs::directory_entry> entries;
-      std::error_code ec;
       for (auto&& entry : fs::directory_iterator{m_logDir, ec}) {
         auto stem = entry.path().stem().string();
         if (wpi::starts_with(stem, "FRC_") &&
@@ -308,6 +314,9 @@ static Instance& GetInstance(std::string_view dir = "",
                              std::string_view filename = "",
                              double period = 0.25) {
   static Instance instance(dir, filename, period);
+  if (!instance.owner) {
+    instance.owner.Start(MakeLogDir(dir), filename, period);
+  }
   return instance;
 }
 
@@ -316,6 +325,12 @@ void DataLogManager::Start(std::string_view dir, std::string_view filename,
   GetInstance(dir, filename, period);
 }
 
+void DataLogManager::Stop() {
+  auto& inst = GetInstance();
+  inst.owner.GetThread()->m_log.Stop();
+  inst.owner.Stop();
+}
+
 void DataLogManager::Log(std::string_view message) {
   GetInstance().owner.GetThread()->m_messageLog.Append(message);
   fmt::print("{}\n", message);

wpilibc/src/main/native/include/frc/DataLogManager.h

@@ -49,6 +49,11 @@ class DataLogManager final {
   static void Start(std::string_view dir = "", std::string_view filename = "",
                     double period = 0.25);
 
+  /**
+   * Stop data log manager.
+   */
+  static void Stop();
+
   /**
    * Log a message to the "messages" entry. The message is also printed to
    * standard output (followed by a newline).

wpilibj/src/main/java/edu/wpi/first/wpilibj/DataLogManager.java

@@ -41,9 +41,10 @@
  */
 public final class DataLogManager {
   private static DataLog m_log;
+  private static boolean m_stopped;
   private static String m_logDir;
   private static boolean m_filenameOverride;
-  private static final Thread m_thread;
+  private static Thread m_thread;
   private static final ZoneId m_utc = ZoneId.of("UTC");
   private static final DateTimeFormatter m_timeFormatter =
       DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss").withZone(m_utc);
@@ -59,11 +60,6 @@ public final class DataLogManager {
 
   private DataLogManager() {}
 
-  static {
-    m_thread = new Thread(DataLogManager::logMain, "DataLogDS");
-    m_thread.setDaemon(true);
-  }
-
   /** Start data log manager with default directory location. */
   public static synchronized void start() {
     start("", "", 0.25);
@@ -100,33 +96,52 @@ public static synchronized void start(String dir, String filename) {
    *     tradeoff
    */
   public static synchronized void start(String dir, String filename, double period) {
-    if (m_log != null) {
-      return;
-    }
-    m_logDir = makeLogDir(dir);
-    m_filenameOverride = !filename.isEmpty();
+    if (m_log == null) {
+      m_logDir = makeLogDir(dir);
+      m_filenameOverride = !filename.isEmpty();
 
-    // Delete all previously existing FRC_TBD_*.wpilog files. These only exist when the robot
-    // never connects to the DS, so they are very unlikely to have useful data and just clutter
-    // the filesystem.
-    File[] files =
-        new File(m_logDir)
-            .listFiles((d, name) -> name.startsWith("FRC_TBD_") && name.endsWith(".wpilog"));
-    if (files != null) {
-      for (File file : files) {
-        if (!file.delete()) {
-          System.err.println("DataLogManager: could not delete " + file);
+      // Delete all previously existing FRC_TBD_*.wpilog files. These only exist when the robot
+      // never connects to the DS, so they are very unlikely to have useful data and just clutter
+      // the filesystem.
+      File[] files =
+          new File(m_logDir)
+              .listFiles((d, name) -> name.startsWith("FRC_TBD_") && name.endsWith(".wpilog"));
+      if (files != null) {
+        for (File file : files) {
+          if (!file.delete()) {
+            System.err.println("DataLogManager: could not delete " + file);
+          }
         }
       }
+      m_log = new DataLog(m_logDir, makeLogFilename(filename), period);
+      m_messageLog = new StringLogEntry(m_log, "messages");
+
+      // Log all NT entries and connections
+      if (m_ntLoggerEnabled) {
+        startNtLog();
+      }
+    } else if (m_stopped) {
+      m_log.setFilename(makeLogFilename(filename));
+      m_log.resume();
+      m_stopped = false;
     }
 
-    m_log = new DataLog(m_logDir, makeLogFilename(filename), period);
-    m_messageLog = new StringLogEntry(m_log, "messages");
-    m_thread.start();
+    if (m_thread == null) {
+      m_thread = new Thread(DataLogManager::logMain, "DataLogDS");
+      m_thread.setDaemon(true);
+      m_thread.start();
+    }
+  }
 
-    // Log all NT entries and connections
-    if (m_ntLoggerEnabled) {
-      startNtLog();
+  /** Stop data log manager. */
+  public static synchronized void stop() {
+    if (m_thread != null) {
+      m_thread.interrupt();
+      m_thread = null;
+    }
+    if (m_log != null) {
+      m_log.stop();
+      m_stopped = true;
     }
   }
 

wpiutil/src/main/java/edu/wpi/first/util/datalog/DataLog.java

@@ -106,11 +106,20 @@ public void pause() {
     DataLogJNI.pause(m_impl);
   }
 
-  /** Resumes appending of data records to the log. */
+  /**
+   * Resumes appending of data records to the log. If called after stop(), opens a new file (with
+   * random name if SetFilename was not called after stop()) and appends Start records and schema
+   * data values for all previously started entries and schemas.
+   */
   public void resume() {
     DataLogJNI.resume(m_impl);
   }
 
+  /** Stops appending all records to the log, and closes the log file. */
+  public void stop() {
+    DataLogJNI.stop(m_impl);
+  }
+
   /**
    * Returns whether there is a data schema already registered with the given name.
    *

wpiutil/src/main/java/edu/wpi/first/util/datalog/DataLogJNI.java

@@ -18,6 +18,8 @@ public class DataLogJNI extends WPIUtilJNI {
 
   static native void resume(long impl);
 
+  static native void stop(long impl);
+
   static native void addSchema(long impl, String name, String type, byte[] schema, long timestamp);
 
   static native void addSchemaString(