Code cleanup around opensearch process info (#15709)

* Code cleanup around opensearch process info

* Code cleanup

* fixed naming and test

* fixed test

* fixed test

* code cleanup

* code cleanup

data-node/src/main/java/org/graylog/datanode/process/OpensearchInfo.java

@@ -16,6 +16,5 @@
  */
 package org.graylog.datanode.process;
 
-public record ProcessInfo(long pid, String nodeName, ProcessState status, boolean isLeaderNode, java.time.Instant started, java.time.Duration totalCpuDuration, String user,
-                          String restBaseUrl) {
+public record OpensearchInfo(String nodeName, ProcessState state, boolean isLeaderNode, String restBaseUrl, ProcessInformation process) {
 }

data-node/src/main/java/org/graylog/datanode/process/ProcessInformation.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2020 Graylog, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the Server Side Public License, version 1,
+ * as published by MongoDB, Inc.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * Server Side Public License for more details.
+ *
+ * You should have received a copy of the Server Side Public License
+ * along with this program. If not, see
+ * <http://www.mongodb.com/licensing/server-side-public-license>.
+ */
+package org.graylog.datanode.process;
+
+import java.time.Instant;
+
+public record ProcessInformation(long pid, boolean alive, Instant started) {
+
+    public static ProcessInformation empty() {
+        return new ProcessInformation(-1, false, null);
+    }
+
+    public static ProcessInformation create(Process p) {
+        return new ProcessInformation(p.pid(), p.isAlive(), p.info().startInstant().orElse(null));
+    }
+}

data-node/src/main/java/org/graylog/datanode/process/WatchdogWithProcessInfo.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2020 Graylog, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the Server Side Public License, version 1,
+ * as published by MongoDB, Inc.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * Server Side Public License for more details.
+ *
+ * You should have received a copy of the Server Side Public License
+ * along with this program. If not, see
+ * <http://www.mongodb.com/licensing/server-side-public-license>.
+ */
+package org.graylog.datanode.process;
+
+import org.apache.commons.exec.ExecuteWatchdog;
+
+import javax.validation.constraints.NotNull;
+import java.util.Optional;
+
+public class WatchdogWithProcessInfo extends ExecuteWatchdog {
+
+    private Process process;
+
+    public WatchdogWithProcessInfo(long timeout) {
+        super(timeout);
+    }
+
+    @Override
+    public synchronized void start(Process processToMonitor) {
+        super.start(processToMonitor);
+        this.process = processToMonitor;
+    }
+
+    @NotNull
+    public ProcessInformation processInfo() {
+        return Optional.ofNullable(process)
+                .map(ProcessInformation::create)
+                .orElse(ProcessInformation.empty());
+    }
+
+}