add a keepAlive example

modules/clients/build.gradle

@@ -145,3 +145,15 @@ tasks.register('runClose', JavaExec) {
     systemProperty 'org.slf4j.simpleLogger.showShortLogName', 'true'
     systemProperty 'org.slf4j.simpleLogger.levelInBrackets', 'true'
 }
+
+tasks.register('runKeepAlive', JavaExec) {
+    classpath = sourceSets.main.runtimeClasspath
+    mainClass = 'com.tsurugidb.tsubakuro.examples.keepAlive.Main'
+
+    systemProperty 'tsurugi.dbname', findProperty('tsurugi.dbname') ?: 'ipc:tsurugi'
+
+    systemProperty 'org.slf4j.simpleLogger.defaultLogLevel', findProperty('loglevel') ?: 'info'
+    systemProperty 'org.slf4j.simpleLogger.showThreadName', 'false'
+    systemProperty 'org.slf4j.simpleLogger.showShortLogName', 'true'
+    systemProperty 'org.slf4j.simpleLogger.levelInBrackets', 'true'
+}

modules/clients/src/main/java/com/tsurugidb/tsubakuro/examples/keepAlive/Main.java

@@ -0,0 +1,90 @@
+package com.tsurugidb.tsubakuro.examples.keepAlive;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.CommandLineParser;
+import org.apache.commons.cli.DefaultParser;
+import org.apache.commons.cli.Option;
+import org.apache.commons.cli.Options;
+import org.apache.commons.cli.ParseException;
+
+import com.tsurugidb.tsubakuro.common.Session;
+import com.tsurugidb.tsubakuro.common.SessionBuilder;
+import com.tsurugidb.tsubakuro.exception.ServerException;
+import com.tsurugidb.tsubakuro.channel.common.connection.UsernamePasswordCredential;
+
+public final class Main {
+    private Main(String[] args) {
+    }
+
+    // set dbname as follows
+    // -Ptsurugi.dbname=ipc:tsurugi or
+    // -Ptsurugi.dbname=tcp://localhost:12345
+    // when run this example by `./gradlew run` command
+    private static String url = System.getProperty("tsurugi.dbname");
+
+    private static boolean keepAlive = true;
+    private static long interval = 1000;
+    private static long loopCount = 200;
+    private static long timeout = 0;
+
+    public static void main(String[] args) {
+        // コマンドラインオプションの設定
+        Options options = new Options();
+
+        options.addOption(Option.builder("n").argName("noKeepAlive").desc("No keep alive.").build());
+        options.addOption(Option.builder("l").argName("loopCount").hasArg().desc("Loop count.").build());
+        options.addOption(Option.builder("t").argName("timeout").hasArg().desc("Timeout.").build());
+
+        CommandLineParser parser = new DefaultParser();
+        CommandLine cmd = null;
+
+        try {
+            cmd = parser.parse(options, args);
+
+            if (cmd.hasOption("n")) {
+                keepAlive = false;
+                System.err.println("no keep alive");
+            }
+            if (cmd.hasOption("l")) {
+                loopCount = Integer.parseInt(cmd.getOptionValue("l"));
+                System.err.println("loop count = " + loopCount);
+            }
+            if (cmd.hasOption("t")) {
+                timeout = Integer.parseInt(cmd.getOptionValue("t"));
+                System.err.println("timeout = " + timeout);
+            }
+        } catch (ParseException e) {
+            System.err.println("cmd parser failed." + e);
+        }
+
+        try (
+             Session session = SessionBuilder.connect(url)
+             .withCredential(new UsernamePasswordCredential("user", "pass"))
+             .withKeepAlive(keepAlive)
+             .create(10, TimeUnit.SECONDS)) {
+            if (timeout > 0) {
+                session.updateExpirationTime(timeout, TimeUnit.SECONDS);
+            }
+            int n = 0;
+            while (true) {
+                if (!session.isAlive()) {
+                    System.out.println("detect tsurugidb session is not alive.");
+                    break;
+                }
+                if (++n > loopCount) {
+                    System.out.println("reach loop count (" + loopCount + ")");
+                    break;
+                }
+                System.out.println("tsurugidb session is alive, N = " + n);
+                Thread.sleep(interval);
+            }
+        } catch (IOException | ServerException | InterruptedException | TimeoutException e) {
+            System.out.println(e);
+        }
+        System.out.println("exiting.");
+    }
+}