Add systemd native access (#106151)

This commit moves systemd access to the NativeAccess lib.

relates #104876

Author: rjernst

libs/native/jna/src/main/java/org/elasticsearch/nativeaccess/jna/JnaNativeLibraryProvider.java

@@ -10,11 +10,12 @@
 
 import org.elasticsearch.nativeaccess.lib.NativeLibraryProvider;
 import org.elasticsearch.nativeaccess.lib.PosixCLibrary;
+import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
 
 import java.util.Map;
 
 public class JnaNativeLibraryProvider extends NativeLibraryProvider {
     public JnaNativeLibraryProvider() {
-        super("jna", Map.of(PosixCLibrary.class, JnaPosixCLibrary::new));
+        super("jna", Map.of(PosixCLibrary.class, JnaPosixCLibrary::new, SystemdLibrary.class, JnaSystemdLibrary::new));
     }
 }

libs/native/jna/src/main/java/org/elasticsearch/nativeaccess/jna/JnaSystemdLibrary.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.nativeaccess.jna;
+
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+
+import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
+
+class JnaSystemdLibrary implements SystemdLibrary {
+    private interface NativeFunctions extends Library {
+        int sd_notify(int unset_environment, String state);
+    }
+
+    private final NativeFunctions functions;
+
+    JnaSystemdLibrary() {
+        this.functions = Native.load("libsystemd.so.0", NativeFunctions.class);
+    }
+
+    @Override
+    public int sd_notify(int unset_environment, String state) {
+        return functions.sd_notify(unset_environment, state);
+    }
+}

libs/native/src/main/java/module-info.java

@@ -14,7 +14,7 @@
     requires org.elasticsearch.base;
     requires org.elasticsearch.logging;
 
-    exports org.elasticsearch.nativeaccess to org.elasticsearch.server;
+    exports org.elasticsearch.nativeaccess to org.elasticsearch.server, org.elasticsearch.systemd;
     // allows jna to implement a library provider, and ProviderLocator to load it
     exports org.elasticsearch.nativeaccess.lib to org.elasticsearch.nativeaccess.jna, org.elasticsearch.base;
 

libs/native/src/main/java/org/elasticsearch/nativeaccess/AbstractNativeAccess.java

@@ -24,4 +24,9 @@ protected AbstractNativeAccess(String name) {
     String getName() {
         return name;
     }
+
+    @Override
+    public Systemd systemd() {
+        return null;
+    }
 }

libs/native/src/main/java/org/elasticsearch/nativeaccess/LinuxNativeAccess.java

@@ -9,9 +9,19 @@
 package org.elasticsearch.nativeaccess;
 
 import org.elasticsearch.nativeaccess.lib.NativeLibraryProvider;
+import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
 
 class LinuxNativeAccess extends PosixNativeAccess {
+
+    Systemd systemd;
+
     LinuxNativeAccess(NativeLibraryProvider libraryProvider) {
         super("Linux", libraryProvider);
+        this.systemd = new Systemd(libraryProvider.getLibrary(SystemdLibrary.class));
+    }
+
+    @Override
+    public Systemd systemd() {
+        return systemd;
     }
 }

libs/native/src/main/java/org/elasticsearch/nativeaccess/NativeAccess.java

@@ -26,4 +26,6 @@ static NativeAccess instance() {
      * @return true if running as root, or false if unsure
      */
     boolean definitelyRunningAsRoot();
+
+    Systemd systemd();
 }

libs/native/src/main/java/org/elasticsearch/nativeaccess/NoopNativeAccess.java

@@ -19,4 +19,10 @@ public boolean definitelyRunningAsRoot() {
         logger.warn("Cannot check if running as root because native access is not available");
         return false;
     }
+
+    @Override
+    public Systemd systemd() {
+        logger.warn("Cannot get systemd access because native access is not available");
+        return null;
+    }
 }

libs/native/src/main/java/org/elasticsearch/nativeaccess/Systemd.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.nativeaccess;
+
+import org.elasticsearch.logging.LogManager;
+import org.elasticsearch.logging.Logger;
+import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
+
+import java.util.Locale;
+
+public class Systemd {
+    private static final Logger logger = LogManager.getLogger(Systemd.class);
+
+    private final SystemdLibrary lib;
+
+    Systemd(SystemdLibrary lib) {
+        this.lib = lib;
+    }
+
+    /**
+     * Notify systemd that the process is ready.
+     *
+     * @throws RuntimeException on failure to notify systemd
+     */
+    public void notify_ready() {
+        notify("READY=1", false);
+    }
+
+    public void notify_extend_timeout(long seconds) {
+        notify("EXTEND_TIMEOUT_USEC=" + (seconds * 1000000), true);
+    }
+
+    public void notify_stopping() {
+        notify("STOPPING=1", true);
+    }
+
+    private void notify(String state, boolean warnOnError) {
+        int rc = lib.sd_notify(0, state);
+        logger.trace("sd_notify({}, {}) returned [{}]", 0, state, rc);
+        if (rc < 0) {
+            String message = String.format(Locale.ROOT, "sd_notify(%d, %s) returned error [%d]", 0, state, rc);
+            if (warnOnError) {
+                logger.warn(message);
+            } else {
+                throw new RuntimeException(message);
+            }
+        }
+    }
+}

libs/native/src/main/java/org/elasticsearch/nativeaccess/lib/NativeLibrary.java

@@ -9,4 +9,4 @@
 package org.elasticsearch.nativeaccess.lib;
 
 /** A marker interface for libraries that can be loaded by {@link org.elasticsearch.nativeaccess.lib.NativeLibraryProvider} */
-public sealed interface NativeLibrary permits PosixCLibrary {}
+public sealed interface NativeLibrary permits PosixCLibrary, SystemdLibrary {}

libs/native/src/main/java/org/elasticsearch/nativeaccess/lib/SystemdLibrary.java

@@ -0,0 +1,13 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.nativeaccess.lib;
+
+public non-sealed interface SystemdLibrary extends NativeLibrary {
+    int sd_notify(int unset_environment, String state);
+}

libs/native/src/main21/java/org/elasticsearch/nativeaccess/jdk/JdkNativeLibraryProvider.java

@@ -10,12 +10,13 @@
 
 import org.elasticsearch.nativeaccess.lib.NativeLibraryProvider;
 import org.elasticsearch.nativeaccess.lib.PosixCLibrary;
+import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
 
 import java.util.Map;
 
 public class JdkNativeLibraryProvider extends NativeLibraryProvider {
 
     public JdkNativeLibraryProvider() {
-        super("jdk", Map.of(PosixCLibrary.class, JdkPosixCLibrary::new));
+        super("jdk", Map.of(PosixCLibrary.class, JdkPosixCLibrary::new, SystemdLibrary.class, JdkSystemdLibrary::new));
     }
 }

libs/native/src/main21/java/org/elasticsearch/nativeaccess/jdk/JdkSystemdLibrary.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.nativeaccess.jdk;
+
+import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.lang.foreign.Arena;
+import java.lang.foreign.FunctionDescriptor;
+import java.lang.foreign.MemorySegment;
+import java.lang.invoke.MethodHandle;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import static java.lang.foreign.ValueLayout.ADDRESS;
+import static java.lang.foreign.ValueLayout.JAVA_INT;
+import static org.elasticsearch.nativeaccess.jdk.LinkerHelper.downcallHandle;
+
+class JdkSystemdLibrary implements SystemdLibrary {
+    static {
+        System.load(findLibSystemd());
+    }
+
+    // On some systems libsystemd does not have a non-versioned symlink. System.loadLibrary only knows how to find
+    // non-versioned library files. So we must manually check the library path to find what we need.
+    static String findLibSystemd() {
+        final String libsystemd = "libsystemd.so.0";
+        String libpath = System.getProperty("java.library.path");
+        for (String basepathStr : libpath.split(":")) {
+            var basepath = Paths.get(basepathStr);
+            if (Files.exists(basepath) == false) {
+                continue;
+            }
+            try (var stream = Files.walk(basepath)) {
+                var foundpath = stream.filter(Files::isDirectory).map(p -> p.resolve(libsystemd)).filter(Files::exists).findAny();
+                if (foundpath.isPresent()) {
+                    return foundpath.get().toAbsolutePath().toString();
+                }
+            } catch (IOException e) {
+                throw new UncheckedIOException(e);
+            }
+
+        }
+        throw new UnsatisfiedLinkError("Could not find " + libsystemd + " in java.library.path: " + libpath);
+    }
+
+    private static final MethodHandle sd_notify$mh = downcallHandle("sd_notify", FunctionDescriptor.of(JAVA_INT, JAVA_INT, ADDRESS));
+
+    @Override
+    public int sd_notify(int unset_environment, String state) {
+        try (Arena arena = Arena.ofConfined()) {
+            MemorySegment nativeState = arena.allocateUtf8String(state);
+            return (int) sd_notify$mh.invokeExact(unset_environment, nativeState);
+        } catch (Throwable t) {
+            throw new AssertionError(t);
+        }
+    }
+}

modules/systemd/build.gradle

@@ -11,3 +11,7 @@ esplugin {
   classname 'org.elasticsearch.systemd.SystemdPlugin'
 }
 
+dependencies {
+  implementation project(':libs:elasticsearch-native')
+}
+

modules/systemd/src/main/java/module-info.java

@@ -12,5 +12,5 @@
     requires org.elasticsearch.xcontent;
     requires org.apache.logging.log4j;
     requires org.apache.lucene.core;
-    requires com.sun.jna;
+    requires org.elasticsearch.nativeaccess;
 }