Fixes #10 by reverting the change from native Unix Domain Sockets to …

…libsysted over JNA.
jpmsilva · Jul 17, 2023 · abf6f77 · abf6f77
1 parent cb3dc4b
commit abf6f77
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Showing 9 changed files with 87 additions and 79 deletions.
diff --git a/do-release b/do-release
@@ -9,5 +9,5 @@ git checkout master && \
 git pull && \
 git checkout development && \
 git pull && \
-"${SCRIPTPATH}"/mvnw jgitflow:release-start -am -pl :jsystemd-core,:jsystemd-spring-boot-starter && \
-"${SCRIPTPATH}"/mvnw jgitflow:release-finish -am -pl :jsystemd-core,:jsystemd-spring-boot-starter
+"${SCRIPTPATH}"/mvnw jgitflow:release-start -P !sample -am -pl :jsystemd-core,:jsystemd-spring-boot-starter && \
+"${SCRIPTPATH}"/mvnw jgitflow:release-finish -P !sample -am -pl :jsystemd-core,:jsystemd-spring-boot-starter
diff --git a/do-site-release b/do-site-release
@@ -5,4 +5,4 @@ SCRIPTPATH=$(dirname "$SCRIPT")
 
 set -e
 
-"${SCRIPTPATH}"/mvnw clean package site site:site -am -pl :jsystemd-core,:jsystemd-spring-boot-starter --debug
+"${SCRIPTPATH}"/mvnw clean package site site:site -P !sample -am -pl :jsystemd-core,:jsystemd-spring-boot-starter --debug
diff --git a/jsystemd-core/pom.xml b/jsystemd-core/pom.xml
@@ -33,6 +33,10 @@ limitations under the License.
   </description>
 
   <dependencies>
+    <dependency>
+      <groupId>net.java.dev.jna</groupId>
+      <artifactId>jna</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>

diff --git a/jsystemd-core/src/main/java/com/github/jpmsilva/jsystemd/SystemdNotify.java b/jsystemd-core/src/main/java/com/github/jpmsilva/jsystemd/SystemdNotify.java
@@ -16,18 +16,12 @@
 
 package com.github.jpmsilva.jsystemd;
 
-import static com.github.jpmsilva.jsystemd.SystemdUtilities.hasNotifySocket;
-import static com.github.jpmsilva.jsystemd.SystemdUtilities.isLinux;
 import static java.lang.invoke.MethodHandles.lookup;
 import static java.util.Objects.requireNonNull;
 import static org.slf4j.LoggerFactory.getLogger;
 
-import java.io.IOException;
-import java.net.StandardProtocolFamily;
+import com.sun.jna.Native;
 import java.net.UnixDomainSocketAddress;
-import java.nio.ByteBuffer;
-import java.nio.channels.SocketChannel;
-import java.nio.file.Path;
 import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 
@@ -41,47 +35,13 @@ public class SystemdNotify {
 
   private static final Logger logger = getLogger(lookup().lookupClass());
 
-  private static final SocketChannel channel = createSocketChannel();
-
-  private static SocketChannel createSocketChannel() {
-    if (isLinux() && hasNotifySocket()) {
-      SocketChannel channel = null;
-      try {
-        Path socketPath = SystemdUtilities.notifySocketPath();
-        if (socketPath.toFile().exists()) {
-          channel = SocketChannel.open(StandardProtocolFamily.UNIX);
-          channel.configureBlocking(true);
-          channel.connect(UnixDomainSocketAddress.of(socketPath));
-          channel.shutdownInput();
-          return channel;
-        } else {
-          logger.warn("Specified socket path does not exist - systemd integration disabled: " + socketPath);
-        }
-      } catch (IOException e) {
-        if (channel != null) {
-          try {
-            channel.close();
-          } catch (IOException ex) {
-            e.addSuppressed(ex);
-          }
-        }
-        if (logger.isDebugEnabled()) {
-          logger.warn("Could not connect to systemd socket", e);
-        } else {
-          logger.warn("Could not connect to systemd socket: " + e.getMessage());
-        }
-      }
-    }
-    return null;
-  }
-
   /**
    * Allows knowing if this library is usable under current execution conditions (operating system type, systemd available, etc...).
    *
    * @return {@code true} if and only if the library can be used
    */
   static boolean usable() {
-    return channel != null && channel.isConnected();
+    return Library.initialized;
   }
 
   /**
@@ -151,34 +111,13 @@ static void stopping() {
    * @param message the message to send, according to <a href="https://www.freedesktop.org/software/systemd/man/sd_notify.html#Description">specification</a>
    */
   private static void invoke(String message) {
-    requireNonNull(message);
-    if (usable() && !message.isEmpty()) {
-      try {
-        synchronized (requireNonNull(channel)) {
-          ByteBuffer buffer = ByteBuffer.allocate(1024);
-          buffer.clear();
-          if (message.endsWith("\n")) {
-            buffer.put(message.getBytes());
-          } else {
-            buffer.put((message + "\n").getBytes());
-          }
-          buffer.flip();
-          while (buffer.hasRemaining()) {
-            channel.write(buffer);
-          }
-        }
-      } catch (IOException e) {
-        if (logger.isDebugEnabled()) {
-          logger.warn("Failed to send systemd message " + message, e);
-        } else {
-          logger.warn("Failed to send systemd message " + message + ": " + e.getMessage());
-        }
-      }
+    if (usable() && message != null && !message.isEmpty()) {
+      Library.sd_notify(0, message);
     }
   }
 
   /**
-   * Registers a JVM shutdown hook that closes the system integration channel.
+   * Registers a JVM shutdown hook that closes the systemd integration channel.
    *
    * @see Runtime#addShutdownHook(Thread)
    * @see #close()
@@ -193,14 +132,25 @@ public static void registerShutdownHook() {
    * <p>Normally, the integration channel will be closed when the JVM shuts down.<br>
    * However, you may wish of explicitly close the integration channel, to ensure that all closeable resources are effectively closed.<br> As such, this method
    * should only be called at most once during the lifecycle of the JVM.
+   *
+   * <p>Currenty this does nothing, as currently the only supported integration channel is the native libsystemd library, which does not need any cleanup.
    */
   public static void close() {
-    if (channel != null) {
+  }
+
+  private static class Library {
+
+    private static boolean initialized = false;
+
+    static {
       try {
-        channel.close();
-      } catch (IOException ignored) {
-        // This is a best effort at this point
+        Native.register("systemd");
+        initialized = true;
+      } catch (UnsatisfiedLinkError ignored) {
       }
     }
+
+    @SuppressWarnings({"UnusedReturnValue", "checkstyle:ParameterName"})
+    public static native int sd_notify(int unset_environment, String state);
   }
 }
diff --git a/jsystemd-spring-boot-sample/pom.xml b/jsystemd-spring-boot-sample/pom.xml
@@ -57,6 +57,14 @@ limitations under the License.
 
   <build>
     <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-deploy-plugin</artifactId>
+        <configuration>
+          <skip>true</skip>
+        </configuration>
+      </plugin>
+
       <plugin>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-maven-plugin</artifactId>

diff --git a/...ing-boot-starter/src/main/java/com/github/jpmsilva/jsystemd/SystemdAutoConfiguration.java b/...ing-boot-starter/src/main/java/com/github/jpmsilva/jsystemd/SystemdAutoConfiguration.java
@@ -35,7 +35,8 @@
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
-import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.boot.availability.AvailabilityChangeEvent;
+import org.springframework.boot.availability.ReadinessState;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -64,13 +65,17 @@ public class SystemdAutoConfiguration {
   }
 
   /**
-   * Event listener for the {@link ApplicationReadyEvent} event to report to systemd that the service is ready.
+   * Event listener for the {@link AvailabilityChangeEvent} event to report to systemd that the service is ready.
    *
-   * @param event the {@link ApplicationReadyEvent} received
+   * <p>The application is considered ready when the event is a {@link ReadinessState} with the state {@link ReadinessState#ACCEPTING_TRAFFIC}.
+   *
+   * @param event the {@link AvailabilityChangeEvent} received
    */
   @EventListener
-  public void started(@SuppressWarnings("unused") ApplicationReadyEvent event) {
-    systemd.ready();
+  public void started(@SuppressWarnings("unused") AvailabilityChangeEvent<ReadinessState> event) {
+    if(event.getState() == ReadinessState.ACCEPTING_TRAFFIC) {
+      systemd.ready();
+    }
   }
 
   @Bean

diff --git a/pom.xml b/pom.xml
@@ -107,6 +107,11 @@ limitations under the License.
 
   <dependencyManagement>
     <dependencies>
+      <dependency>
+        <groupId>net.java.dev.jna</groupId>
+        <artifactId>jna</artifactId>
+        <version>5.13.0</version>
+      </dependency>
       <dependency>
         <groupId>org.slf4j</groupId>
         <artifactId>slf4j-api</artifactId>
@@ -268,6 +273,16 @@ limitations under the License.
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-javadoc-plugin</artifactId>
           <version>${plugin.javadoc.version}</version>
+          <configuration>
+            <links>
+              <link>https://docs.oracle.com/en/java/javase/17/docs/api/</link>
+              <link>https://docs.spring.io/spring-boot/docs/3.0.0/api/</link>
+              <link>https://docs.spring.io/spring-framework/docs/6.0.2/javadoc-api/</link>
+              <link>https://java-native-access.github.io/jna/5.13.0/javadoc/</link>
+            </links>
+            <doctitle>${project.name} ${project.version}</doctitle>
+            <windowtitle>${project.artifactId} ${project.version}</windowtitle>
+          </configuration>
         </plugin>
 
         <plugin>
@@ -305,6 +320,9 @@ limitations under the License.
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-pmd-plugin</artifactId>
           <version>${plugin.pmd.version}</version>
+          <configuration>
+            <xrefLocation></xrefLocation>
+          </configuration>
         </plugin>
 
         <plugin>
@@ -390,6 +408,15 @@ limitations under the License.
   </build>
 
   <profiles>
+    <profile>
+      <id>sample</id>
+      <activation>
+        <activeByDefault>true</activeByDefault>
+      </activation>
+      <modules>
+        <module>jsystemd-spring-boot-sample</module>
+      </modules>
+    </profile>
     <profile>
       <id>release-profile</id>
       <activation>
@@ -564,7 +591,6 @@ limitations under the License.
 
   <modules>
     <module>jsystemd-core</module>
-    <module>jsystemd-spring-boot-sample</module>
     <module>jsystemd-spring-boot-starter</module>
   </modules>
 </project>
diff --git a/src/site/markdown/native-library.md b/src/site/markdown/native-library.md
@@ -0,0 +1,14 @@
+# Native library
+
+The integration uses [JNA](https://github.com/java-native-access/jna) (`net.java.dev.jna:jna`) to interface
+with [libsystemd](https://github.com/systemd/systemd/tree/master/src/libsystemd) natively.
+
+## Running without JNA
+
+It used to be possible to switch the implementation from JNA with an executable call to the
+[systemd-notify](https://www.freedesktop.org/software/systemd/man/systemd-notify.html) program that is bundled with systemd.
+
+However, that method is no longer supported.
+
+For the time being, JNA is the only reliable way to interface with systemd via libsystemd, as the JVM does not
+yet [implement proper support for Datagram Channels (SOCK_DGRAM) over Unix Domain Sockets (AF_UNIX)](https://bugs.openjdk.org/browse/JDK-8297837). 
diff --git a/src/site/site.xml b/src/site/site.xml
@@ -30,6 +30,7 @@
       <item name="Startup progress" href="startup-progress.html"/>
       <item name="Startup timeout" href="startup-timeout.html"/>
       <item name="Tomcat status" href="tomcat-status.html"/>
+      <item name="Native library" href="native-library.html"/>
       <item name="Conditionals" href="conditionals.html"/>
       <item name="API (Javadocs)" href="apidocs/index.html"/>
     </menu>
Original file line number	Diff line number	Diff line change
Expand Up		@@ -5,4 +5,4 @@ SCRIPTPATH=$(dirname "$SCRIPT")

		set -e

		"${SCRIPTPATH}"/mvnw clean package site site:site -am -pl :jsystemd-core,:jsystemd-spring-boot-starter --debug
		"${SCRIPTPATH}"/mvnw clean package site site:site -P !sample -am -pl :jsystemd-core,:jsystemd-spring-boot-starter --debug