implement basic mpv ipc

src/main/java/com/mykola2312/mptv/Main.java

@@ -73,14 +73,14 @@ public class Main {
         flyway.migrate();
 
         // load sources, start crawlers
-        Crawler crawler = new Crawler();
-        crawler.updateSources(config.sources);
-        crawler.crawl();
+        // Crawler crawler = new Crawler();
+        // crawler.updateSources(config.sources);
+        // crawler.crawl();
 
         // task dispatcher
         TaskDispatcher dispatcher = new TaskDispatcher();
         dispatcher.updateTaskConfig(config.tasks);
-        dispatcher.registerTask(crawler);
+        //dispatcher.registerTask(crawler); // TODO: enable
 
         ProcessService processService = new ProcessService();
         dispatcher.registerTask(processService);
@@ -93,9 +93,13 @@ public class Main {
 
         try {
             MPV mpv = new MPV("test.mp4");
-            logger.info("spawned mpv");
+            if (mpv.spawn()) {
+                logger.info("spawned mpv");
 
-            processService.registerProcess(mpv);
+                processService.registerProcess(mpv);
+            } else {
+                logger.error("failed to spawn mpv");
+            }
         } catch (IOException e) {
             logger.error("failed to start mpv", e);
         }

src/main/java/com/mykola2312/mptv/mpv/MPV.java

@@ -1,23 +1,40 @@
 package com.mykola2312.mptv.mpv;
 
 import java.io.IOException;
+import java.nio.file.Path;
 
 import com.mykola2312.mptv.task.TaskProcess;
 
 public class MPV implements TaskProcess {
     private final String url;
     private Process process;
+    private MPVSocket socket = null;
 
     public MPV(String url) throws IOException {
         this.url = url;
-        spawn();
     }
 
+    private static final Path MPV_SOCKET_PATH = Path.of("/tmp/mptv-mpv.sock");
+
     @Override
-    public void spawn() throws IOException {
+    public boolean spawn() throws IOException {
+        // to prevent possible file descriptor leaks
+        if (socket != null) {
+            socket.close();
+            socket = null;
+        }
+
         process = Runtime.getRuntime().exec(new String[] {
-            "mpv", url
+            "mpv", url, "--input-ipc-server=" + MPV_SOCKET_PATH
         });
+
+        socket = new MPVSocket();
+        socket.waitForConnection(MPV_SOCKET_PATH);
+
+        // TODO: remove test code
+        socket.writeCommandRaw(new MPVCommandRaw("set_property", "volume", "0"));
+
+        return isAlive();
     }
 
     @Override
@@ -27,6 +44,9 @@ public class MPV implements TaskProcess {
 
     @Override
     public void stop() {
+        socket.close();
+        socket = null;
+    
         process.destroyForcibly();
     }
 }

src/main/java/com/mykola2312/mptv/mpv/MPVCommandRaw.java

@@ -0,0 +1,24 @@
+package com.mykola2312.mptv.mpv;
+
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class MPVCommandRaw {
+    public ArrayList<String> command;
+
+    public MPVCommandRaw(String name, String... args) {
+        command = new ArrayList<>();
+        command.add(name);
+        command.addAll(Arrays.asList(args));
+    }
+
+    public byte[] serialize() throws JsonProcessingException {
+        ObjectMapper mapper = new ObjectMapper();
+        String jsonCommand = mapper.writeValueAsString(this);
+        return jsonCommand.getBytes(StandardCharsets.UTF_8);
+    }
+}

src/main/java/com/mykola2312/mptv/mpv/MPVSocket.java

@@ -0,0 +1,62 @@
+package com.mykola2312.mptv.mpv;
+
+import java.io.IOException;
+import java.net.SocketException;
+import java.nio.file.Path;
+
+import org.newsclub.net.unix.AFOutputStream;
+import org.newsclub.net.unix.AFUNIXSocket;
+import org.newsclub.net.unix.AFUNIXSocketAddress;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+
+public class MPVSocket {
+    private static final Logger logger = LoggerFactory.getLogger(MPVSocket.class);
+
+    private AFUNIXSocket socket;
+
+    private static final long WAIT_MILLIS = 250;
+    private static final int WAIT_ATTEMPTS = 5;
+
+    public void waitForConnection(Path socketPath) throws IOException {
+        for (int i = 0; i < WAIT_ATTEMPTS; i++) {
+            try {
+                Thread.sleep(WAIT_MILLIS);
+
+                socket = AFUNIXSocket.newInstance();
+                socket.connect(AFUNIXSocketAddress.of(socketPath));
+                
+                logger.info(String.format("connected to socket %s", socket.toString()));
+            } catch (SocketException e) {
+                logger.error("SocketException", e);
+                close();
+            } catch (InterruptedException e) {
+                break;
+            }
+        }
+    }
+
+    public void close() {
+        try {
+            socket.close();
+        } catch (IOException e) {
+            logger.error("failed to close socket", e);
+        }
+    }
+
+    public void writeCommandRaw(MPVCommandRaw command) {
+        try {
+            AFOutputStream output = socket.getOutputStream();
+
+            output.write(command.serialize());
+            output.write('\n');
+            output.flush();
+        } catch (JsonProcessingException e) {
+            logger.error("failed to serialize command", e);
+        } catch (IOException e) {
+            logger.error("io exception", e);
+        }
+    }
+}

src/main/java/com/mykola2312/mptv/task/TaskProcess.java

@@ -3,7 +3,7 @@ package com.mykola2312.mptv.task;
 import java.io.IOException;
 
 public interface TaskProcess {
-    public void spawn() throws IOException;
+    public boolean spawn() throws IOException;
     public boolean isAlive();
     public void stop();
 }