docs: refactor highvolume example

docs/examples/java/src/main/java/com/taos/example/highvolume/FastWriteExample.java

@@ -2,30 +2,30 @@ package com.taos.example.highvolume;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingDeque;
 
 // ANCHOR: main
 public class FastWriteExample {
 
-    final static int readTaskCount = 1;
+    final static int readTaskCount = 2;
     final static int writeTaskCount = 4;
-    final static List<ReadTask> readTasks = new ArrayList<>();
-    final static List<WriteTask> writeTasks = new ArrayList<>();
+    final static int taskQueueCapacity = 1000;
+    final static List<BlockingQueue> taskQueues = new ArrayList<>();
 
     public static void main(String[] args) throws InterruptedException {
-        // Create writing tasks.
-        // Every writing task contains a work thread and a task queue.
+        // Create task queues, whiting tasks and start writing threads.
         for (int i = 0; i < writeTaskCount; ++i) {
-            WriteTask task = new WriteTask();
-            task.start();
-            writeTasks.add(new WriteTask());
+            BlockingQueue<String> queue = new LinkedBlockingDeque<>(taskQueueCapacity);
+            WriteTask task = new WriteTask(queue);
+            Thread t = new Thread(task);
+            t.start();
         }
 
-        // Create reading tasks.
-        // Every reading task contains a work thread and a reference to each writing task.
+        // create reading tasks and start reading threads
         for (int i = 0; i < readTaskCount; ++i) {
-            ReadTask task = new ReadTask(i, writeTasks);
-            task.start();
-            readTasks.add(task);
+            ReadTask task = new ReadTask(taskQueues);
+            Thread t = new Thread(task);
         }
 
         while (true) {

docs/examples/java/src/main/java/com/taos/example/highvolume/WriteTask.java

@@ -10,28 +10,12 @@ import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingDeque;
 
 // ANCHOR: WriteTask
-class WriteTask {
+class WriteTask implements Runnable {
     final static int maxBatchSize = 500;
-    //
-    final static int taskQueueCapacity = 1000;
+    private final BlockingQueue<String> queue;
 
-    private Thread writeThread = new Thread(this::doWriteTask);
-
-    private BlockingQueue<String> queue = new LinkedBlockingDeque<>(taskQueueCapacity);
-
-    /**
-     * Public interface for adding task to task queue.
-     * It will be invoked in read thread.
-     */
-    public void put(String line) throws InterruptedException {
-        queue.put(line);
-    }
-
-    /**
-     * Start writing thread.
-     */
-    public void start() {
-        writeThread.start();
+    public WriteTask(BlockingQueue<String> taskQueue) {
+        this.queue = taskQueue;
     }
 
     private static Connection getConnection() throws SQLException {
@@ -39,7 +23,7 @@ class WriteTask {
         return DriverManager.getConnection(jdbcUrl);
     }
 
-    private void doWriteTask() {
+    public void run() {
         int count = 0;
         try {
             Connection conn = getConnection();