update at 2021-07-15 18:35:46 by ehlxr

src/main/java/io/github/ehlxr/ClassLoaderTest.java

@@ -0,0 +1,35 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr;
+
+/**
+ * @author ehlxr
+ * @since 2021-07-07 22:54.
+ */
+public class ClassLoaderTest {
+    public static void main(String[] args) {
+        System.out.println(ClassLoader.getSystemClassLoader());
+    }
+}

src/main/java/io/github/ehlxr/SlideWindow.java

@@ -0,0 +1,96 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr;
+
+import java.time.LocalTime;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * 滑动时间窗口限流工具
+ * 本限流工具只适用于单机版，如果想要做全局限流，可以按本程序的思想，用redis的List结构去实现
+ *
+ * @author dijia478
+ * @date 2020-10-13 10:53
+ */
+public class SlideWindow {
+
+    /**
+     * 队列id和队列的映射关系，队列里面存储的是每一次通过时候的时间戳，这样可以使得程序里有多个限流队列
+     */
+    private volatile static Map<String, List<Long>> MAP = new ConcurrentHashMap<>();
+
+    private SlideWindow() {
+    }
+
+    public static void main(String[] args) throws InterruptedException {
+        while (true) {
+            // 任意10秒内，只允许2次通过
+            System.out.println(LocalTime.now().toString() + SlideWindow.isGo("ListId", 5, 1000L));
+            // 睡眠0-10秒
+            // Thread.sleep(1000 * new Random().nextInt(10));
+        }
+    }
+
+    /**
+     * 滑动时间窗口限流算法
+     * 在指定时间窗口，指定限制次数内，是否允许通过
+     *
+     * @param listId     队列id
+     * @param count      限制次数
+     * @param timeWindow 时间窗口大小
+     * @return 是否允许通过
+     */
+    public static synchronized boolean isGo(String listId, int count, long timeWindow) {
+        // 获取当前时间
+        long nowTime = System.currentTimeMillis();
+        // 根据队列id，取出对应的限流队列，若没有则创建
+        List<Long> list = MAP.computeIfAbsent(listId, k -> new LinkedList<>());
+        // 如果队列还没满，则允许通过，并添加当前时间戳到队列开始位置
+        if (list.size() < count) {
+            list.add(0, nowTime);
+            return true;
+        }
+
+        // 队列已满（达到限制次数），则获取队列中最早添加的时间戳
+        Long farTime = list.get(count - 1);
+        // 用当前时间戳 减去 最早添加的时间戳
+        if (nowTime - farTime <= timeWindow) {
+            // 若结果小于等于timeWindow，则说明在timeWindow内，通过的次数大于count
+            // 不允许通过
+            return false;
+        } else {
+            // 若结果大于timeWindow，则说明在timeWindow内，通过的次数小于等于count
+            // 允许通过，并删除最早添加的时间戳，将当前时间添加到队列开始位置
+            list.remove(count - 1);
+            list.add(0, nowTime);
+            return true;
+        }
+    }
+
+}

src/main/java/io/github/ehlxr/jvm/stack/ReturnAddressTest.java

@@ -0,0 +1,47 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr.jvm.stack;
+
+/**
+ * @author ehlxr
+ * @since 2021-07-11 15:19.
+ */
+public class ReturnAddressTest {
+
+    public void methodA() {
+        int k = 10;
+        int l = 20;
+
+        methodB();
+    }
+
+    public void methodB() {
+        int i = 10;
+        int j = 20;
+
+        int a = i + j;
+    }
+
+}