From a96b3392edad759e8083cc15840c86c2f3f8673d Mon Sep 17 00:00:00 2001
From: Luck <git@lucko.me>
Date: Mon, 31 Dec 2018 20:03:11 +0000
Subject: Some minor optimizations to ThreadDumper implementations

---
 .../java/me/lucko/spark/util/ThreadFinder.java     | 60 ++++++++++++++++++++++
 .../src/main/java/me/lucko/spark/util/Threads.java | 58 ---------------------
 2 files changed, 60 insertions(+), 58 deletions(-)
 create mode 100644 spark-common/src/main/java/me/lucko/spark/util/ThreadFinder.java
 delete mode 100644 spark-common/src/main/java/me/lucko/spark/util/Threads.java

(limited to 'spark-common/src/main/java/me/lucko/spark/util')

diff --git a/spark-common/src/main/java/me/lucko/spark/util/ThreadFinder.java b/spark-common/src/main/java/me/lucko/spark/util/ThreadFinder.java
new file mode 100644
index 0000000..a74f85a
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/util/ThreadFinder.java
@@ -0,0 +1,60 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.util;
+
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+/**
+ * Utility to find active threads.
+ */
+public final class ThreadFinder {
+
+    private static final ThreadGroup ROOT_THREAD_GROUP;
+    static {
+        ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();
+        ThreadGroup parentGroup;
+        while ((parentGroup = rootGroup.getParent()) != null) {
+            rootGroup = parentGroup;
+        }
+        ROOT_THREAD_GROUP = rootGroup;
+    }
+
+    // cache the approx active count at the time of construction.
+    // the usages of this class are likely to be somewhat short-lived, so it's good
+    // enough to just cache a value on init.
+    private final int approxActiveCount = ROOT_THREAD_GROUP.activeCount();
+
+    /**
+     * Gets a stream of all known active threads.
+     *
+     * @return a stream of threads
+     */
+    public Stream<Thread> getThreads() {
+        Thread[] threads = new Thread[this.approxActiveCount + 20]; // +20 to allow a bit of growth for newly created threads
+        while (ROOT_THREAD_GROUP.enumerate(threads, true ) == threads.length) {
+            threads = new Thread[threads.length * 2];
+        }
+        return Arrays.stream(threads).filter(Objects::nonNull);
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/util/Threads.java b/spark-common/src/main/java/me/lucko/spark/util/Threads.java
deleted file mode 100644
index d1efdff..0000000
--- a/spark-common/src/main/java/me/lucko/spark/util/Threads.java
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * This file is part of spark.
- *
- *  Copyright (c) lucko (Luck) <luck@lucko.me>
- *  Copyright (c) contributors
- *
- *  This program is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-package me.lucko.spark.util;
-
-import java.util.Arrays;
-import java.util.Objects;
-import java.util.stream.Stream;
-
-/**
- * Utilities for working with {@link Thread}s.
- */
-public final class Threads {
-
-    private Threads() {}
-
-    private static final ThreadGroup ROOT_THREAD_GROUP;
-
-    static {
-        ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();
-        ThreadGroup parentGroup;
-        while ((parentGroup = rootGroup.getParent()) != null) {
-            rootGroup = parentGroup;
-        }
-        ROOT_THREAD_GROUP = rootGroup;
-    }
-
-    /**
-     * Gets a stream of all known active threads.
-     *
-     * @return a stream of threads
-     */
-    public static Stream<Thread> getThreads() {
-        Thread[] threads = new Thread[ROOT_THREAD_GROUP.activeCount()];
-        while (ROOT_THREAD_GROUP.enumerate(threads, true ) == threads.length) {
-            threads = new Thread[threads.length * 2];
-        }
-        return Arrays.stream(threads).filter(Objects::nonNull);
-    }
-
-}
-- 
cgit