2 files changed, 116 insertions, 9 deletions
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/BackgroundSamplerManager.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/BackgroundSamplerManager.java
new file mode 100644
index 0000000..d655739
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/BackgroundSamplerManager.java
@@ -0,0 +1,116 @@
+/*
+ * 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.common.sampler;
+
+import me.lucko.spark.common.SparkPlatform;
+import me.lucko.spark.common.platform.PlatformInfo;
+import me.lucko.spark.common.util.Configuration;
+
+import java.util.logging.Level;
+
+public class BackgroundSamplerManager {
+
+    private static final String OPTION_ENABLED = "backgroundProfiler";
+    private static final String OPTION_ENGINE = "backgroundProfilerEngine";
+    private static final String OPTION_INTERVAL = "backgroundProfilerInterval";
+
+    private static final String MARKER_FAILED = "_marker_background_profiler_failed";
+
+    private final SparkPlatform platform;
+    private final Configuration configuration;
+    private final boolean enabled;
+
+    public BackgroundSamplerManager(SparkPlatform platform, Configuration configuration) {
+        this.platform = platform;
+        this.configuration = configuration;
+        this.enabled = this.configuration.getBoolean(
+                OPTION_ENABLED,
+                this.platform.getPlugin().getPlatformInfo().getType() == PlatformInfo.Type.SERVER
+        );
+    }
+
+    public void initialise() {
+        if (!this.enabled) {
+            return;
+        }
+
+        // are we enabling the background profiler by default for the first time?
+        boolean didEnableByDefault = false;
+        if (!this.configuration.contains(OPTION_ENABLED)) {
+            this.configuration.setBoolean(OPTION_ENABLED, true);
+            didEnableByDefault = true;
+        }
+
+        // did the background profiler fail to start on the previous attempt?
+        if (this.configuration.getBoolean(MARKER_FAILED, false)) {
+            this.platform.getPlugin().log(Level.WARNING, "It seems the background profiler failed to start when spark was last enabled. Sorry about that!");
+            this.platform.getPlugin().log(Level.WARNING, "In the future, spark will try to use the built-in Java profiling engine instead.");
+
+            this.configuration.remove(MARKER_FAILED);
+            this.configuration.setString(OPTION_ENGINE, "java");
+            this.configuration.save();
+        }
+
+        this.platform.getPlugin().log(Level.INFO, "Starting background profiler...");
+
+        if (didEnableByDefault) {
+            // set the failed marker and save before we try to start the profiler,
+            // then remove the marker afterwards if everything goes ok!
+            this.configuration.setBoolean(MARKER_FAILED, true);
+            this.configuration.save();
+        }
+
+        try {
+            startSampler();
+
+            if (didEnableByDefault) {
+                this.configuration.remove(MARKER_FAILED);
+                this.configuration.save();
+            }
+
+        } catch (Throwable e) {
+            e.printStackTrace();
+        }
+    }
+
+    public boolean restartBackgroundSampler() {
+        if (this.enabled) {
+            startSampler();
+            return true;
+        }
+        return false;
+    }
+
+    private void startSampler() {
+        boolean forceJavaEngine = this.configuration.getString(OPTION_ENGINE, "async").equals("java");
+
+        Sampler sampler = new SamplerBuilder()
+                .background(true)
+                .threadDumper(this.platform.getPlugin().getDefaultThreadDumper())
+                .threadGrouper(ThreadGrouper.BY_POOL)
+                .samplingInterval(this.configuration.getInteger(OPTION_INTERVAL, 10))
+                .forceJavaSampler(forceJavaEngine)
+                .start(this.platform);
+
+        this.platform.getSamplerContainer().setActiveSampler(sampler);
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerContainer.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerContainer.java
index d55909c..15b1029 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerContainer.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerContainer.java
@@ -28,11 +28,6 @@ import java.util.concurrent.atomic.AtomicReference;
 public class SamplerContainer implements AutoCloseable {
 
     private final AtomicReference<Sampler> activeSampler = new AtomicReference<>();
-    private final boolean backgroundProfilerEnabled;
-
-    public SamplerContainer(boolean backgroundProfilerEnabled) {
-        this.backgroundProfilerEnabled = backgroundProfilerEnabled;
-    }
 
     /**
      * Gets the active sampler, or null if a sampler is not active.
@@ -73,10 +68,6 @@ public class SamplerContainer implements AutoCloseable {
         }
     }
 
-    public boolean isBackgroundProfilerEnabled() {
-        return this.backgroundProfilerEnabled;
-    }
-
     @Override
     public void close() {
         stopActiveSampler(true);