Limit profile length to 1 hour

12 files changed, 254 insertions, 57 deletions

diff --git a/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java b/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
index 4c3875c..a015e42 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
@@ -45,6 +45,7 @@ import me.lucko.spark.common.monitor.ping.PingStatistics;
 import me.lucko.spark.common.monitor.ping.PlayerPingProvider;
 import me.lucko.spark.common.monitor.tick.TickStatistics;
 import me.lucko.spark.common.platform.PlatformStatisticsProvider;
+import me.lucko.spark.common.sampler.SamplerContainer;
 import me.lucko.spark.common.sampler.source.ClassSourceLookup;
 import me.lucko.spark.common.tick.TickHook;
 import me.lucko.spark.common.tick.TickReporter;
@@ -98,6 +99,7 @@ public class SparkPlatform {
     private final List<Command> commands;
     private final ReentrantLock commandExecuteLock = new ReentrantLock(true);
     private final ActivityLog activityLog;
+    private final SamplerContainer samplerContainer;
     private final TickHook tickHook;
     private final TickReporter tickReporter;
     private final TickStatistics tickStatistics;
@@ -137,6 +139,8 @@ public class SparkPlatform {
         this.activityLog = new ActivityLog(plugin.getPluginDirectory().resolve("activity.json"));
         this.activityLog.load();
 
+        this.samplerContainer = new SamplerContainer();
+
         this.tickHook = plugin.createTickHook();
         this.tickReporter = plugin.createTickReporter();
         this.tickStatistics = this.tickHook != null || this.tickReporter != null ? new TickStatistics() : null;
@@ -229,6 +233,10 @@ public class SparkPlatform {
         return this.activityLog;
     }
 
+    public SamplerContainer getSamplerContainer() {
+        return this.samplerContainer;
+    }
+
     public TickHook getTickHook() {
         return this.tickHook;
     }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java b/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java
index 6dbf913..00bf1a9 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java
@@ -68,17 +68,6 @@ import static net.kyori.adventure.text.format.NamedTextColor.WHITE;
 public class SamplerModule implements CommandModule {
     private static final String SPARK_SAMPLER_MEDIA_TYPE = "application/x-spark-sampler";
 
-    /** The sampler instance currently running, if any */
-    private Sampler activeSampler = null;
-
-    @Override
-    public void close() {
-        if (this.activeSampler != null) {
-            this.activeSampler.stop();
-            this.activeSampler = null;
-        }
-    }
-
     @Override
     public void registerCommands(Consumer<Command> consumer) {
         consumer.accept(Command.builder()
@@ -121,7 +110,7 @@ public class SamplerModule implements CommandModule {
         }
 
         if (arguments.boolFlag("cancel")) {
-            profilerCancel(resp);
+            profilerCancel(platform, resp);
             return;
         }
 
@@ -134,7 +123,7 @@ public class SamplerModule implements CommandModule {
     }
 
     private void profilerStart(SparkPlatform platform, CommandSender sender, CommandResponseHandler resp, Arguments arguments) {
-        if (this.activeSampler != null) {
+        if (platform.getSamplerContainer().getActiveSampler() != null) {
             profilerInfo(platform, resp);
             return;
         }
@@ -210,7 +199,8 @@ public class SamplerModule implements CommandModule {
         if (ticksOver != -1) {
             builder.ticksOver(ticksOver, tickHook);
         }
-        Sampler sampler = this.activeSampler = builder.start(platform);
+        Sampler sampler = builder.start(platform);
+        platform.getSamplerContainer().setActiveSampler(sampler);
 
         resp.broadcastPrefixed(text()
                 .append(text("Profiler is now running!", GOLD))
@@ -227,7 +217,7 @@ public class SamplerModule implements CommandModule {
             resp.broadcastPrefixed(text("The results will be automatically returned after the profiler has been running for " + timeoutSeconds + " seconds."));
         }
 
-        CompletableFuture<Sampler> future = this.activeSampler.getFuture();
+        CompletableFuture<Sampler> future = sampler.getFuture();
 
         // send message if profiling fails
         future.whenCompleteAsync((s, throwable) -> {
@@ -238,11 +228,7 @@ public class SamplerModule implements CommandModule {
         });
 
         // set activeSampler to null when complete.
-        future.whenCompleteAsync((s, throwable) -> {
-            if (sampler == this.activeSampler) {
-                this.activeSampler = null;
-            }
-        });
+        sampler.getFuture().whenCompleteAsync((s, throwable) -> platform.getSamplerContainer().unsetActiveSampler(s));
 
         // await the result
         if (timeoutSeconds != -1) {
@@ -258,17 +244,18 @@ public class SamplerModule implements CommandModule {
     }
 
     private void profilerInfo(SparkPlatform platform, CommandResponseHandler resp) {
-        if (this.activeSampler == null) {
+        Sampler sampler = platform.getSamplerContainer().getActiveSampler();
+        if (sampler == null) {
             resp.replyPrefixed(text("The profiler isn't running!"));
             resp.replyPrefixed(text("To start a new one, run:"));
             resp.replyPrefixed(cmdPrompt("/" + platform.getPlugin().getCommandName() + " profiler"));
         } else {
             resp.replyPrefixed(text("Profiler is already running!", GOLD));
 
-            long runningTime = (System.currentTimeMillis() - this.activeSampler.getStartTime()) / 1000L;
+            long runningTime = (System.currentTimeMillis() - sampler.getStartTime()) / 1000L;
             resp.replyPrefixed(text("So far, it has profiled for " + runningTime + " seconds."));
 
-            long timeout = this.activeSampler.getAutoEndTime();
+            long timeout = sampler.getAutoEndTime();
             if (timeout == -1) {
                 resp.replyPrefixed(text("To stop the profiler and upload the results, run:"));
                 resp.replyPrefixed(cmdPrompt("/" + platform.getPlugin().getCommandName() + " profiler --stop"));
@@ -282,20 +269,24 @@ public class SamplerModule implements CommandModule {
         }
     }
 
-    private void profilerCancel(CommandResponseHandler resp) {
-        if (this.activeSampler == null) {
+    private void profilerCancel(SparkPlatform platform, CommandResponseHandler resp) {
+        Sampler sampler = platform.getSamplerContainer().getActiveSampler();
+        if (sampler == null) {
             resp.replyPrefixed(text("There isn't an active profiler running."));
         } else {
-            close();
+            platform.getSamplerContainer().stopActiveSampler();
             resp.broadcastPrefixed(text("Profiler has been cancelled.", GOLD));
         }
     }
 
     private void profilerStop(SparkPlatform platform, CommandSender sender, CommandResponseHandler resp, Arguments arguments) {
-        if (this.activeSampler == null) {
+        Sampler sampler = platform.getSamplerContainer().getActiveSampler();
+
+        if (sampler == null) {
             resp.replyPrefixed(text("There isn't an active profiler running."));
         } else {
-            this.activeSampler.stop();
+            platform.getSamplerContainer().unsetActiveSampler(sampler);
+            sampler.stop();
 
             boolean saveToFile = arguments.boolFlag("save-to-file");
             if (saveToFile) {
@@ -307,8 +298,7 @@ public class SamplerModule implements CommandModule {
             String comment = Iterables.getFirst(arguments.stringFlag("comment"), null);
             MethodDisambiguator methodDisambiguator = new MethodDisambiguator();
             MergeMode mergeMode = arguments.boolFlag("separate-parent-calls") ? MergeMode.separateParentCalls(methodDisambiguator) : MergeMode.sameMethod(methodDisambiguator);
-            handleUpload(platform, resp, this.activeSampler, comment, mergeMode, saveToFile);
-            this.activeSampler = null;
+            handleUpload(platform, resp, sampler, comment, mergeMode, saveToFile);
         }
     }
 
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java
index 52a7387..382950a 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java
@@ -93,15 +93,28 @@ public class SamplerBuilder {
     }
 
     public Sampler start(SparkPlatform platform) {
+        boolean onlyTicksOverMode = this.ticksOver != -1 && this.tickHook != null;
+        boolean canUseAsyncProfiler = this.useAsyncProfiler &&
+                !(this.ignoreSleeping || this.ignoreNative) &&
+                !(this.threadDumper instanceof ThreadDumper.Regex) &&
+                AsyncProfilerAccess.getInstance(platform).checkSupported(platform);
+
+
         int intervalMicros = (int) (this.samplingInterval * 1000d);
 
         Sampler sampler;
-        if (this.ticksOver != -1 && this.tickHook != null) {
-            sampler = new JavaSampler(platform, intervalMicros, this.threadDumper, this.threadGrouper, this.timeout, this.ignoreSleeping, this.ignoreNative, this.tickHook, this.ticksOver);
-        } else if (this.useAsyncProfiler && !(this.threadDumper instanceof ThreadDumper.Regex) && AsyncProfilerAccess.getInstance(platform).checkSupported(platform)) {
-            sampler = new AsyncSampler(platform, intervalMicros, this.threadDumper, this.threadGrouper, this.timeout);
+        if (onlyTicksOverMode) {
+            sampler = new JavaSampler(platform, intervalMicros, this.threadDumper,
+                    this.threadGrouper, this.timeout, this.ignoreSleeping, this.ignoreNative,
+                    this.tickHook, this.ticksOver);
+
+        } else if (canUseAsyncProfiler) {
+            sampler = new AsyncSampler(platform, intervalMicros, this.threadDumper,
+                    this.threadGrouper, this.timeout);
+
         } else {
-            sampler = new JavaSampler(platform, intervalMicros, this.threadDumper, this.threadGrouper, this.timeout, this.ignoreSleeping, this.ignoreNative);
+            sampler = new JavaSampler(platform, intervalMicros, this.threadDumper,
+                    this.threadGrouper, this.timeout, this.ignoreSleeping, this.ignoreNative);
         }
 
         sampler.start();
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
new file mode 100644
index 0000000..55913d8
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerContainer.java
@@ -0,0 +1,76 @@
+/*
+ * 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 java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * Container for the active sampler.
+ */
+public class SamplerContainer implements AutoCloseable {
+
+    private final AtomicReference<Sampler> activeSampler = new AtomicReference<>();
+
+    /**
+     * Gets the active sampler, or null if a sampler is not active.
+     *
+     * @return the active sampler
+     */
+    public Sampler getActiveSampler() {
+        return this.activeSampler.get();
+    }
+
+    /**
+     * Sets the active sampler, throwing an exception if another sampler is already active.
+     *
+     * @param sampler the sampler
+     */
+    public void setActiveSampler(Sampler sampler) {
+        if (!this.activeSampler.compareAndSet(null, sampler)) {
+            throw new IllegalStateException("Attempted to set active sampler when another was already active!");
+        }
+    }
+
+    /**
+     * Unsets the active sampler, if the provided sampler is active.
+     *
+     * @param sampler the sampler
+     */
+    public void unsetActiveSampler(Sampler sampler) {
+        this.activeSampler.compareAndSet(sampler, null);
+    }
+
+    /**
+     * Stops the active sampler, if there is one.
+     */
+    public void stopActiveSampler() {
+        Sampler sampler = this.activeSampler.getAndSet(null);
+        if (sampler != null) {
+            sampler.stop();
+        }
+    }
+
+    @Override
+    public void close() {
+        stopActiveSampler();
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/AbstractDataAggregator.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/AbstractDataAggregator.java
index ad9dee4..2c003e5 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/AbstractDataAggregator.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/AbstractDataAggregator.java
@@ -27,6 +27,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.IntPredicate;
 
 /**
  * Abstract implementation of {@link DataAggregator}.
@@ -52,6 +53,11 @@ public abstract class AbstractDataAggregator implements DataAggregator {
     }
 
     @Override
+    public void pruneData(IntPredicate timeWindowPredicate) {
+        this.threadData.values().removeIf(node -> node.removeTimeWindowsRecursively(timeWindowPredicate));
+    }
+
+    @Override
     public List<ThreadNode> exportData() {
         List<ThreadNode> data = new ArrayList<>(this.threadData.values());
         for (ThreadNode node : data) {
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java
index 5590a96..ed33204 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java
@@ -24,6 +24,7 @@ import me.lucko.spark.common.sampler.node.ThreadNode;
 import me.lucko.spark.proto.SparkSamplerProtos.SamplerMetadata;
 
 import java.util.List;
+import java.util.function.IntPredicate;
 
 /**
  * Aggregates sampling data.
@@ -38,6 +39,13 @@ public interface DataAggregator {
     List<ThreadNode> exportData();
 
     /**
+     * Prunes windows of data from this aggregator if the given {@code timeWindowPredicate} returns true.
+     *
+     * @param timeWindowPredicate the predicate
+     */
+    void pruneData(IntPredicate timeWindowPredicate);
+
+    /**
      * Gets metadata about the data aggregator instance.
      */
     SamplerMetadata.DataAggregator getMetadata();
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/async/AsyncSampler.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/async/AsyncSampler.java
index 2c9bb5f..cbc81c7 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/async/AsyncSampler.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/async/AsyncSampler.java
@@ -76,15 +76,20 @@ public class AsyncSampler extends AbstractSampler {
             this.windowStatisticsCollector.startCountingTicks(tickHook);
         }
 
-        int window = ProfilingWindowUtils.unixMillisToWindow(System.currentTimeMillis());
+        int window = ProfilingWindowUtils.windowNow();
 
         AsyncProfilerJob job = this.profilerAccess.startNewProfilerJob();
         job.init(this.platform, this.interval, this.threadDumper, window);
         job.start();
         this.currentJob = job;
 
-        // rotate the sampler job every minute to put data into a new window
-        this.scheduler.scheduleAtFixedRate(this::rotateProfilerJob, 1, 1, TimeUnit.MINUTES);
+        // rotate the sampler job to put data into a new window
+        this.scheduler.scheduleAtFixedRate(
+                this::rotateProfilerJob,
+                ProfilingWindowUtils.WINDOW_SIZE_SECONDS,
+                ProfilingWindowUtils.WINDOW_SIZE_SECONDS,
+                TimeUnit.SECONDS
+        );
 
         recordInitialGcStats();
         scheduleTimeout();
@@ -117,6 +122,9 @@ public class AsyncSampler extends AbstractSampler {
 
                 // aggregate the output of the previous job
                 previousJob.aggregate(this.dataAggregator);
+
+                // prune data older than the history size
+                this.dataAggregator.pruneData(ProfilingWindowUtils.keepHistoryBefore(window));
             }
         } catch (Throwable e) {
             e.printStackTrace();
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/java/JavaSampler.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/java/JavaSampler.java
index 8c96fd3..6aad5e3 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/java/JavaSampler.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/java/JavaSampler.java
@@ -34,8 +34,6 @@ import me.lucko.spark.common.sampler.window.WindowStatisticsCollector;
 import me.lucko.spark.common.tick.TickHook;
 import me.lucko.spark.proto.SparkSamplerProtos.SamplerData;
 
-import org.checkerframework.checker.units.qual.A;
-
 import java.lang.management.ManagementFactory;
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
@@ -145,10 +143,15 @@ public class JavaSampler extends AbstractSampler implements Runnable {
                 JavaSampler.this.dataAggregator.insertData(threadInfo, this.window);
             }
 
-            // if we have just stepped over into a new window, collect statistics for the previous window
+            // if we have just stepped over into a new window...
             int previousWindow = JavaSampler.this.lastWindow.getAndSet(this.window);
             if (previousWindow != 0 && previousWindow != this.window) {
+
+                // collect statistics for the previous window
                 JavaSampler.this.windowStatisticsCollector.measureNow(previousWindow);
+
+                // prune data older than the history size
+                JavaSampler.this.dataAggregator.pruneData(ProfilingWindowUtils.keepHistoryBefore(this.window));
             }
         }
     }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java
index e6f6cf5..2e4b055 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java
@@ -20,17 +20,18 @@
 
 package me.lucko.spark.common.sampler.node;
 
-import me.lucko.spark.common.sampler.async.jfr.Dictionary;
 import me.lucko.spark.common.sampler.window.ProtoTimeEncoder;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.LongAdder;
-import java.util.stream.IntStream;
+import java.util.function.IntPredicate;
 
 /**
  * Encapsulates a timed node in the sampling stack.
@@ -43,9 +44,9 @@ public abstract class AbstractNode {
     private final Map<StackTraceNode.Description, StackTraceNode> children = new ConcurrentHashMap<>();
 
     /** The accumulated sample time for this node, measured in microseconds */
-    // long key = the window (effectively System.currentTimeMillis() / 60_000)
+    // Integer key = the window (effectively System.currentTimeMillis() / 60_000)
     // LongAdder value = accumulated time in microseconds
-    private final Dictionary<LongAdder> times = new Dictionary<>();
+    private final Map<Integer, LongAdder> times = new HashMap<>();
 
     /**
      * Gets the time accumulator for a given window
@@ -67,10 +68,18 @@ public abstract class AbstractNode {
      *
      * @return the time windows
      */
-    public IntStream getTimeWindows() {
-        IntStream.Builder keys = IntStream.builder();
-        this.times.forEach((key, value) -> keys.add((int) key));
-        return keys.build();
+    public Set<Integer> getTimeWindows() {
+        return this.times.keySet();
+    }
+
+    /**
+     * Removes time windows from this node if they pass the given {@code predicate} test.
+     *
+     * @param predicate the predicate
+     * @return true if any time windows were removed
+     */
+    public boolean removeTimeWindows(IntPredicate predicate) {
+        return this.times.keySet().removeIf(predicate::test);
     }
 
     /**
@@ -100,7 +109,7 @@ public abstract class AbstractNode {
      * @param other the other node
      */
     protected void merge(AbstractNode other) {
-        other.times.forEach((key, value) -> getTimeAccumulator((int) key).add(value.longValue()));
+        other.times.forEach((key, value) -> getTimeAccumulator(key).add(value.longValue()));
         for (Map.Entry<StackTraceNode.Description, StackTraceNode> child : other.children.entrySet()) {
             resolveChild(child.getKey()).merge(child.getValue());
         }
@@ -127,7 +136,6 @@ public abstract class AbstractNode {
             list.add(child);
         }
 
-        //list.sort(null);
         return list;
     }
 
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java
index 9faece6..5035046 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java
@@ -25,9 +25,13 @@ import me.lucko.spark.common.util.IndexedListBuilder;
 import me.lucko.spark.proto.SparkSamplerProtos;
 
 import java.util.ArrayDeque;
+import java.util.Collection;
 import java.util.Deque;
+import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Queue;
+import java.util.function.IntPredicate;
 
 /**
  * The root of a sampling stack for a given thread / thread group.
@@ -89,6 +93,46 @@ public final class ThreadNode extends AbstractNode {
         }
     }
 
+    /**
+     * Removes time windows that match the given {@code predicate}.
+     *
+     * @param predicate the predicate to use to test the time windows
+     * @return true if this node is now empty
+     */
+    public boolean removeTimeWindowsRecursively(IntPredicate predicate) {
+        Queue<AbstractNode> queue = new ArrayDeque<>();
+        queue.add(this);
+
+        while (!queue.isEmpty()) {
+            AbstractNode node = queue.remove();
+            Collection<StackTraceNode> children = node.getChildren();
+
+            boolean needToProcessChildren = false;
+
+            for (Iterator<StackTraceNode> it = children.iterator(); it.hasNext(); ) {
+                StackTraceNode child = it.next();
+
+                boolean windowsWereRemoved = child.removeTimeWindows(predicate);
+                boolean childIsNowEmpty = child.getTimeWindows().isEmpty();
+
+                if (childIsNowEmpty) {
+                    it.remove();
+                    continue;
+                }
+
+                if (windowsWereRemoved) {
+                    needToProcessChildren = true;
+                }
+            }
+
+            if (needToProcessChildren) {
+                queue.addAll(children);
+            }
+        }
+
+        return getTimeWindows().isEmpty();
+    }
+
     public SparkSamplerProtos.ThreadNode toProto(MergeMode mergeMode, ProtoTimeEncoder timeEncoder) {
         SparkSamplerProtos.ThreadNode.Builder proto = SparkSamplerProtos.ThreadNode.newBuilder()
                 .setName(getThreadLabel());
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProfilingWindowUtils.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProfilingWindowUtils.java
index 109adb3..be6f08a 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProfilingWindowUtils.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProfilingWindowUtils.java
@@ -20,17 +20,51 @@
 
 package me.lucko.spark.common.sampler.window;
 
+import me.lucko.spark.common.sampler.aggregator.DataAggregator;
+
+import java.util.function.IntPredicate;
+
 public enum ProfilingWindowUtils {
     ;
 
     /**
+     * The size/duration of a profiling window in seconds.
+     * (1 window = 1 minute)
+     */
+    public static final int WINDOW_SIZE_SECONDS = 60;
+
+    /**
+     * The number of windows to record in continuous profiling before data is dropped.
+     * (60 windows * 1 minute = 1 hour of profiling data)
+     */
+    public static final int HISTORY_SIZE = Integer.getInteger("spark.continuousProfilingHistorySize", 60);
+
+    /**
      * Gets the profiling window for the given time in unix-millis.
      *
      * @param time the time in milliseconds
      * @return the window
      */
     public static int unixMillisToWindow(long time) {
-        // one window per minute
-        return (int) (time / 60_000);
+        return (int) (time / (WINDOW_SIZE_SECONDS * 1000L));
+    }
+
+    /**
+     * Gets the window at the current time.
+     *
+     * @return the window
+     */
+    public static int windowNow() {
+        return unixMillisToWindow(System.currentTimeMillis());
+    }
+
+    /**
+     * Gets a prune predicate that can be passed to {@link DataAggregator#pruneData(IntPredicate)}.
+     *
+     * @return the prune predicate
+     */
+    public static IntPredicate keepHistoryBefore(int currentWindow) {
+        // windows that were earlier than (currentWindow minus history size) should be pruned
+        return window -> window < (currentWindow - HISTORY_SIZE);
     }
 }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProtoTimeEncoder.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProtoTimeEncoder.java
index edb2309..03da075 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProtoTimeEncoder.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/window/ProtoTimeEncoder.java
@@ -21,7 +21,6 @@
 package me.lucko.spark.common.sampler.window;
 
 import me.lucko.spark.common.sampler.async.jfr.Dictionary;
-import me.lucko.spark.common.sampler.node.AbstractNode;
 import me.lucko.spark.common.sampler.node.ThreadNode;
 
 import java.util.HashMap;
@@ -42,7 +41,7 @@ public class ProtoTimeEncoder {
     public ProtoTimeEncoder(List<ThreadNode> sourceData) {
         // get an array of all keys that show up in the source data
         this.keys = sourceData.stream()
-                .map(AbstractNode::getTimeWindows)
+                .map(n -> n.getTimeWindows().stream().mapToInt(i -> i))
                 .reduce(IntStream.empty(), IntStream::concat)
                 .distinct()
                 .sorted()
@@ -70,14 +69,14 @@ public class ProtoTimeEncoder {
      * @param times a dictionary of times (unix-time millis -> duration in microseconds)
      * @return the times encoded as a double array
      */
-    public double[] encode(Dictionary<LongAdder> times) {
+    public double[] encode(Map<Integer, LongAdder> times) {
         // construct an array of values - length needs to exactly match the
         // number of keys, even if some values are zero.
         double[] array = new double[this.keys.length];
 
         times.forEach((key, value) -> {
             // get the index for the given key
-            Integer idx = this.keysToIndex.get((int) key);
+            Integer idx = this.keysToIndex.get(key);
             if (idx == null) {
                 throw new RuntimeException("No index for key " + key + " in " + this.keysToIndex.keySet());
             }