fix: snapshot entity metrics on main thread

Reviewed-on: #3

.gitea/workflows/build.yml

@@ -79,14 +79,15 @@ jobs:
           fi
           VERSION=${TAG#v}
           JAR_PATH=$(ls build/libs/*.jar | head -n 1)
-          RELEASE_ID=$(curl -sS -X POST \
+          RELEASE_RESPONSE=$(curl -sS -X POST \
             -H "Authorization: token ${GITEA_TOKEN}" \
             -H "Content-Type: application/json" \
             "${GITEA_API}/repos/${GITHUB_REPOSITORY}/releases" \
-            -d "{\"tag_name\":\"${TAG}\",\"name\":\"${TAG}\",\"draft\":false,\"prerelease\":false}" \
+            -d "{\"tag_name\":\"${TAG}\",\"name\":\"${TAG}\",\"draft\":false,\"prerelease\":false}")
-            | python -c "import sys, json; print(json.load(sys.stdin).get('id', ''))")
+          RELEASE_ID=$(printf "%s" "$RELEASE_RESPONSE" | node -e "const fs=require('fs');const data=fs.readFileSync(0,'utf8');const json=JSON.parse(data);process.stdout.write(String(json.id||''));")
           if [ -z "$RELEASE_ID" ]; then
             echo "Failed to create release."
+            echo "$RELEASE_RESPONSE"
             exit 1
           fi
           curl -sS -X POST \

Dockerfile

@@ -1,4 +1,4 @@
-FROM gradle:8.6-jdk21
+FROM gradle:8.14-jdk21
 
 WORKDIR /workspace
 

README.md

@@ -51,6 +51,7 @@ http:
 metrics:
   enable_jvm: true
   enable_process: true
+  entity_snapshot_interval_seconds: 15
 movement:
   count_block_changes_only: true
 ```
@@ -77,7 +78,7 @@ The Gitea workflow expects these secrets/variables:
 
 ## Metrics
 
-Some metrics depend on server implementations (TPS/MSPT, player ping, tile entities). If a method is unavailable on your server build, those metrics are omitted.
+Some metrics depend on server implementations (TPS/MSPT, player ping, tile entities). If a method is unavailable on your server build, those metrics are omitted. Entity and tile counts are updated on a periodic main-thread snapshot.
 
 | Metric | Type | Labels | Description |
 | --- | --- | --- | --- |

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.3-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME

gradlew

@@ -15,6 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 
 ##############################################################################
 #
@@ -55,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -84,7 +86,7 @@ done
 # shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
 # Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
-APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -112,7 +114,7 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -203,7 +205,7 @@ fi
 DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Collect all arguments for the java command:
-#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
 #     and any embedded shellness will be escaped.
 #   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
 #     treated as '${Hostname}' itself on the command line.
@@ -211,7 +213,7 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
         -classpath "$CLASSPATH" \
-        org.gradle.wrapper.GradleWrapperMain \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
 # Stop when "xargs" is not available.

gradlew.bat

@@ -13,6 +13,8 @@
 @rem See the License for the specific language governing permissions and
 @rem limitations under the License.
 @rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
 
 @if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
@@ -68,11 +70,11 @@ goto fail
 :execute
 @rem Setup the command line
 
-set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell

src/main/java/com/prometheus/spigot/PrometheusSpigotPlugin.java

@@ -17,7 +17,9 @@ import java.net.InetSocketAddress;
 import java.util.Locale;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import org.bukkit.Bukkit;
 import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.scheduler.BukkitTask;
 
 public final class PrometheusSpigotPlugin extends JavaPlugin {
     private HttpServer httpServer;
@@ -25,6 +27,7 @@ public final class PrometheusSpigotPlugin extends JavaPlugin {
     private MetricsRegistry metricsRegistry;
     private String bearerToken;
     private boolean countBlockMovementOnly;
+    private BukkitTask snapshotTask;
 
     @Override
     public void onEnable() {
@@ -43,6 +46,8 @@ public final class PrometheusSpigotPlugin extends JavaPlugin {
 
         metricsRegistry = new MetricsRegistry(getServer(), enableJvm, enableProcess);
 
+        scheduleSnapshotTask();
+
         registerListeners();
         startHttpServer();
     }
@@ -57,6 +62,10 @@ public final class PrometheusSpigotPlugin extends JavaPlugin {
             httpExecutor.shutdownNow();
             httpExecutor = null;
         }
+        if (snapshotTask != null) {
+            snapshotTask.cancel();
+            snapshotTask = null;
+        }
     }
 
     private void registerListeners() {
@@ -95,4 +104,12 @@ public final class PrometheusSpigotPlugin extends JavaPlugin {
         httpServer.start();
         getLogger().info(String.format(Locale.ROOT, "Prometheus endpoint listening on http://%s:%d%s", bindAddress, port, path));
     }
+
+    private void scheduleSnapshotTask() {
+        int intervalSeconds = getConfig().getInt("metrics.entity_snapshot_interval_seconds", 15);
+        long intervalTicks = Math.max(20L, intervalSeconds * 20L);
+
+        metricsRegistry.refreshEntitySnapshots();
+        snapshotTask = Bukkit.getScheduler().runTaskTimer(this, metricsRegistry::refreshEntitySnapshots, intervalTicks, intervalTicks);
+    }
 }

src/main/java/com/prometheus/spigot/metrics/MetricsRegistry.java

@@ -6,6 +6,7 @@ import java.lang.management.MemoryUsage;
 import java.lang.management.ThreadMXBean;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
@@ -31,6 +32,8 @@ public final class MetricsRegistry {
     private final Method serverMsptMethod;
     private final Method playerPingMethod;
     private final Method chunkTileEntitiesMethod;
+    private volatile Map<String, Long> entityCountsSnapshot = Collections.emptyMap();
+    private volatile Map<String, Long> tileEntityCountsSnapshot = Collections.emptyMap();
 
     private final LongAdder chatMessages = new LongAdder();
     private final LongAdder playerMovements = new LongAdder();
@@ -120,6 +123,37 @@ public final class MetricsRegistry {
         pluginDisables.increment();
     }
 
+    public void refreshEntitySnapshots() {
+        Map<String, Long> entityCounts = new HashMap<>();
+        Map<String, Long> tileCounts = new HashMap<>();
+
+        for (var world : server.getWorlds()) {
+            for (Entity entity : world.getEntities()) {
+                EntityType type = entity.getType();
+                String label = normalizeLabel(type.name());
+                entityCounts.merge(label, 1L, Long::sum);
+            }
+
+            if (chunkTileEntitiesMethod != null) {
+                for (Chunk chunk : world.getLoadedChunks()) {
+                    Object result = invoke(chunkTileEntitiesMethod, chunk);
+                    if (!(result instanceof Object[] states)) {
+                        continue;
+                    }
+                    for (Object state : states) {
+                        if (state instanceof BlockState blockState) {
+                            String label = normalizeLabel(blockState.getType().name());
+                            tileCounts.merge(label, 1L, Long::sum);
+                        }
+                    }
+                }
+            }
+        }
+
+        entityCountsSnapshot = Collections.unmodifiableMap(entityCounts);
+        tileEntityCountsSnapshot = Collections.unmodifiableMap(tileCounts);
+    }
+
     public String render() {
         StringBuilder builder = new StringBuilder();
 
@@ -226,37 +260,14 @@ public final class MetricsRegistry {
     }
 
     private void appendEntityMetrics(StringBuilder builder) {
-        Map<String, Long> entityCounts = new HashMap<>();
+        appendLabeledGauge(builder, "spigot_entities_total", "Entities by type", "type", entityCountsSnapshot);
-        for (var world : server.getWorlds()) {
-            for (Entity entity : world.getEntities()) {
-                EntityType type = entity.getType();
-                String label = normalizeLabel(type.name());
-                entityCounts.merge(label, 1L, Long::sum);
-            }
-        }
-        appendLabeledGauge(builder, "spigot_entities_total", "Entities by type", "type", entityCounts);
     }
 
     private void appendTileEntityMetrics(StringBuilder builder) {
         if (chunkTileEntitiesMethod == null) {
             return;
         }
-        Map<String, Long> tileCounts = new HashMap<>();
+        appendLabeledGauge(builder, "spigot_tile_entities_total", "Tile entities by type", "type", tileEntityCountsSnapshot);
-        for (var world : server.getWorlds()) {
-            for (Chunk chunk : world.getLoadedChunks()) {
-                Object result = invoke(chunkTileEntitiesMethod, chunk);
-                if (!(result instanceof Object[] states)) {
-                    continue;
-                }
-                for (Object state : states) {
-                    if (state instanceof BlockState blockState) {
-                        String label = normalizeLabel(blockState.getType().name());
-                        tileCounts.merge(label, 1L, Long::sum);
-                    }
-                }
-            }
-        }
-        appendLabeledGauge(builder, "spigot_tile_entities_total", "Tile entities by type", "type", tileCounts);
     }
 
     private void appendPlayerPingMetrics(StringBuilder builder) {

src/main/resources/config.yml

@@ -6,5 +6,6 @@ http:
 metrics:
   enable_jvm: true
   enable_process: true
+  entity_snapshot_interval_seconds: 15
 movement:
   count_block_changes_only: true