Add System.out/err catcher

paper-server/src/main/java/io/papermc/paper/logging/SysoutCatcher.java

@@ -0,0 +1,94 @@
+package io.papermc.paper.logging;
+
+import org.bukkit.Bukkit;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+
+public final class SysoutCatcher {
+    private static final boolean SUPPRESS_NAGS = Boolean.getBoolean("io.papermc.paper.suppress.sout.nags");
+    // Nanoseconds between nag at most; if interval is caught first, this is reset.
+    // <= 0 for disabling.
+    private static final long NAG_TIMEOUT = TimeUnit.MILLISECONDS.toNanos(
+        Long.getLong("io.papermc.paper.sout.nags.timeout", TimeUnit.MINUTES.toMillis(5L)));
+    // Count since last nag; if timeout is first, this is reset.
+    // <= 0 for disabling.
+    private static final long NAG_INTERVAL = Long.getLong("io.papermc.paper.sout.nags.interval", 200L);
+
+    // We don't particularly care about how correct this is at any given moment; let's do it on a best attempt basis.
+    // The records are also pretty small, so let's just go for a size of 64 to start...
+    //
+    // Content: Plugin name => nag object
+    //  Why plugin name?: This doesn't store a reference to the plugin; keeps the reload ability.
+    //  Why not clean on reload?: Effort.
+    private final ConcurrentMap<String, PluginNag> nagRecords = new ConcurrentHashMap<>(64);
+
+    public SysoutCatcher() {
+        System.setOut(new WrappedOutStream(System.out, Level.INFO, "[STDOUT] "));
+        System.setErr(new WrappedOutStream(System.err, Level.SEVERE, "[STDERR] "));
+    }
+
+    private final class WrappedOutStream extends PrintStream {
+        private static final StackWalker STACK_WALKER = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE);
+        private final Level level;
+        private final String prefix;
+
+        public WrappedOutStream(@NotNull final OutputStream out, final Level level, final String prefix) {
+            super(out);
+            this.level = level;
+            this.prefix = prefix;
+        }
+
+        @Override
+        public void println(@Nullable final String line) {
+            final Class<?> clazz = STACK_WALKER.getCallerClass();
+            try {
+                final JavaPlugin plugin = JavaPlugin.getProvidingPlugin(clazz);
+
+                // Instead of just printing the message, send it to the plugin's logger
+                plugin.getLogger().log(this.level, this.prefix + line);
+
+                if (SysoutCatcher.SUPPRESS_NAGS) {
+                    return;
+                }
+                if (SysoutCatcher.NAG_INTERVAL > 0 || SysoutCatcher.NAG_TIMEOUT > 0) {
+                    final PluginNag nagRecord = SysoutCatcher.this.nagRecords.computeIfAbsent(plugin.getName(), k -> new PluginNag());
+                    final boolean hasTimePassed = SysoutCatcher.NAG_TIMEOUT > 0
+                        && (nagRecord.lastNagTimestamp == Long.MIN_VALUE
+                        || nagRecord.lastNagTimestamp + SysoutCatcher.NAG_TIMEOUT <= System.nanoTime());
+                    final boolean hasMessagesPassed = SysoutCatcher.NAG_INTERVAL > 0
+                        && (nagRecord.messagesSinceNag == Long.MIN_VALUE
+                        || ++nagRecord.messagesSinceNag >= SysoutCatcher.NAG_INTERVAL);
+                    if (!hasMessagesPassed && !hasTimePassed) {
+                        return;
+                    }
+                    nagRecord.lastNagTimestamp = System.nanoTime();
+                    nagRecord.messagesSinceNag = 0;
+                }
+                Bukkit.getLogger().warning(
+                    String.format("Nag author(s): '%s' of '%s' about their usage of System.out/err.print. "
+                            + "Please use your plugin's logger instead (JavaPlugin#getLogger).",
+                        plugin.getPluginMeta().getAuthors(),
+                        plugin.getPluginMeta().getDisplayName())
+                );
+            } catch (final IllegalArgumentException | IllegalStateException e) {
+                // If anything happens, the calling class doesn't exist, there is no JavaPlugin that "owns" the calling class, etc
+                // Just print out normally, with some added information
+                Bukkit.getLogger().log(this.level, String.format("%s[%s] %s", this.prefix, clazz.getName(), line));
+            }
+        }
+    }
+
+    private static class PluginNag {
+        private long lastNagTimestamp = Long.MIN_VALUE;
+        private long messagesSinceNag = Long.MIN_VALUE;
+    }
+}

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -310,6 +310,7 @@ public final class CraftServer implements Server {
     public Set<String> activeCompatibilities = Collections.emptySet();
     private final io.papermc.paper.datapack.PaperDatapackManager datapackManager; // Paper
     public static Exception excessiveVelEx; // Paper - Velocity warnings
+    private final io.papermc.paper.logging.SysoutCatcher sysoutCatcher = new io.papermc.paper.logging.SysoutCatcher(); // Paper
 
     static {
         ConfigurationSerialization.registerClass(CraftOfflinePlayer.class);