Introducing BufferRecyclerPool (#1064)

Author: mariofusco

src/main/java/com/fasterxml/jackson/core/JsonFactory.java

@@ -19,12 +19,7 @@
 import com.fasterxml.jackson.core.json.async.NonBlockingJsonParser;
 import com.fasterxml.jackson.core.sym.ByteQuadsCanonicalizer;
 import com.fasterxml.jackson.core.sym.CharsToNameCanonicalizer;
-import com.fasterxml.jackson.core.util.BufferRecycler;
-import com.fasterxml.jackson.core.util.BufferRecyclerPool;
-import com.fasterxml.jackson.core.util.BufferRecyclers;
-import com.fasterxml.jackson.core.util.JacksonFeature;
-import com.fasterxml.jackson.core.util.JsonGeneratorDecorator;
-import com.fasterxml.jackson.core.util.Separators;
+import com.fasterxml.jackson.core.util.*;
 
 /**
  * The main factory class of Jackson package, used to configure and
@@ -115,8 +110,10 @@ public enum Feature
         FAIL_ON_SYMBOL_HASH_OVERFLOW(true),
 
         /**
-         * Feature that determines whether we will use {@link BufferRecycler} with
-         * {@link ThreadLocal} and {@link SoftReference}, for efficient reuse of
+         * Feature that determines whether we will use a {@link BufferRecyclerPool}
+         * for allocating and possibly recycling {@link BufferRecycler} or not.
+         * The default {@link BufferRecyclerPool} implementation uses
+         * {@link ThreadLocal} and {@link SoftReference} for efficient reuse of
          * underlying input/output buffers.
          * This usually makes sense on normal J2SE/J2EE server-side processing;
          * but may not make sense on platforms where {@link SoftReference} handling
@@ -125,6 +122,10 @@ public enum Feature
          * <a href="https://github.com/FasterXML/jackson-core/issues/189">jackson-core#189</a>
          * for a possible case)
          *<p>
+         * Note that since 2.16 naming here is somewhat misleading as this is used
+         * to now enable or disable pooling; but the actual pooling implementation
+         * is configurable and may not be based on {@link ThreadLocal}.
+         *<p>
          * This setting is enabled by default.
          *
          * @since 2.6
@@ -370,7 +371,7 @@ public static int collectDefaults() {
     public JsonFactory() { this((ObjectCodec) null); }
 
     public JsonFactory(ObjectCodec oc) {
-        _bufferRecyclerPool = BufferRecyclers.defaultRecyclerPool();
+        _bufferRecyclerPool = BufferRecyclerPool.defaultPool();
         _objectCodec = oc;
         _quoteChar = DEFAULT_QUOTE_CHAR;
         _streamReadConstraints = StreamReadConstraints.defaults();
@@ -1873,6 +1874,7 @@ protected JsonParser _createParser(InputStream in, IOContext ctxt) throws IOExce
                     e.addSuppressed(e2);
                 }
             }
+            ctxt.close();
             throw e;
         }
     }
@@ -2151,7 +2153,7 @@ protected JsonGenerator _decorate(JsonGenerator g) {
      */
     public BufferRecycler _getBufferRecycler()
     {
-        return _getBufferRecyclerPool().acquireBufferRecycler(this);
+        return _getBufferRecyclerPool().acquireBufferRecycler();
     }
 
     /**
@@ -2165,7 +2167,7 @@ public BufferRecyclerPool _getBufferRecyclerPool() {
         //   scheme, for cases where it is considered harmful (possibly
         //   on Android, for example)
         if (!Feature.USE_THREAD_LOCAL_FOR_BUFFER_RECYCLING.enabledIn(_factoryFeatures)) {
-            return BufferRecyclers.nopRecyclerPool();
+            return BufferRecyclerPool.nonRecyclingPool();
         }
         return _bufferRecyclerPool;
     }

src/main/java/com/fasterxml/jackson/core/TSFBuilder.java

@@ -9,7 +9,6 @@
 import com.fasterxml.jackson.core.json.JsonReadFeature;
 import com.fasterxml.jackson.core.json.JsonWriteFeature;
 import com.fasterxml.jackson.core.util.BufferRecyclerPool;
-import com.fasterxml.jackson.core.util.BufferRecyclers;
 import com.fasterxml.jackson.core.util.JsonGeneratorDecorator;
 
 /**
@@ -142,7 +141,7 @@ protected TSFBuilder(JsonFactory base)
     protected TSFBuilder(int factoryFeatures,
             int parserFeatures, int generatorFeatures)
     {
-        _bufferRecyclerPool = BufferRecyclers.defaultRecyclerPool();
+        _bufferRecyclerPool = BufferRecyclerPool.defaultPool();
 
         _factoryFeatures = factoryFeatures;
         _streamReadFeatures = parserFeatures;

src/main/java/com/fasterxml/jackson/core/base/ParserBase.java

@@ -395,6 +395,7 @@ protected void _checkStdFeatureChanges(int newFeatureFlags, int changedFeatures)
                 // as per [JACKSON-324], do in finally block
                 // Also, internal buffer(s) can now be released as well
                 _releaseBuffers();
+                _ioContext.close();
             }
         }
     }

src/main/java/com/fasterxml/jackson/core/io/IOContext.java

@@ -16,7 +16,7 @@
  *<p>
  * NOTE: non-final since 2.4, to allow sub-classing.
  */
-public class IOContext
+public class IOContext implements AutoCloseable
 {
     /*
     /**********************************************************************
@@ -119,6 +119,8 @@ public class IOContext
      */
     protected char[] _nameCopyBuffer;
 
+    private boolean _closed = false;
+
     /*
     /**********************************************************************
     /* Life-cycle
@@ -458,4 +460,12 @@ private IllegalArgumentException wrongBuf() {
         // sanity check failed; trying to return different, smaller buffer.
         return new IllegalArgumentException("Trying to release buffer smaller than original");
     }
+
+    @Override
+    public void close() {
+        if (!_closed) {
+            _bufferRecycler.release();
+            _closed = true;
+        }
+    }
 }

src/main/java/com/fasterxml/jackson/core/io/UTF8Writer.java

@@ -76,6 +76,7 @@ public void close()
                 illegalSurrogate(code);
             }
         }
+        _context.close();
     }
 
     @Override

src/main/java/com/fasterxml/jackson/core/json/JsonGeneratorImpl.java

@@ -120,6 +120,14 @@ public abstract class JsonGeneratorImpl extends GeneratorBase
     /**********************************************************
      */
 
+    @Override
+    public void close() throws IOException {
+        if (!isClosed()) {
+            super.close();
+            _ioContext.close();
+        }
+    }
+
     @SuppressWarnings("deprecation")
     public JsonGeneratorImpl(IOContext ctxt, int features, ObjectCodec codec)
     {
@@ -237,6 +245,23 @@ public JacksonFeatureSet<StreamWriteCapability> getWriteCapabilities() {
         return JSON_WRITE_CAPABILITIES;
     }
 
+    /*
+    /**********************************************************
+    /* Misc other accessors
+    /**********************************************************
+     */
+
+    /**
+     * Accessor for use by {@code jackson-core} itself (tests in particular).
+     *
+     * @return {@link IOContext} in use by this generator
+     *
+     * @since 2.16
+     */
+    public IOContext ioContext() {
+        return _ioContext;
+    }
+
     /*
     /**********************************************************
     /* Shared helper methods

src/main/java/com/fasterxml/jackson/core/util/BufferRecycler.java

@@ -1,17 +1,21 @@
 package com.fasterxml.jackson.core.util;
 
+import java.util.Objects;
 import java.util.concurrent.atomic.AtomicReferenceArray;
 
 /**
  * This is a small utility class, whose main functionality is to allow
- * simple reuse of raw byte/char buffers. It is usually used through
- * <code>ThreadLocal</code> member of the owning class pointing to
- * instance of this class through a <code>SoftReference</code>. The
- * end result is a low-overhead GC-cleanable recycling: hopefully
+ * simple reuse of raw byte/char buffers. It is usually allocated through
+ * {@link BufferRecyclerPool} (starting with 2.16): multiple pool
+ * implementations exists.
+ * The default pool implementation uses
+ * {@code ThreadLocal} combined with {@code SoftReference}.
+ * The end result is a low-overhead GC-cleanable recycling: hopefully
  * ideal for use by stream readers.
  *<p>
  * Rewritten in 2.10 to be thread-safe (see [jackson-core#479] for details),
- * to not rely on {@code ThreadLocal} access.
+ * to not rely on {@code ThreadLocal} access.<br />
+ * Rewritten in 2.16 to work with {@link BufferRecyclerPool} abstraction.
  */
 public class BufferRecycler
 {
@@ -82,6 +86,8 @@ public class BufferRecycler
     // Note: changed from simple array in 2.10:
     protected final AtomicReferenceArray<char[]> _charBuffers;
 
+    private BufferRecyclerPool _pool;
+
     /*
     /**********************************************************
     /* Construction
@@ -189,4 +195,36 @@ protected int charBufferLength(int ix) {
 
     protected byte[] balloc(int size) { return new byte[size]; }
     protected char[] calloc(int size) { return new char[size]; }
+
+    /**
+     * Method called by owner of this recycler instance, to provide reference to
+     * {@link BufferRecyclerPool} into which instance is to be released (if any)
+     *
+     * @since 2.16
+     */
+    BufferRecycler withPool(BufferRecyclerPool pool) {
+        if (this._pool != null) {
+            throw new IllegalStateException("BufferRecycler already linked to pool: "+pool);
+        }
+        // assign to pool to which this BufferRecycler belongs in order to release it
+        // to the same pool when the work will be completed
+        _pool = Objects.requireNonNull(pool);
+        return this;
+    }
+
+    /**
+     * Method called when owner of this recycler no longer wishes use it; this should
+     * return it to pool passed via {@code withPool()} (if any).
+     *
+     * @since 2.16
+     */
+    public void release() {
+        if (_pool != null) {
+            BufferRecyclerPool tmpPool = _pool;
+            // nullify the reference to the pool in order to avoid the risk of releasing
+            // the same BufferRecycler more than once, thus compromising the pool integrity
+            _pool = null;
+            tmpPool.releaseBufferRecycler(this);
+        }
+    }
 }