Some refactoring pre #479

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

@@ -1,6 +1,7 @@
 package com.fasterxml.jackson.core.io;
 
 import java.lang.ref.SoftReference;
+import java.util.Arrays;
 
 import com.fasterxml.jackson.core.util.ByteArrayBuilder;
 import com.fasterxml.jackson.core.util.TextBuffer;
@@ -52,12 +53,6 @@ public final class JsonStringEncoder
     /**********************************************************************
      */
 
-    /**
-     * Lazily constructed text buffer used to produce JSON encoded Strings
-     * as characters (without UTF-8 encoding)
-     */
-    protected TextBuffer _text;
-
     /**
      * Lazily-constructed builder used for UTF-8 encoding of text values
      * (quoted and unquoted)
@@ -109,12 +104,8 @@ public static JsonStringEncoder getInstance() {
      */
     public char[] quoteAsString(String input)
     {
-        TextBuffer textBuffer = _text;
-        if (textBuffer == null) {
-            // no allocator; can add if we must, shouldn't need to
-            _text = textBuffer = new TextBuffer(null);
-        }
-        char[] outputBuffer = textBuffer.emptyAndGetCurrentSegment();
+        TextBuffer textBuffer = null;
+        char[] outputBuffer = new char[100];
         final int[] escCodes = CharTypes.get7BitOutputEscapes();
         final int escCodeCount = escCodes.length;
         int inPtr = 0;
@@ -130,6 +121,9 @@ public char[] quoteAsString(String input)
                     break tight_loop;
                 }
                 if (outPtr >= outputBuffer.length) {
+                    if (textBuffer == null) {
+                        textBuffer = TextBuffer.fromInitial(outputBuffer);
+                    }
                     outputBuffer = textBuffer.finishCurrentSegment();
                     outPtr = 0;
                 }
@@ -150,6 +144,9 @@ public char[] quoteAsString(String input)
                 if (first > 0) {
                     System.arraycopy(_qbuf, 0, outputBuffer, outPtr, first);
                 }
+                if (textBuffer == null) {
+                    textBuffer = TextBuffer.fromInitial(outputBuffer);
+                }
                 outputBuffer = textBuffer.finishCurrentSegment();
                 int second = length - first;
                 System.arraycopy(_qbuf, first, outputBuffer, 0, second);
@@ -159,6 +156,10 @@ public char[] quoteAsString(String input)
                 outPtr += length;
             }
         }
+
+        if (textBuffer == null) {
+            return Arrays.copyOfRange(outputBuffer, 0, outPtr);
+        }
         textBuffer.setCurrentLength(outPtr);
         return textBuffer.contentsAsArray();
     }
@@ -175,11 +176,9 @@ public char[] quoteAsString(CharSequence input)
             return quoteAsString((String) input);
         }
 
-        TextBuffer textBuffer = _text;
-        if (textBuffer == null) {
-            _text = textBuffer = new TextBuffer(null);
-        }
-        char[] outputBuffer = textBuffer.emptyAndGetCurrentSegment();
+        TextBuffer textBuffer = null;
+
+        char[] outputBuffer = new char[100];
         final int[] escCodes = CharTypes.get7BitOutputEscapes();
         final int escCodeCount = escCodes.length;
         int inPtr = 0;
@@ -195,6 +194,9 @@ public char[] quoteAsString(CharSequence input)
                     break tight_loop;
                 }
                 if (outPtr >= outputBuffer.length) {
+                    if (textBuffer == null) {
+                        textBuffer = TextBuffer.fromInitial(outputBuffer);
+                    }
                     outputBuffer = textBuffer.finishCurrentSegment();
                     outPtr = 0;
                 }
@@ -203,6 +205,7 @@ public char[] quoteAsString(CharSequence input)
                     break outer;
                 }
             }
+            // something to escape; 2 or 6-char variant? 
             char d = input.charAt(inPtr++);
             int escCode = escCodes[d];
             int length = (escCode < 0)
@@ -214,6 +217,9 @@ public char[] quoteAsString(CharSequence input)
                 if (first > 0) {
                     System.arraycopy(_qbuf, 0, outputBuffer, outPtr, first);
                 }
+                if (textBuffer == null) {
+                    textBuffer = TextBuffer.fromInitial(outputBuffer);
+                }
                 outputBuffer = textBuffer.finishCurrentSegment();
                 int second = length - first;
                 System.arraycopy(_qbuf, first, outputBuffer, 0, second);
@@ -223,6 +229,10 @@ public char[] quoteAsString(CharSequence input)
                 outPtr += length;
             }
         }
+
+        if (textBuffer == null) {
+            return Arrays.copyOfRange(outputBuffer, 0, outPtr);
+        }
         textBuffer.setCurrentLength(outPtr);
         return textBuffer.contentsAsArray();
     }

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

@@ -30,9 +30,11 @@ public final class TextBuffer
 
     /**
      * Let's start with sizable but not huge buffer, will grow as necessary
+     *<p>
+     * Reduced from 1000 down to 500 in 2.10.
      */
-    final static int MIN_SEGMENT_LEN = 1000;
-    
+    final static int MIN_SEGMENT_LEN = 500;
+
     /**
      * Let's limit maximum segment length to something sensible.
      * For 2.10, let's limit to using 64kc chunks (128 kB) -- was 256kC/512kB up to 2.9
@@ -122,6 +124,26 @@ public TextBuffer(BufferRecycler allocator) {
         _allocator = allocator;
     }
 
+    /**
+     * @since 2.10
+     */
+    protected TextBuffer(BufferRecycler allocator, char[] initialSegment) {
+        _allocator = allocator;
+        _currentSegment = initialSegment;
+        _currentSize = initialSegment.length;
+        _inputStart = -1;
+    }
+
+    /**
+     * Factory method for constructing an instance with no allocator, and
+     * with initial full segment.
+     *
+     * @since 2.10
+     */
+    public static TextBuffer fromInitial(char[] initialSegment) {
+        return new TextBuffer(null, initialSegment);
+    }
+
     /**
      * Method called to indicate that the underlying buffers should now
      * be recycled if they haven't yet been recycled. Although caller

src/test/java/com/fasterxml/jackson/core/util/TestTextBuffer.java

@@ -102,10 +102,11 @@ public void testResetWithAndSetCurrentAndReturn() {
     public void testGetCurrentSegment() {
         TextBuffer textBuffer = new TextBuffer(null);
         textBuffer.emptyAndGetCurrentSegment();
-        textBuffer.setCurrentAndReturn(1000);
+        // 26-Aug-2019, tatu: Value depends on "minimum segment size":
+        textBuffer.setCurrentAndReturn(500);
         textBuffer.getCurrentSegment();
 
-        assertEquals(1000, textBuffer.size());
+        assertEquals(500, textBuffer.size());
     }
 
     public void testAppendTakingTwoAndThreeInts() {