fast float/double writer option (#749)

FasterXML · Jun 22, 2022 · 84dd12a · 84dd12a
1 parent 011e31f
commit 84dd12a
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Showing 9 changed files with 118 additions and 35 deletions.
diff --git a/src/main/java/com/fasterxml/jackson/core/JsonGenerator.java b/src/main/java/com/fasterxml/jackson/core/JsonGenerator.java
@@ -240,6 +240,15 @@ public enum Feature {
          * @since 2.5
          */
         IGNORE_UNKNOWN(false),
+
+        /**
+         * Feature that determines whether to use standard Java code to write floats/doubles (default) or
+         * use the Schubfach algorithm which is faster. The latter approach may lead to small
+         * differences in the precision of the float/double that is written to the JSON output.
+         *
+         * @since 2.14
+         */
+        USE_FAST_DOUBLE_WRITER(false)
         ;
 
         private final boolean _defaultState;

diff --git a/src/main/java/com/fasterxml/jackson/core/StreamWriteFeature.java b/src/main/java/com/fasterxml/jackson/core/StreamWriteFeature.java
@@ -110,6 +110,15 @@ public enum StreamWriteFeature
      * property will result in a {@link JsonProcessingException}
      */
     IGNORE_UNKNOWN(JsonGenerator.Feature.IGNORE_UNKNOWN),
+
+    /**
+     * Feature that determines whether to use standard Java code to write floats/doubles (default) or
+     * use the Schubfach algorithm which is faster. The latter approach may lead to small
+     * differences in the precision of the float/double that is written to the JSON output.
+     *
+     * @since 2.14
+     */
+    USE_FAST_DOUBLE_WRITER(JsonGenerator.Feature.USE_FAST_DOUBLE_WRITER)
     ;
 
     /**

diff --git a/src/main/java/com/fasterxml/jackson/core/io/NumberOutput.java b/src/main/java/com/fasterxml/jackson/core/io/NumberOutput.java
@@ -1,5 +1,8 @@
 package com.fasterxml.jackson.core.io;
 
+import com.fasterxml.jackson.core.io.schubfach.DoubleToDecimal;
+import com.fasterxml.jackson.core.io.schubfach.FloatToDecimal;
+
 public final class NumberOutput
 {
     private static int MILLION = 1000000;
@@ -273,13 +276,41 @@ public static String toString(long v) {
         return Long.toString(v);
     }
 
-    public static String toString(double v) {
-        return Double.toString(v);
+    /**
+     * @param v double
+     * @return double as a string
+     */
+    public static String toString(final double v) {
+        return toString(v, false);
+    }
+
+    /**
+     * @param v double
+     * @param useFastWriter whether to use Schubfach algorithm to write output (default false)
+     * @return double as a string
+     * @since 2.14
+     */
+    public static String toString(final double v, final boolean useFastWriter) {
+        return useFastWriter ? DoubleToDecimal.toString(v) : Double.toString(v);
     }
 
-    // @since 2.6
-    public static String toString(float v) {
-        return Float.toString(v);
+    /**
+     * @param v float
+     * @return float as a string
+     * @since 2.6
+     */
+    public static String toString(final float v) {
+        return toString(v, false);
+    }
+
+    /**
+     * @param v float
+     * @param useFastWriter whether to use Schubfach algorithm to write output (default false)
+     * @return float as a string
+     * @since 2.14
+     */
+    public static String toString(final float v, final boolean useFastWriter) {
+        return useFastWriter ? FloatToDecimal.toString(v) : Float.toString(v);
     }
 
     /*

diff --git a/src/main/java/com/fasterxml/jackson/core/json/UTF8JsonGenerator.java b/src/main/java/com/fasterxml/jackson/core/json/UTF8JsonGenerator.java
@@ -1027,12 +1027,12 @@ public void writeNumber(double d) throws IOException
         if (_cfgNumbersAsStrings ||
             (NumberOutput.notFinite(d)
                 && Feature.QUOTE_NON_NUMERIC_NUMBERS.enabledIn(_features))) {
-            writeString(String.valueOf(d));
+            writeString(NumberOutput.toString(d, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
             return;
         }
         // What is the max length for doubles? 40 chars?
         _verifyValueWrite(WRITE_NUMBER);
-        writeRaw(String.valueOf(d));
+        writeRaw(NumberOutput.toString(d, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
     }
 
     @SuppressWarnings("deprecation")
@@ -1042,12 +1042,12 @@ public void writeNumber(float f) throws IOException
         if (_cfgNumbersAsStrings ||
             (NumberOutput.notFinite(f)
                 && Feature.QUOTE_NON_NUMERIC_NUMBERS.enabledIn(_features))) {
-            writeString(String.valueOf(f));
+            writeString(NumberOutput.toString(f, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
             return;
         }
         // What is the max length for floats?
         _verifyValueWrite(WRITE_NUMBER);
-        writeRaw(String.valueOf(f));
+        writeRaw(NumberOutput.toString(f, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
     }
 
     @Override

diff --git a/src/main/java/com/fasterxml/jackson/core/json/WriterBasedJsonGenerator.java b/src/main/java/com/fasterxml/jackson/core/json/WriterBasedJsonGenerator.java
@@ -801,12 +801,12 @@ public void writeNumber(double d) throws IOException
     {
         if (_cfgNumbersAsStrings ||
                 (NumberOutput.notFinite(d) && isEnabled(Feature.QUOTE_NON_NUMERIC_NUMBERS))) {
-            writeString(String.valueOf(d));
+            writeString(NumberOutput.toString(d, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
             return;
         }
         // What is the max length for doubles? 40 chars?
         _verifyValueWrite(WRITE_NUMBER);
-        writeRaw(String.valueOf(d));
+        writeRaw(NumberOutput.toString(d, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
     }
 
     @SuppressWarnings("deprecation")
@@ -815,12 +815,12 @@ public void writeNumber(float f) throws IOException
     {
         if (_cfgNumbersAsStrings ||
                 (NumberOutput.notFinite(f) && isEnabled(Feature.QUOTE_NON_NUMERIC_NUMBERS))) {
-            writeString(String.valueOf(f));
+            writeString(NumberOutput.toString(f, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
             return;
         }
         // What is the max length for floats?
         _verifyValueWrite(WRITE_NUMBER);
-        writeRaw(String.valueOf(f));
+        writeRaw(NumberOutput.toString(f, isEnabled(Feature.USE_FAST_DOUBLE_WRITER)));
     }
 
     @Override

diff --git a/src/test/java/com/fasterxml/jackson/core/write/ArrayGenerationTest.java b/src/test/java/com/fasterxml/jackson/core/write/ArrayGenerationTest.java
@@ -13,7 +13,11 @@
 public class ArrayGenerationTest extends BaseTest
 {
     private final JsonFactory FACTORY = new JsonFactory();
-
+
+    protected JsonFactory jsonFactory() {
+        return FACTORY;
+    }
+
     public void testIntArray() throws Exception
     {
         _testIntArray(false);
@@ -124,8 +128,8 @@ private void _testIntArray(boolean useBytes, int elements, int pre, int post) th
         StringWriter sw = new StringWriter();
         ByteArrayOutputStream bytes = new ByteArrayOutputStream();
 
-        JsonGenerator gen = useBytes ? FACTORY.createGenerator(bytes)
-                : FACTORY.createGenerator(sw);
+        JsonGenerator gen = useBytes ? jsonFactory().createGenerator(bytes)
+                : jsonFactory().createGenerator(sw);
 
         gen.writeArray(values, pre, elements);
         gen.close();
@@ -137,8 +141,8 @@ private void _testIntArray(boolean useBytes, int elements, int pre, int post) th
             json = sw.toString();
         }
 
-        JsonParser p = useBytes ? FACTORY.createParser(bytes.toByteArray())
-                : FACTORY.createParser(json);
+        JsonParser p = useBytes ? jsonFactory().createParser(bytes.toByteArray())
+                : jsonFactory().createParser(json);
         assertToken(JsonToken.START_ARRAY, p.nextToken());
         for (int i = 0; i < elements; ++i) {
             if ((i & 1) == 0) { // alternate
@@ -165,8 +169,8 @@ private void _testLongArray(boolean useBytes, int elements, int pre, int post) t
         StringWriter sw = new StringWriter();
         ByteArrayOutputStream bytes = new ByteArrayOutputStream();
 
-        JsonGenerator gen = useBytes ? FACTORY.createGenerator(bytes)
-                : FACTORY.createGenerator(sw);
+        JsonGenerator gen = useBytes ? jsonFactory().createGenerator(bytes)
+                : jsonFactory().createGenerator(sw);
 
         gen.writeArray(values, pre, elements);
         gen.close();
@@ -178,8 +182,8 @@ private void _testLongArray(boolean useBytes, int elements, int pre, int post) t
             json = sw.toString();
         }
 
-        JsonParser p = useBytes ? FACTORY.createParser(bytes.toByteArray())
-                : FACTORY.createParser(json);
+        JsonParser p = useBytes ? jsonFactory().createParser(bytes.toByteArray())
+                : jsonFactory().createParser(json);
         assertToken(JsonToken.START_ARRAY, p.nextToken());
         for (int i = 0; i < elements; ++i) {
             if ((i & 1) == 0) { // alternate
@@ -206,8 +210,8 @@ private void _testDoubleArray(boolean useBytes, int elements, int pre, int post)
         StringWriter sw = new StringWriter();
         ByteArrayOutputStream bytes = new ByteArrayOutputStream();
 
-        JsonGenerator gen = useBytes ? FACTORY.createGenerator(bytes)
-                : FACTORY.createGenerator(sw);
+        JsonGenerator gen = useBytes ? jsonFactory().createGenerator(bytes)
+                : jsonFactory().createGenerator(sw);
 
         gen.writeArray(values, pre, elements);
         gen.close();
@@ -219,8 +223,8 @@ private void _testDoubleArray(boolean useBytes, int elements, int pre, int post)
             json = sw.toString();
         }
 
-        JsonParser p = useBytes ? FACTORY.createParser(bytes.toByteArray())
-                : FACTORY.createParser(json);
+        JsonParser p = useBytes ? jsonFactory().createParser(bytes.toByteArray())
+                : jsonFactory().createParser(json);
         assertToken(JsonToken.START_ARRAY, p.nextToken());
         for (int i = 0; i < elements; ++i) {
             JsonToken t = p.nextToken();
@@ -248,8 +252,8 @@ private void _testStringArray(boolean useBytes, int elements, int pre, int post)
         StringWriter sw = new StringWriter();
         ByteArrayOutputStream bytes = new ByteArrayOutputStream();
 
-        JsonGenerator gen = useBytes ? FACTORY.createGenerator(bytes)
-                : FACTORY.createGenerator(sw);
+        JsonGenerator gen = useBytes ? jsonFactory().createGenerator(bytes)
+                : jsonFactory().createGenerator(sw);
 
         gen.writeArray(values, pre, elements);
         gen.close();
@@ -261,8 +265,8 @@ private void _testStringArray(boolean useBytes, int elements, int pre, int post)
             json = sw.toString();
         }
 
-        JsonParser p = useBytes ? FACTORY.createParser(bytes.toByteArray())
-                : FACTORY.createParser(json);
+        JsonParser p = useBytes ? jsonFactory().createParser(bytes.toByteArray())
+                : jsonFactory().createParser(json);
         assertToken(JsonToken.START_ARRAY, p.nextToken());
         for (int i = 0; i < elements; ++i) {
             JsonToken t = p.nextToken();

diff --git a/src/test/java/com/fasterxml/jackson/core/write/FastDoubleArrayGenerationTest.java b/src/test/java/com/fasterxml/jackson/core/write/FastDoubleArrayGenerationTest.java
@@ -0,0 +1,12 @@
+package com.fasterxml.jackson.core.write;
+
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.StreamWriteFeature;
+
+public class FastDoubleArrayGenerationTest extends ArrayGenerationTest {
+    private final JsonFactory FACTORY = JsonFactory.builder().enable(StreamWriteFeature.USE_FAST_DOUBLE_WRITER).build();
+
+    protected JsonFactory jsonFactory() {
+        return FACTORY;
+    }
+}
diff --git a/src/test/java/com/fasterxml/jackson/core/write/FastDoubleObjectWriteTest.java b/src/test/java/com/fasterxml/jackson/core/write/FastDoubleObjectWriteTest.java
@@ -0,0 +1,12 @@
+package com.fasterxml.jackson.core.write;
+
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.StreamWriteFeature;
+
+public class FastDoubleObjectWriteTest extends ObjectWriteTest {
+    private final JsonFactory FACTORY = JsonFactory.builder().enable(StreamWriteFeature.USE_FAST_DOUBLE_WRITER).build();
+
+    protected JsonFactory jsonFactory() {
+        return FACTORY;
+    }
+}
diff --git a/src/test/java/com/fasterxml/jackson/core/write/ObjectWriteTest.java b/src/test/java/com/fasterxml/jackson/core/write/ObjectWriteTest.java
@@ -13,11 +13,17 @@
 public class ObjectWriteTest
     extends BaseTest
 {
+    private final JsonFactory FACTORY = new JsonFactory();
+
+    protected JsonFactory jsonFactory() {
+        return FACTORY;
+    }
+
     public void testEmptyObjectWrite()
         throws Exception
     {
         StringWriter sw = new StringWriter();
-        JsonGenerator gen = new JsonFactory().createGenerator(sw);
+        JsonGenerator gen = jsonFactory().createGenerator(sw);
 
         JsonStreamContext ctxt = gen.getOutputContext();
         assertTrue(ctxt.inRoot());
@@ -59,7 +65,7 @@ public void testInvalidObjectWrite()
         throws Exception
     {
         StringWriter sw = new StringWriter();
-        JsonGenerator gen = new JsonFactory().createGenerator(sw);
+        JsonGenerator gen = jsonFactory().createGenerator(sw);
         gen.writeStartObject();
         // Mismatch:
         try {
@@ -75,7 +81,7 @@ public void testSimpleObjectWrite()
         throws Exception
     {
         StringWriter sw = new StringWriter();
-        JsonGenerator gen = new JsonFactory().createGenerator(sw);
+        JsonGenerator gen = jsonFactory().createGenerator(sw);
         gen.writeStartObject();
         gen.writeFieldName("first");
         gen.writeNumber(-901);
@@ -111,7 +117,7 @@ public void testConvenienceMethods()
         throws Exception
     {
         StringWriter sw = new StringWriter();
-        JsonGenerator gen = new JsonFactory().createGenerator(sw);
+        JsonGenerator gen = jsonFactory().createGenerator(sw);
         gen.writeStartObject();
 
         final String TEXT = "\"some\nString!\"";
@@ -219,7 +225,7 @@ public void testConvenienceMethodsWithNulls()
         throws Exception
     {
         StringWriter sw = new StringWriter();
-        JsonGenerator gen = new JsonFactory().createGenerator(sw);
+        JsonGenerator gen = jsonFactory().createGenerator(sw);
         gen.writeStartObject();
 
         gen.writeStringField("str", null);