Gets rid of the variable map, using only the Marker pool, reducing allocations by 66%.

Author: tgregg

src/main/java/com/amazon/ion/impl/LazyEExpressionArgsReader.java

@@ -3,6 +3,7 @@
 package com.amazon.ion.impl;
 
 import com.amazon.ion.IonCursor;
+import com.amazon.ion.IonException;
 import com.amazon.ion.IonType;
 import com.amazon.ion.MacroAwareIonWriter;
 import com.amazon.ion.SymbolToken;
@@ -58,10 +59,7 @@ abstract class LazyEExpressionArgsReader {
     // Whether to produce a tape that preserves the invocation verbatim.
     private boolean verbatimTranscode = false;
 
-    //private Marker[][] markerMapPool = new Marker[4][];
-    //private int markerMapPoolIndex = -1;
-
-    private Marker[] markerPool = new Marker[16];
+    private Marker[] markerPool = new Marker[256];
     private int markerPoolIndex = -1;
 
     /**
@@ -81,9 +79,9 @@ abstract class LazyEExpressionArgsReader {
         });
     }
 
-    private Marker getMarker() {
-        int index = ++markerPoolIndex;
-        if (index == markerPool.length) {
+    private Marker getMarker(int index) {
+        markerPoolIndex = Math.max(markerPoolIndex, index);
+        while (index >= markerPool.length) {
             markerPool = Arrays.copyOf(markerPool, markerPool.length * 2);
         }
         Marker marker = markerPool[index];
@@ -94,24 +92,6 @@ private Marker getMarker() {
         return marker;
     }
 
-    /* NOTE: pooling the marker map cuts allocation rate by a lot, but is slower because of the need to Arrays.fill
-    private Marker[] getMarkerMap(int minimumSize) {
-        int index = ++markerMapPoolIndex;
-        if (index == markerMapPool.length) {
-            markerMapPool = Arrays.copyOf(markerMapPool, markerMapPool.length * 2);
-        }
-        Marker[] markerMap = markerMapPool[index];
-        if (markerMap == null || markerMap.length < minimumSize) {
-            markerMap = new Marker[minimumSize];
-            markerMapPool[index] = markerMap;
-        } else {
-            Arrays.fill(markerMap, null);
-        }
-        return markerMap;
-    }
-
-     */
-
     /**
      * @return true if the value upon which the reader is positioned represents a macro invocation; otherwise, false.
      */
@@ -251,12 +231,10 @@ protected void readValueAsExpression(boolean isImplicitRest) {
         }
     }
 
-    private int collectAndFlattenComplexEExpression(int numberOfParameters, ExpressionTape.Core macroBodyTape, List<Macro.Parameter> signature, PresenceBitmap presenceBitmap) {
+    private int collectAndFlattenComplexEExpression(int numberOfParameters, ExpressionTape.Core macroBodyTape, List<Macro.Parameter> signature, PresenceBitmap presenceBitmap, int markerPoolStartIndex) {
         // TODO drop expression groups? No longer needed after the variables are resolved. Further simplifies the evaluator. Might miss validation? Also, would need to distribute field names over the elements of the group.
         int macroBodyTapeIndex = 0;
         int numberOfVariables = macroBodyTape.getNumberOfVariables();
-        // Key: signature index. Value: Marker for the location of the argument in the stream or tape.
-        Marker[] variableMap = new Marker[numberOfVariables]; //getMarkerMap(numberOfVariables); //new Marker[numberOfVariables];
         int numberOfDuplicatedVariables = 0;
         int numberOfOutOfOrderVariables = 0;
         for (int i = 0; i < numberOfVariables; i++) {
@@ -275,11 +253,10 @@ private int collectAndFlattenComplexEExpression(int numberOfParameters, Expressi
                         presenceBitmap == null ? PresenceBitmap.EXPRESSION : presenceBitmap.get(invocationOrdinal),
                         invocationOrdinal == (numberOfParameters - 1)
                     );
-                    Marker marker = getMarker();
+                    Marker marker = getMarker(markerPoolStartIndex + invocationOrdinal);
                     marker.typeId = null;
                     marker.startIndex = startIndexInTape;
                     marker.endIndex = expressionTape.size();
-                    variableMap[variableOrdinal] = marker;
                     break;
                 } else if (invocationOrdinal < variableOrdinal) {
                     // The variable for this ordinal cannot have been read yet.
@@ -291,16 +268,15 @@ private int collectAndFlattenComplexEExpression(int numberOfParameters, Expressi
                         invocationOrdinal == (numberOfParameters - 1)
                     );
                     expressionTape = expressionTapeOrdered;
-                    Marker marker = getMarker();
+                    Marker marker = getMarker(markerPoolStartIndex + invocationOrdinal);
                     marker.startIndex = scratchStartIndex;
                     marker.endIndex = expressionTapeScratch.size();
                     // This is a sentinel to denote that the expression is in the scratch tape.
                     marker.typeId = IonTypeID.ALWAYS_INVALID_TYPE_ID;
-                    variableMap[invocationOrdinal] = marker;
                     numberOfOutOfOrderVariables++;
                 } else {
                     // This is a variable that has already been encountered.
-                    Marker marker = variableMap[variableOrdinal];
+                    Marker marker = markerPool[markerPoolStartIndex + variableOrdinal];
                     if (marker == null) {
                         throw new IllegalStateException("Every variable ordinal must be recorded as it is encountered.");
                     }
@@ -313,7 +289,7 @@ private int collectAndFlattenComplexEExpression(int numberOfParameters, Expressi
                 invocationOrdinal++;
             }
         }
-        //--markerMapPoolIndex;
+        markerPoolIndex = markerPoolStartIndex;
         return macroBodyTapeIndex;
     }
 
@@ -350,7 +326,7 @@ private ExpressionTape collectAndFlattenUserEExpressionArgs(boolean isTopLevel,
         } else if (macro.isSimple()) {
             macroBodyTapeIndex = collectAndFlattenSimpleEExpression(numberOfParameters, macroBodyTape, signature, presenceBitmap);
         } else {
-            macroBodyTapeIndex = collectAndFlattenComplexEExpression(numberOfParameters, macroBodyTape, signature, presenceBitmap);
+            macroBodyTapeIndex = collectAndFlattenComplexEExpression(numberOfParameters, macroBodyTape, signature, presenceBitmap, markerPoolIndex + 1);
         }
         // Copy everything after the last parameter.
         expressionTape.copyFromRange(macroBodyTape, macroBodyTapeIndex, macroBodyTape.size());
@@ -436,6 +412,7 @@ public void transcodeAndBeginEvaluatingMacroInvocation(LazyMacroEvaluator macroE
         macroEvaluator.initExpansion(fieldName, collectEExpressionArgs(true));
         verbatimExpressionTape.transcodeArgumentsTo(transcoder);
         verbatimExpressionTape.clear();
+        markerPoolIndex = -1;
     }
 
     /**