IGNITE-28747 GridToStringBuilder#handleRecursion may cause NPE. Colle…

modules/commons/src/main/java/org/apache/ignite/internal/util/GridStringBuilder.java

@@ -68,6 +68,7 @@ public GridStringBuilder(CharSequence seq) {
     /**
      *
      * @param len Length to set.
+     * @throws UnsupportedOperationException if length limit is not supported by this GridStringBuilder
      */
     public void setLength(int len) {
         impl.setLength(len);
@@ -255,6 +256,7 @@ public GridStringBuilder appendCodePoint(int codePoint) {
      * @param start Start position to delete from.
      * @param end End position.
      * @return This buffer for chaining method calls.
+     * @throws UnsupportedOperationException if not supported by this imlementation
      */
     public GridStringBuilder d(int start, int end) {
         impl.delete(start, end);
@@ -266,6 +268,7 @@ public GridStringBuilder d(int start, int end) {
      *
      * @param index Index to delete character at.
      * @return This buffer for chaining method calls.
+     * @throws UnsupportedOperationException if not supported by this imlementation
      */
     public GridStringBuilder d(int index) {
         impl.deleteCharAt(index);
@@ -290,6 +293,7 @@ public GridStringBuilder nl() {
      * @param end End position.
      * @param str String to replace with.
      * @return This buffer for chaining method calls.
+     * @throws UnsupportedOperationException if not supported by this imlementation
      */
     public GridStringBuilder r(int start, int end, String str) {
         impl.replace(start, end, str);

modules/commons/src/main/java/org/apache/ignite/internal/util/tostring/CircularStringBuilder.java

@@ -17,13 +17,10 @@
 
 package org.apache.ignite.internal.util.tostring;
 
-import java.util.Arrays;
-
 /**
  * Basic string builder over circular buffer.
  */
 public class CircularStringBuilder {
-
     /** Value */
     private final char value[];
 
@@ -47,16 +44,6 @@ public class CircularStringBuilder {
         value = new char[capacity];
     }
 
-    /**
-     * Reset internal builder state
-     */
-    public void reset() {
-        Arrays.fill(value, (char)0);
-        finishAt = -1;
-        full = false;
-        skipped = 0;
-    }
-
     /**
      * Returns the length (character count).
      *
@@ -170,13 +157,102 @@ private CircularStringBuilder appendNull() {
         return this;
     }
 
+    /**
+     * Inserts a string into the buffer at the specified logical offset.
+     * This method is optimized to minimize the number of elements moved by choosing
+     * to shift elements from the closest end (left or right) to the insertion point.
+     *
+     * @param offset      The logical position (accounting for skipped characters)
+     *                    at which to insert.
+     * @param valToInsert The string to be inserted.
+     * @throws StringIndexOutOfBoundsException if the offset is invalid.
+     */
+    public void insert(int offset, String valToInsert) {
+        int curLength = length();
+        int offsetInsideBuf = offset - skipped;
+        if (offset < 0 || offsetInsideBuf > curLength)
+            throw new StringIndexOutOfBoundsException("Offset " + offset + " out of bounds for length " + curLength);
+        if (valToInsert == null)
+            valToInsert = "null";
+        int insertLength = valToInsert.length();
+        if (insertLength == 0)
+            return;
+        if (offsetInsideBuf == curLength) {
+            append(valToInsert);
+            return;
+        }
+        int spareSpace = value.length - curLength;
+        int insertCnt = Math.min(valToInsert.length(), spareSpace + offsetInsideBuf);
+        if (insertCnt <= 0) {
+            skipped += valToInsert.length();
+            return;
+        }
+        int bufStartShiftedOffset = full ? (finishAt + 1) % value.length : 0;
+        int shiftedOffset = (bufStartShiftedOffset + offsetInsideBuf) % value.length;
+        int moveRightCnt = ((shiftedOffset <= finishAt ? 0 : curLength) + finishAt + 1) - shiftedOffset;
+        if (!full || offset - skipped > curLength / 2) {
+            shiftRight(insertCnt, moveRightCnt);
+            int charsToSkip = Math.max(0, insertCnt - spareSpace);
+            finishAt = (finishAt + insertCnt) % value.length;
+            shiftedOffset = (shiftedOffset + insertCnt) % value.length;
+            full = curLength + insertCnt >= value.length;
+            insertStringTail(valToInsert, shiftedOffset, insertCnt);
+            skipped += charsToSkip;
+        }
+        else {
+            int moveLeftCnt = (curLength - moveRightCnt - insertCnt);
+            shiftLeft(insertCnt, moveLeftCnt);
+            insertStringTail(valToInsert, shiftedOffset, insertCnt);
+            skipped += valToInsert.length();
+        }
+    }
+
     /**
      * @return Count of skipped elements.
      */
     public int getSkipped() {
         return skipped;
     }
 
+    /**
+     * Returns a substring from the logical sequence of characters, accounting for
+     * the circular buffer structure and any skipped characters.
+     *
+     * <p>This method first validates the indices against the total logical length
+     * (skipped + visible characters). If the requested range is empty or fully within
+     * the skipped portion, an empty string is returned for efficiency.
+     *
+     * <p>It then calculates the physical indices in the internal array. If the
+     * substring wraps around the end of the circular buffer, it performs a two-part
+     * copy operation to assemble the result.
+     *
+     * @param beginIdx the beginning index, inclusive.
+     * @param endIdx the ending index, exclusive.
+     * @return a new String containing the specified subsequence.
+     * @throws StringIndexOutOfBoundsException if beginIdx or endIdx are negative,
+     *         or if endIdx is greater than the total logical length.
+     * @throws IllegalArgumentException if beginIdx is greater than endIdx.
+     */
+    public String substring(int beginIdx, int endIdx) {
+        if (beginIdx < 0 || endIdx < 0 || endIdx > skipped + length())
+            throw new StringIndexOutOfBoundsException(
+                    "Some of indexes is out of bounds. Begind index = " + beginIdx + " end index = " + endIdx);
+        if (beginIdx > endIdx)
+            throw new IllegalArgumentException(
+                    "Begin index can not be greater then end index (begin = " + beginIdx + " end = " + endIdx + ")");
+        if (endIdx <= skipped || beginIdx == endIdx) return "";
+        char resultArr[] = new char[Math.max(skipped, endIdx) - Math.max(skipped, beginIdx)];
+        int effectiveBeginIdx = ((full ? (finishAt + 1) : 0) + Math.max(skipped, beginIdx) - skipped) % value.length;
+        int effectiveEndIdx = ((full ? (finishAt + 1) : 0) + Math.max(skipped, endIdx) - skipped) % value.length;
+        if (effectiveBeginIdx >= effectiveEndIdx) {
+            System.arraycopy(value, effectiveBeginIdx, resultArr, 0, length() - effectiveBeginIdx);
+            System.arraycopy(value, 0, resultArr, length() - effectiveBeginIdx, effectiveEndIdx);
+        }
+        else
+            System.arraycopy(value, effectiveBeginIdx, resultArr, 0, effectiveEndIdx - effectiveBeginIdx);
+        return new String(resultArr);
+    }
+
     /** {@inheritDoc} */
     @Override public String toString() {
         // Create a copy, don't share the array
@@ -192,4 +268,53 @@ public int getSkipped() {
         else
             return new String(value, 0, finishAt + 1);
     }
+
+    /**
+     * Performs an in-place rightward shift of elements within the circular buffer.
+     * This is used to create space for new data by moving a block of existing elements.
+     * <p>
+     * The shift is executed in reverse order (from the end of the block to the beginning)
+     * to prevent overwriting source elements before they are copied.
+     *
+     * @param shift The starting offset from the 'finishAt' index, defining the beginning
+     *              of the block to be moved.
+     * @param moveSteps The number of elements to be shifted to the right.
+     */
+    private void shiftRight(int shift, int moveSteps) {
+        for (int i = 0; i < moveSteps; i++) {
+            int pointer = (finishAt + shift - i) % value.length;
+            value[pointer] = value[(value.length + pointer - shift) % value.length];
+        }
+    }
+
+    /**
+     * Performs a leftward shift of elements in the circular buffer.
+     * Copies elements from a source position to a destination position,
+     * effectively overwriting a range of values.
+     * <p>
+     * @param shift The offset for the source element.
+     * @param shiftsCnt The count of elements to shift.
+     */
+    private void shiftLeft(int shift, int shiftsCnt) {
+        for (int i = 0; i < shiftsCnt; i++) {
+            int pointer = (finishAt + 1 + i) % value.length;
+            value[pointer] = value[(pointer + shift) % value.length];
+        }
+    }
+
+    /**
+     * Inserts a substring from the source string into the buffer at the specified tail position.
+     * <p>
+     * The insertion is performed in reverse order (from the last character to the first) to
+     * prevent overwriting source data in the buffer before it is copied. This is a common
+     * technique for in-place buffer manipulation.
+     *
+     * @param src The source string to copy characters from.
+     * @param tailEndOffset The physical index in the buffer where the last character will be placed.
+     * @param insertCnt The number of characters from the source string to insert.
+     */
+    private void insertStringTail(String src, int tailEndOffset, int insertCnt) {
+        for (int i = 0; i < insertCnt; i++)
+            value[(value.length + tailEndOffset - i - 1) % value.length] = src.charAt(src.length() - 1 - i);
+    }
 }

modules/commons/src/main/java/org/apache/ignite/internal/util/tostring/GridToStringArrayNode.java

@@ -0,0 +1,82 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.ignite.internal.util.tostring;
+
+import org.apache.ignite.internal.util.GridStringBuilder;
+
+import static org.apache.ignite.internal.util.tostring.GridToStringBuilder.COLLECTION_LIMIT;
+import static org.apache.ignite.internal.util.tostring.GridToStringNodeFactory.getGridToStringNode;
+
+/**
+ * A node that represents an array in the string representation.
+ * It creates nodes for each element of the array and formats the output with square brackets.
+ */
+class GridToStringArrayNode extends NodeRecursionMonitor {
+    /** An array of child nodes, each representing an element of the source array. */
+    private final GridToStringNode[] nodes;
+
+    /** The rule for appending a hint about skipped elements if the array is too large. */
+    private final LongSequenceSkipRule skipRule;
+
+    /** The class object representing the type of the array. */
+    private final Class<?> arrType;
+
+    /**
+     * Constructs a new array node.
+     * Iterates over the input array, creates a node for each element,
+     * and populates the internal array up to the collection size limit.
+     * @param propName The property name.
+     * @param arr The source array.
+     * @param arrType The class object of the array's type.
+     */
+    GridToStringArrayNode(String propName, Object[] arr, Class<?> arrType) {
+        super(propName, arr);
+        try {
+            aqcuireRecursionMonitor(this);
+            this.arrType = arrType;
+            skipRule = new LongSequenceSkipRule(() -> arr.length);
+            nodes = new GridToStringNode[Math.min(COLLECTION_LIMIT, arr.length)];
+            for (int i = 0; i < nodes.length; i++) {
+                final int idx = i;
+                nodes[idx] = getGridToStringNode(null, () -> arr[idx], () -> arr[idx].getClass());
+            }
+        }
+        finally {
+            releaseRecursionMonitor();
+        }
+    }
+
+    /**
+     * Appends the string representation of the array to the builder.
+     * The format is: ArrayType [element1, element2, ...].
+     * Also appends a hint about skipped elements if necessary.
+     * @param sb The string builder to append to.
+     */
+    @Override void appendNode(GridStringBuilder sb) {
+        super.appendNode(sb);
+        sb.a(arrType.getSimpleName()).a(" [");
+        for (int i = 0; i < nodes.length - 2; i++) {
+            nodes[i].appendNode(sb);
+            sb.a(", ");
+        }
+        if (nodes.length > 0)
+            nodes[nodes.length - 1].appendNode(sb);
+        skipRule.appendSkippedCountHint(sb);
+        sb.a("]");
+    }
+}