HADOOP-19180. EC: Fix calculation errors caused by special index order (#6813). Contributed by zhengchenyu.

Reviewed-by: He Xiaoqiao <hexiaoqiao@apache.org>
Signed-off-by: Shuyan Zhang <zhangshuyan@apache.org>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/rawcoder/RSRawDecoder.java

@@ -51,7 +51,6 @@ public class RSRawDecoder extends RawErasureDecoder {
   private byte[] gfTables;
   private int[] cachedErasedIndexes;
   private int[] validIndexes;
-  private int numErasedDataUnits;
   private boolean[] erasureFlags;
 
   public RSRawDecoder(ErasureCoderOptions coderOptions) {
@@ -120,14 +119,10 @@ public class RSRawDecoder extends RawErasureDecoder {
     this.gfTables = new byte[getNumAllUnits() * getNumDataUnits() * 32];
 
     this.erasureFlags = new boolean[getNumAllUnits()];
-    this.numErasedDataUnits = 0;
 
     for (int i = 0; i < erasedIndexes.length; i++) {
       int index = erasedIndexes[i];
       erasureFlags[index] = true;
-      if (index < getNumDataUnits()) {
-        numErasedDataUnits++;
-      }
     }
 
     generateDecodeMatrix(erasedIndexes);
@@ -156,21 +151,22 @@ public class RSRawDecoder extends RawErasureDecoder {
 
     GF256.gfInvertMatrix(tmpMatrix, invertMatrix, getNumDataUnits());
 
-    for (i = 0; i < numErasedDataUnits; i++) {
-      for (j = 0; j < getNumDataUnits(); j++) {
-        decodeMatrix[getNumDataUnits() * i + j] =
-                invertMatrix[getNumDataUnits() * erasedIndexes[i] + j];
-      }
-    }
-
-    for (p = numErasedDataUnits; p < erasedIndexes.length; p++) {
-      for (i = 0; i < getNumDataUnits(); i++) {
-        s = 0;
+    for (p = 0; p < erasedIndexes.length; p++) {
+      int erasedIndex = erasedIndexes[p];
+      if (erasedIndex < getNumDataUnits()) {
         for (j = 0; j < getNumDataUnits(); j++) {
-          s ^= GF256.gfMul(invertMatrix[j * getNumDataUnits() + i],
-                  encodeMatrix[getNumDataUnits() * erasedIndexes[p] + j]);
+          decodeMatrix[getNumDataUnits() * p + j] =
+              invertMatrix[getNumDataUnits() * erasedIndexes[p] + j];
+        }
+      } else {
+        for (i = 0; i < getNumDataUnits(); i++) {
+          s = 0;
+          for (j = 0; j < getNumDataUnits(); j++) {
+            s ^= GF256.gfMul(invertMatrix[j * getNumDataUnits() + i],
+                encodeMatrix[getNumDataUnits() * erasedIndexes[p] + j]);
+          }
+          decodeMatrix[getNumDataUnits() * p + i] = s;
         }
-        decodeMatrix[getNumDataUnits() * p + i] = s;
       }
     }
   }

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/erasurecode/erasure_coder.c

@@ -132,9 +132,6 @@ static int processErasures(IsalDecoder* pCoder, unsigned char** inputs,
     index = erasedIndexes[i];
     pCoder->erasedIndexes[i] = index;
     pCoder->erasureFlags[index] = 1;
-    if (index < numDataUnits) {
-      pCoder->numErasedDataUnits++;
-    }
   }
 
   pCoder->numErased = numErased;
@@ -175,7 +172,6 @@ int decode(IsalDecoder* pCoder, unsigned char** inputs,
 
 // Clear variables used per decode call
 void clearDecoder(IsalDecoder* decoder) {
-  decoder->numErasedDataUnits = 0;
   decoder->numErased = 0;
   memset(decoder->gftbls, 0, sizeof(decoder->gftbls));
   memset(decoder->decodeMatrix, 0, sizeof(decoder->decodeMatrix));
@@ -205,24 +201,24 @@ int generateDecodeMatrix(IsalDecoder* pCoder) {
   h_gf_invert_matrix(pCoder->tmpMatrix,
                                 pCoder->invertMatrix, numDataUnits);
 
-  for (i = 0; i < pCoder->numErasedDataUnits; i++) {
+  for (p = 0; p < pCoder->numErased; p++) {
     for (j = 0; j < numDataUnits; j++) {
-      pCoder->decodeMatrix[numDataUnits * i + j] =
-                      pCoder->invertMatrix[numDataUnits *
-                      pCoder->erasedIndexes[i] + j];
-    }
-  }
-
-  for (p = pCoder->numErasedDataUnits; p < pCoder->numErased; p++) {
-    for (i = 0; i < numDataUnits; i++) {
-      s = 0;
-      for (j = 0; j < numDataUnits; j++) {
-        s ^= h_gf_mul(pCoder->invertMatrix[j * numDataUnits + i],
-          pCoder->encodeMatrix[numDataUnits *
-                                        pCoder->erasedIndexes[p] + j]);
+      int erasedIndex = pCoder->erasedIndexes[p];
+      if (erasedIndex < numDataUnits) {
+        pCoder->decodeMatrix[numDataUnits * p + j] =
+            pCoder->invertMatrix[numDataUnits *
+                                     pCoder->erasedIndexes[p] + j];
+      } else {
+        for (i = 0; i < numDataUnits; i++) {
+          s = 0;
+          for (j = 0; j < numDataUnits; j++) {
+            s ^= h_gf_mul(pCoder->invertMatrix[j * numDataUnits + i],
+                          pCoder->encodeMatrix[numDataUnits *
+                            pCoder->erasedIndexes[p] + j]);
+          }
+          pCoder->decodeMatrix[numDataUnits * p + i] = s;
+        }
       }
-
-      pCoder->decodeMatrix[numDataUnits * p + i] = s;
     }
   }
 

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/erasurecode/erasure_coder.h

@@ -62,7 +62,6 @@ typedef struct _IsalDecoder {
   unsigned char erasureFlags[MMAX];
   int erasedIndexes[MMAX];
   int numErased;
-  int numErasedDataUnits;
   unsigned char* realInputs[MMAX];
 } IsalDecoder;
 

hadoop-common-project/hadoop-common/src/main/native/src/test/org/apache/hadoop/io/erasurecode/erasure_code_test.c

@@ -27,25 +27,27 @@
 #include "erasure_code.h"
 #include "gf_util.h"
 #include "erasure_coder.h"
+#include "dump.h"
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 int main(int argc, char *argv[]) {
-  int i, j;
+  int i, j, k, l;
   char err[256];
   size_t err_len = sizeof(err);
   int chunkSize = 1024;
   int numDataUnits = 6;
   int numParityUnits = 3;
+  int numTotalUnits = numDataUnits + numParityUnits;
   unsigned char** dataUnits;
   unsigned char** parityUnits;
   IsalEncoder* pEncoder;
-  int erasedIndexes[2];
+  int erasedIndexes[3];
   unsigned char* allUnits[MMAX];
   IsalDecoder* pDecoder;
-  unsigned char* decodingOutput[2];
+  unsigned char* decodingOutput[3];
   unsigned char** backupUnits;
 
   if (0 == build_support_erasurecode()) {
@@ -82,6 +84,11 @@ int main(int argc, char *argv[]) {
     }
   }
 
+  // Allocate decode output
+  for (i = 0; i < 3; i++) {
+    decodingOutput[i] = malloc(chunkSize);
+  }
+
   pEncoder = (IsalEncoder*)malloc(sizeof(IsalEncoder));
   memset(pEncoder, 0, sizeof(*pEncoder));
   initEncoder(pEncoder, numDataUnits, numParityUnits);
@@ -95,26 +102,53 @@ int main(int argc, char *argv[]) {
   memcpy(allUnits + numDataUnits, parityUnits,
                             numParityUnits * (sizeof (unsigned char*)));
 
-  erasedIndexes[0] = 1;
-  erasedIndexes[1] = 7;
-
-  backupUnits[0] = allUnits[1];
-  backupUnits[1] = allUnits[7];
-
-  allUnits[0] = NULL; // Not to read
-  allUnits[1] = NULL;
-  allUnits[7] = NULL;
-
-  decodingOutput[0] = malloc(chunkSize);
-  decodingOutput[1] = malloc(chunkSize);
-
-  decode(pDecoder, allUnits, erasedIndexes, 2, decodingOutput, chunkSize);
-
-  for (i = 0; i < pDecoder->numErased; i++) {
-    if (0 != memcmp(decodingOutput[i], backupUnits[i], chunkSize)) {
-      fprintf(stderr, "Decoding failed\n\n");
-      dumpDecoder(pDecoder);
-      return -1;
+  for (i = 0; i < numTotalUnits; i++) {
+    for (j = 0; j < numTotalUnits; j++) {
+      for (k = 0; k < numTotalUnits; k++) {
+        int numErased;
+        if (i == j && j == k) {
+          erasedIndexes[0] = i;
+          numErased = 1;
+          backupUnits[0] = allUnits[i];
+          allUnits[i] = NULL;
+        } else if (i == j) {
+          erasedIndexes[0] = i;
+          erasedIndexes[1] = k;
+          numErased = 2;
+          backupUnits[0] = allUnits[i];
+          backupUnits[1] = allUnits[k];
+          allUnits[i] = NULL;
+          allUnits[k] = NULL;
+        } else if (i == k || j == k) {
+          erasedIndexes[0] = i;
+          erasedIndexes[1] = j;
+          numErased = 2;
+          backupUnits[0] = allUnits[i];
+          backupUnits[1] = allUnits[j];
+          allUnits[i] = NULL;
+          allUnits[j] = NULL;
+        } else {
+          erasedIndexes[0] = i;
+          erasedIndexes[1] = j;
+          erasedIndexes[2] = k;
+          numErased = 3;
+          backupUnits[0] = allUnits[i];
+          backupUnits[1] = allUnits[j];
+          backupUnits[2] = allUnits[k];
+          allUnits[i] = NULL;
+          allUnits[j] = NULL;
+          allUnits[k] = NULL;
+        }
+        decode(pDecoder, allUnits, erasedIndexes, numErased, decodingOutput, chunkSize);
+        for (l = 0; l < pDecoder->numErased; l++) {
+          if (0 != memcmp(decodingOutput[l], backupUnits[l], chunkSize)) {
+            printf("Decoding failed\n");
+            dumpDecoder(pDecoder);
+            return -1;
+          }
+          allUnits[erasedIndexes[l]] = backupUnits[l];
+        }
+      }
     }
   }
 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/erasurecode/TestErasureCodingEncodeAndDecode.java

@@ -0,0 +1,108 @@
+/**
+ * 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.hadoop.io.erasurecode;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureDecoder;
+import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureEncoder;
+import org.junit.Test;
+
+import java.util.Random;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class TestErasureCodingEncodeAndDecode {
+
+  private final static int CHUNCK = 1024;
+  private final static int DATAB_LOCKS = 6;
+  private final static int PARITY_BLOCKS = 3;
+  private final static int TOTAL_BLOCKS = DATAB_LOCKS + PARITY_BLOCKS;
+
+  @Test
+  public void testEncodeAndDecode() throws Exception {
+    Configuration conf = new Configuration();
+    int totalBytes = CHUNCK * DATAB_LOCKS;
+    Random random = new Random();
+    byte[] tmpBytes = new byte[totalBytes];
+    random.nextBytes(tmpBytes);
+    byte[][] data = new byte[DATAB_LOCKS][CHUNCK];
+    for (int i = 0; i < DATAB_LOCKS; i++) {
+      System.arraycopy(tmpBytes, i * CHUNCK, data[i], 0, CHUNCK);
+    }
+    ErasureCoderOptions coderOptions = new ErasureCoderOptions(DATAB_LOCKS, PARITY_BLOCKS);
+
+    // 1 Encode
+    RawErasureEncoder encoder =
+        CodecUtil.createRawEncoder(conf, ErasureCodeConstants.RS_CODEC_NAME, coderOptions);
+    byte[][] parity = new byte[PARITY_BLOCKS][CHUNCK];
+    encoder.encode(data, parity);
+
+    // 2 Compose the complete data
+    byte[][] all = new byte[DATAB_LOCKS + PARITY_BLOCKS][CHUNCK];
+    for (int i = 0; i < DATAB_LOCKS; i++) {
+      System.arraycopy(data[i], 0, all[i], 0, CHUNCK);
+    }
+    for (int i = 0; i < PARITY_BLOCKS; i++) {
+      System.arraycopy(parity[i], 0, all[i + DATAB_LOCKS], 0, CHUNCK);
+    }
+
+    // 3 Decode
+    RawErasureDecoder rawDecoder =
+        CodecUtil.createRawDecoder(conf, ErasureCodeConstants.RS_CODEC_NAME, coderOptions);
+    byte[][] backup = new byte[PARITY_BLOCKS][CHUNCK];
+    for (int i = 0; i < TOTAL_BLOCKS; i++) {
+      for (int j = 0; j < TOTAL_BLOCKS; j++) {
+        for (int k = 0; k < TOTAL_BLOCKS; k++) {
+          int[] erasedIndexes;
+          if (i == j && j == k) {
+            erasedIndexes = new int[]{i};
+            backup[0] = all[i];
+            all[i] = null;
+          } else if (i == j) {
+            erasedIndexes = new int[]{i, k};
+            backup[0] = all[i];
+            backup[1] = all[k];
+            all[i] = null;
+            all[k] = null;
+          } else if ((i == k) || ((j == k))) {
+            erasedIndexes = new int[]{i, j};
+            backup[0] = all[i];
+            backup[1] = all[j];
+            all[i] = null;
+            all[j] = null;
+          } else {
+            erasedIndexes = new int[]{i, j, k};
+            backup[0] = all[i];
+            backup[1] = all[j];
+            backup[2] = all[k];
+            all[i] = null;
+            all[j] = null;
+            all[k] = null;
+          }
+          byte[][] decoded = new byte[erasedIndexes.length][CHUNCK];
+          rawDecoder.decode(all, erasedIndexes, decoded);
+          for (int l = 0; l < erasedIndexes.length; l++) {
+            assertArrayEquals(backup[l], decoded[l]);
+            all[erasedIndexes[l]] = backup[l];
+          }
+        }
+      }
+    }
+  }
+}