[Java] Check if the repeating group or var data is present in the acting version when doing OTF decoding. Issue aeron-io#386.

Author: mjpt777

sbe-tool/src/main/java/uk/co/real_logic/sbe/otf/OtfMessageDecoder.java

@@ -63,7 +63,8 @@ public static int decode(
 
  final long packedValues = decodeGroups(buffer, bufferIdx, actingVersion, msgTokens, tokenIdx, numTokens, listener);
 
- bufferIdx = decodeData(buffer, bufferIndex(packedValues), msgTokens, tokenIndex(packedValues), numTokens, listener);
+ bufferIdx = decodeData(
+ buffer, bufferIndex(packedValues), msgTokens, tokenIndex(packedValues), numTokens, actingVersion, listener);
 
  listener.onEndMessage(msgTokens.get(numTokens - 1));
 
@@ -138,22 +139,30 @@ private static long decodeGroups(
  break;
  }
 
+ final boolean isPresent = token.version() <= actingVersion;
+
  final Token blockLengthToken = tokens.get(tokenIdx + 2);
- final int blockLength = Types.getInt(
+ final int blockLength = isPresent ? Types.getInt(
  buffer,
  bufferIdx + blockLengthToken.offset(),
  blockLengthToken.encoding().primitiveType(),
- blockLengthToken.encoding().byteOrder());
+ blockLengthToken.encoding().byteOrder())
+ : 0;
 
  final Token numInGroupToken = tokens.get(tokenIdx + 3);
- final int numInGroup = Types.getInt(
+ final int numInGroup = isPresent ? Types.getInt(
  buffer,
  bufferIdx + numInGroupToken.offset(),
  numInGroupToken.encoding().primitiveType(),
- numInGroupToken.encoding().byteOrder());
+ numInGroupToken.encoding().byteOrder())
+ : 0;
 
  final Token dimensionTypeComposite = tokens.get(tokenIdx + 1);
- bufferIdx += dimensionTypeComposite.encodedLength();
+
+ if (isPresent)
+ {
+ bufferIdx += dimensionTypeComposite.encodedLength();
+ }
 
  final int beginFieldsIdx = tokenIdx + dimensionTypeComposite.componentTokenCount() + 1;
 
@@ -171,7 +180,7 @@ private static long decodeGroups(
  buffer, bufferIdx, actingVersion, tokens, afterFieldsIdx, numTokens, listener);
 
  bufferIdx = decodeData(
- buffer, bufferIndex(packedValues), tokens, tokenIndex(packedValues), numTokens, listener);
+ buffer, bufferIndex(packedValues), tokens, tokenIndex(packedValues), numTokens, actingVersion, listener);
 
  listener.onEndGroup(token, i, numInGroup);
  }
@@ -194,7 +203,7 @@ private static void decodeComposite(
  {
  listener.onBeginComposite(fieldToken, tokens, tokenIdx, toIndex);
 
- for (int i = tokenIdx + 1; i < toIndex;)
+ for (int i = tokenIdx + 1; i < toIndex; )
  {
  final Token typeToken = tokens.get(i);
  final int nextFieldIdx = i + typeToken.componentTokenCount();
@@ -235,6 +244,7 @@ private static int decodeData(
  final List<Token> tokens,
  int tokenIdx,
  final int numTokens,
+ final int actingVersion,
  final TokenListener listener)
  {
  while (tokenIdx < numTokens)
@@ -245,15 +255,21 @@ private static int decodeData(
  break;
  }
 
+ final boolean isPresent = token.version() <= actingVersion;
+
  final Token lengthToken = tokens.get(tokenIdx + 2);
- final int length = Types.getInt(
+ final int length = isPresent ? Types.getInt(
  buffer,
  bufferIdx + lengthToken.offset(),
  lengthToken.encoding().primitiveType(),
- lengthToken.encoding().byteOrder());
+ lengthToken.encoding().byteOrder())
+ : 0;
 
  final Token dataToken = tokens.get(tokenIdx + 3);
- bufferIdx += dataToken.offset();
+ if (isPresent)
+ {
+ bufferIdx += dataToken.offset();
+ }
 
  listener.onVarData(token, buffer, bufferIdx, length, dataToken);