What is the maximum key length allowed?

[CrendKing]

I noticed that even in Jackson 2.4, if a JSON key is longer than 262144 bytes, ArrayIndexOutOfBoundsException is thrown from TextBuffer. Below is the stack trace:

java.lang.ArrayIndexOutOfBoundsException
    at java.lang.System.arraycopy(Native Method)
    at com.fasterxml.jackson.core.util.TextBuffer.expandCurrentSegment(TextBuffer.java:604)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.addName(UTF8StreamJsonParser.java:2034)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.findName(UTF8StreamJsonParser.java:1928)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.parseLongFieldName(UTF8StreamJsonParser.java:1534)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.parseMediumFieldName(UTF8StreamJsonParser.java:1502)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._parseFieldName(UTF8StreamJsonParser.java:1437)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:668)
    ... <below are our code> ...

Looking at TextBuffer.expandCurrentSegment(TextBuffer.java:604), once the length of _currentSegment is increased to MAX_SEGMENT_LEN + 1 (262145) bytes, the newLen will stay at MAX_SEGMENT_LEN, which is smaller than len. Therefore System.arraycopy() will fail.

I understand it is rare to have key larger than 262144 bytes, but it would be nice if

• Jackson explicitly throw exception stating that key is too long.
• Document that the maximum key length is 262144 bytes.

OR

• Update TextBuffer to support super long key.

Thanks!

[cowtowncoder]

No such limit is intended, so this sounds like a bug. Will fix it; no reason not to support whatever fits in memory. Note that maximum segment is not directly relevant to maximum key length -- the point of segments is not to require a single contiguous array, or intermediate copies.

[cowtowncoder]

Actually, looking at code, expansion is used for case of property names (where names are kept in a single buffer) -- not so for text values, but here it is done. Regardless, something to fix.