[CASSANDRA-1680] Behavior of column value ByteBuffer returned from Thrift calls is surprising

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Invalid
• Severity: Normal
• Assignee: Unassigned
• Reporter: James P. Ancona
• Created: 28/Oct/10 22:26
• Updated: 16/Apr/19 09:33
• Resolved: 28/Oct/10 22:35

Description

The Thrift Column object has a public ByteBuffer value member. In order to safely use that member, you must first process it by calling TBaseHelper.rightSize(). The Thrift Column object does this when getValue() is called, but of course has no way to do so when the value ByteBuffer is accessed directly. The end result is that you get unexpected results when accessing the ByteBuffer's underlying byte array. I suppose that arguably users of thrift should understand ByteBuffer semantics well enough to avoid getting burned, but I think in practice this is unlikely.

You can reproduce the problem with the following sequence of operations in cassandra-cli in the cassandra-0.7 branch:

 
[default@MyKeyspace] create column family CF1 with comparator=UTF8Type
76ab2284-e2e1-11df-93c0-e700f669bcfc
[default@MyKeyspace] set CF1[key][integer] = Integer(12345678987654321)
Value inserted.
[default@MyKeyspace] get CF1[key][integer]
=> (column=integer, value=12345678987654321, timestamp=1288304422843000)
[default@MyKeyspace] get CF1[key]         
=> (column=integer, value=-8104275257521291409654259134258589618690198366301968500366925384201062337700106679188936883799193604223363867889371831541230052432517523790062908835405316953744191265273683116032, timestamp=1288304422843000)
Returned 1 results.

Note that the first Get returns the value that was set, but the second returns a bogus value because it goes through a code path that uses the value ByteBuffer directly. I can supply a patch for cassandra-cli, but I wonder if there's something that can be done at the Thrift level to make it harder for this to occur.