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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-6234) Improve Documentation of VariableWidthVector Behavior
Date Wed, 14 Mar 2018 01:00:59 GMT

    [ https://issues.apache.org/jira/browse/DRILL-6234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16397932#comment-16397932
] 

ASF GitHub Bot commented on DRILL-6234:
---------------------------------------

Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/1164#discussion_r174328025
  
    --- Diff: exec/vector/src/main/codegen/templates/VariableLengthVectors.java ---
    @@ -514,6 +516,22 @@ public boolean isNull(int index){
        *   The equivalent Java primitive is '${minor.javaType!type.javaType}'
        *
        * NB: this class is automatically generated from ValueVectorTypes.tdd using FreeMarker.
    +   * </p>
    +   * <h2>Contract</h2>
    --- End diff --
    
    Might be worth summarizing how to use this:
    
    1) Write to values sequentially. Fixed-width vectors allow random access, but special
care is needed.
    2) Keep track in client code of the total time count. Call `setValueCount()` once the
vector is full to set the final value. (The vector does not know its count while a write is
in progress.)
    3) Either take responsibility for allocating enough memory, or call the `setSafe()` methods
to automatically extend the vector.
    4) Once vectors are written, they are immutable; no additional writes of any kind are
allowed to that vector.


> Improve Documentation of VariableWidthVector Behavior
> -----------------------------------------------------
>
>                 Key: DRILL-6234
>                 URL: https://issues.apache.org/jira/browse/DRILL-6234
>             Project: Apache Drill
>          Issue Type: Improvement
>            Reporter: Timothy Farkas
>            Assignee: Timothy Farkas
>            Priority: Major
>
> Doing the following will throw an Index out of bounds exception.
> {code}
>       final VarCharVector vector = new VarCharVector(field, allocator);
>       vector.allocateNew();
>       vector.getMutator().setValueCount(100);
> {code}
> The expected behavior is to resize the array appropriately. If an index is uninitialized
you should not call get for that index.
> {code}
> 	at org.apache.drill.exec.memory.BoundsChecking.checkIndex(BoundsChecking.java:80)
> 	at org.apache.drill.exec.memory.BoundsChecking.lengthCheck(BoundsChecking.java:86)
> 	at io.netty.buffer.DrillBuf.chk(DrillBuf.java:114)
> 	at io.netty.buffer.DrillBuf.getInt(DrillBuf.java:484)
> 	at org.apache.drill.exec.vector.UInt4Vector$Accessor.get(UInt4Vector.java:432)
> 	at org.apache.drill.exec.vector.VarCharVector$Mutator.setValueCount(VarCharVector.java:729)
> 	at org.apache.drill.exec.vector.VarCharVectorTest.testExpandingNonEmptyVectorSetValueCount(VarCharVectorTest.java:97)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at java.lang.reflect.Method.invoke(Method.java:606)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at java.lang.reflect.Method.invoke(Method.java:606)
> 	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
> 	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
> 	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
> 	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
> {code}



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