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https://issues.apache.org/jira/browse/PIG-1611?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thejas M Nair updated PIG-1611:
-------------------------------
Attachment: PIG-1611.1.patch
Attaching an incomplete version of the patch for review. I am looking for
feedback on this design/plan -
- An interface ErrorCode has been created within PigException class.
PigException and subclasses will create an enum class that will implement this
interface. An example of enum implementing this interface is
UnionOnSchemaSetException in
src/org/apache/pig/impl/logicalLayer/validators/UnionOnSchemaSetException.java
.
- If one enum class was used for all error codes, most patches would end up
modifying this same file at same location, and that will result in conflicts
while merging the changes. So I chose to have an enum class in each
PigException subclass to reduce the chances of that happening.
- The enum constructor would take the arguments (String msg, byte errorType,
boolean retriable) . There can be another constructors that just takes the
(String msg) or (String msg, byte errorType) as arguments if user wants
defaults for errorType (BUG) and retriable (false). Having errorType and
retriable information along with the enum will make it easier to generate the
documentation for error codes.
for example -
{code}
SCH_MERGE_ER("Error creating merged schemas for union-onschema
operator", PigException.INPUT, false),
ERROR_ADDING_UNION_OP("Error adding union operator ", PigException.BUG,
false);
{code}
- Example of class using new exception constructor is in
src/org/apache/pig/impl/logicalLayer/UnionOnSchemaSetter.java .
- Existing exception constructors that use error code number are being
deprecated, so that developers use the new constructors that use. This patch
will not change current code that is already using old constructors.
- Other exception classes need to be updated to have the ErrorCode enum and new
constructors.
> use enums for error code
> ------------------------
>
> Key: PIG-1611
> URL: https://issues.apache.org/jira/browse/PIG-1611
> Project: Pig
> Issue Type: Sub-task
> Reporter: Thejas M Nair
> Fix For: 0.9.0
>
> Attachments: PIG-1611.1.patch
>
>
> Pig code is using integer constants for error code, and the value of the
> error code is reserved using
> http://wiki.apache.org/pig/PigErrorHandlingFunctionalSpecification .
> This process is cumbersome and error prone.
> It will be better to use enum values instead. The enum value can contain the
> error message and encapsulate the error code.
> For example -
> {code}
> Replace
> throw new SchemaMergeException("Error in merging schema", 2124,
> PigException.BUG);
> with
> throw new SchemaMergeException(SCHEMA_MERGE_EX, PigException.BUG);
> {code}
> Where SCHEMA_MERGE_EX belongs to a error codes enum. We can use the ordinal
> value of the enum and an offset to determine the error code.
> The error code will be passed through the constructor of the enum.
> {code}
> SCHEMA_MERGE_EX("Error in merging schema");
> {code}
> For documentation, the error code and error messages can be dumped using code
> that uses the enum error code class.
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