[Performance] Changes to code generated by code generator for performance
improvements
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Key: QPID-268
URL: https://issues.apache.org/jira/browse/QPID-268
Project: Qpid
Issue Type: Improvement
Components: Java Common
Reporter: Rob Godfrey
Testing has shown that we can get not insignificant performance improvements by
changing the code generated by the code generator.
Firstly we can reduce the overhead of object creation by removing unnecessary
string concatenation in using strings for lookups. That is - no longer use a
String representation of the protocol version to do lookups.
Secondly we can create AMQMethodBody objects with a constructor which takes in
the byte buffer, and gets the object to populate itself from this, rather than
first creating an empty object and then asking it to populate itself. The
first course of action seems to allow the run-time compiler to optimize-out
some aspects of the the object creation.
Thirdly we can change the way the generated classes ask for their packed bit
arrays to be encoded and decoded. Instead of creating temporary boolean[]
objects, we process the packing into byte objects in place.
The changes also allow further performance improvements to be made later by
changing the way objects are looked up in the registries. For instance, in the
MainRegistry the template could now be changed to allow looking up the
MethodBody objects in a sparse multi-dimensional array, rather than a Long
indexed HashMap. This can now be done purely by changing the template and
without having to change the code generator.
See attached patch file.
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