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Server-Side Procedures

Custom procedures allow adding a new non-transactional procedure and registering it with Garnet. This registered procedure can then be invoked from any Garnet client to perform a multi-command non-transactional operation on the Garnet server.

Developing custom server side procedures​

CustomProcedure is the base class for all custom procedures. To develop a new one, this class has to be extended and then include the custom logic. There is one method to be implemented in a new custom procedure:

  • Execute<TGarnetApi>(TGarnetApi garnetApi, ref CustomProcedureInput procInput, ref MemoryResult<byte> output)

The Execute method has the core logic of the custom procedure. Its implementation could process input passed in through the (input) parameter and perform operations on Garnet by invoking any of the APIs available on IGarnetApi. This method then generates the output of the procedure as well.

These are the helper methods for developing custom procedures same as that of custom transactions detailed here.

Registering the custom procedure is done on the server-side by calling the

NewProcedure(string name, CustomProcedure customProcedure, RespCommandsInfo commandInfo = null)

method on the Garnet server object's RegisterAPI object with its name, an instance of the custom procedure class and optional commandInfo.

NOTE When invoking APIs on IGarnetApi multiple times with large outputs, it is possible to exhaust the internal buffer capacity. If such usage scenarios are expected, the buffer could be reset as described below.

  • Retrieve the initial buffer offset using IGarnetApi.GetScratchBufferOffset
  • Invoke necessary apis on IGarnetApi
  • Reset the buffer back to where it was using IGarnetApi.ResetScratchBuffer(offset)
tip

As a reference of an implementation of a custom procedure, see the example in GarnetServer\Extensions\Sum.cs.