[Xapian-devel] GSoC 2012: Erlang Bindings

[Michael Uvarov]

Hello,

I am Uvarov Michael.
I am studding at Southern Federal University in Russia from 2008.
My github profile is here: https://github.com/freeakk
I want to implement a binding as an Erlang driver. I already have an
experience with NIFs (Native Implemented Functions)
(Code is here https://github.com/freeakk/i18n).

I implemented basic operations with Unicode both in pure Erlang and as NIF.
I think, that Erlang will be a good choice for binding, because it has a nice
inter-node communication interface. This interface can be used as a transport
for access to a remote database.

I have few questions and ideas about Xapian:

First of all, how does Xapian handle concurrent access to shared resources?
How many connections can be established to one database for reading and writing?
Who does coordinate parallel access to same database?
Are opening and closing a database expensive operations or not?
Is a minimal example of using Xapian with a real data set?
Are there datasets for an efficiently testing?

I think it is a good idea for implementing this binding as a linked-in driver.
A driver provides a queue and Xapian classes are not thread-safe. So, it will
be a mapping: one driver port -- one opening connection to a base.
NIFs will require an implementing of a thread pool in C, but it is not
a trivial
task.
Calls of NIFs can block a schedule of an virtual machine. It is also not good,
because other green processes will wait.

I will wait for answers and your questions.

--
Best regards,
Uvarov Michael