Add memcache increment and decrement

[iwalz]

This is a fix for #1083. It looks like the suggested changes for memcached are already done in 2.0 (if you want to I can prepare a PR against that too). I'm sorry about the formatting issue for the PR review, tried to fix it but seem to be screwed up anyways ... I was not sure where to send the PR against and how to handle phalcon.c in a PR. Since incr and decr are atomic, this is very useful i guess.

I thought about error handling in that implementation, but increase or decrease a non-numeric value simply raises a notice (which I was not able to prevent without shutup in userspace) and a not-existent value returns false. I can't really think of any other error-related use case.

[phalcon]

Since those methods are only implemented in the memcache adapter, it would make the other adapters look a bit different

[iwalz]

I thought about an implementation for the other adapters too, but there's a significant difference between the memcache service and the others. Following example:

$cache->set('foo', $cache->get('foo') + 1);

Can be done in any adapter this way. But memcache is a bit special, increment and decrement are the only atomic operations in memcache. Other adapters are a kind of atomic by nature, but memcache isn't - so these operations are very usefull, especially for memcache users. APC didn't even provide an increment/decrement function itself. For XCache it's the same as for memcache, so it makes sense there. You want me to add this functionality for XCache the same way and for the others "wrappers" for the example above?

What about the 2.0 Branch? Do you want a port for that?

[phalcon]

Yes, I think those methods need to be implemented in every adapter even if the result functionality is not atomic, that's is something we could mention in the docs and the developer can take decisions on it.

Regarding 2.0, this version will be written in Zephir, maybe this is not the moment to start a port since the language is still in development. Thanks

[iwalz]

Okay, let me add xcache later today and the other through the weekend. Are you in general fine with the implementation itself?

[iwalz]

Dev is still ongoing, I'll ping you once it's ready for review again. Thanks for the hints.
I got really strange behaviours on xcache - different behaviours on different travis boxes and even others on my local dev environment. It's conflicting with APC and some versions seem to not have an inc and dec function - but the doc is quite ... Let's say there is not much for xcache ;-) So I needed to push often to trigger a travis build and fix errors that are happening there and not locally.

[phalcon]

Did you finish your development? Can be this merged?

[iwalz]

Not yet, file and mongo still needs to be done. I've moved to a new
appartment and there's no internet connection till 9.9 - will finish it as
soon as possible.

[phalcon]

Thanks, please let us know when it's ready

[phalcon]

Also, could you submit this to the 1.3.0 branch?

[iwalz]

@phalcon I'm struggling a bit with the mongo implementation. I got weird travis behaviours and the mongo db tests where prefixed with a "_" before (to not execute the tests). The test suite runs fine locally but from "Cannot convert to ordinal value" to segmentation faults, everything is possible on travis ... Can someone have a quick look on the mongodb increment & decrement and point me to the right direction?

[iwalz]

ping @phalcon
Should be fine for review again. The travis failures seem not related.
I had a very strange looking commit once I sent the PR to 1.3 - will investigate

[phalcon]

I'm going to close this, could you please submit this in 1.3.0?

[iwalz]

Yes, you can close this. I'm still investigating how to solve my conflicts the best, otherwise I've to redo it for 1.3.0. Any suggestion how to fix it the best? Mergeing seem not possible at all ...

# git clone https://github.com/phalcon/cphalcon.git .
# git checkout 1.2.3
# git checkout 1.3.0
# git merge 1.2.3

Gives me a conflict for ~50 files

[ghost]

You can try to create the patch for 1.2.3 and your branch, then checkout to 1.3.0 and try to apply the patch, This will result in conflicts, but there should be much less conflicts than you have now.