Add GreedyCacheStrategy

[jeromegamez]

First of all: thank you for this middleware - it's well designed, and it was a pleasure integrating it (and saved me a lot of time) ❤️.

A propos ":heart:": it breaks mine to propose an addition that is not RFC-compliant, but I think it could still be useful for certain edge cases.

In my case, I had to access

• a remote resource which provided no cache control headers
• an unreliable remote resource which would not be accessible from time to time

This is where the Greedy Cache Strategy came to life - it stores responses in the cache for a fixed amount of time, and I use it in a second middleware inside the HandlerStack:

use Doctrine\Common\Cache\ArrayCache;
use Doctrine\Common\Cache\ChainCache;
use Doctrine\Common\Cache\FilesystemCache;
use GuzzleHttp\Client;
use GuzzleHttp\HandlerStack;
use Kevinrob\GuzzleCache\CacheMiddleware;
use Kevinrob\GuzzleCache\Storage\DoctrineCacheStorage;
use Kevinrob\GuzzleCache\Strategy\GreedyCacheStrategy;
use Kevinrob\GuzzleCache\Strategy\PrivateCacheStrategy;

$caches = [
    new ArrayCache(),
    new FilesystemCache('/tmp/'),
];

$stack = HandlerStack::create();

// The normal cache
$stack->push(new CacheMiddleware(
    new PrivateCacheStrategy(
        new DoctrineCacheStorage(new ChainCache($caches))
    )
), 'cache');

// Notice the ->before() instead of ->push().
// We want the greedy cache to have a lesser priority
$stack->before('cache', new CacheMiddleware(
    new GreedyCacheStrategy(
        new DoctrineCacheStorage(new ChainCache($caches)), $ttl = 600
    )
), 'greedy-cache');

$client = new Client(['handler' => $stack]);

echo $stack;

At least it adds a "Warning" header (see #24) 😄

Cheers!
Jérôme

[Kevinrob]

Thank you for your interest. It's nice to see that this is useful to someone!

I think that is a good thing to have this strategy. Sometimes we don't have the choice about following RFC 😉 .
I will review your PR ASAP.

[Kevinrob]

Maybe here we can follow the RFC 7234 fromating? Like:
299 - "This response is cached although the response headers indicate not to do it!"
https://tools.ietf.org/html/rfc7234#section-5.5

What do you think @jeromegamez ?

[jeromegamez]

Darnit, I just saw "Warning header" and thought that this was all - didn't recognize that the following section is a detailed specification :D.

I will change it as soon as I can, thanks for the heads up!

[Kevinrob]

For me it's all good! Thanks 👍
(except for the warning header, cf. my comment)

[jeromegamez]

@Kevinrob Done! I shortened the warning message a bit, because if we are in the response headers, we shouldn't need to say "This response is…" :)

[jeromegamez]

Thanks for merging!

[Kevinrob]

You're welcome! Thanks for sharing your code!