Multiget

[e120281]

Hi Jeremy,

I thought it would be nice to be able to take advantage of memcached multiget functionality. In current implementation multiget (I give array of keys to get function) fails because of "$key = $this->prefix . $key;" line.

public function get($key)
{
    if ($this->isSafe()) {
        $key = $this->prefix . $key;
        return $this->mem->get($key);
    }

    return false;
}

Something like below should do the work, I guess. Please let me know what you think.

public function get($key)
{
    if ($this->isSafe()) {
        if (is_array($key)) {
            if ($this->prefix != '') {
                for ($i = 0; $i < count($key); $i++) {
                    $key[$i] = $this->prefix . $key[$i];
                }
            }
        }
        else {
            $key = $this->prefix . $key;
        }

        return $this->mem->get($key);
    }

    return false;
}

[jeremylivingston]

Is there a reason why you're checking to see if the prefix isn't an empty string in the array situation?

[beryllium]

Took me a second to figure it out, but: In a situation with no prefix, the raw array is passed to get(); when there is a prefix, the array is modified so all the individual keys are assigned the prefix before being passed to get().

[jeremylivingston]

Ah, you're right. I think we could apply this same behavior when the key is a string. I can restructure this code to make it a little clearer.

@beryllium, are you okay with this change?

[beryllium]

Mostly - but I would prefer to use a foreach($key as $index=>$value) instead of for() loop, this might be safer for handling non-numeric array keys:

foreach($key as $index=>$value)
{
    $key[$index] = $this->prefix . $value;
}

We might also want to ignore or unset array elements that are empty strings, although I'm not 100% certain if that is necessary or desired:

foreach($key as $index=>$value)
{
    if (empty($value)) 
    {
        unset($key[$index]);
        continue;
    }

    $key[$index] = $this->prefix . $value;
}

[jeremylivingston]

I think that Memcache would simply ignore empty strings, wouldn't it? If we want to prevent these from being passed, we should probably also prevent it for the string case too. Maybe I can add the array functionality for this phase, then validate keys as a follow up.

[beryllium]

Sounds good. Key validation quirks would be a good thing for travis/unit tests, eh? :)

[jeremylivingston]

After I started working toward a solution, I realized that there could be an issue with this.

When you call memcache::get() with an array of keys, it will return an associative array with the keys and their values. If you use a prefix for your client, this array will contain the prefix in each of those keys.

Should these be stripped out before they're returned? Otherwise, you're going to have to be aware of the keys in every place that you retrieve an array from the cache. I'm leaning towards yes, but wanted to run it by you.

[beryllium]

Yes, I think they should be stripped out. Seems to make the most sense that way, with the prefix acting like a namespace.

[jeremylivingston]

I added the functionality to the get() method. Please take a look when you have a moment.