PHP - File Caching

<?php
              $myData = file_get_contents("");
              $myObject = json_decode($myData);
              $myObjectMap = $myObject->result;
            ?>

can i somehow build in that it only request every 5 minutes because if there are many users on the site it request too much?

// cachePath is name of the path and file used to store cached current conditions gathered from the API request
$cachePath  = "./cache/nowcast-cache.txt";

// URL to the API request
$url = "http://api.wunderground.com/api/XXXXXXXXXXXX/geolookup/conditions/q/TX/mesquite.json";

date_default_timezone_set('America/Chicago');

/**
* Request jobs from  API
*
* Split the request into smaller request chunks
* and then consolidate them into a single array to limit the API
* requests.
*/
function api_request()
{
    file_put_contents($cachePath,
file_get_contents($url));
}

/**
 * API Request Caching
 *
 *	Use server-side caching to store API request's as JSON at a set
 *	interval, rather than each pageload.
 *
 * @arg Argument description and usage info
 */


function json_cached_api_results( $cache_file = NULL, $expires = NULL ) {
	global $request_type, $purge_cache, $limit_reached, $request_limit;

	if( !$cache_file ) $cache_file = dirname(__FILE__) . $cachePath;
	if( !$expires) $expires = time() - 2*60*60;

	if( !file_exists($cache_file) ) die("Cache file is missing: $cache_file");

	// Check that the file is older than the expire time and that it's not empty
	if ( filectime($cache_file) < $expires || file_get_contents($cache_file)  == '' || $purge_cache && intval($_SESSION['views']) <= $request_limit ) {

		// File is too old, refresh cache
		$api_results = api_request();
		$json_results = json_encode($api_results);

		// Remove cache file on error to avoid writing wrong xml
		if ( $api_results && $json_results )
			file_put_contents($cache_file, $json_results);
		else
			unlink($cache_file);
	} else {
		// Check for the number of purge cache requests to avoid abuse
		if( intval($_SESSION['views']) >= $request_limit )
			$limit_reached = " <span class='error'>Request limit reached ($request_limit). Please try purging the cache later.</span>";
		// Fetch cache
		$json_results = file_get_contents($cache_file);
		$request_type = 'JSON';
	}

	return json_decode($json_results);
}

print_r($json_results);

https://test.sites.example.com/administrator/index.php?cid=2&controller=sell&id=643341356

https://test.sites.example.com/index.php?admin=administrator&cid=2&controller=sell&id=643341356

<script src="/lib/js/clientConstants.php?b=1" type="text/javascript">

Purpose: Building a search function for a site, that's supposed to be fast, give results as a user types.

Queries would be something like: "brand1 brand2 brand3" .

My idea is , instead of querying the database on each ajax request. A keyed array is created once. Like: ['brand1' => id , 'brand2 => id2 ]. This array is stored in memory. The next time a query is sent, the array which is instantly available in memory, and can be simply queried $storedArray['brand1']to fetch any existing ids instantly. The array size would be about 750 Kb. 60000 rows.

I don't have much experience with caching , so looking for advise whether what I am trying to do even makes any sense or necessary. I know there are solutions like memcache. But not sure if my tiny project requires them. Also does opcache help here ? Would serializing the array be too slow ? 

Please ask if any questions.

Thanks

I am running a nginx web server. with this following config

return 302 https://www.mysite.com/game_errorpage.php?sub=$name;

The intent, is if someone types in  "blah.mysite.com" and that subdomain (game server) is not running, I want them to be redirected to a error page.  This error page then starts the game game server in question.  This all works up to to this point.  Then I want to redirect the user back to the original request url, to log into their game "blah.mysite.com"  I use the following php 

header("Location: https://blah.mysite.com");
exit();

The issue I have is, because the browser has it cached already as https://www.mysite.com/game_errorpage.php?sub=$name  it keeps returning there even though the game server is now running.   The only thing I can do is close all the browsers and open a new window in Chrome using "Incognito" then type the url again.

I have the following in my global file, for all pages. 

header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

So I am looking for some creative solutions.

Thanks.

Brad