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使用缓存提升性能¶Phalcon 提供 Phalcon\Cache 类，以便更快的访问经常使用的数据或已经处理过的数据。 Phalcon\Cache 使用C语言编写，实现更高的性能，并减少系统开销。 这个类提供前端和后端两个组件，前端组件作为输入源或接口，后端提供存储选项。 什么时候使用缓存?¶虽然这个组件是非常高效快速的，但如果使用不当，也有可能导致性能问题，从而得不偿失。 我们建议你在使用缓存之前检查以下情况：
缓存行为¶缓存的执行分为两个部分：
片断缓存¶片断缓存是缓存HTML或者TEXT文本的一部分，然后原样返回。输出自动捕获来自ob_* 函数或PHP输出，以便它可以保存到缓存中。 下面的例子演示了这种用法。 它接收PHP生成的输出，并将其存储到一个文件中，文件的内容172800秒(2天)更新一次。 这种缓存机制的实现，使我们既能获得性能，而又不执行Phalcon\Tag::linkTo的调用。 <?php
//Create an Output frontend. Cache the files for 2 days
$frontCache = new Phalcon\Cache\Frontend\Output(array(
"lifetime" => 172800
));
// Create the component that will cache from the "Output" to a "File" backend
// Set the cache file directory - it's important to keep the "/" at the end of
// the value for the folder
$cache = new Phalcon\Cache\Backend\File($frontCache, array(
"cacheDir" => "../app/cache/"
));
// Get/Set the cache file to ../app/cache/my-cache.html
$content = $cache->start("my-cache.html");
// If $content is null then the content will be generated for the cache
if ($content === null) {
//Print date and time
echo date("r");
//Generate a link to the sign-up action
echo Phalcon\Tag::linkTo(
array(
"user/signup",
"Sign Up",
"class" => "signup-button"
)
);
// Store the output into the cache file
$cache->save();
} else {
// Echo the cached output
echo $content;
}
NOTE In the example above, our code remains the same, echoing output to the user as it has been doing before. 缓存组件透明的捕获该输出，并将其存储到缓存文件中(前提是已经生成cache对象),或将其之前的缓存发送给用户，从而避免代价昂贵的开销。 Caching Arbitrary Data¶缓存是应用程序重要的组成部分。缓存可以减少数据库负载，重复使用常用的数据（但不更新），从而加快了您的应用程序。 File Backend Example¶缓存适配器之一’File’，此适配器的属性只有一个，它用来指定缓存文件的存储位置。使用 cacheDir选项进行控制，且 必须 以’/’结尾。 <?php
// Cache the files for 2 days using a Data frontend
$frontCache = new Phalcon\Cache\Frontend\Data(array(
"lifetime" => 172800
));
// Create the component that will cache "Data" to a "File" backend
// Set the cache file directory - important to keep the "/" at the end of
// of the value for the folder
$cache = new Phalcon\Cache\Backend\File($frontCache, array(
"cacheDir" => "../app/cache/"
));
// Try to get cached records
$cacheKey = 'robots_order_id.cache';
$robots = $cache->get($cacheKey);
if ($robots === null) {
// $robots is null because of cache expiration or data does not exist
// Make the database call and populate the variable
$robots = Robots::find(array("order" => "id"));
// Store it in the cache
$cache->save($cacheKey, $robots);
}
// Use $robots :)
foreach ($robots as $robot) {
echo $robot->name, "\n";
}
Memcached Backend Example¶上面的例子稍微改变一下(主要是配置方面)，就可以使用Memcache做为后端存储器了。 <?php
//Cache data for one hour
$frontCache = new Phalcon\Cache\Frontend\Data(array(
"lifetime" => 3600
));
// Create the component that will cache "Data" to a "Memcached" backend
// Memcached connection settings
$cache = new Phalcon\Cache\Backend\Memcached($frontCache, array(
"host" => "localhost",
"port" => "11211"
));
// Try to get cached records
$cacheKey = 'robots_order_id.cache';
$robots = $cache->get($cacheKey);
if ($robots === null) {
// $robots is null because of cache expiration or data does not exist
// Make the database call and populate the variable
$robots = Robots::find(array("order" => "id"));
// Store it in the cache
$cache->save($cacheKey, $robots);
}
// Use $robots :)
foreach ($robots as $robot) {
echo $robot->name, "\n";
}
Querying the cache¶缓存唯一标识符元素为KEY，在后端文件中，KEY值即是实际文件名。从缓存中检索数据，我们只需要通过KEY来调用即可。如果该KEY不存在，get方法将返回null。 <?php
// Retrieve products by key "myProducts"
$products = $cache->get("myProducts");
如果你想知道缓存中都有哪些KEY，你可以调用queryKeys方法： <?php
// Query all keys used in the cache
$keys = $cache->queryKeys();
foreach ($keys as $key) {
$data = $cache->get($key);
echo "Key=", $key, " Data=", $data;
}
//Query keys in the cache that begins with "my-prefix"
$keys = $cache->queryKeys("my-prefix");
删除缓存数据¶很多时候，你需要强行删除无效的缓存条目(由于数据更新的原因)，唯一的要求就是，你得知道该缓存的KEY。 <?php
// Delete an item with a specific key
$cache->queryKeys("someKey");
// Delete all items from the cache
$keys = $cache->queryKeys();
foreach ($keys as $key) {
$cache->delete($key);
}
检测缓存是否存在¶通过给定的KEY值，可以检测缓存是否存在。 <?php
if ($cache->exists("someKey")) {
echo $cache->get("someKey");
}
else {
echo "Cache does not exists!";
}
前端适配器¶The available frontend adapters that are used as interfaces or input sources to the cache are:
实现自定义的前端适配器¶The Phalcon\Cache\FrontendInterface interface must be implemented in order to create your own frontend adapters or extend the existing ones. 后端适配器¶可用的后端存储器列表：
实现自定义后端适配器¶The Phalcon\Cache\BackendInterface interface must be implemented in order to create your own backend adapters or extend the existing ones. 文件缓存选项¶This backend will store cached content into files in the local server. The available options for this backend are:
Memcached缓存选项¶This backend will store cached content on a memcached server. The available options for this backend are:
APC缓存选项¶This backend will store cached content on Alternative PHP Cache (APC). This cache backend does not require any additional configuration options. Mongo缓存选项¶This backend will store cached content on a MongoDB server. The available options for this backend are:
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