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| <?php
interface CacheReader {
public function get(string $key);
public function has(string $key): bool;
}
interface CacheWriter {
public function set(string $key, $value, int $ttl = 3600): void;
public function delete(string $key): void;
}
interface CacheStats {
public function getHitRate(): float;
public function getStats(): array;
}
class CacheManager {
public function __construct(
private CacheReader&CacheWriter $cache
) {}
public function remember(string $key, callable $callback, int $ttl = 3600) {
if ($this->cache->has($key)) {
return $this->cache->get($key);
}
$value = $callback();
$this->cache->set($key, $value, $ttl);
return $value;
}
public function getWithStats(string $key, CacheReader&CacheWriter&CacheStats $statsCache) {
$value = $statsCache->get($key);
echo "缓存命中率: " . $statsCache->getHitRate() . "%\n";
echo "缓存统计: " . json_encode($statsCache->getStats()) . "\n";
return $value;
}
}
class MemoryCache implements CacheReader, CacheWriter {
private array $data = [];
private array $expiry = [];
public function get(string $key) {
if (!$this->has($key)) {
return null;
}
return $this->data[$key];
}
public function has(string $key): bool {
if (!isset($this->data[$key])) {
return false;
}
if (isset($this->expiry[$key]) && $this->expiry[$key] < time()) {
$this->delete($key);
return false;
}
return true;
}
public function set(string $key, $value, int $ttl = 3600): void {
$this->data[$key] = $value;
$this->expiry[$key] = time() + $ttl;
}
public function delete(string $key): void {
unset($this->data[$key], $this->expiry[$key]);
}
}
class StatisticsCache extends MemoryCache implements CacheStats {
private int $hits = 0;
private int $misses = 0;
private int $writes = 0;
public function get(string $key) {
$value = parent::get($key);
if ($value !== null) {
$this->hits++;
} else {
$this->misses++;
}
return $value;
}
public function set(string $key, $value, int $ttl = 3600): void {
parent::set($key, $value, $ttl);
$this->writes++;
}
public function getHitRate(): float {
$total = $this->hits + $this->misses;
return $total > 0 ? ($this->hits / $total) * 100 : 0;
}
public function getStats(): array {
return [
'hits' => $this->hits,
'misses' => $this->misses,
'writes' => $this->writes,
'hit_rate' => $this->getHitRate()
];
}
}
echo "=== 缓存系统示例 ===\n";
$basicCache = new MemoryCache();
$statsCache = new StatisticsCache();
$cacheManager = new CacheManager($basicCache);
$expensiveData = $cacheManager->remember('user:123', function() {
echo "执行昂贵的数据库查询...\n";
return ['id' => 123, 'name' => '张三', 'email' => 'zhangsan@example.com'];
});
echo "用户数据: " . json_encode($expensiveData) . "\n";
$cachedData = $cacheManager->remember('user:123', function() {
echo "这不应该被执行\n";
return null;
});
echo "缓存数据: " . json_encode($cachedData) . "\n";
$statsCache->set('test:key', 'test value');
$statsCache->get('test:key');
$statsCache->get('nonexistent');
$cacheManager->getWithStats('test:key', $statsCache);
?>
|
