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FileCache.php
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FileCache.php
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<?php
declare(strict_types=1);
namespace Phan\Library;
use RuntimeException;
/**
* An LRU cache for the contents of files (FileCacheEntry), and data structures derived from contents of files.
*/
final class FileCache
{
public const MINIMUM_CACHE_SIZE = 20;
/**
* @var int - Maximum cache size
*/
private static $max_size = self::MINIMUM_CACHE_SIZE;
/**
* @var array<string,FileCacheEntry> - An ordered php associative array, with most recently used at the end of the array.
*/
private static $cache_entries = [];
/**
* Sets the cache size to $max_size (or self::MINIMUM_CACHE_SIZE if that's larger).
* Entries will be removed until there are $max_size or fewer entries.
*/
public static function setMaxCacheSize(int $max_size): void
{
self::$max_size = \max($max_size, self::MINIMUM_CACHE_SIZE);
while (\count(self::$cache_entries) > self::$max_size) {
\array_shift(self::$cache_entries);
}
}
/**
* Raise the cache size to $max_size (or the original cache size or self::MINIMUM_CACHE_SIZE if that's larger).
* Entries will not be removed.
*/
public static function raiseMaxCacheSize(int $max_size): void
{
self::$max_size = \max($max_size, self::$max_size ?? self::MINIMUM_CACHE_SIZE);
}
/**
* Adds an entry recording that $file_name has contents $file_contents,
* overwriting any previous entries
*/
public static function addEntry(string $file_name, string $contents): FileCacheEntry
{
$old_entry = self::$cache_entries[$file_name] ?? null;
if ($old_entry) {
unset(self::$cache_entries[$file_name]);
if ($old_entry->getContents() === $contents) {
// If the contents didn't change, keep the cache entry and move it to the end (Most recently used).
self::$cache_entries[$file_name] = $old_entry;
return $old_entry;
}
}
$entry = new FileCacheEntry($contents);
self::$cache_entries[$file_name] = $entry;
if (\count(self::$cache_entries) > self::$max_size) {
// Ensure that the size <= self::$max_size. Remove the least recently used entry (front of list).
\array_shift(self::$cache_entries);
}
return $entry;
}
/**
* @return ?FileCacheEntry if the entry exists in cache, return it.
* Otherwise, return null.
*/
public static function getEntry(string $file_name): ?FileCacheEntry
{
$entry = self::$cache_entries[$file_name] ?? null;
if ($entry) {
// Move the entry to the end (most recently used) and return it.
unset(self::$cache_entries[$file_name]);
self::$cache_entries[$file_name] = $entry;
return $entry;
}
return null;
}
/**
* @param string $file_name an absolute path to a file on disk
* @return FileCacheEntry This will load the file from the filesystem if it could not be found.
* @throws RuntimeException if the file could not be loaded
*/
public static function getOrReadEntry(string $file_name): FileCacheEntry
{
$entry = self::getEntry($file_name);
if ($entry !== null) {
return $entry;
}
if (!\file_exists($file_name)) {
throw new RuntimeException("FileCache::getOrReadEntry: unable to find '$file_name'\n");
}
if (!\is_readable($file_name)) {
throw new RuntimeException("FileCache::getOrReadEntry: unable to read '$file_name'\n");
}
$contents = \file_get_contents($file_name);
if (!\is_string($contents)) {
throw new RuntimeException("FileCache::getOrReadEntry: file_get_contents failed for '$file_name'\n");
}
$entry = self::addEntry($file_name, $contents);
return $entry;
}
/**
* Clear the cache (E.g. after pausing, accepting a daemon mode request, then resuming)
*/
public static function clear(): void
{
self::$cache_entries = [];
}
/**
* @return list<string> list of file paths with most recently used entries at the end.
*/
public static function getCachedFileList(): array
{
return \array_keys(self::$cache_entries);
}
}

File Metadata

Mime Type
text/x-php
Expires
Sat, May 16, 21:08 (1 d, 16 h)
Storage Engine
local-disk
Storage Format
Raw Data
Storage Handle
f7/c9/93a1300a39c416f75e62f71439ad
Default Alt Text
FileCache.php (4 KB)

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