Replace various magic numbers with easy-to-verify expressions

Follows-up I8518e0488 (9c02258a04).

Instead of documenting how to compute the number to manually verify
it, use the expression directly. This should make it significantly
easier to understand, verify, and modify.

Noteworthy:

* Language.php, I kept 31_556_952 as-is because the
  calculation would otherwise involve a float. It also has the benefit
  of allowing the long durations to build upon that as a given number.

* SqlBlobStore.php, remove this irrelevant default value as it is
  unreachable. The only call to new SqlBlobStore is BlobStoreFactory,
  which always calls setCacheExpiry. For back-compat and to keep
  tests as-is, move to re-used constant between class and config.

Change-Id: I86b034883bd7efdf93b8365b43178af826f1c703

1 files changed, 8 insertions, 5 deletions

diff --git a/includes/Storage/SqlBlobStore.php b/includes/Storage/SqlBlobStore.php
index 944aa08e1285..892eaa3f48b9 100644
--- a/includes/Storage/SqlBlobStore.php
+++ b/includes/Storage/SqlBlobStore.php
@@ -53,6 +53,9 @@ class SqlBlobStore implements IDBAccessObject, BlobStore {
 	// Note: the name has been taken unchanged from the old Revision class.
 	public const TEXT_CACHE_GROUP = 'revisiontext:10';
 
+	/** @internal */
+	public const DEFAULT_TTL = 7 * 24 * 3600; // 7 days
+
 	/**
 	 * @var ILoadBalancer
 	 */
@@ -76,7 +79,7 @@ class SqlBlobStore implements IDBAccessObject, BlobStore {
 	/**
 	 * @var int
 	 */
-	private $cacheExpiry = 604_800; // 7 days
+	private $cacheExpiry = self::DEFAULT_TTL;
 
 	/**
 	 * @var bool
@@ -117,28 +120,28 @@ class SqlBlobStore implements IDBAccessObject, BlobStore {
 	}
 
 	/**
-	 * @return int time for which blobs can be cached, in seconds
+	 * @return int Time for which blobs can be cached, in seconds
 	 */
 	public function getCacheExpiry() {
 		return $this->cacheExpiry;
 	}
 
 	/**
-	 * @param int $cacheExpiry time for which blobs can be cached, in seconds
+	 * @param int $cacheExpiry Time for which blobs can be cached, in seconds
 	 */
 	public function setCacheExpiry( int $cacheExpiry ) {
 		$this->cacheExpiry = $cacheExpiry;
 	}
 
 	/**
-	 * @return bool whether blobs should be compressed for storage
+	 * @return bool Whether blobs should be compressed for storage
 	 */
 	public function getCompressBlobs() {
 		return $this->compressBlobs;
 	}
 
 	/**
-	 * @param bool $compressBlobs whether blobs should be compressed for storage
+	 * @param bool $compressBlobs Whether blobs should be compressed for storage
 	 */
 	public function setCompressBlobs( $compressBlobs ) {
 		$this->compressBlobs = $compressBlobs;