Merge "objectcache: optimize MemcachedPeclBagOStuff::*Multi() write methods"

[lhc/web/wiklou.git] / includes / libs / objectcache / BagOStuff.php

diff --git a/includes/libs/objectcache/BagOStuff.php b/includes/libs/objectcache/BagOStuff.php
index c47f6ee..4819f0e 100644 (file)
--- a/includes/libs/objectcache/BagOStuff.php
+++ b/includes/libs/objectcache/BagOStuff.php
@@ -97,14 +97,15 @@ abstract class BagOStuff implements IExpiringStore, IStoreKeyEncoder, LoggerAwar
        /** @var int[] Map of (ATTR_* class constant => QOS_* class constant) */
        protected $attrMap = [];
 
-       /** Bitfield constants for get()/getMulti() */
-       const READ_LATEST = 1; // use latest data for replicated stores
-       const READ_VERIFIED = 2; // promise that caller can tell when keys are stale
-       /** Bitfield constants for set()/merge() */
-       const WRITE_SYNC = 4; // synchronously write to all locations for replicated stores
-       const WRITE_CACHE_ONLY = 8; // Only change state of the in-memory cache
-       const WRITE_ALLOW_SEGMENTS = 16; // Allow partitioning of the value if it is large
-       const WRITE_PRUNE_SEGMENTS = 32; // Delete all partition segments of the value
+       /** Bitfield constants for get()/getMulti(); these are only advisory */
+       const READ_LATEST = 1; // if supported, avoid reading stale data due to replication
+       const READ_VERIFIED = 2; // promise that the caller handles detection of staleness
+       /** Bitfield constants for set()/merge(); these are only advisory */
+       const WRITE_SYNC = 4; // if supported, block until the write is fully replicated
+       const WRITE_CACHE_ONLY = 8; // only change state of the in-memory cache
+       const WRITE_ALLOW_SEGMENTS = 16; // allow partitioning of the value if it is large
+       const WRITE_PRUNE_SEGMENTS = 32; // delete all the segments if the value is partitioned
+       const WRITE_BACKGROUND = 64; // if supported,
 
        /** @var string Component to use for key construction of blob segment keys */
        const SEGMENT_COMPONENT = 'segment';
@@ -682,25 +683,33 @@ abstract class BagOStuff implements IExpiringStore, IStoreKeyEncoder, LoggerAwar
 
        /**
         * Get an associative array containing the item for each of the keys that have items.
-        * @param string[] $keys List of keys
+        * @param string[] $keys List of keys; can be a map of (unused => key) for convenience
         * @param int $flags Bitfield; supports READ_LATEST [optional]
-        * @return array Map of (key => value) for existing keys
+        * @return mixed[] Map of (key => value) for existing keys; preserves the order of $keys
         */
        public function getMulti( array $keys, $flags = 0 ) {
-               $valuesBykey = $this->doGetMulti( $keys, $flags );
-               foreach ( $valuesBykey as $key => $value ) {
+               $foundByKey = $this->doGetMulti( $keys, $flags );
+
+               $res = [];
+               foreach ( $keys as $key ) {
                        // Resolve one blob at a time (avoids too much I/O at once)
-                       $valuesBykey[$key] = $this->resolveSegments( $key, $value );
+                       if ( array_key_exists( $key, $foundByKey ) ) {
+                               // A value should not appear in the key if a segment is missing
+                               $value = $this->resolveSegments( $key, $foundByKey[$key] );
+                               if ( $value !== false ) {
+                                       $res[$key] = $value;
+                               }
+                       }
                }
 
-               return $valuesBykey;
+               return $res;
        }
 
        /**
         * Get an associative array containing the item for each of the keys that have items.
         * @param string[] $keys List of keys
         * @param int $flags Bitfield; supports READ_LATEST [optional]
-        * @return array Map of (key => value) for existing keys
+        * @return mixed[] Map of (key => value) for existing keys
         */
        protected function doGetMulti( array $keys, $flags = 0 ) {
                $res = [];
@@ -719,6 +728,8 @@ abstract class BagOStuff implements IExpiringStore, IStoreKeyEncoder, LoggerAwar
         *
         * This does not support WRITE_ALLOW_SEGMENTS to avoid excessive read I/O
         *
+        * WRITE_BACKGROUND can be used for bulk insertion where the response is not vital
+        *
         * @param mixed[] $data Map of (key => value)
         * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
         * @param int $flags Bitfield of BagOStuff::WRITE_* constants (since 1.33)
@@ -751,6 +762,8 @@ abstract class BagOStuff implements IExpiringStore, IStoreKeyEncoder, LoggerAwar
         *
         * This does not support WRITE_ALLOW_SEGMENTS to avoid excessive read I/O
         *
+        * WRITE_BACKGROUND can be used for bulk deletion where the response is not vital
+        *
         * @param string[] $keys List of keys
         * @param int $flags Bitfield of BagOStuff::WRITE_* constants
         * @return bool Success