QFileInfo: Implement additional caching of FileOwner strings

Reduce overhead of the uid/gid to user/group name conversion by caching
results from QAbstractFileEngine::owner().

Merge-request: 446
Reviewed-by: João Abecasis <joao@trolltech.com>

2 files changed, 18 insertions, 2 deletions

diff --git a/src/corelib/io/qfileinfo.cpp b/src/corelib/io/qfileinfo.cpp
index f4e92a5..d827f57 100644
--- a/src/corelib/io/qfileinfo.cpp
+++ b/src/corelib/io/qfileinfo.cpp
@@ -137,6 +137,18 @@ QString QFileInfoPrivate::getFileName(QAbstractFileEngine::FileName name) const
     return ret;
 }
 
+QString QFileInfoPrivate::getFileOwner(QAbstractFileEngine::FileOwner own) const
+{
+    if (data->cache_enabled && !data->fileOwners[(int)own].isNull())
+        return data->fileOwners[(int)own];
+    QString ret = data->fileEngine->owner(own);
+    if (ret.isNull())
+        ret = QLatin1String("");
+    if (data->cache_enabled)
+        data->fileOwners[(int)own] = ret;
+    return ret;
+}
+
 uint QFileInfoPrivate::getFileFlags(QAbstractFileEngine::FileFlags request) const
 {
     // We split the testing into tests for for LinkType, BundleType, PermsMask
@@ -1089,7 +1101,7 @@ QString QFileInfo::owner() const
     Q_D(const QFileInfo);
     if(!d->data->fileEngine)
         return QLatin1String("");
-    return d->data->fileEngine->owner(QAbstractFileEngine::OwnerUser);
+    return d->getFileOwner(QAbstractFileEngine::OwnerUser);
 }
 
 /*!
@@ -1125,7 +1137,7 @@ QString QFileInfo::group() const
     Q_D(const QFileInfo);
     if(!d->data->fileEngine)
         return QLatin1String("");
-    return d->data->fileEngine->owner(QAbstractFileEngine::OwnerGroup);
+    return d->getFileOwner(QAbstractFileEngine::OwnerGroup);
 }
 
 /*!
diff --git a/src/corelib/io/qfileinfo_p.h b/src/corelib/io/qfileinfo_p.h
index bf02aaa..d97a0cf 100644
--- a/src/corelib/io/qfileinfo_p.h
+++ b/src/corelib/io/qfileinfo_p.h
@@ -78,6 +78,7 @@ public:
     uint getFileFlags(QAbstractFileEngine::FileFlags) const;
     QDateTime &getFileTime(QAbstractFileEngine::FileTime) const;
     QString getFileName(QAbstractFileEngine::FileName) const;
+    QString getFileOwner(QAbstractFileEngine::FileOwner own) const;
 
     enum { CachedFileFlags=0x01, CachedLinkTypeFlag=0x02, CachedBundleTypeFlag=0x04,
            CachedMTime=0x10, CachedCTime=0x20, CachedATime=0x40,
@@ -103,12 +104,15 @@ public:
             clearFlags();
             for (int i = QAbstractFileEngine::NFileNames - 1 ; i >= 0 ; --i)
                 fileNames[i].clear();
+            fileOwners[1].clear();
+            fileOwners[0].clear();
         }
         mutable QAtomicInt ref;
 
         QAbstractFileEngine *fileEngine;
         mutable QString fileName;
         mutable QString fileNames[QAbstractFileEngine::NFileNames];
+        mutable QString fileOwners[2];
 
         mutable uint cachedFlags : 31;
         mutable uint cache_enabled : 1;