Consistency for File State (#374)

* Delete file immediately (not async) in CachePurge
* Make timeout minimum 1s
* Add lazy open state in flock, since it affects the whole file's state (not just one handle).
* Refactor isDownloadRequired, and use LazyOpen state variable to allow downloading when the file is lazy opened (but not completely opened).
* Refactor openFile
* Fix open handle count issue with Rename (by James)

---------

Co-authored-by: James Fantin-Hardesty <24646452+jfantinhardesty@users.noreply.github.com>

common/lock_map.go

@@ -44,6 +44,8 @@ type LockMapItem struct {
 	exLocked     bool
 	mtx          sync.Mutex
 	downloadTime time.Time
+	// track if file is in lazy open state
+	LazyOpen bool
 }
 
 // Map holding locks for all the files

component/azstorage/block_blob.go

@@ -569,7 +569,7 @@ func (bb *BlockBlob) List(prefix string, marker *string, count int32) ([]*intern
 	var dirList = make(map[string]bool)
 	for _, blobInfo := range listBlob.Segment.BlobItems {
 		blobInfo.Name = bb.getFileName(*blobInfo.Name)
-		attr := &internal.ObjAttr{}
+		var attr *internal.ObjAttr
 		if blobInfo.Properties.CustomerProvidedKeySHA256 != nil && *blobInfo.Properties.CustomerProvidedKeySHA256 != "" {
 			log.Trace("BlockBlob::List : blob is encrypted with customer provided key so fetching metadata explicitly using REST")
 			attr, err = bb.getAttrUsingRest(*blobInfo.Name)

component/file_cache/cache_policy.go

@@ -56,8 +56,8 @@ type cachePolicy interface {
 
 	UpdateConfig(cachePolicyConfig) error
 
-	CacheValid(name string) // Mark the file as hit
-	CachePurge(name string) // Schedule the file for deletion
+	CacheValid(name string)                            // Mark the file as hit
+	CachePurge(name string, flock *common.LockMapItem) // Delete the file from cache
 
 	IsCached(name string) bool // Whether or not the cache policy considers this file cached