[BlobStorage] BlobMemoryController & tests

storage/browser/blob/shareable_blob_data_item.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef STORAGE_BROWSER_BLOB_SHAREABLE_BLOB_DATA_ITEM_H_
 #define STORAGE_BROWSER_BLOB_SHAREABLE_BLOB_DATA_ITEM_H_
 
 #include <string>
 
+#include "base/callback_helpers.h"
 #include "base/containers/hash_tables.h"
 #include "base/hash.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "storage/browser/blob/blob_memory_controller.h"
+#include "storage/browser/storage_browser_export.h"
 #include "storage/common/data_element.h"
 
 namespace storage {
 class BlobDataItem;
 class InternalBlobData;
 
-// This class allows blob items to be shared between blobs, and is only used by
-// BlobStorageContext. This class contains both the blob data item and the uuids
-// of all the blobs using this item.
+// This class allows blob items to be shared between blobs.  This class contains
+// both the blob data item and the uuids of all the blobs using this item.
 // The data in this class (the item) is immutable, but the item itself can be
 // swapped out with an item with the same data but a different backing (think
 // RAM vs file backed).
-class ShareableBlobDataItem : public base::RefCounted<ShareableBlobDataItem> {
+// We also allow the storage of a deletion closure which is used for memory
+// quota reclamation.
+class STORAGE_EXPORT ShareableBlobDataItem
+    : public base::RefCounted<ShareableBlobDataItem> {
  public:
-  ShareableBlobDataItem(const std::string& blob_uuid,
-                        const scoped_refptr<BlobDataItem>& item);
+  enum State {
+    // We're an item that needs quota (either disk or memory).
+    QUOTA_NEEDED,
+    // We have requested quota from the BlobMemoryController.
+    QUOTA_REQUESTED,
+    // Space has been allocated for this item in the BlobMemoryController, but
+    // it may not yet be populated.
+    QUOTA_GRANTED,
+    // We're a populated item that needed quota.
+    POPULATED_WITH_QUOTA,
+    // We're a populated item that didn't need quota.
+    POPULATED_WITHOUT_QUOTA
+  };
 
-  const scoped_refptr<BlobDataItem>& item();
+  ShareableBlobDataItem(const std::string& referencing_blob_uuid,
+                        scoped_refptr<BlobDataItem> item,
+                        State state);
 
-  base::hash_set<std::string>& referencing_blobs() {
+  const scoped_refptr<BlobDataItem>& item() const { return item_; }
+
+  scoped_refptr<BlobDataItem>* item_mutable() { return &item_; }
+
+  void set_item(scoped_refptr<BlobDataItem> item);
+
+  // This is a unique auto-incrementing id assigned to this item on
+  // construction. It is used to keep track of this item in an LRU data
+  // structure for eviction to disk.
+  uint64_t item_id() const { return item_id_; }
+
+  const base::hash_set<std::string>& referencing_blobs() const {
     return referencing_blobs_;
   }
 
+  base::hash_set<std::string>* referencing_blobs_mutable() {
+    return &referencing_blobs_;
+  }
+
+  State state() const { return state_; }
+
+  void set_state(State state) { state_ = state; }
+
+  bool IsPopulated() const {
+    return state_ == POPULATED_WITH_QUOTA || state_ == POPULATED_WITHOUT_QUOTA;
+  }
+
+  bool HasGrantedQuota() const {
+    return state_ == POPULATED_WITH_QUOTA || state_ == QUOTA_GRANTED;
+  }
+
  private:
+  friend class BlobMemoryController;
   friend class base::RefCounted<ShareableBlobDataItem>;
-  friend class InternalBlobData;
+  friend STORAGE_EXPORT void PrintTo(const ShareableBlobDataItem& x,
+                                     ::std::ostream* os);
+
   ~ShareableBlobDataItem();
 
+  void set_memory_quota_allocation(
+      BlobMemoryController::MemoryAllocation quota_release_callback) {
+    memory_quota_allocation_ = std::move(quota_release_callback);
+  }
+
+  BlobMemoryController::MemoryAllocation* memory_quota_allocation() {
+    return &memory_quota_allocation_;
+  }
+
+  // This is a unique identifier for this ShareableBlobDataItem.
+  const uint64_t item_id_;
+  State state_;
   scoped_refptr<BlobDataItem> item_;
-
   base::hash_set<std::string> referencing_blobs_;
+  BlobMemoryController::MemoryAllocation memory_quota_allocation_;

[michaeln, 2016/10/14 01:53:26]

very opaque and mysterious data member?

[dmurph, 2016/10/14 23:31:48]

Done.

 
   DISALLOW_COPY_AND_ASSIGN(ShareableBlobDataItem);
 };
 
+STORAGE_EXPORT bool operator==(const ShareableBlobDataItem& a,
+                               const ShareableBlobDataItem& b);
+STORAGE_EXPORT bool operator!=(const ShareableBlobDataItem& a,
+                               const ShareableBlobDataItem& b);
+
 }  // namespace storage
 #endif  // STORAGE_BROWSER_BLOB_SHAREABLE_BLOB_DATA_ITEM_H_