| // Copyright 2018 The Fuchsia 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 SRC_STORAGE_BLOBFS_INCLUDE_BLOBFS_CACHE_POLICY_H_ |
| #define SRC_STORAGE_BLOBFS_INCLUDE_BLOBFS_CACHE_POLICY_H_ |
| |
| namespace blobfs { |
| |
| // CachePolicy describes the techniques used to cache blobs in memory, avoiding re-reading and |
| // re-verifying them from disk. |
| enum class CachePolicy { |
| // When all strong references to a node are closed, |ActivateLowMemory()| is invoked. |
| // |
| // This option avoids using memory for any longer than it needs to, but may result in higher |
| // performance penalties for blobs that are frequently opened and closed. |
| EvictImmediately, |
| |
| // The node is never evicted from memory, unless it has been fully deleted and there are no |
| // additional references. |
| // |
| // This option costs a significant amount of memory, but it results in high performance. |
| // On systems where kernel page eviction is enabled, if blobfs is in paged mode, this |
| // memory cost is reduced, since the kernel can reclaim data pages as needed. This is the |
| // recommended configuration. (Note that the kernel does not reclaim in-memory metadata |
| // such as merkle trees.) |
| NeverEvict, |
| }; |
| |
| } // namespace blobfs |
| |
| #endif // SRC_STORAGE_BLOBFS_INCLUDE_BLOBFS_CACHE_POLICY_H_ |
