From: Sage Weil <sage@redhat.com>
Date: Fri, 10 Jun 2016 13:24:10 +0000 (-0400)
Subject: os/bluestore: cache: define 'empty' buffer
X-Git-Tag: v11.0.0~70^2~14
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=ba0a7c4027d6c9a4e4b66aeef8e18813bc21111a;p=ceph.git

os/bluestore: cache: define 'empty' buffer

This is a buffer with no data.  It's a placeholder that is there to be used
by cache replacement algorithms like 2Q and MQ that needs history for
trimmed buffers.

Signed-off-by: Sage Weil <sage@redhat.com>
---

diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index 5d103748efae..d160f66caea0 100644
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -111,14 +111,14 @@ public:
   /// cached buffer
   struct Buffer {
     enum {
-      STATE_UNDEF = 0,
-      STATE_CLEAN,
-      STATE_WRITING,
+      STATE_EMPTY,     ///< empty buffer -- used for cache history
+      STATE_CLEAN,     ///< clean data that is up to date
+      STATE_WRITING,   ///< data that is being written (io not yet complete)
       STATE_READING,
     };
     static const char *get_state_name(int s) {
       switch (s) {
-      case STATE_UNDEF: return "undef";
+      case STATE_EMPTY: return "empty";
       case STATE_CLEAN: return "clean";
       case STATE_WRITING: return "writing";
       case STATE_READING: return "reading";
@@ -154,6 +154,9 @@ public:
       : space(space), state(s), flags(f), seq(q), offset(o),
 	length(b.length()), data(b) {}
 
+    bool is_empty() const {
+      return state == STATE_EMPTY;
+    }
     bool is_clean() const {
       return state == STATE_CLEAN;
     }