From: Greg Farnum <greg@inktank.com>
Date: Thu, 30 Jan 2014 22:21:52 +0000 (-0800)
Subject: shared_cache: expose prior existence when inserting an element
X-Git-Tag: v0.85~37^2~7
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=4c2828ed1492beb0fa2c4ec2997dd6b282f2a0e9;p=ceph.git

shared_cache: expose prior existence when inserting an element

The LRU now handles you attempting to insert multiple values for the
same key, by telling you that you've done so and returning the
existing value before it manages to muck up existing data.
The param 'existed' is not mandatory, default value is NULL.

Signed-off-by: Greg Farnum <greg@inktank.com>

Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>
---

diff --git a/src/common/shared_cache.hpp b/src/common/shared_cache.hpp
index 2f5f05a0d644..6e05a6880a30 100644
--- a/src/common/shared_cache.hpp
+++ b/src/common/shared_cache.hpp
@@ -169,12 +169,35 @@ public:
     return val;
   }
 
-  VPtr add(K key, V *value) {
+  /***
+   * Inserts a key if not present, or bumps it to the front of the LRU if
+   * it is, and then gives you a reference to the value. If the key already
+   * existed, you are responsible for deleting the new value you tried to
+   * insert.
+   *
+   * @param key The key to insert
+   * @param value The value that goes with the key
+   * @param existed Set to true if the value was already in the
+   * map, false otherwise
+   * @return A reference to the map's value for the given key
+   */
+  VPtr add(K key, V *value, bool *existed = NULL) {
     VPtr val(value, Cleanup(this, key));
     list<VPtr> to_release;
     {
       Mutex::Locker l(lock);
-      weak_refs.insert(make_pair(key, val));
+      typename map<K, WeakVPtr>::iterator actual = weak_refs.lower_bound(key);
+      if (actual != weak_refs.end() && actual->first == key) {
+        if (existed) 
+          *existed = true;
+
+        return actual->second.lock();
+      }
+
+      if (existed)      
+        *existed = false;
+
+      weak_refs.insert(actual, make_pair(key, val));
       lru_add(key, val, &to_release);
     }
     return val;
diff --git a/src/os/FDCache.h b/src/os/FDCache.h
index ba11e1207399..712355b48192 100644
--- a/src/os/FDCache.h
+++ b/src/os/FDCache.h
@@ -67,8 +67,8 @@ public:
     return registry.lookup(hoid);
   }
 
-  FDRef add(const ghobject_t &hoid, int fd) {
-    return registry.add(hoid, new FD(fd));
+  FDRef add(const ghobject_t &hoid, int fd, bool *existed) {
+    return registry.add(hoid, new FD(fd), existed);
   }
 
   /// clear cached fd for hoid, subsequent lookups will get an empty FD
diff --git a/src/os/FileStore.cc b/src/os/FileStore.cc
index 165412dfab36..b3f06f20d631 100644
--- a/src/os/FileStore.cc
+++ b/src/os/FileStore.cc
@@ -293,7 +293,9 @@ int FileStore::lfn_open(coll_t cid,
       VOID_TEMP_FAILURE_RETRY(::close(fd));
       return 0;
     } else {
-      *outfd = fdcache.add(oid, fd);
+      bool existed;
+      *outfd = fdcache.add(oid, fd, &existed);
+      assert(!existed);
     }
   } else {
     *outfd = FDRef(new FDCache::FD(fd));
diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index a6568d0526e7..070c473da3a5 100644
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -1154,7 +1154,11 @@ OSDMapRef OSDService::_add_map(OSDMap *o)
       OSDMap::dedup(for_dedup.get(), o);
     }
   }
-  OSDMapRef l = map_cache.add(e, o);
+  bool existed;
+  OSDMapRef l = map_cache.add(e, o, &existed);
+  if (existed) {
+    delete o;
+  }
   return l;
 }