From d94fce028680176be11b8acd1d02632eeabc16df Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Thu, 8 Jun 2017 12:14:39 -0400
Subject: [PATCH] kv/RocksDBStore: allow cache_size to be specified explicitly

(Not via a config option)

Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/kv/KeyValueDB.h    |  4 ++++
 src/kv/RocksDBStore.cc | 11 +++++++----
 src/kv/RocksDBStore.h  |  6 ++++++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/kv/KeyValueDB.h b/src/kv/KeyValueDB.h
index 9f454ac973a..37a78480f14 100644
--- a/src/kv/KeyValueDB.h
+++ b/src/kv/KeyValueDB.h
@@ -304,6 +304,10 @@ public:
     return -EOPNOTSUPP;
   }
 
+  virtual int set_cache_size(uint64_t) {
+    return -EOPNOTSUPP;
+  }
+
   virtual ~KeyValueDB() {}
 
   /// compact the underlying store
diff --git a/src/kv/RocksDBStore.cc b/src/kv/RocksDBStore.cc
index c6d3e5e553f..db985f0aa6e 100644
--- a/src/kv/RocksDBStore.cc
+++ b/src/kv/RocksDBStore.cc
@@ -298,11 +298,14 @@ int RocksDBStore::do_open(ostream &out, bool create_if_missing)
   }
 
   std::shared_ptr<rocksdb::Cache> cache;
+  if (!cache_size) {
+    cache_size = g_conf->rocksdb_cache_size;
+  }
   if (g_conf->rocksdb_cache_type == "lru") {
-    cache = rocksdb::NewLRUCache(g_conf->rocksdb_cache_size,
+    cache = rocksdb::NewLRUCache(cache_size,
 				 g_conf->rocksdb_cache_shard_bits);
   } else if (g_conf->rocksdb_cache_type == "clock") {
-    cache = rocksdb::NewClockCache(g_conf->rocksdb_cache_size,
+    cache = rocksdb::NewClockCache(cache_size,
 				   g_conf->rocksdb_cache_shard_bits);
   } else {
     derr << "unrecognized rocksdb_cache_type '" << g_conf->rocksdb_cache_type
@@ -320,8 +323,8 @@ int RocksDBStore::do_open(ostream &out, bool create_if_missing)
   }
   opt.table_factory.reset(rocksdb::NewBlockBasedTableFactory(bbt_opts));
   dout(10) << __func__ << " set block size to " << g_conf->rocksdb_block_size
-           << " cache size to " << g_conf->rocksdb_cache_size
-           << " num of cache shards to "
+           << ", cache size to " << prettybyte_t(cache_size)
+           << ", cache shards to "
 	   << (1 << g_conf->rocksdb_cache_shard_bits) << dendl;
 
   opt.merge_operator.reset(new MergeOperatorRouter(*this));
diff --git a/src/kv/RocksDBStore.h b/src/kv/RocksDBStore.h
index 4d25408a5f0..c437badebab 100644
--- a/src/kv/RocksDBStore.h
+++ b/src/kv/RocksDBStore.h
@@ -75,6 +75,8 @@ class RocksDBStore : public KeyValueDB {
   rocksdb::BlockBasedTableOptions bbt_opts;
   string options_str;
 
+  uint64_t cache_size = 0;
+
   int do_open(ostream &out, bool create_if_missing);
 
   // manage async compactions
@@ -435,6 +437,10 @@ err:
     return total_size;
   }
 
+  int set_cache_size(uint64_t s) override {
+    cache_size = s;
+    return 0;
+  }
 
 protected:
   WholeSpaceIterator _get_iterator() override;