5 files changed, 42 insertions, 1 deletions
diff --git a/db/db_impl.cc b/db/db_impl.cc
index 3fd21b0..dc645d0 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -1425,6 +1425,19 @@ bool DBImpl::GetProperty(const Slice& property, std::string* value) {
   } else if (in == "sstables") {
     *value = versions_->current()->DebugString();
     return true;
+  } else if (in == "approximate-memory-usage") {
+    size_t total_usage = options_.block_cache->TotalCharge();
+    if (mem_) {
+      total_usage += mem_->ApproximateMemoryUsage();
+    }
+    if (imm_) {
+      total_usage += imm_->ApproximateMemoryUsage();
+    }
+    char buf[50];
+    snprintf(buf, sizeof(buf), "%llu",
+             static_cast<unsigned long long>(total_usage));
+    value->append(buf);
+    return true;
   }
 
   return false;
diff --git a/db/db_test.cc b/db/db_test.cc
index 74ba8b0..a0b08bc 100644
--- a/db/db_test.cc
+++ b/db/db_test.cc
@@ -563,6 +563,17 @@ TEST(DBTest, GetFromVersions) {
   } while (ChangeOptions());
 }
 
+TEST(DBTest, GetMemUsage) {
+  do {
+    ASSERT_OK(Put("foo", "v1"));
+    std::string val;
+    ASSERT_TRUE(db_->GetProperty("leveldb.approximate-memory-usage", &val));
+    int mem_usage = atoi(val.c_str());
+    ASSERT_GT(mem_usage, 0);
+    ASSERT_LT(mem_usage, 5*1024*1024);
+  } while (ChangeOptions());
+}
+
 TEST(DBTest, GetSnapshot) {
   do {
     // Try with both a short key and a long key
diff --git a/include/leveldb/cache.h b/include/leveldb/cache.h
index 5f86cd0..6819d5b 100644
--- a/include/leveldb/cache.h
+++ b/include/leveldb/cache.h
@@ -88,6 +88,10 @@ class Cache {
   // leveldb may change Prune() to a pure abstract method.
   virtual void Prune() {}
 
+  // Return an estimate of the combined charges of all elements stored in the
+  // cache.
+  virtual size_t TotalCharge() const = 0;
+
  private:
   void LRU_Remove(Handle* e);
   void LRU_Append(Handle* e);
diff --git a/include/leveldb/db.h b/include/leveldb/db.h
index 4c169bf..53c7068 100644
--- a/include/leveldb/db.h
+++ b/include/leveldb/db.h
@@ -115,6 +115,8 @@ class DB {
   //     about the internal operation of the DB.
   //  "leveldb.sstables" - returns a multi-line string that describes all
   //     of the sstables that make up the db contents.
+  //  "leveldb.approximate-memory-usage" - returns the approximate number of
+  //     bytes of memory in use by the DB.
   virtual bool GetProperty(const Slice& property, std::string* value) = 0;
 
   // For each i in [0,n-1], store in "sizes[i]", the approximate
diff --git a/util/cache.cc b/util/cache.cc
index 7f5fc07..0881bce 100644
--- a/util/cache.cc
+++ b/util/cache.cc
@@ -148,6 +148,10 @@ class LRUCache {
   void Release(Cache::Handle* handle);
   void Erase(const Slice& key, uint32_t hash);
   void Prune();
+  size_t TotalCharge() const {
+    MutexLock l(&mutex_);
+    return usage_;
+  }
 
  private:
   void LRU_Remove(LRUHandle* e);
@@ -158,7 +162,7 @@ class LRUCache {
   size_t capacity_;
 
   // mutex_ protects the following state.
-  port::Mutex mutex_;
+  mutable port::Mutex mutex_;
   size_t usage_;
 
   // Dummy head of LRU list.
@@ -333,6 +337,13 @@ class ShardedLRUCache : public Cache {
       shard_[s].Prune();
     }
   }
+  virtual size_t TotalCharge() const {
+    size_t total = 0;
+    for (int s = 0; s < kNumShards; s++) {
+      total += shard_[s].TotalCharge();
+    }
+    return total;
+  }
 };
 
 }  // end anonymous namespace