Merge pull request #137 from akyrtzi/keep-original-database-size

[Database] When opening an existing database make sure to preserve its original size

Author: akyrtzi

lib/Database/Database.cpp

@@ -173,8 +173,16 @@ Database::Implementation::create(StringRef path, bool readonly, Optional<size_t>
     db->DBEnv = lmdb::env::create();
     db->DBEnv.set_max_dbs(14);
 
-    // Start with 64MB. We'll update with the actual size after we open the database.
-    db->MapSize = initialDBSize.getValueOr(64ULL*1024ULL*1024ULL);
+    uint64_t dbFileSize = 0;
+    if (existingDB) {
+      if (std::error_code ec = llvm::sys::fs::file_size(dbPath + "/data.mdb", dbFileSize)) {
+        LOG_WARN_FUNC("failed reading database file size " << dbPath << "/data.mdb: " << ec.message());
+      }
+    }
+    // Start with 64MB.
+    uint64_t initialSize = initialDBSize.getValueOr(64ULL*1024ULL*1024ULL);
+
+    db->MapSize = std::max(dbFileSize, initialSize);
     db->DBEnv.set_mapsize(db->MapSize);
 
     unsigned openflags = MDB_NOMEMINIT|MDB_WRITEMAP|MDB_NOSYNC;
@@ -183,11 +191,6 @@ Database::Implementation::create(StringRef path, bool readonly, Optional<size_t>
     db->DBEnv.open(dbPath, openflags);
     db->MaxKeySize = lmdb::env_get_max_keysize(db->DBEnv);
 
-    // Get actual map size of the database.
-    MDB_envinfo envInfo;
-    lmdb::env_info(db->DBEnv, &envInfo);
-    db->MapSize = envInfo.me_mapsize;
-
     unsigned txnflags = lmdb::txn::default_flags;
     if (readonly)
       txnflags |= MDB_RDONLY;