Implementation of the LevelDb Storage Engine, which will allow the Database to store data locally on disk between runs.

This is just the implementation and tests, hooking it into the library will be in a separate CL.

PiperOrigin-RevId: 312746071

Author: amablue

CMakeLists.txt

@@ -189,6 +189,12 @@ if(FIREBASE_CPP_BUILD_TESTS AND NOT FIRESTORE_USE_EXTERNAL_CMAKE_BUILD)
   add_external_library(googletest)
 endif()
 
+if((FIREBASE_INCLUDE_DATABASE AND DESKTOP) AND NOT FIREBASE_INCLUDE_FIRESTORE)
+  # LevelDB is needed for Desktop and Firestore, but if firestore is being built
+  # LevelDB will already be included.
+  add_external_library(leveldb)
+endif()
+
 # Some of the external libraries are not used for mobile.
 if(DESKTOP)
   # Use the static versions of the OpenSSL libraries.

cmake/external/CMakeLists.txt

@@ -30,6 +30,7 @@ include(firestore)
 if (${FIREBASE_EXTERNAL_PLATFORM} STREQUAL "DESKTOP")
   include(curl)
   include(libuv)
+  include(leveldb)
   include(nanopb)
   include(uWebSockets)
   include(zlib)

cmake/external/leveldb.cmake

@@ -0,0 +1,37 @@
+# Copyright 2017 Google
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+include(ExternalProject)
+
+if(TARGET leveldb)
+  return()
+endif()
+
+set(version 1.22)
+
+ExternalProject_Add(
+  leveldb
+
+  DOWNLOAD_DIR ${FIREBASE_DOWNLOAD_DIR}
+  DOWNLOAD_NAME leveldb-${version}.tar.gz
+  URL https://github.com/google/leveldb/archive/${version}.tar.gz
+  URL_HASH SHA256=55423cac9e3306f4a9502c738a001e4a339d1a38ffbee7572d4a07d5d63949b2
+
+  PREFIX ${PROJECT_BINARY_DIR}
+
+  CONFIGURE_COMMAND ""
+  BUILD_COMMAND     ""
+  INSTALL_COMMAND   ""
+  TEST_COMMAND      ""
+)

database/CMakeLists.txt

@@ -114,6 +114,7 @@ set(desktop_SRCS
     src/desktop/mutable_data_desktop.cc
     src/desktop/persistence/flatbuffer_conversions.cc
     src/desktop/persistence/in_memory_persistence_storage_engine.cc
+    src/desktop/persistence/level_db_persistence_storage_engine.cc
     src/desktop/persistence/noop_persistence_manager.cc
     src/desktop/persistence/persistence_manager.cc
     src/desktop/persistence/prune_forest.cc
@@ -157,6 +158,7 @@ else()
       desktop_flatbuffers
       firebase_rest_lib
       ${OPENSSL_CRYPTO_LIBRARY}
+      leveldb
       libuWS)
 
   set(additional_DEFINES