feat(index): store index blobs in LMDB behind BlobDatabase

CMakeLists.txt

@@ -190,6 +190,7 @@ target_link_libraries(clice-core PUBLIC
     kota::codec::toml
     kota::option
     simdjson::simdjson
+    lmdb
 )
 
 file(GLOB CLICE_DRIVER_SOURCES CONFIGURE_DEPENDS "${PROJECT_SOURCE_DIR}/src/driver/*.cc")

cmake/package.cmake

@@ -44,4 +44,27 @@ set(KOTA_CODEC_ENABLE_FLATBUFFERS ON)
 set(KOTA_ENABLE_EXCEPTIONS OFF)
 set(KOTA_ENABLE_RTTI OFF)
 
-FetchContent_MakeAvailable(kotatsu spdlog croaring)
+# lmdb — index blob database backend (index::BlobDatabase). Upstream ships
+# no CMake; the two-file static library is defined below. Pinned to the
+# 0.9 stable line.
+FetchContent_Declare(
+    lmdb
+    GIT_REPOSITORY https://github.com/LMDB/lmdb.git
+    GIT_TAG LMDB_0.9.31
+    GIT_SHALLOW TRUE
+)
+
+FetchContent_MakeAvailable(kotatsu spdlog croaring lmdb)
+
+add_library(lmdb STATIC
+    ${lmdb_SOURCE_DIR}/libraries/liblmdb/mdb.c
+    ${lmdb_SOURCE_DIR}/libraries/liblmdb/midl.c)
+target_include_directories(lmdb SYSTEM PUBLIC ${lmdb_SOURCE_DIR}/libraries/liblmdb)
+# Third-party C, not held to the project's warning set.
+if(MSVC)
+    target_compile_options(lmdb PRIVATE /w)
+else()
+    target_compile_options(lmdb PRIVATE -w)
+endif()
+find_package(Threads REQUIRED)
+target_link_libraries(lmdb PUBLIC Threads::Threads)

src/driver/index.cc

@@ -104,7 +104,7 @@ kota::task<> run_indexing_task(MasterServer& server, std::string root, int& exit
     // or an unreadable global blob disabled persistence) the run would
     // only warm this process's memory and a rerun would start from
     // nothing — fail instead of pretending.
-    if(!server.workspace.index_storage) {
+    if(!server.workspace.index_db) {
         LOG_ERROR("Cannot persist the index at {}; see the log for the cause and rerun",
                   std::string_view(server.workspace.config.project.cache_dir));
         exit_code = 1;
@@ -211,7 +211,7 @@ int run_stats_once(llvm::StringRef root, std::uint32_t top, bool allow_retry) {
     Workspace workspace;
     workspace.config = std::move(config);
     workspace.store.emplace(std::move(*store));
-    workspace.index_storage = index::make_fs_index_storage(*workspace.store);
+    workspace.index_db = index::open_database(*workspace.store, workspace.config.project.index_db);
     // A namespace whose directory scan failed looks empty while its blobs
     // exist — reporting "Index is empty" with exit code 0 would be a lie.
     if(auto ec = workspace.store->scan_error()) {
@@ -231,7 +231,7 @@ int run_stats_once(llvm::StringRef root, std::uint32_t top, bool allow_retry) {
     }
     // load() detaches the storage when the global blob exists but cannot
     // be read — a transient IO error, not an empty index.
-    if(workspace.index_storage == nullptr) {
+    if(workspace.index_db == nullptr) {
         LOG_ERROR("Failed to read the index cache at {}; the cache was left untouched",
                   std::string_view(workspace.config.project.cache_dir));
         return 1;