From d3624c328f78b7360eb2932d1970aa2826142f2e Mon Sep 17 00:00:00 2001
From: Shannon Booth <shannon@serenityos.org>
Date: Sat, 14 Feb 2026 10:50:11 +0100
Subject: [PATCH] LibDatabase: Allow creating a memory backed database

---
 Libraries/LibDatabase/Database.cpp     | 20 +++++++++++++++-----
 Libraries/LibDatabase/Database.h       |  8 +++++---
 Libraries/LibHTTP/Cache/CacheIndex.cpp |  4 +++-
 3 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/Libraries/LibDatabase/Database.cpp b/Libraries/LibDatabase/Database.cpp
index 567f3d4150..b6023e0a69 100644
--- a/Libraries/LibDatabase/Database.cpp
+++ b/Libraries/LibDatabase/Database.cpp
@@ -54,15 +54,25 @@ static constexpr StringView sql_error(int error_code)
     __ENUMERATE_TYPE(unsigned long long) \
     __ENUMERATE_TYPE(bool)
 
+ErrorOr<NonnullRefPtr<Database>> Database::create_memory_backed()
+{
+    sqlite3* sql_database { nullptr };
+    SQL_TRY(sqlite3_open(":memory:", &sql_database));
+    return create(sql_database);
+}
+
 ErrorOr<NonnullRefPtr<Database>> Database::create(ByteString const& directory, StringView name)
 {
     TRY(Core::Directory::create(directory, Core::Directory::CreateDirectories::Yes));
     LexicalPath database_path { ByteString::formatted("{}/{}.db", directory, name) };
+    sqlite3* sql_database { nullptr };
+    SQL_TRY(sqlite3_open(database_path.string().characters(), &sql_database));
+    return create(sql_database, database_path);
+}
 
-    sqlite3* m_database { nullptr };
-    SQL_TRY(sqlite3_open(database_path.string().characters(), &m_database));
-
-    auto database = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) Database(move(database_path), m_database)));
+ErrorOr<NonnullRefPtr<Database>> Database::create(sqlite3* sql_database, Optional<LexicalPath> database_path)
+{
+    auto database = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) Database(sql_database, move(database_path))));
 
     // Enable the WAL and set the synchronous pragma to normal by default for performance.
     TRY(database->set_journal_mode_pragma(JournalMode::WriteAheadLog));
@@ -71,7 +81,7 @@ ErrorOr<NonnullRefPtr<Database>> Database::create(ByteString const& directory, S
     return database;
 }
 
-Database::Database(LexicalPath database_path, sqlite3* database)
+Database::Database(sqlite3* database, Optional<LexicalPath> database_path)
     : m_database_path(move(database_path))
     , m_database(database)
 {
diff --git a/Libraries/LibDatabase/Database.h b/Libraries/LibDatabase/Database.h
index dd543f8ee0..00163bb843 100644
--- a/Libraries/LibDatabase/Database.h
+++ b/Libraries/LibDatabase/Database.h
@@ -23,12 +23,13 @@ namespace Database {
 
 class DATABASE_API Database : public RefCounted<Database> {
 public:
+    static ErrorOr<NonnullRefPtr<Database>> create_memory_backed();
     static ErrorOr<NonnullRefPtr<Database>> create(ByteString const& directory, StringView name);
     ~Database();
 
     using OnResult = Function<void(StatementID)>;
 
-    LexicalPath const& database_path() const { return m_database_path; }
+    Optional<LexicalPath> const& database_path() const { return m_database_path; }
 
     ErrorOr<StatementID> prepare_statement(StringView statement);
 
@@ -72,7 +73,8 @@ public:
     ErrorOr<void> set_synchronous_pragma(Synchronous);
 
 private:
-    Database(LexicalPath, sqlite3*);
+    static ErrorOr<NonnullRefPtr<Database>> create(sqlite3*, Optional<LexicalPath> database_path = {});
+    Database(sqlite3*, Optional<LexicalPath> database_path);
 
     void execute_statement_internal(StatementID, OnResult);
 
@@ -87,7 +89,7 @@ private:
         return m_prepared_statements[statement_id];
     }
 
-    LexicalPath m_database_path;
+    Optional<LexicalPath> m_database_path;
     sqlite3* m_database { nullptr };
     Vector<sqlite3_stmt*> m_prepared_statements;
 };
diff --git a/Libraries/LibHTTP/Cache/CacheIndex.cpp b/Libraries/LibHTTP/Cache/CacheIndex.cpp
index 6fcf54e89b..37d3edf621 100644
--- a/Libraries/LibHTTP/Cache/CacheIndex.cpp
+++ b/Libraries/LibHTTP/Cache/CacheIndex.cpp
@@ -129,7 +129,9 @@ ErrorOr<CacheIndex> CacheIndex::create(Database::Database& database)
         WHERE last_access_time >= ?;
     )#"sv));
 
-    auto disk_space = TRY(FileSystem::compute_disk_space(database.database_path().parent()));
+    auto database_path = database.database_path();
+    VERIFY(database_path.has_value()); // We assume a disk backed database for CacheIndex.
+    auto disk_space = TRY(FileSystem::compute_disk_space(database.database_path().value().parent()));
     auto maximum_disk_cache_size = compute_maximum_disk_cache_size(disk_space.free_bytes);
 
     Limits limits {