Cleans up RocksDB wrapper code and implements backup from read-only and secondary instances

lib/tests/store.rs

@@ -312,17 +312,34 @@ fn test_backup() -> Result<(), Box<dyn Error>> {
         GraphNameRef::DefaultGraph,
     );
     let store_dir = TempDir::default();
-    let backup_dir = TempDir::default();
+    let secondary_store_dir = TempDir::default();
+    let backup_from_rw_dir = TempDir::default();
+    let backup_from_ro_dir = TempDir::default();
+    let backup_from_secondary_dir = TempDir::default();
 
     let store = Store::open(&store_dir)?;
     store.insert(quad)?;
-    store.backup(&backup_dir)?;
-    store.remove(quad)?;
+    let secondary_store = Store::open_secondary(&store_dir, secondary_store_dir)?;
+    store.flush()?;
 
+    store.backup(&backup_from_rw_dir)?;
+    secondary_store.backup(&backup_from_secondary_dir)?;
+    store.remove(quad)?;
     assert!(!store.contains(quad)?);
-    let backup = Store::open(&backup_dir.0)?;
-    backup.validate()?;
-    assert!(backup.contains(quad)?);
+
+    let backup_from_rw = Store::open_read_only(&backup_from_rw_dir.0)?;
+    backup_from_rw.validate()?;
+    assert!(backup_from_rw.contains(quad)?);
+    backup_from_rw.backup(&backup_from_ro_dir)?;
+
+    let backup_from_ro = Store::open_read_only(&backup_from_ro_dir.0)?;
+    backup_from_ro.validate()?;
+    assert!(backup_from_ro.contains(quad)?);
+
+    let backup_from_secondary = Store::open_read_only(&backup_from_secondary_dir.0)?;
+    backup_from_secondary.validate()?;
+    assert!(backup_from_secondary.contains(quad)?);
+
     Ok(())
 }
 

oxrocksdb-sys/api/c.cc

@@ -106,6 +106,20 @@ rocksdb_t* rocksdb_open_as_secondary_column_families_with_status(
   return result;
 }
 
+void rocksdb_create_checkpoint_with_status(rocksdb_t* db,
+                                           const char* checkpoint_dir,
+                                           rocksdb_status_t* statusptr) {
+  Checkpoint* checkpoint;
+  Status s = Checkpoint::Create(db->rep, &checkpoint);
+  if (!s.ok()) {
+    SaveStatus(statusptr, s);
+    return;
+  }
+  SaveStatus(statusptr,
+             checkpoint->CreateCheckpoint(std::string(checkpoint_dir)));
+  delete checkpoint;
+}
+
 rocksdb_transactiondb_t* rocksdb_transactiondb_open_column_families_with_status(
     const rocksdb_options_t* options,
     const rocksdb_transactiondb_options_t* txn_db_options, const char* name,

oxrocksdb-sys/api/c.h

@@ -90,6 +90,9 @@ rocksdb_open_as_secondary_column_families_with_status(
     rocksdb_column_family_handle_t** column_family_handles,
     rocksdb_status_t* statusptr);
 
+extern ROCKSDB_LIBRARY_API void rocksdb_create_checkpoint_with_status(
+    rocksdb_t* db, const char* checkpoint_dir, rocksdb_status_t* statusptr);
+
 extern ROCKSDB_LIBRARY_API rocksdb_transactiondb_t*
 rocksdb_transactiondb_open_column_families_with_status(
     const rocksdb_options_t* options,

server/src/main.rs

@@ -56,8 +56,9 @@ enum Command {
     },
     /// Start Oxigraph HTTP server in read-only mode.
     ///
-    /// It allows to read the database while other processes are accessing it.
-    /// Changes done after this process has been launched will not be seen.
+    /// It allows to read the database while other processes are also reading it.
+    /// Opening as read-only while having an other process writing the database is undefined behavior.
+    /// Please use the serve-secondary command in this case.
     ServeReadOnly {
         /// Directory in which the data stored by Oxigraph are persisted.
         #[arg(short, long)]