From d5eec5d528363c2ab6587f08ffa5ea72e7bb8a75 Mon Sep 17 00:00:00 2001
From: Piotr Sarna <sarna@chiselstrike.com>
Date: Thu, 11 May 2023 14:11:10 +0200
Subject: [PATCH] cursor: add MVCCScanCursorPosition

---
 core/mvcc/bindings/c/include/mvcc.h | 2 ++
 core/mvcc/bindings/c/src/lib.rs     | 9 ++++++++-
 core/mvcc/mvcc-rs/src/cursor.rs     | 9 ++++++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/core/mvcc/bindings/c/include/mvcc.h b/core/mvcc/bindings/c/include/mvcc.h
index 5c3a94cfc..bd6aaa4d8 100644
--- a/core/mvcc/bindings/c/include/mvcc.h
+++ b/core/mvcc/bindings/c/include/mvcc.h
@@ -39,6 +39,8 @@ MVCCError MVCCScanCursorRead(MVCCScanCursorRef cursor, uint8_t **value_ptr, int6
 
 int MVCCScanCursorNext(MVCCScanCursorRef cursor);
 
+uint64_t MVCCScanCursorPosition(MVCCScanCursorRef cursor);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
diff --git a/core/mvcc/bindings/c/src/lib.rs b/core/mvcc/bindings/c/src/lib.rs
index 21dbe4315..16254194a 100644
--- a/core/mvcc/bindings/c/src/lib.rs
+++ b/core/mvcc/bindings/c/src/lib.rs
@@ -200,7 +200,7 @@ pub unsafe extern "C" fn MVCCScanCursorRead(
 
     // TODO: deduplicate with MVCCDatabaseRead()
     match runtime.block_on(async move {
-        let maybe_row = cursor.current().await?;
+        let maybe_row = cursor.current_row().await?;
         match maybe_row {
             Some(row) => {
                 tracing::debug!("Found row {row:?}");
@@ -243,3 +243,10 @@ pub unsafe extern "C" fn MVCCScanCursorNext(cursor: MVCCScanCursorRef) -> std::f
         0
     }
 }
+
+#[no_mangle]
+pub unsafe extern "C" fn MVCCScanCursorPosition(cursor: MVCCScanCursorRef) -> u64 {
+    let cursor_ctx = unsafe { &mut *cursor.ptr };
+    let cursor = &mut cursor_ctx.cursor;
+    cursor.current_row_id().unwrap_or(0)
+}
\ No newline at end of file
diff --git a/core/mvcc/mvcc-rs/src/cursor.rs b/core/mvcc/mvcc-rs/src/cursor.rs
index cced5df5a..856ce1dbc 100644
--- a/core/mvcc/mvcc-rs/src/cursor.rs
+++ b/core/mvcc/mvcc-rs/src/cursor.rs
@@ -36,7 +36,14 @@ impl<
         })
     }
 
-    pub async fn current(&self) -> Result<Option<Row>> {
+    pub fn current_row_id(&self) -> Option<u64> {
+        if self.index >= self.row_ids.len() {
+            return None;
+        }
+        Some(self.row_ids[self.index])
+    }
+
+    pub async fn current_row(&self) -> Result<Option<Row>> {
         if self.index >= self.row_ids.len() {
             return Ok(None);
         }