Method insert_into_pointer_map

crates/table/src/table.rs:1014–1051

Insert the row identified by `ptr` into the table's [`PointerMap`], if the table has one. This checks for set semantic violations. If a set semantic conflict (i.e. duplicate row) is detected by the pointer map, the row will be deleted and an error returned. If the pointer map confirms that the row was unique, returns the `RowHash` of that row. If this table has no `PointerMap`, returns `Ok(None)

(
        &'a mut self,
        blob_store: &'a mut dyn BlobStore,
        ptr: RowPointer,
    )

    /// SAFETY: `self.is_row_present(row)` must hold.
    /// Post-condition: If this method returns `Ok(_)`, the row still exists.
    unsafe fn insert_into_pointer_map<'a>(
        &'a mut self,
        blob_store: &'a mut dyn BlobStore,
        ptr: RowPointer,
    ) -> Result<Option<RowHash>, DuplicateError> {
        if self.pointer_map.is_none() {
            // No pointer map? Set semantic constraint is checked by a unique index instead.
            return Ok(None);
        };

        // SAFETY:
        // - `self` trivially has the same `row_layout` as `self`.
        // - Caller promised that `self.is_row_present(row)` holds.
        let (hash, existing_row) = unsafe { Self::find_same_row_via_pointer_map(self, self, blob_store, ptr, None) };

        if let Some(existing_row) = existing_row {
            // If an equal row was already present,
            // roll back our optimistic insert to avoid violating set semantics.

            // SAFETY: Caller promised that `ptr` is a valid row in `self`.
            unsafe {
                self.inner
                    .pages
                    .delete_row(&self.inner.visitor_prog, self.row_size(), ptr, blob_store)
            };
            return Err(DuplicateError(existing_row));
        }

        // If the optimistic insertion was correct,
        // i.e. this is not a set-semantic duplicate,
        // add it to the `pointer_map`.
        self.pointer_map
            .as_mut()
            .expect("pointer map should exist, as it did previously")
            .insert(hash, ptr);

        Ok(Some(hash))
    }

    /// Returns the list of pointers to rows which hash to `row_hash`.
    ///