Add allow_ingest_behind ffi call for DB Options (rust-rocksdb#808)

Author: siyuan0322

.github/workflows/rust.yml

@@ -104,6 +104,8 @@ jobs:
         run: |
           cargo test --all
           cargo test --all --features multi-threaded-cf
+      - name: Free disk space
+        run: cargo clean
       - name: Run rocksdb tests (jemalloc)
         if: runner.os != 'Windows'
         run: cargo test --all --features jemalloc

src/db_options.rs

@@ -3056,6 +3056,24 @@ impl Options {
             ffi::rocksdb_options_set_blob_compaction_readahead_size(self.inner, val);
         }
     }
+
+    /// Set this option to true during creation of database if you want
+    /// to be able to ingest behind (call IngestExternalFile() skipping keys
+    /// that already exist, rather than overwriting matching keys).
+    /// Setting this option to true has the following effects:
+    /// 1) Disable some internal optimizations around SST file compression.
+    /// 2) Reserve the last level for ingested files only.
+    /// 3) Compaction will not include any file from the last level.
+    /// Note that only Universal Compaction supports allow_ingest_behind.
+    /// `num_levels` should be >= 3 if this option is turned on.
+    ///
+    /// DEFAULT: false
+    /// Immutable.
+    pub fn set_allow_ingest_behind(&mut self, val: bool) {
+        unsafe {
+            ffi::rocksdb_options_set_allow_ingest_behind(self.inner, c_uchar::from(val));
+        }
+    }
 }
 
 impl Default for Options {

tests/test_comparator.rs

@@ -7,10 +7,10 @@ pub fn rocks_old_compare(one: &[u8], two: &[u8]) -> Ordering {
     one.cmp(two)
 }
 
+type CompareFn = dyn Fn(&[u8], &[u8]) -> Ordering;
+
 /// create database add some values, and iterate over these
-pub fn write_to_db_with_comparator(
-    compare_fn: Box<dyn Fn(&[u8], &[u8]) -> Ordering>,
-) -> Vec<String> {
+pub fn write_to_db_with_comparator(compare_fn: Box<CompareFn>) -> Vec<String> {
     let mut result_vec = Vec::new();
 
     let path = "_path_for_rocksdb_storage";