issue/43 TODO hunt

1 files changed, 67 insertions, 4 deletions

diff --git a/src/indexer/doc_opstamp_mapping.rs b/src/indexer/doc_opstamp_mapping.rs
index 8430024..16eb1ff 100644
--- a/src/indexer/doc_opstamp_mapping.rs
+++ b/src/indexer/doc_opstamp_mapping.rs
@@ -1,6 +1,22 @@
 use std::sync::Arc;
 use DocId;
 
+
+// Doc to opstamp is used to identify which
+// document should be deleted.
+// 
+// Since the docset matching the query of a delete operation
+// is not computed right when the delete operation is received,
+// we need to find a way to evaluate, for each document,
+// whether the document was added before or after
+// the delete operation. This anteriority is used by comparing
+// the docstamp of the document.
+//
+// The doc to opstamp mapping stores precisely an array
+// indexed by doc id and storing the opstamp of the document.
+// 
+// This mapping is (for the moment) stricly increasing
+// because of the way document id are allocated.
 #[derive(Clone)]
 pub enum DocToOpstampMapping {
     WithMap(Arc<Vec<u64>>),
@@ -13,12 +29,18 @@ impl From<Vec<u64>> for DocToOpstampMapping {
     }
 }
 
-impl DocToOpstampMapping { 
-    // TODO Unit test
-    pub fn compute_doc_limit(&self, opstamp: u64) -> DocId {
+impl DocToOpstampMapping {
+    
+    /// Given an opstamp return the limit doc id L
+    /// such that all doc id D such that 
+    // D >= L iff opstamp(D) >= than `target_opstamp`.
+    //
+    // The edge case opstamp = some doc opstamp is in practise
+    // never called.
+    pub fn compute_doc_limit(&self, target_opstamp: u64) -> DocId {
         match *self {
             DocToOpstampMapping::WithMap(ref doc_opstamps) => {
-                match doc_opstamps.binary_search(&opstamp) {
+                match doc_opstamps.binary_search(&target_opstamp) {
                     Ok(doc_id) => doc_id as DocId,
                     Err(doc_id) => doc_id as DocId,
                 }
@@ -28,3 +50,44 @@ impl DocToOpstampMapping {
     }
 }
 
+#[cfg(test)]
+mod tests {
+
+    use super::DocToOpstampMapping;
+
+    #[test]
+    fn test_doc_to_opstamp_mapping_none() {
+        let doc_to_opstamp_mapping = DocToOpstampMapping::None;
+        assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(1), u32::max_value());
+    }
+
+    #[test]
+    fn test_doc_to_opstamp_mapping_complex() {
+        {
+            let doc_to_opstamp_mapping = DocToOpstampMapping::from(vec!());
+            assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(0u64), 0);
+            assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(2u64), 0);
+        }
+        {
+            let doc_to_opstamp_mapping = DocToOpstampMapping::from(vec!(1u64));
+            assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(0u64), 0);
+            assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(2u64), 1);
+        }
+        {
+            let doc_to_opstamp_mapping = DocToOpstampMapping::from(vec!(1u64, 12u64, 17u64, 23u64));
+            assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(0u64), 0);
+            for i in 2u64..13u64 {
+                assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(i), 1);
+            }
+            for i in 13u64..18u64 {
+                assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(i), 2);
+            }
+            for i in 18u64..24u64 {
+                assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(i), 3);
+            }
+            for i in 24u64..30u64 {
+                assert_eq!(doc_to_opstamp_mapping.compute_doc_limit(i), 4);
+            }
+        }
+    }
+}
\ No newline at end of file