From 0104e93ba9539e3f93493643f55b56a4da63c096 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <renault.cle@gmail.com>
Date: Mon, 15 Apr 2019 16:07:41 +0200
Subject: [PATCH] feat: Introduce index events to update the WordIndex

---
 meilidb-data/Cargo.toml         |  1 +
 meilidb-data/src/index_event.rs | 45 +++++++++++++++++++++++++++++++++
 meilidb-data/src/lib.rs         |  2 +-
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 meilidb-data/src/index_event.rs

diff --git a/meilidb-data/Cargo.toml b/meilidb-data/Cargo.toml
index 7c13e9f72..18b8ad1e6 100644
--- a/meilidb-data/Cargo.toml
+++ b/meilidb-data/Cargo.toml
@@ -6,6 +6,7 @@ edition = "2018"
 
 [dependencies]
 bincode = "1.1.2"
+byteorder = "1.3.1"
 hashbrown = { version = "0.1.8", features = ["serde"] }
 linked-hash-map = { version = "0.5.2", features = ["serde_impl"] }
 meilidb-core = { path = "../meilidb-core", version = "0.1.0" }
diff --git a/meilidb-data/src/index_event.rs b/meilidb-data/src/index_event.rs
new file mode 100644
index 000000000..40d54cbf3
--- /dev/null
+++ b/meilidb-data/src/index_event.rs
@@ -0,0 +1,45 @@
+use std::error::Error;
+
+use byteorder::{ReadBytesExt, WriteBytesExt};
+
+use meilidb_core::{Index as WordIndex};
+use meilidb_core::data::DocIds;
+use meilidb_core::write_to_bytes::WriteToBytes;
+use meilidb_core::shared_data_cursor::{SharedDataCursor, FromSharedDataCursor};
+
+enum NewIndexEvent<'a> {
+    RemovedDocuments(&'a DocIds),
+    UpdatedDocuments(&'a WordIndex),
+}
+
+impl<'a> WriteToBytes for NewIndexEvent<'a> {
+    fn write_to_bytes(&self, bytes: &mut Vec<u8>) {
+        match self {
+            NewIndexEvent::RemovedDocuments(doc_ids) => {
+                let _ = bytes.write_u8(0);
+                doc_ids.write_to_bytes(bytes);
+            },
+            NewIndexEvent::UpdatedDocuments(index) => {
+                let _ = bytes.write_u8(1);
+                index.write_to_bytes(bytes);
+            }
+        }
+    }
+}
+
+enum IndexEvent {
+    RemovedDocuments(DocIds),
+    UpdatedDocuments(WordIndex),
+}
+
+impl FromSharedDataCursor for IndexEvent {
+    type Error = Box<Error>;
+
+    fn from_shared_data_cursor(cursor: &mut SharedDataCursor) -> Result<Self, Self::Error> {
+        match cursor.read_u8()? {
+            0 => DocIds::from_shared_data_cursor(cursor).map(IndexEvent::RemovedDocuments),
+            1 => WordIndex::from_shared_data_cursor(cursor).map(IndexEvent::UpdatedDocuments),
+            _ => Err("invalid index event type".into()),
+        }
+    }
+}
diff --git a/meilidb-data/src/lib.rs b/meilidb-data/src/lib.rs
index c601105ed..a19418a3f 100644
--- a/meilidb-data/src/lib.rs
+++ b/meilidb-data/src/lib.rs
@@ -1,4 +1,5 @@
 mod database;
+mod index_event;
 mod indexer;
 mod number;
 mod ranked_map;
@@ -8,4 +9,3 @@ pub use self::database::{Database, Index};
 pub use self::number::Number;
 pub use self::ranked_map::RankedMap;
 pub use self::schema::{Schema, SchemaAttr};
-pub use self::indexer::Indexer;