From 1743922dfd784e6cec328ac9e577ff8594f24f4f Mon Sep 17 00:00:00 2001
From: Ziyang Hu <hu.ziyang@cantab.net>
Date: Thu, 10 Nov 2022 14:02:09 +0800
Subject: [PATCH] towards storage API

---
 Cargo.toml              |  2 +-
 src/lib.rs              |  1 +
 src/runtime/relation.rs |  9 -----
 src/storage/mod.rs      | 32 +++++++++++++++++
 src/storage/rocks.rs    | 78 +++++++++++++++++++++++++++++++++++++++++
 src/storage/sled.rs     |  4 +++
 src/storage/tikv.rs     |  4 +++
 7 files changed, 120 insertions(+), 10 deletions(-)
 create mode 100644 src/storage/mod.rs
 create mode 100644 src/storage/rocks.rs
 create mode 100644 src/storage/sled.rs
 create mode 100644 src/storage/tikv.rs

diff --git a/Cargo.toml b/Cargo.toml
index 67e7ef0b..9ba179da 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "cozo"
-version = "0.1.6"
+version = "0.1.7"
 edition = "2021"
 description = "A general-purpose, transactional, relational database that uses Datalog and focuses on graph data and algorithms"
 authors = ["Ziyang Hu"]
diff --git a/src/lib.rs b/src/lib.rs
index a4c36f19..72e5bcda 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -26,3 +26,4 @@ pub(crate) mod parse;
 pub(crate) mod query;
 pub(crate) mod runtime;
 pub(crate) mod utils;
+pub(crate) mod storage;
diff --git a/src/runtime/relation.rs b/src/runtime/relation.rs
index 27d6e44c..ebda8f05 100644
--- a/src/runtime/relation.rs
+++ b/src/runtime/relation.rs
@@ -280,9 +280,6 @@ impl RelationIterator {
             None => None,
             Some((k_slice, v_slice)) => {
                 if self.upper_bound.as_slice() <= k_slice {
-                    //
-                    // }
-                    // if compare_tuple_keys(&self.upper_bound, k_slice) != Greater {
                     None
                 } else {
                     let mut tup = Tuple::decode_from_key(k_slice);
@@ -290,12 +287,6 @@ impl RelationIterator {
                         let vals: Vec<DataValue> = rmp_serde::from_slice(&v_slice[ENCODED_KEY_MIN_LEN..]).unwrap();
                         tup.0.extend(vals);
                     }
-                    // if !v_slice.is_empty() {
-                    //     let v_tup = EncodedTuple(v_slice);
-                    //     if v_tup.arity() > 0 {
-                    //         tup.0.extend(v_tup.decode().0);
-                    //     }
-                    // }
                     Some(tup)
                 }
             }
diff --git a/src/storage/mod.rs b/src/storage/mod.rs
new file mode 100644
index 00000000..2ee9d26a
--- /dev/null
+++ b/src/storage/mod.rs
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2022, The Cozo Project Authors. Licensed under MPL-2.0.
+ */
+
+use miette::Result;
+
+pub(crate) mod rocks;
+pub(crate) mod sled;
+pub(crate) mod tikv;
+
+pub(crate) trait Storage {
+    type Tx: StoreTx;
+
+    fn tx(&self) -> Result<Self::Tx>;
+    fn del_range(&self, lower: &[u8], upper: &[u8]) -> Result<()>;
+}
+
+pub(crate) trait StoreTx {
+    type ReadSlice: AsRef<[u8]>;
+    type IterSlice: AsRef<[u8]>;
+
+    type KeyIter: Iterator<Item = Result<Self::IterSlice>>;
+    type KeyValueIter: Iterator<Item = Result<(Self::IterSlice, Self::IterSlice)>>;
+
+    fn get(&self, key: &[u8], for_update: bool) -> Result<Option<Self::ReadSlice>>;
+    fn put(&mut self, key: &[u8], val: &[u8]) -> Result<()>;
+    fn del(&mut self, key: &[u8]) -> Result<()>;
+    fn exists(&self, key: &[u8], for_update: bool) -> Result<bool>;
+    fn commit(&mut self) -> Result<()>;
+    fn range_scan(&self, lower: &[u8], upper: &[u8]) -> Self::KeyValueIter;
+    fn range_key_scan(&self, lower: &[u8], upper: &[u8]) -> Self::KeyIter;
+}
diff --git a/src/storage/rocks.rs b/src/storage/rocks.rs
new file mode 100644
index 00000000..21af33f8
--- /dev/null
+++ b/src/storage/rocks.rs
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2022, The Cozo Project Authors. Licensed under MPL-2.0.
+ */
+
+use miette::Result;
+
+use crate::storage::{Storage, StoreTx};
+
+struct RocksDbStorage;
+
+impl Storage for RocksDbStorage {
+    type Tx = RocksDbTx;
+
+    fn tx(&self) -> miette::Result<Self::Tx> {
+        todo!()
+    }
+
+    fn del_range(&self, lower: &[u8], upper: &[u8]) -> miette::Result<()> {
+        todo!()
+    }
+}
+
+struct RocksDbTx;
+
+impl StoreTx for RocksDbTx {
+    type ReadSlice = Vec<u8>;
+    type IterSlice = Vec<u8>;
+    type KeyIter = RocksDbKeyIter;
+    type KeyValueIter = RocksDbIter;
+
+    fn get(&self, key: &[u8], for_update: bool) -> miette::Result<Option<Self::ReadSlice>> {
+        todo!()
+    }
+
+    fn put(&mut self, key: &[u8], val: &[u8]) -> miette::Result<()> {
+        todo!()
+    }
+
+    fn del(&mut self, key: &[u8]) -> miette::Result<()> {
+        todo!()
+    }
+
+    fn exists(&self, key: &[u8], for_update: bool) -> miette::Result<bool> {
+        todo!()
+    }
+
+    fn commit(&mut self) -> miette::Result<()> {
+        todo!()
+    }
+
+    fn range_scan(&self, lower: &[u8], upper: &[u8]) -> Self::KeyValueIter {
+        todo!()
+    }
+
+    fn range_key_scan(&self, lower: &[u8], upper: &[u8]) -> Self::KeyIter {
+        todo!()
+    }
+}
+
+struct RocksDbKeyIter;
+
+impl Iterator for RocksDbKeyIter {
+    type Item = Result<Vec<u8>>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        todo!()
+    }
+}
+
+struct RocksDbIter;
+
+impl Iterator for RocksDbIter {
+    type Item = Result<(Vec<u8>, Vec<u8>)>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        todo!()
+    }
+}
\ No newline at end of file
diff --git a/src/storage/sled.rs b/src/storage/sled.rs
new file mode 100644
index 00000000..54b1970e
--- /dev/null
+++ b/src/storage/sled.rs
@@ -0,0 +1,4 @@
+/*
+ * Copyright 2022, The Cozo Project Authors. Licensed under MPL-2.0.
+ */
+
diff --git a/src/storage/tikv.rs b/src/storage/tikv.rs
new file mode 100644
index 00000000..54b1970e
--- /dev/null
+++ b/src/storage/tikv.rs
@@ -0,0 +1,4 @@
+/*
+ * Copyright 2022, The Cozo Project Authors. Licensed under MPL-2.0.
+ */
+