Add a couple kv-cache helper functions. (#2206)

candle-nn/src/kv_cache.rs

@@ -47,6 +47,10 @@ impl Cache {
         self.all_data.narrow(self.dim, 0, self.current_seq_len)
     }
 
+    pub fn reset(&mut self) {
+        self.current_seq_len = 0
+    }
+
     pub fn append(&mut self, src: &Tensor) -> Result<()> {
         let seq_len = src.dim(self.dim)?;
         if self.current_seq_len + seq_len > self.max_seq_len {
@@ -83,6 +87,22 @@ impl KvCache {
         Ok(Self { k, v })
     }
 
+    pub fn k_cache(&self) -> &Cache {
+        &self.k
+    }
+
+    pub fn v_cache(&self) -> &Cache {
+        &self.v
+    }
+
+    pub fn k_cache_mut(&mut self) -> &mut Cache {
+        &mut self.k
+    }
+
+    pub fn v_cache_mut(&mut self) -> &mut Cache {
+        &mut self.v
+    }
+
     pub fn k(&self) -> Result<Tensor> {
         self.k.current_data()
     }
@@ -98,4 +118,13 @@ impl KvCache {
         let v = self.v.current_data()?;
         Ok((k, v))
     }
+
+    pub fn current_seq_len(&self) -> usize {
+        self.k.current_seq_len()
+    }
+
+    pub fn reset(&mut self) {
+        self.k.reset();
+        self.v.reset();
+    }
 }