Updated buffer

common/sys/src/plugin/module.rs

@@ -17,7 +17,7 @@ pub type Function<'a> = Func<'a, (i32, u32), i32>;
 #[derive(Clone)]
 // This structure represent the WASM State of the plugin.
 pub struct PluginModule {
-    wasm_instance: Arc<Mutex<Instance>>,
+    wasm_state: Arc<Mutex<WasmState>>,
     events: HashSet<String>,
 }
 
@@ -30,10 +30,9 @@ impl PluginModule {
                 "raw_emit_actions" => func!(read_action),
             }})
             .map_err(PluginModuleError::Instantiate)?;
-
         Ok(Self {
             events: instance.exports.into_iter().map(|(name, _)| name).collect(),
-            wasm_instance: Arc::new(Mutex::new(instance)),
+            wasm_state: Arc::new(Mutex::new(WasmState::new(instance))),
         })
     }
 
@@ -51,16 +50,8 @@ impl PluginModule {
             return None;
         }
         let bytes = {
-            let instance = self.wasm_instance.lock().unwrap();
-            let func = match instance
-                .exports
-                .get(event_name)
-                .map_err(PluginModuleError::FunctionGet)
-            {
-                Ok(e) => e,
-                Err(e) => return Some(Err(e)),
-            };
-            match execute_raw(&instance, &func, &request.bytes)
+            let mut state = self.wasm_state.lock().unwrap();
+            match execute_raw(&mut state, event_name, &request.bytes)
                 .map_err(PluginModuleError::RunFunction)
             {
                 Ok(e) => e,
@@ -71,6 +62,28 @@ impl PluginModule {
     }
 }
 
+pub struct WasmMemoryContext {
+    memory_buffer_size: usize,
+    memory_pointer: i32,
+}
+
+pub struct WasmState {
+    instance: Instance,
+    memory: WasmMemoryContext,
+}
+
+impl WasmState {
+    fn new(instance: Instance) -> Self {
+        Self {
+            instance,
+            memory: WasmMemoryContext {
+                memory_buffer_size: 0,
+                memory_pointer: 0,
+            },
+        }
+    }
+}
+
 // This structure represent a Pre-encoded event object (Useful to avoid
 // reencoding for each module in every plugin)
 pub struct PreparedEventQuery<T> {
@@ -97,17 +110,23 @@ impl<T: Event> PreparedEventQuery<T> {
 // an interface to limit unsafe behaviours
 #[allow(clippy::needless_range_loop)]
 fn execute_raw(
-    instance: &Instance,
-    function: &Function,
+    context: &mut WasmState,
+    event_name: &str,
     bytes: &[u8],
 ) -> Result<Vec<u8>, RuntimeError> {
     // This reserves space for the buffer
     let len = bytes.len();
     let start = {
-        let memory_pos = reserve_wasm_memory_buffer(len, instance)
+        let memory_pos = reserve_wasm_memory_buffer(len, &context.instance, &mut context.memory)
             .expect("Fatal error while allocating memory for a plugin! Closing server...")
             as usize;
-        let memory = instance.context().memory(0);
+
+        let function: Func<(i32, u32), i32> = context
+            .instance
+            .exports
+            .get(event_name)
+            .expect("Function not found this should never happen");
+        let memory = context.instance.context().memory(0);
         let view = memory.view::<u8>();
         for (cell, byte) in view[memory_pos..memory_pos + len].iter().zip(bytes.iter()) {
             cell.set(*byte)
@@ -115,7 +134,7 @@ fn execute_raw(
         function.call(memory_pos as i32, len as u32)? as usize
     };
 
-    let memory = instance.context().memory(0);
+    let memory = context.instance.context().memory(0);
     let view = memory.view::<u8>();
     let mut new_len_bytes = [0u8; 4];
     // TODO: It is probably better to dirrectly make the new_len_bytes
@@ -168,11 +187,18 @@ pub fn read_action(ctx: &mut Ctx, ptr: u32, len: u32) {
 fn reserve_wasm_memory_buffer<'a>(
     value: usize,
     instance: &'a Instance,
+    context: &mut WasmMemoryContext,
 ) -> Result<i32, MemoryAllocationError> {
-    instance
+    if context.memory_buffer_size >= value {
+        return Ok(context.memory_pointer);
+    }
+    let pointer = instance
         .exports
         .get::<Func<'a, i32, i32>>("wasm_prepare_buffer")
         .map_err(MemoryAllocationError::AllocatorNotFound)?
         .call(value as i32)
-        .map_err(MemoryAllocationError::CantAllocate)
+        .map_err(MemoryAllocationError::CantAllocate)?;
+    context.memory_buffer_size = value;
+    context.memory_pointer = pointer;
+    Ok(pointer)
 }