work in progress

src/write_batcher.rs

@@ -0,0 +1,61 @@
+use anyhow::{anyhow, Result};
+use std::sync::{Arc, Mutex};
+
+use crate::checksum;
+use crate::io_engine::*;
+use crate::pdata::space_map::*;
+
+//------------------------------------------
+
+pub struct WriteBatcher {
+    engine: Arc<dyn IoEngine + Send + Sync>,
+    sm: Arc<Mutex<dyn SpaceMap>>,
+
+    batch_size: usize,
+    queue: Vec<Block>,
+}
+
+impl WriteBatcher {
+    pub fn new(
+        engine: Arc<dyn IoEngine + Send + Sync>,
+        sm: Arc<Mutex<dyn SpaceMap>>,
+        batch_size: usize,
+    ) -> WriteBatcher {
+        WriteBatcher {
+            engine,
+            sm,
+            batch_size,
+            queue: Vec::with_capacity(batch_size),
+        }
+    }
+
+    pub fn alloc(&mut self) -> Result<u64> {
+        let mut sm = self.sm.lock().unwrap();
+        let b = sm.alloc()?;
+
+        if b.is_none() {
+            return Err(anyhow!("out of metadata space"));
+        }
+
+        Ok(b.unwrap())
+    }
+
+    pub fn write(&mut self, b: Block, kind: checksum::BT) -> Result<()> {
+        checksum::write_checksum(&mut b.get_data(), kind)?;
+
+        if self.queue.len() == self.batch_size {
+            self.flush()?;
+        }
+
+        self.queue.push(b);
+        Ok(())
+    }
+
+    pub fn flush(&mut self) -> Result<()> {
+        self.engine.write_many(&self.queue)?;
+        self.queue.clear();
+        Ok(())
+    }
+}
+
+//------------------------------------------