feat: file cache skeleton (#173)

storage/Cargo.toml

@@ -15,6 +15,7 @@ aws-sdk-s3 = "0.8"
 aws-smithy-http = "0.38"
 aws-smithy-types = "0.38"
 aws-types = { version = "0.8", features = ["hardcoded-credentials"] }
+bitvec = "1"
 bytes = "1"
 bytesize = "1.1.0"
 clap = { version = "3.1.6", features = ["derive"] }
@@ -27,7 +28,7 @@ lazy_static = "1.4.0"
 libc = "0.2"
 lz4 = "1.23.1"
 moka = { version = "0.7", features = ["future"] }
-nix = { version = "0.24.1", features = ["fs", "aio"] }
+nix = { version = "0.24.1", features = ["fs", "aio", "uio"] }
 parking_lot = "0.12"
 prometheus = "0.13.0"
 rand = "0.8.5"

storage/src/file_cache/buffer.rs

@@ -68,6 +68,19 @@ impl<const ALIGN: usize, const SMOOTH: usize, const DEFAULT: usize>
         self.write_at(src, self.len)
     }
 
+    pub fn reserve(&mut self, capacity: usize) {
+        if capacity > self.capacity {
+            self.grow_at(capacity);
+        }
+    }
+
+    pub fn resize(&mut self, len: usize) {
+        if len > self.capacity {
+            self.grow_at(len);
+        }
+        self.len = len;
+    }
+
     pub fn slice(&self, range: impl RangeBounds<usize>) -> &[u8] {
         let (start, end) = self.bounds(range);
         let slice = unsafe { std::slice::from_raw_parts(self.ptr.add(start), end - start) };

storage/src/file_cache/error.rs

@@ -6,6 +6,10 @@ pub enum Error {
     NixError(#[from] nix::errno::Errno),
     #[error("join error: {0}")]
     JoinError(#[from] tokio::task::JoinError),
+    #[error("magic not match")]
+    MagicNotMatch,
+    #[error("invalid version")]
+    InvalidVersion(u32),
 }
 
 pub type Result<T> = core::result::Result<T, Error>;