refactor(proto): replace anyhow with thiserror in writers

proto/src/writer/backend.rs

@@ -3,10 +3,11 @@ use crate::writer::oneway::OneWayProtoWriter;
 use crate::writer::protowriter::ProtoWriter;
 use async_trait::async_trait;
 use tokio::io::{AsyncWrite, AsyncWriteExt};
+use crate::writer::errors::ProtoWriteError;
 
 #[async_trait]
 pub trait BackendProtoWriter: OneWayProtoWriter<BackendMessage> {
-    async fn write_ssl_reject(&mut self) -> anyhow::Result<()>;
+    async fn write_ssl_reject(&mut self) -> Result<(), ProtoWriteError>;
 }
 
 #[async_trait]
@@ -14,7 +15,7 @@ impl<W> BackendProtoWriter for ProtoWriter<W>
 where
     W: AsyncWrite + Unpin + Send,
 {
-    async fn write_ssl_reject(&mut self) -> anyhow::Result<()> {
+    async fn write_ssl_reject(&mut self) -> Result<(), ProtoWriteError> {
         self.inner.write_u8(b'N').await?;
         Ok(())
     }

proto/src/writer/errors.rs

@@ -0,0 +1,11 @@
+use thiserror::Error;
+use tokio::io;
+use crate::message::errors::ProtoSerializeError;
+
+#[derive(Debug, Error)]
+pub enum ProtoWriteError {
+    #[error("writing to socket failed")]
+    Io(#[from] io::Error),
+    #[error("serialization of inner data failed")]
+    Serialize(#[from] ProtoSerializeError),
+}

proto/src/writer/mod.rs

@@ -2,3 +2,4 @@ pub mod backend;
 pub mod frontend;
 pub mod oneway;
 pub mod protowriter;
+pub mod errors;

proto/src/writer/oneway.rs

@@ -2,13 +2,14 @@ use crate::message::proto_message::ProtoMessage;
 use crate::writer::protowriter::ProtoWriter;
 use async_trait::async_trait;
 use tokio::io::{AsyncWrite, AsyncWriteExt};
+use crate::writer::errors::ProtoWriteError;
 
 #[async_trait]
 pub trait OneWayProtoWriter<T>
 where
     T: ProtoMessage,
 {
-    async fn write_proto(&mut self, message: T) -> anyhow::Result<()>;
+    async fn write_proto(&mut self, message: T) -> Result<(), ProtoWriteError>;
 }
 
 #[async_trait]
@@ -17,7 +18,7 @@ where
     W: AsyncWrite + Unpin + Send,
     T: ProtoMessage + Send + 'static,
 {
-    async fn write_proto(&mut self, message: T) -> anyhow::Result<()> {
+    async fn write_proto(&mut self, message: T) -> Result<(), ProtoWriteError> {
         let variant = message.variant();
         let mut data = message.serialize()?;
         let length = data.len() as i32 + 4;

proto/src/writer/protowriter.rs

@@ -1,4 +1,5 @@
 use async_trait::async_trait;
+use tokio::io;
 use tokio::io::{AsyncWrite, AsyncWriteExt};
 
 pub struct ProtoWriter<W>
@@ -19,7 +20,7 @@ where
 
 #[async_trait]
 pub trait ProtoFlush {
-    async fn flush(&mut self) -> anyhow::Result<()>;
+    async fn flush(&mut self) -> Result<(), io::Error>;
 }
 
 #[async_trait]
@@ -27,7 +28,7 @@ impl<W> ProtoFlush for ProtoWriter<W>
 where
     W: AsyncWrite + Unpin + Send,
 {
-    async fn flush(&mut self) -> anyhow::Result<()> {
+    async fn flush(&mut self) -> Result<(), io::Error> {
         self.inner.flush().await?;
         Ok(())
     }