From f9be964c3f3efd10f1bd9cf752d839f8133edcc1 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Fri, 20 Nov 2020 23:33:30 +0100
Subject: [PATCH] Warning when cannot decode entry (data format
 incompatibilities)

---
 src/table/table.rs | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/table/table.rs b/src/table/table.rs
index 2beac3f4..54a42d34 100644
--- a/src/table/table.rs
+++ b/src/table/table.rs
@@ -2,6 +2,8 @@ use std::collections::{BTreeMap, HashMap};
 use std::sync::Arc;
 use std::time::Duration;
 
+use log::warn;
+
 use arc_swap::ArcSwapOption;
 use futures::stream::*;
 use serde::{Deserialize, Serialize};
@@ -185,7 +187,7 @@ where
 		for resp in resps {
 			if let TableRPC::ReadEntryResponse(value) = resp {
 				if let Some(v_bytes) = value {
-					let v = Self::decode_entry(v_bytes.as_slice())?;
+					let v = self.decode_entry(v_bytes.as_slice())?;
 					ret = match ret {
 						None => Some(v),
 						Some(mut x) => {
@@ -241,7 +243,7 @@ where
 		for resp in resps {
 			if let TableRPC::Update(entries) = resp {
 				for entry_bytes in entries.iter() {
-					let entry = Self::decode_entry(entry_bytes.as_slice())?;
+					let entry = self.decode_entry(entry_bytes.as_slice())?;
 					let entry_key = self.tree_key(entry.partition_key(), entry.sort_key());
 					match ret.remove(&entry_key) {
 						None => {
@@ -363,7 +365,7 @@ where
 			let keep = match filter {
 				None => true,
 				Some(f) => {
-					let entry = Self::decode_entry(value.as_ref())?;
+					let entry = self.decode_entry(value.as_ref())?;
 					F::matches_filter(&entry, f)
 				}
 			};
@@ -382,14 +384,14 @@ where
 		let mut epidemic_propagate = vec![];
 
 		for update_bytes in entries.iter() {
-			let update = Self::decode_entry(update_bytes.as_slice())?;
+			let update = self.decode_entry(update_bytes.as_slice())?;
 
 			let tree_key = self.tree_key(update.partition_key(), update.sort_key());
 
 			let (old_entry, new_entry) = self.store.transaction(|db| {
 				let (old_entry, new_entry) = match db.get(&tree_key)? {
 					Some(prev_bytes) => {
-						let old_entry = Self::decode_entry(&prev_bytes)
+						let old_entry = self.decode_entry(&prev_bytes)
 							.map_err(sled::ConflictableTransactionError::Abort)?;
 						let mut new_entry = old_entry.clone();
 						new_entry.merge(&update);
@@ -437,7 +439,7 @@ where
 				break;
 			}
 			if let Some(old_val) = self.store.remove(&key)? {
-				let old_entry = Self::decode_entry(&old_val)?;
+				let old_entry = self.decode_entry(&old_val)?;
 				self.instance.updated(Some(old_entry), None).await?;
 				self.system
 					.background
@@ -455,12 +457,15 @@ where
 		ret
 	}
 
-	fn decode_entry(bytes: &[u8]) -> Result<F::E, Error> {
+	fn decode_entry(&self, bytes: &[u8]) -> Result<F::E, Error> {
 		match rmp_serde::decode::from_read_ref::<_, F::E>(bytes) {
 			Ok(x) => Ok(x),
 			Err(e) => match F::try_migrate(bytes) {
 				Some(x) => Ok(x),
-				None => Err(e.into()),
+				None => {
+					warn!("Unable to decode entry of {}: {}", self.name, e);
+					Err(e.into())
+				}
 			},
 		}
 	}