log a warning when serialization fails

Author: sokra

lib/cache/FileCachePlugin.js

@@ -8,7 +8,7 @@
 const path = require("path");
 const createHash = require("../util/createHash");
 const makeSerializable = require("../util/makeSerializable");
-const { serializer } = require("../util/serialization");
+const { serializer, NOT_SERIALIZABLE } = require("../util/serialization");
 
 /** @typedef {import("webpack-sources").Source} Source */
 /** @typedef {import("../../declarations/WebpackOptions").FileCacheOptions} FileCacheOptions */
@@ -23,6 +23,7 @@ class Pack {
 		this.unserializable = new Set();
 		this.used = new Set();
 		this.invalid = false;
+		this.log = 0;
 	}
 
 	get(identifier) {
@@ -48,6 +49,10 @@ class Pack {
 		}
 	}
 
+	setLogLevel(log) {
+		this.log = log;
+	}
+
 	_updateLastAccess() {
 		const now = Date.now();
 		for (const identifier of this.used) {
@@ -65,6 +70,13 @@ class Pack {
 				write(identifier);
 				write(data);
 			} catch (err) {
+				if (this.log >= 1 && err !== NOT_SERIALIZABLE) {
+					console.warn(
+						`Caching failed for ${identifier}: ${
+							this.log >= 4 ? err.stack : err
+						}\nWe will not try to cache this entry again until the cache file is deleted.`
+					);
+				}
 				rollback(s);
 				this.unserializable.add(identifier);
 				continue;
@@ -294,6 +306,7 @@ class FileCachePlugin {
 					console.warn(`Storing pack...`);
 				}
 				pack.collectGarbage(1000 * 60 * 60 * 24 * 2);
+				pack.setLogLevel(log);
 				// You might think this breaks all access to the existing pack
 				// which are still referenced, but serializing the pack memorizes
 				// all data in the pack and makes it no longer need the backing file

lib/serialization/ObjectMiddleware.js

@@ -482,3 +482,4 @@ class ObjectMiddleware extends SerializerMiddleware {
 }
 
 module.exports = ObjectMiddleware;
+module.exports.NOT_SERIALIZABLE = NOT_SERIALIZABLE;

lib/util/serialization.js

@@ -18,6 +18,7 @@ const { register, registerLoader, registerNotSerializable } = ObjectMiddleware;
 exports.register = register;
 exports.registerLoader = registerLoader;
 exports.registerNotSerializable = registerNotSerializable;
+exports.NOT_SERIALIZABLE = ObjectMiddleware.NOT_SERIALIZABLE;
 exports.serializer = new Serializer(
 	[new ObjectMiddleware(), new BinaryMiddleware(), new FileMiddleware()],
 	{