concurrency errors when printing source.TypedSource

[nicks]

Repro steps:

• Write a custom implementation of source.TypedSource
• Add a Watch on it

Result:
Non-deterministically, controller-runtime blows up with this error:

fatal error: concurrent map iteration and map write

(full stack trace included below)

The Problem

Controller does a fmt.Printf on the Source, which implicitly reads all the internal properties.

controller-runtime/pkg/internal/controller/controller.go

Line 178 in 1ac370e

log := c.LogConstructor(nil).WithValues("source", fmt.Sprintf("%s", watch))

All the built-in Sources implement fmt.Stringer with a concurrency-safe String() string method, so do not have this problem.

Suggestion: the TypedSource interface should also implement fmt.Stringer, so that all implementers have to implement String()

Additional info

Full stack trace:

goroutine 194539 [running]:
reflect.mapiternext(0x18c24c9?)
	/usr/local/go/src/runtime/map.go:1537 +0x13
reflect.(*MapIter).Next(0xc005b6ad38?)
	/usr/local/go/src/reflect/value.go:1989 +0x74
internal/fmtsort.Sort({0x42cf740?, 0xc0202be2c8?, 0xc0267a4380?})
	/usr/local/go/src/internal/fmtsort/sort.go:59 +0x1a7
fmt.(*pp).printValue(0xc012c1b930, {0x42cf740?, 0xc0202be2c8?, 0x5cc9b4207?}, 0x76, 0x3)
	/usr/local/go/src/fmt/print.go:816 +0x988
fmt.(*pp).printValue(0xc012c1b930, {0x4659fe0?, 0xc0202be2a0?, 0xc01f0d7320?}, 0x76, 0x2)
	/usr/local/go/src/fmt/print.go:853 +0x11be
fmt.(*pp).printValue(0xc012c1b930, {0x44e0640?, 0xc0202be2a0?, 0x74cea8f28e70?}, 0x76, 0x1)
	/usr/local/go/src/fmt/print.go:853 +0x11be
fmt.(*pp).printValue(0xc012c1b930, {0x4569ce0?, 0xc0202be2a0?, 0x182a8dd?}, 0x76, 0x0)
	/usr/local/go/src/fmt/print.go:921 +0xae5
fmt.(*pp).badVerb(0xc012c1b930, 0x73)
	/usr/local/go/src/fmt/print.go:394 +0x47f
fmt.(*pp).fmtPointer(0xc012c1b930, {0x4569ce0?, 0xc0202be2a0?, 0x18dcd70?}, 0x73)
	/usr/local/go/src/fmt/print.go:583 +0x414
fmt.(*pp).printValue(0xc012c1b930, {0x4569ce0?, 0xc0202be2a0?, 0x17c6cf0?}, 0x73, 0x2)
	/usr/local/go/src/fmt/print.go:927 +0x1165
fmt.(*pp).printValue(0xc012c1b930, {0x4662ee0?, 0xc02581a9c0?, 0x18dcd70?}, 0x73, 0x1)
	/usr/local/go/src/fmt/print.go:853 +0x11be
fmt.(*pp).printValue(0xc012c1b930, {0x456e1e0?, 0xc02581a9c0?, 0x38?}, 0x73, 0x0)
	/usr/local/go/src/fmt/print.go:921 +0xae5
fmt.(*pp).printArg(0xc012c1b930, {0x456e1e0, 0xc02581a9c0}, 0x73)
	/usr/local/go/src/fmt/print.go:759 +0x4bb
fmt.(*pp).doPrintf(0xc012c1b930, {0x485887b, 0x2}, {0xc005b6beb0, 0x1, 0x1})
	/usr/local/go/src/fmt/print.go:1074 +0x37e
fmt.Sprintf({0x485887b, 0x2}, {0xc00c637eb0, 0x1, 0x1})
	/usr/local/go/src/fmt/print.go:239 +0x53
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start.func2({0x4f37800, 0xc029b08780}, 0xc023ab4790, 0x4f61f00)
	/home/circleci/go/src/github.com/tilt-dev/tilt/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:175 +0x187
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start(0x4f61f00, {0x4f37800, 0xc029b08780})
	/home/circleci/go/src/github.com/tilt-dev/tilt/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:231 +0x186
sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile.func1(0xc02257a840)
	/home/circleci/go/src/github.com/tilt-dev/tilt/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:226 +0xc2
created by sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile in goroutine 194352
	/home/circleci/go/src/github.com/tilt-dev/tilt/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:210 +0x19d