Golang: a bit of house keeping

[hypnoce]

Commit Message: Align all loggers to use golang component Id. Improve sendLocalReply by using go memory pinning instead of string copy.
Additional Description:
Risk Level: Low
Testing: no need as it is only refactoring
Docs Changes:
Release Notes: updated current.yaml
Platform Specific Features: N/A

[hypnoce]

@doujiang24 during my coding, I came accros various little cleanup. Let me know if you find them usefull.

[doujiang24]

@hypnoce Cool, thanks for your work.

[doujiang24]

why remove this?

[hypnoce]

Because the buffer is (silently) pinned (no GC and no memory move) until the C call returns and we are garantee that when the C call returns, the golang strings point to the buf underlying byte array, preventing any GC of that array.

[doujiang24]

nope, I do not think so, go compiler just make sure it's escaped to heap.

[hypnoce]

buf backing array is heap allocated and tracked by go GC (it's considered as a go pointer) since its size is dynamic and cannot be known at compile time.
The buf struct itself is stack allocated but the backing array will not be GCed as it is referenced by the strings.

For instance

func main() {
	str := foo(10)
	runtime.GC()
	runtime.GC()
	println(str)
	runtime.GC()
	runtime.GC()
	str2 := foo2(10)
	runtime.GC()
	runtime.GC()
	println(str2)
	runtime.GC()
	runtime.GC()
}

func foo(bytes int) string {
	buf := make([]byte, bytes)
	buf[0] = 'a'
	buf[1] = 'b'
	data := unsafe.SliceData(buf)
	runtime.SetFinalizer(data, func(*uint8) {
		println("foo1 backing array finalizer called")
	})
	myString := unsafe.String(data, 2)
	return myString
}

func foo2(bytes int) string {
	buf := make([]byte, bytes)
	buf[0] = 'a'
	buf[1] = 'b'
	runtime.SetFinalizer(unsafe.SliceData(buf), func(*uint8) {
		println("foo2 backing array finalizer called")
	})
	myString := "cd"
	return myString
}

This outputs

ab
foo1 backing array finalizer called
foo2 backing array finalizer called
cd

Maybe I missed something but in this exemple buf does not escape to heap while the backing array is kept because referenced by the string.
WDYT ?

[doujiang24]

ditto.