Golang channel notes

channel_notes.txt

Channel Behaviors

* A receive from a nil channel blocks forever
* A receive from a closed channel returns the zero value immediately
* A receive on an empty channel blocks

* A send to a nil channel blocks forever
* A send to a closed channel panics
* A send to a full (or unbuffered) channel blocks until reader has read data

* A for .. range reads until channel closes

* Calling close() on a nil channel panics

// F returns read-only channel of int.
func F() <-chan int { ... }

// F returns a write-only channel of int.
func F() chan<- int { ... }


I believe there are only two values for a channel's buffer, 0 and 1.
Setting a value higher than 1 is really saying "well, I sort of want to
buffer as much as I can, I hope this number is enough", and that is not a
stable way to design systems.
  -- Dave Cheney


Principles of designing Go APIs with channels

From https://inconshreveable.com/07-08-2014/principles-of-designing-go-apis-with-channels/

Principle #1
------------
An API should declare the directionality of its channels.

Principle #2
------------
An API that sends an unbounded stream of values into a channel must document how it behaves for slow consumers.

Principle #3
------------
An API that sends a bounded set of values into a channel it accepted as an argument must document how it behaves for slow consumers.

Principle #4
------------
An API that sends an unbounded stream of values into a channel should accept the channel as an argument instead of returning a new channel.

Principle #5
------------
An API which sends a bounded number of values may do so safely by returning an appropriately buffered channel.