doc: add explanation of the keywords used with goroutine

master
oscarzhou 2021-04-26 20:40:06 +12:00
parent e98d57e6d1
commit 684b0a09b8
1 changed files with 36 additions and 1 deletions

View File

@ -1,3 +1,38 @@
# go-concurrency
Aims to learn the knowledge about concurrency in Go
## Flow control with channels
1. We can imagine that channel is a pipe, `chan<-` means to send a value into the channel. `<-chan` means to receive a value from the channel.
2. `select ... case` can execute sending value into a channel
## Range and Close
1. A sender can close a channel to indicate that no more values will be sent.
2. Receivers can test whether a channel has been closed by assigning a second parameter to the receive expression. `v, ok := <-ch`, `ok` is `false` if there are no more values to receive and the channel is closed.
3. The loop for `i:= range c` receives values from the channel repeatedly until it is closed.
4. Only the sender should close a channel, never the receiver. Sending on a closed channel will cause a panic.
5. Channels aren't like files; you don't usually need to close them. Closing is only necessary when the receiver must be told there are no more values coming, such as to terminate a `range` loop.
## Select
1. The `select` statement lets a goroutine wait on multiple communication operations
2. A `select` blocks until one of its cases can run, then it executes that case. It chooses one at random if multiple are ready
## Default selection
1. The `default` case in a `select` is run if no other case is ready.
2. Use a `default` case to try a send or receive without blocking
```
select {
case i:= <-c:
// use i
default:
// receive when c is blocked
}
```