goroutines-async-channel-receive-no-waiting

README

goroutines-async-channel-receive-no-waiting

A goroutine asynchronously sending data (via a channel buffer) and a goroutine receiving that data, using the latest (if available) and does not wait.

These are my 5 main example of using goroutines,

• goroutines-async-channel-receive-no-waiting <- You are here
• goroutines-async-channel-send-receive-waiting
• goroutines-multi-core
• goroutines-waitgroup
• goroutines-worker-pools

GitHub Webpage

ASYNCHRONOUS CHANNEL

sendData() will,

• Send data every x seconds to the channel buffer

rcvData() will,

• Receive the latest data every x seconds from the channel buffer (if available)
• If there are no data, just use the previous data

rcvData() FUNCTION - NO WAITING

Since the channel is asynchronous, the channel buffer could be empty or full depending on how much faster or slower the sendData() goroutine is. Hence, we don't want the rvcData() function to wait.

To solve the problem of the rvcData() function waiting around,

• If there is something in channel
  • Read and continue reading until empty channel (hence, get latest one)
  • break out of loop
• If there is nothing in channel
  • default and break out of the loop

for {
    select {
    case newVal := <-rcvCh:
        data = newVal
        fmt.Printf("%40d - Received data %v\n", counter, data)
        continue
    default:
    }
    break
}

RUN

go run goroutines-async-channel-receive-no-waiting.go

Simply press return to exit.

Example output when receiver faster than sender,

sendData() will send data every 5 seconds
rcvData() will receive data every 2 seconds

                                       1 - START RECEIVING DATA
                                       1 - Using data empty
   1 - START SENDING DATA
   1 - Sent data 1
                                       2 - START RECEIVING DATA
                                       2 - Received data 1
                                       2 - Using data 1
                                       3 - START RECEIVING DATA
                                       3 - Using data 1
   2 - START SENDING DATA
   2 - Sent data 2
                                       4 - START RECEIVING DATA
                                       4 - Received data 2
                                       4 - Using data 2
                                       5 - START RECEIVING DATA
                                       5 - Using data 2
                                       6 - START RECEIVING DATA
                                       6 - Using data 2

Try slowing down or speeding up the goroutines by changing,

const sendSpeedSeconds = X
const rcvSpeedSeconds = X