first

course/13-channels/exercises/4-buffered_channels/code.go

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+package main
+
+import "fmt"
+
+func addEmailsToQueue(emails []string) chan string {
+	emailsToSend := make(chan string)
+	for _, email := range emails {
+		emailsToSend <- email
+	}
+	return emailsToSend
+}
+
+// TEST SUITE - Don't Touch Below This Line
+
+func sendEmails(batchSize int, ch chan string) {
+	for i := 0; i < batchSize; i++ {
+		email := <-ch
+		fmt.Println("Sending email:", email)
+	}
+}
+
+func test(emails ...string) {
+	fmt.Printf("Adding %v emails to queue...\n", len(emails))
+	ch := addEmailsToQueue(emails)
+	fmt.Println("Sending emails...")
+	sendEmails(len(emails), ch)
+	fmt.Println("==========================================")
+}
+
+func main() {
+	test("Hello John, tell Kathy I said hi", "Whazzup bruther")
+	test("I find that hard to believe.", "When? I don't know if I can", "What time are you thinking?")
+	test("She says hi!", "Yeah its tomorrow. So we're good.", "Cool see you then!", "Bye!")
+}

course/13-channels/exercises/4-buffered_channels/complete.go

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+package main
+
+import "fmt"
+
+func addEmailsToQueue(emails []string) chan string {
+	emailsToSend := make(chan string, len(emails))
+	for _, email := range emails {
+		emailsToSend <- email
+	}
+	return emailsToSend
+}
+
+// TEST SUITE - Don't Touch Below This Line
+
+func sendEmails(batchSize int, ch chan string) {
+	for i := 0; i < batchSize; i++ {
+		email := <-ch
+		fmt.Println("Sending email:", email)
+	}
+}
+
+func test(emails ...string) {
+	fmt.Printf("Adding %v emails to queue...\n", len(emails))
+	ch := addEmailsToQueue(emails)
+	fmt.Println("Sending emails...")
+	sendEmails(len(emails), ch)
+	fmt.Println("==========================================")
+}
+
+func main() {
+	test("Hello John, tell Kathy I said hi", "Whazzup bruther")
+	test("I find that hard to believe.", "When? I don't know if I can", "What time are you thinking?")
+	test("She says hi!", "Yeah its tomorrow. So we're good.", "Cool see you then!", "Bye!")
+}

course/13-channels/exercises/4-buffered_channels/expected.txt

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+Adding 2 emails to queue...
+Sending emails...
+Sending email: Hello John, tell Kathy I said hi
+Sending email: Whazzup bruther
+==========================================
+Adding 3 emails to queue...
+Sending emails...
+Sending email: I find that hard to believe.
+Sending email: When? I don't know if I can
+Sending email: What time are you thinking?
+==========================================
+Adding 4 emails to queue...
+Sending emails...
+Sending email: She says hi!
+Sending email: Yeah its tomorrow. So we're good.
+Sending email: Cool see you then!
+Sending email: Bye!
+==========================================

course/13-channels/exercises/4-buffered_channels/readme.md

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+# Buffered Channels
+
+Channels can *optionally* be buffered.
+
+## Creating a channel with a buffer
+
+You can provide a buffer length as the second argument to `make()` to create a buffered channel:
+
+```go
+ch := make(chan int, 100)
+```
+
+Sending on a buffered channel only blocks when the buffer is *full*. 
+
+Receiving blocks only when the buffer is *empty*.
+
+## Assignment
+
+We want to be able to send emails in *batches*. A *writing* goroutine will write an entire batch of email messages to a buffered channel, and later, once the channel is full, a *reading* goroutine will read all of the messages from the channel and send them out to our clients.
+
+Complete the `addEmailsToQueue` function. It should create a buffered channel with a buffer large enough to store all of the `emails` it's given. It should then write the emails to the channel in order, and finally return the channel.