sinchan

Go channels on Javascript

Install

npm install sinchan

or

yarn add sinchan

Unbuffered channel

Use new sinchan.Channel() to create an unbuffered channel.

var sinchan = require("sinchan");

var ch = new sinchan.Channel();

ch.read().then(val => {
  console.log(val); // Prints "Hi!"
});

ch.write("Hi!");

Channel.write returns a promise that is resolved when the written value has been read from the unbuffered channel.

var sinchan = require("sinchan");

var ch = new sinchan.Channel();

ch.write("Hi!").then(() => {
  console.log("write resolved"); // Will be printed after 3 seconds
});

setTimeout(() => {
  ch.read().then(val => {
    console.log("read: ", val);
  });
}, 3000);

Buffered channel

Use new sinchan.Channel(buffersize) to create a buffered channel.

On a buffered channel writes will be resolved when they enter the buffer. If it is full they will wait to be resolved until someone reads and the write can enter the buffer.

var sinchan = require("sinchan");

var ch = new sinchan.Channel(1); // Buffered channel: buffer size 1

ch.write("This is write 1").then(() => {
  console.log("write 1 resolved"); // Will be printed immediately
});

ch.write("This is write 2").then(() => {
  console.log("write 2 resolved"); // Will be printed after 3 seconds
});

setTimeout(() => {
  for (i = 0; i < 2; i++) {
    ch.read().then(val => {
      console.log("read: ", val);
    });
  }
}, 3000);

Closed channels

If you try to write on an closed channel the call will throw an error.

var sinchan = require("sinchan");

var ch = new sinchan.Channel();
ch.close();

ch.write("Hi!").catch(e => {
  console.log(e);
});

When closing a buffered channel you can read the values that remain on the buffer but any following reads will return null. Also all writes that where waiting to enter the buffer will be rejected.

var sinchan = require("sinchan");

var ch = new sinchan.Channel(1);

ch.write("This is write 1")
  .then(() => {
    console.log("write 1 resolved");
  })
  .catch(e => {
    console.log("write 1 error:", e);
  });

ch.write("This is write 2")
  .then(() => {
    console.log("write 2 resolved");
  })
  .catch(e => {
    console.log("write 2 error:", e);
  });

setTimeout(() => {
  ch.close();
  ch.read()
    .then(val => {
      console.log("read 1: ", val);
    })
    .catch(e => {
      console.log("read 1 error: ", e);
    });

  ch.read()
    .then(val => {
      console.log("read 2: ", val);
    })
    .catch(e => {
      console.log("read 2 error: ", e);
    });
}, 3000);

Will print

write 1 resolved
<3 seconds wait...>
read 1:  This is write 1
read 2:  null
write 2 error: Error: Closed channel

You can check if a channel is closed with Channel.isClosed()

var sinchan = require("sinchan");

var ch = new sinchan.Channel();

ch.close();
console.log(ch.isClosed()); // Will print: true