Basic Queue in TypeScript

/**

* @class

* Class representing an Item in a Queue

*/

class Item {

constructor(v) {

this.v = v;

this.n = null;

}

val() {

return this.v;

}

setNext(i) {

this.n = i;

}

next() {

return this.n;

}

}

/**

* @class

* Class representing a Queue

*

* This is a basic linked list impelementation for a FIFO queue.

*/

class Queue {

constructor(item) {

if (undefined == item) {

this.items = 0;

this.start = null;

this.end = null;

this.item = null;

return;

}

this.items = 1;

this.item = item;

this.start = item;

this.end = item;

}

add(item) {

if (this.items == 0) {

this.items = 1;

this.item = item;

this.start = item;

this.end = item;

} else {

this.items++;

let tail = this.end;

tail.setNext(item);

this.end = item;

}

}

pop() {

let item = this.start;

if (null != item.next()) {

this.start = item.next();

}

this.items--;

return item;

}

}

Min Priority Queue in TypeScript

/**

* @class

* Class representing a min/max PriorityQueue

*

* The default is a minPriorityQueue if no value is used in the constructor.

* If you want a maxPriorityQueue, pass true in the constructor e.g.

*

* let maxPQ = new PriorityQueue(true);

* let minPQ = new PriorityQueue();

*

* AppsScripts won't let you define private methods, so here are the public methds

*

* add(v {int}) // adds a new value into the queue

* contains(v {int}) // returns true if the queue contains the value

* isEmpty() {bool} // returns true if there are no ints in the queue

* pop() {int} // returns the min/max value in the queue

*

*/

class PriorityQueue {

constructor(isMax) {

if (undefined == isMax || null == isMax || false == isMax) {

this.isMax = false;

} else {

this.isMax = true;

}

this.heap = [];

this.index = new Map();

this.size = this.heap.length;

}

contains(v) {

return this.index.has(v);

}

exch(i, j) {

let t = this.heap[i];

this.heap[i] = this.heap[j];

this.index.set(t, j);

this.index.set(this.heap[j], i);

this.heap[j] = t;

}

add(v) {

if (this.contains(v)) return;

this.size++;

this.heap[this.size] = v;

this.swim(this.size);

this.index.set(v, this.size);

}

isEmpty() {

return this.size == 0;

}

length() {

return this.size;

}

less(i, j) {

if (this.isMax) {

return this.heap[i] < this.heap[j];

}

return this.heap[i] > this.heap[j];

}

pop() {

let max = this.heap[1];

this.exch(1, this.size--);

this.heap.pop();

this.sink(1);

return max;

}

sink(n) {

while (n*2 <= this.size) {

let j = n*2;

if (j < this.size && this.less(j, j+1)) j++;

if (!this.less(n, j)) break;

this.exch(n, j);

n = j;

}

}

swim(n) {

while (n > 1 && this.less(Math.floor(n/2), n)) {

this.exch(Math.floor(n/2), n);

n = Math.floor(n/2);

}

}

}

function testArray() {

console.log("Testing a min PQ.");

let t = new PriorityQueue(false);

console.log("Inserting 7, 5, 9, 3, 10, 1");

t.add(7);

t.add(5);

t.add(9);

t.add(7);

t.add(3);

t.add(10);

t.add(1);

console.log(`Does the queue contain 5? : ${t.contains(5)}`);

console.log(`Does the queue contain 3? : ${t.contains(3)}`);

let incr = 0;

let output = "";

while (!t.isEmpty() && incr++ < 10)

output += `${t.pop()} `;

console.log(`Output: ${output}`);

console.log("Testing a max PQ.");

console.log("Inserting 7, 5, 9, 3, 10, 1");

output = "";

t = new PriorityQueue(true);

t.add(7);

t.add(5);

t.add(9);

t.add(3);

t.add(10);

t.add(1);

console.log(`Does the queue contain 5? : ${t.contains(5)}`);

console.log(`Does the queue contain 3? : ${t.contains(3)}`);

incr = 0;

while (!t.isEmpty() && incr++ < 10)

output += `${t.pop()} `;

console.log(`Output: ${output}`);

}

Updating your expired GPG keys

 If you ever need to update your expired gpg keys, it's not terrible. First thing to do is to figure out which key you're working with, use

$> gpg --list-keys

Which should show you something like this

-----------------------------

pub   rsa3072 2020-12-29 [SC] [expired: 2024-12-31]

      09CF4ABCD7487EF21E9AFC859B4CE836EAAF3E31

uid   [ expired] Russell Simpkins <russellsimpkins@gmail.com>

Then you can edit the key using the ID

$> gpg --edit-key 09CF4ABCD7487EF21E9AFC859B4CE836EAAF3E31

gpg (GnuPG) 2.2.19; Copyright (C) 2019 Free Software Foundation, Inc.

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.

Secret key is available.

sec  rsa3072/9B4CE836EAAF3E31

     created: 2020-12-29  expires: 2026-01-02  usage: SC

     trust: ultimate      validity: ultimate

ssb  rsa3072/CC533814855BD92B

     created: 2020-12-29  expired: 2024-12-31  usage: E

[ultimate] (1). Russell Simpkins <russellsimpkins@gmail.com>

To change or update the expiration time, type the following

$> expire

It will prompt you to choose, I like to update mine yearly but you can pick whatever option you want. If you have a sub key like I do, then you will want to update that as well. Just pick the key using the following command

$> key 1

gpg> key 1

sec  rsa3072/9B4CE836EAAF3E31

     created: 2020-12-29  expires: 2026-01-02  usage: SC

     trust: ultimate      validity: ultimate

ssb* rsa3072/CC533814855BD92B

     created: 2020-12-29  expired: 2024-12-31  usage: E

[ultimate] (1). Russell Simpkins <russellsimpkins@gmail.com>

Notice that ssb has an asterisks next to it, that's how you know you're editing the sub key. Follow the same and type "expire" to set it's expiration date. That's it. Type "quit" to exit.

App Scripts are pretty neat

I was doing some analysis and looking to create a graph in my Google Spreadsheet. The data had gaps and I was looking for a quick/easy way to set all empty cells to zero. I found an example after searching that I turned into the following:

function fillBlanks() {

var sheet = SpreadsheetApp.getActiveSheet();

var sheetLR = sheet.getLastRow();

var sheetLC = sheet.getLastColumn();

var range = sheet.getRange(1, 1, sheetLR, sheetLC);

var values = range.getValues();

for (var r = 1; r < sheetLR; r++) {

for (var c = 0; c < sheetLC; c++) {

if(String(values[r][c]).trim() == "") {

values[r][c] = 0;

}

}

}

range.setValues(values);

}

fillBlanks()

Have your spreadsheet open, then run it from App Scripts. Feel free to take, modify and re-use as you see fit.

gRPC SSL certs on Windows with WSL2

The past few days has been one hell of a nightmare. I have been creating gRPC gateway services and we wanted to implement server side HTTP2 push. Turns out HTTP2 & gRPC requires you to implement SSL to take advantage of HTTP2 push in the browser. Implementing SSL is a pain in the a$$. You need to make sure everything is running with the correct hostnames and almost all of the documentation out there is for folks who have said the heck with it and opted for self signed certificates. I couldn't find any good tutorials for setting up a valid SSL cert. 

I ran into too many issues. The first one that took many hours to identify, if you are doing your development on Windows 10 + WSL2, it's not straight forward how best to update /etc/hosts. Recall that for HTTPS to work, you need the hostname to match which means you need DNS to resolve. Here's how to fix this. Open up a terminal on your linux (I use Ubuntu) and run ifconfig. Take the result of that and update your /etc/hosts file (this requires root/sudo.) Then open up notepad as an Administrator and update your c:\Windows\System32\drives\etc\hosts and save that. 

If you do this, you can successfully open up your web browser and use  your custom domain name AND use curl to test your custom domain name. 

I lost countless hours on this one part - trying like hell to figure out why my custom domain wasn't resolving to 127.0.0.1. I think Windows/WSL2 have something about 127.0.0.1 and the secret was getting the IP for the WSL2 Linux distro.

Once you've got your hostnames configured in /etc/hosts, you can move on to securing your golang services. One thing you may need to do is to concatenate your SSL certificate with the providers intermediary certificate. This isn't terribly difficult. Simple create a new text file, have your valid cert in PEM format then a new line and the intermediary. If done correctly, it will look like this: (these are not real - this is just an example)

-----BEGIN CERTIFICATE-----
t1befnVnPZlIlyEMDw/WPyR4Bfi1cemqjaKSxzR+lEtCTQC7xKM8678RMHBtZ7/v
NsfRUitk6otcQnBX/sErZmFxqdPyl7aOpifkj+pQV0mfn3bGTPhSPfc6BM84lZo8
W2HRMbWsw5Z5ZIwEfMEbaCtbtw==
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIDdzCCAl+gAwIBAgIEAgAAuTANBgkqhkiG9w0BAQUFADBaMQswCQYDVQQGEwJJ
RTESMBAGA1UEChMJQmFsdGltb3JlMRMwEQYDVQQLEwpDeWJlclRydXN0MSIwIAYD
-----END CERTIFICATE-----

You can start your gRPC service over TLS like this:

serverOptions := []grpc.ServerOption{
    grpc.UnaryInterceptor(interceptor.Unary()),
    grpc.StreamInterceptor(interceptor.Stream()),
}
if enableTLS {
    tlsCredentials, err := credentials.NewServerTLSFromFile(serverCertFile, serverKeyFile)
    if err != nil {
        return fmt.Errorf("cannot load TLS credentials: %w", err)
    }
    serverOptions = append(serverOptions, grpc.Creds(tlsCredentials))
}
s := grpc.NewServer(serverOptions...)

That will load the gRPC service over TLS in manner that any client can validate the SSL certificate. It's important to note that you may not need to add the intermediary certificate. Try starting your gRPC service and then connecting to it. I found this handy curl command for testing gRPC HTTP2 POSTs to get Streaming responses.

curl -i --http2 -H "Content-Type: application/grpc" -H "TE: trailers" -X POST https://youhost.com/grpc.Service/Message

Feel free to add -vvv to that if you're having issues. Now that you have your golang gRPC service running under TLS, you just need to adjust your gateway client to handle HTTPS connections. Here's a snippet:

config := &tls.Config{
    InsecureSkipVerify: false,
}
return grpc.DialContext(ctx, addr, grpc.WithTransportCredentials(credentials.NewTLS(config)))

With that, your gateway can connect to the gRPC service using TLS. If you've got Nginx in front of everything, you may find this blog helpful. I found that it was 90% correct. They share some configuration that mostly works, but my version of Nginx didn't like putting the locations outside of the server entry. 

Managing passwords with GPG

I recently moved back to working on Windows. I've been really enjoying the development setup of Windows 10 with WDL 2 which allows me to have Ubuntu right at hand. The one downside is that I can't open my Apple encrypted .dmg file. I have been in the habit of keeping my passwords in a clear text file, but storing it on an encrypted disk image that I keep on my cloud back up drive. I know that these companies claim to not check the contents, but this makes it nearly impossible. Now that I'm on Windows, I needed another solution and decided to get back to gpg. I created the following bash functions to let me view my password file quickly and easily.

Here's the code in a gist. I put the logic in my ~/.bashrc so that I can access the file by typing "pw". When I'm done getting information or adding a new password, the code re-encrypts the file, cleans up the temporary file and maintains a minimum backup of previous encrypted files.

Fun things to do with Docker

I recently got back to doing some dev work and I'm using docker. Docker is nice in that you can make build boxes and run them which can be really handy if you're developing on a mac but your code is destined for some linux variant.

One thing I found helpful today was to mount my local project so that I could run inside my Docker centos box. I did it with something like this:

$> docker run -di --mount type=bind,source="/path/to/project/folder",target=/var/opt/project"image:tag"

When run in that manner, I can have a container running that has my local project in /var/opt/project. I can edit the code and run it after shelling onto the box. Other common commands I use a lot.

$> docker ps
$> docker exec -it <id> /bin/bash
$> docker stop <id>