dht | Golang implementation of a distributed hash table | Hashing library
kandi X-RAY | dht Summary
kandi X-RAY | dht Summary
dht is a distributed hash table implementation that uses Consul and rendezvous hashing to distribute keys among distributed nodes. Because it uses rendezvous hashing to determine key placement, removing a node from the hash table is minimally disruptive in terms of key re-assignment.
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Top functions reviewed by kandi - BETA
- Join creates a new node
- newCheckListenerAndServer returns a new listener and http . Server .
- Leave terminates the node .
dht Key Features
dht Examples and Code Snippets
Community Discussions
Trending Discussions on dht
QUESTION
The Discrete Hartley Transform can be computed as
...ANSWER
Answered 2021-Jun-12 at 04:10The issue is about the flipping part. To show with an example:
QUESTION
I have a PowerShell script that I have developed and tested in Visual Studio Code that runs without error. However, when I attempt to run the same script from a PowerShell command line, it fails with several errors, the first one being a complaint about the use of Param on the first line of the script. I have PS 5.1 installed on my machine.
When launched from the command line, here is what I execute:
powershell -ExecutionPolicy Bypass -File Export_PI.ps1 -Project Catalyst-DHT
When I run this script from Visual Studio Code, I substitute a hard-coded value in lieu of the parameter -Project
for testing purposes. When I run it from the PS command line, this is the first error I get:
Param : The term 'Param' is not recognized as the name of a cmdlet, function, script file, or operable program.
I have read elsewhere that this typically occurs when Param() is not the first non-commented line in the script. In my script, it is the first non-commented line:
$ProjectName = Param([String]$Project)
I'm not a PowerShell guru, so this could well be a newbie mistake. I'm hoping someone can help me figure it out. Thanks.
...ANSWER
Answered 2021-Jun-11 at 18:07The line
I have PS 5.1 installed on my machine.
is most likely the issue you are having. VSC uses PowerShell Core (6 <=) and not PowerShell Desktop (6 >)
Also the line
QUESTION
I'm having hard time setting up 2 node Cassandra cluster on Ec2 instances. This is 2.2.19 version. I cannot upgrade due to some other dependencies involved.
The Ec2 instances are in private subnet. Assigned static private ips
Here is my cassandra.yaml
...ANSWER
Answered 2021-Jun-08 at 17:33Answering my own question
Ec2snitch uses IMDVs1 to get metadata http://169.254.169.254/latest/meta-data/placement/availability-zone to determine certain properties.
I created Ec2 instances through terraform where my code has
QUESTION
im starting with django and iot and i've decided to start (for learning purposes) an app that connects to my sensors attached to my raspberry pi.
The thing that im struggling is the next one:
I've done a class for my DHT11 sensor (temperature and humidity), and i've declared all values and wrote a method, which gets and prints the values of the sensor, and made a page where i show all the properties of the object, like "asigned pin" or the "name" of it; all fine until here. this is the class:
...ANSWER
Answered 2021-Jun-04 at 01:53I think you are trying call a server side function from front end button click.
Button is a UI object that doesn't have direct access to the DJango methods.
You can call a rest API on button click and get the temperature and humidity data as HttpResponse, then show the data in HTML the way you want
If you want to update the sensor data dynamically, you can go for Sockets
QUESTION
I've got a problem with a current project that aims to transmit data from a sensor to a platform in real time. It is a DHT22 sensor which is able to measure temperature and humidity. The idea was to save the data in a csv file and then send it to the platform using another script (sending the data from the csv file to the platform has always worked). The problem is that the data is stored in the csv file, but only in intervals of about 15 minutes and always in blocks of 800. The real-time aspect therefore does not come into play.
I used the following script to save the data as a csv file:
...ANSWER
Answered 2021-May-27 at 15:54The problem you are having is that you "write" to the file object but in the code you never flush it. So what you are writing stays in some buffer. Usually the flush happens automatically when the context that is created by with open()
ends, but it never ends because you have an infinite loop inside there.
To fix this just surround every write individually by with open()
.
QUESTION
Since collisions found in SHA-1, BitTorrent moved to more secure hash function SHA-2, but why not to create hash format representation like magnet:?xt=urn:bt_[hash_function_name]:info_hash ?
Example: magnet:?xt=urn:bt_sha3:123456789101112131415
It's like 2+2 that people will continue building up more advanced computers. And collisions can be made in near future, and looking into new protocol, we can already see that its adoption is happening very slowly, it wouldn't be nicest thing if say in 2030 new collision occured, then developers will have to change this protocol again?
V1 DHT is not compatible with V2 anyway.
So my noob question goes to @the8472
...ANSWER
Answered 2021-May-18 at 17:14It's like 2+2 that people will continue building up more advanced computers.
The primary cause for collision attacks is weaknesses in the hash function. Faster computers only provide very modest improvements as for every additional bit you to twice as much compute power. Even the still quite hypothetical general purpose quantum computers would only cut down collision resistance from N/2 to N/3.
Also, collision attacks are not a major threat to bittorrent. They could break certificate based systems built on top of bittorrent, e.g. where some 3rd entity vouches for the correctness of content described by a hash. But the primary use of hashes in bittorrent (integrity, i.e. getting bit-exact copies of whatever the initial seed published) is only vulnerable to preimage attacks.
and looking into new protocol, we can already see that its adoption is happening very slowly, it wouldn't be nicest thing if say in 2030 new collision occured, then developers will have to change this protocol again?
Bittorrent v2 specifies a meta version
field in the info dictionary and requires that clients check for compatibility first before attempting to use the torrent, this will make future upgrades smaller and easier to roll out.
But they are not specified in advance since we don't know which hashes or other security-related changes will be needed in the future. Specifying and negotiating more than one supported cryptographic primitive tends to be error-prone and increases implementation complexity.
The v2 magnet link already provides flexibility by adopting the multihash format.
V1 DHT is not compatible with V2 anyway.
That is incorrect.
QUESTION
Pictures of the wiring of the DHT11 to the ESP
When I try to read temperatures in Fahrenheit, Celsius and to get the Humidity, it always says 'nan' on the serial monitor. I'm working the Arduino IDE with the Generic ESP8266 Module and I got the libraries "DHT-Sensor-Library" and the "Adafruit-Unified-Sensor"-Library installed.
I know it stands for "Not a number", but why? I looked on here before and tried using (isnan) and store it in a backup-variable, but that didn't work either.
...ANSWER
Answered 2021-Apr-08 at 12:53It looks like you're trying to power the DHT11 directly from a GPIO pin.
GPIO pins are intended to send signals. When you use them for power, the results can be unpredictable.
Instead, try powering it from one of the "always-on" 3.3V pins.
If that doesn't work, try powering the DHT11 from an external power source (preferably 5V).
If that doesn't work, please post a picture of your circuit.
QUESTION
I am using Cassandra v3.9. I updated the config files as shown below but 25.80.44.50 won't join the cluster (it was formally part of the 2-node clusrter along with 25.80.44.51).
When I reverted back to a 2 node cluster, the database was corrupted and I had to restore from a backup.
Node 1 Config: ...ANSWER
Answered 2021-Mar-24 at 18:02Try setting your seeds
list to be the same across all 3 nodes.
Right now, it's different for each node...which works only when one of the nodes in the seed list is already running. The first node in the cluster needs to find itself in that seed list.
In a small cluster like this, I'd take the seeds
setting from your first node, and make sure all other nodes' seeds
properties match it:
QUESTION
i am trying to get my raspberry pi to print data from external sensors to a display and save it to a .txt at the same time.
What i did works fine when launching the script in a shell via ssh. But that stops the script after closing the shell.
So i tried to put it in the rc.local file to launch it while booting. But that works only half way, as it shows the data on the display but it doesn't save it to a file.
...ANSWER
Answered 2021-Mar-22 at 23:11You are running an infinite loop, so you need to close the file stream to save changes into your file. If you run your script without the loop you can see that the changes are saved even without closing the steam and that's because it handles implicitly. So you need to open and close the file stream which can easily be done with the with
keyword. I think the code below works fine for you.
QUESTION
I have a time-series, which essentially amounts to some instrument recording the current time whenever it makes a "detection". The sampling rate is therefore not in constant time, however we can treat it as such by "re-sampling", relying on the fact that the detections are made reliably and we can simply insert 0's to "fill in" the gaps. This will be important later...
The instrument should detect the "signals" sent by another, nearby instrument. This second instrument emits a signal at some unknown period, T
(e.g. 1 signal per second), with a "jitter" likely on the order of a few tenths of a percent of the period.
My goal is to determine this period (or frequency, if you like) using only the timestamps recorded by the "detecting" instrument. Unfortunately, however, the detector is flooded with noise, and a significant amount (I estimate 97-98%
) of "detections" (and therefore "points" in the time-series) are due to noise. Therefore, extracting the period will require more careful analysis.
My first thought was to simply feed the time series into an FFT algorithm (I'm using FFTW
/DHT
), however this wasn't particularly enlightening. I've also tried my own (admittedly rather crude) algorithm, which simply computed a cross-correlation of the series with "clean" series of increasing period. I didn't get very far with this, either, and there are quite a handful of details to consider (phase, etc).
It occurs to me that something like this must've been done before, and surely there's a "nice" way to accomplish it.
...ANSWER
Answered 2021-Mar-20 at 14:25Here's my approach. Given a period, we can score it using a dynamic program to find the subsequence of detection times that includes the first and last detection and maximizes the sum of gap log-likelihoods, where the gap log-likelihood is defined as minus the square of the difference of the gap and the period (Gaussian jitter model).
If we have approximately the right period, then we can get a very good gap sequence (some weirdness at the beginning and end and wherever there is a missed detection, but this is OK).
If we have the wrong period, then we end up with basically exponential jitter, which has low log-likelihood.
The C++ below generates fake detection times with a planted period and then searches over periods. Scores are normalized by a (bad) estimate of the score for Poisson noise, so wrong periods score about 0.4. See the plot below.
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