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Principle and Implementation of Consistent Hash Algorithm

In the mapping relationship between objects and nodes in a distributed system, the traditional scheme is to use the hash value of the object, take the modulo of the number of nodes, and then map to the corresponding numbered nodes. 해시게임In this scheme, when the number of nodes changes, most objects in The mapping relationship will fail and need to be migrated; while in the consistent hash algorithm, when the number of nodes changes, very few objects whose mapping relationship fails, and the migration cost is also very small. This paper summarizes the algorithm principle and Java implementation of consistent hashing and enumerates its applications.

1 Overview

1.1 Traditional Hash (Hard Hash)
In a distributed system, assuming there are n nodes, the traditional scheme uses mod(key, n) to map data and nodes.
When expanding or shrinking (even if only one node is added or removed), the mapping relationship becomes mod(key, n+1) / mod(key, n-1), and the mapping relationship of most data will fail.

1.2 Consistent Hashing
In 1997, 6 people including David Karger of the Massachusetts Institute of Technology (MIT) published the academic paper “Consistent hashing and random trees: distributed caching protocols for relieving hot spots on the World Wide Web Distributed Cache Protocol for Hotspots on the World Wide Web)”, for a hash table with K keywords and n slots (nodes in a distributed system), after adding or reducing slots, the average only needs to be K/n keywords. Remap.

1.3 Hash Metrics
To evaluate the pros and cons of a hash algorithm, there are the following indicators, and consistent hashing all satisfy:

Balance: The hash addresses of keywords are evenly distributed in the address space so that the address space can be fully utilized, which is a basic feature of the hash design.
Monotonicity: Monotonicity means that when the address space increases, the hash address of the keyword obtained by the hash function can also be mapped to a new address space, rather than being limited to the original address space. Or when the address space is reduced, it can only be mapped to the effective address space. Simple hash functions often fail to satisfy this property.
Spread: Hash is often used in distributed environments, where end users store their content in different buffers through a hash function. At this point, the terminal may not see all the buffers, but only a part of them. When the terminal wants to map the content to the buffer through the hashing process, the buffer range seen by different terminals may be different, resulting in inconsistent hash results. The final result is that the same content is mapped to different terminals by different terminals. in the buffer. This situation should obviously be avoided because it causes the same content to be stored in different buffers, reducing the efficiency of system storage. Scattering is defined as the severity of the above-mentioned occurrences. A good hash algorithm should be able to avoid inconsistencies as much as possible, that is, to reduce the dispersion as much as possible.
Load: The problem of the load is actually another way of looking at the problem of decentralization. Since different terminals may map the same content to different buffers, a particular buffer may also be mapped to different content by different users. Like decentralization, this should be avoided, so a good hashing algorithm should minimize the buffering load.

2 Algorithm principle

2.1 Mapping scheme
2.1.1 Public Hash Functions and Hash Rings
Design the hash function Hash(key), the value range is required to be [0, 2^32)
The distribution of each hash value on the Hash ring in the above figure: the position of the clock at 12 o’clock is 0, increasing in a clockwise direction, and the left position near 12 o’clock is 2^32-1.

2.1.2 Node (Node) Mapping to Hash Ring
As shown by the green ball on the hash ring, the four nodes Node A/B/C/D,
Its IP address or machine name is mapped to the hash ring after the same Hash() calculation.

2.1.3 Objects are mapped to hash rings
As shown by the yellow ball on the hash ring, the four objects Object A/B/C/D,
Its key value, after the same Hash() calculation, is mapped to the hash ring.

2.1.4 Objects are mapped to Nodes
After both objects and nodes are mapped to the same hash ring, to determine which node an object is mapped to,
Just start with that object and look clockwise along the hash ring, the first node you find, that is.
It can be seen that Object A/B/C/D is mapped to Node A/B/C/D respectively.

2.2 delete node
Real-world scenario: Delete nodes when the server is scaled down, or some nodes go down. As shown in the figure below, to delete the node Node C:
Only affects the object between the node to be deleted (Node C) and the previous (clockwise is the forward direction) node (Node B), that is, Object C,
The mapping relationship of these objects is adjusted and mapped to the next node Node D of the node to be deleted according to the rules in 2.1.4.
The mapping relationship of other objects does not need to be adjusted.

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tips

Rumours About the Apple Watch 8

If you’re looking to upgrade your Apple Watch, you should check out the new Apple Watch 8. 스마트워치 추천 If you’re looking for a watch with more features and a bigger display, the Apple series 8 is a great choice. It is also expected to have a blood sugar sensor and a longer battery life. Rumor has it that the Apple Watch 8 will also monitor your blood pressure. While it is too early to confirm that, there are some interesting rumors.

Body temperature sensor

If you’ve been waiting for an Apple Watch to come out with a body temperature sensor, you’re not alone. A rumor circulated last year that Apple would include this feature in the Apple Watch Series 7 – but they ultimately canceled it due to problems with the algorithm. It’s possible that the body temperature sensor will be included in the next iteration of the Apple Watch, though. Analyst Ming-Chi Kuo believes it’s highly unlikely that the company will include it this year.

The body temperature sensor is another popular feature that has been heavily rumored for the Apple Watch Series 8. Bloomberg’s Mark Gurman has a track record for predicting the future of Apple products, and The Wall Street Journal published an article about this feature last September. Apple analyst Ming-Chi Kuo has also predicted the addition of a body temperature sensor, although he says the device would be limited. Nevertheless, the temperature sensor is an important feature and Apple should consider adding it if they are confident that it’s worth the wait.

Bigger display

Rumours about the Apple Watch Series 8 have been swirling for months now, and now that the new device is here, we can speculate about the size of its display. Apple introduced two different sizes for its current watch series, the 38mm and 41mm versions, so this means the next one will be even bigger. Ross Young, CEO of Display Supply Chain Consultants, suggested that the watch series 8 could have three different sizes. If so, that would make it the largest Apple Watch ever, so if you’re looking for the largest Apple Watch, now is the time to wait.

In addition to the larger display, Apple has improved the way some of the faces are designed. Some are optimized for the larger screen, and the iPhone Health app could add sleep tracking, women’s health features, and medication tracking. While we can’t predict when Apple will launch the new Watch Series 8, we can expect some exciting changes in its design. The most important change, however, may be the addition of a third model.

Improved activity tracking

If you’re considering buying an Apple Watch 8 soon, you should know that the new version will come with a number of new health features. One of these is improved activity tracking. The new watch has a built-in blood oxygen sensor, which is less accurate than a fingertip sensor. It may be possible to leverage this data, but it’s not advised to do so without the guidance of a physician.

The Apple Watch 8 will come with a new software update called watchOS 8. The next major version of the software will introduce new health features and include texting and photo sharing. There will also be new HomeKit integrations. In addition, Apple says the update will fix several bugs and improve stability. The watchOS 8 update is slated to release sometime in 2024 or 2025. If it does, you’ll likely be able to get it then.

In-display fingerprint sensor

The in-display fingerprint sensor on Apple’s latest smartwatch could work through a display instead of a physical button. Apple has already patented a capacitive sensor with an electrostatic lens. This sensor is already available in smartphones, but it may soon appear in a smartwatch. The iPhone 8 will also come with a fingerprint sensor that recognizes your fingerprint optically. Despite the recent release of Apple’s iPhone X, the device’s fingerprint recognition technology may not be quite as robust as that of competitors.

An in-display fingerprint sensor will allow Apple to improve security while also ensuring that only you can access your device. The new Apple Watch 8’s home button is protected by a sapphire crystal. The biometric information is stored on the device and is safe to use. For example, Apple’s watch uses a 500 dpi sensor. A single pixel is approximately 50 microns. However, the chip itself is only 170 microns thin. The manufacturer says the new sensor can be twice as fast as 3D facial recognition.

Flat-edged design

There is an ongoing speculation that Apple will release a new Apple Watch with flat edges. The last one debuted with rounded sides, but now there are new renders of a flat-edged Apple Watch. If Apple follows through on its plan for a flat-edged watch, we could see it sometime later this year. If the flat-edged design does appear, we’ll likely see it with the upcoming Apple Watch Series 8.

Despite the rumors of an upcoming flat-edged Apple Watch, the new model is likely to keep its original shape. A leaker known as ShrimpApplePro has confirmed the design of the new Apple Watch. Using renders of Apple Watch series 7, the rumormonger cited the ‘ShrimpApplePro’ leaker as his source. If this turns out to be true, the flat-edged design will become the new Apple Watch for 2017.

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health

Exercise to make your legs thin.

To make your lower body line thin, you want to begin yoga works out. Expanding the power of activity by adding disfigurement to the fundamental yoga stance can finish a versatile line while eliminating fat. Likewise, it can relax the body, further develop blood course, and forestall cellulite. Allow me to present a five-minute yoga exercise to lose leg fat.

주변 스크린골프

brief yoga exercise to lose leg fat at home.

1. Board change.

Rests on the mat in an essential board stance and start. What’s more raise your left foot up high and pull it toward your chest. Raise your legs to make a downdog pose, pull it, and return to the board pose. Rehash for 30 seconds and continue for 30 seconds with the contrary leg.

2. Wheel misshapening.

While lying on the mat, press your hands and feet to the floor and float your body in the air. You can make the wheel stance of yoga. Hold it up so your body is bended however much as could be expected. Then, at that point, lift and lower your right foot, lift and lower your left foot. Rehash for 1 moment.

3. Downdog.

Stoop on the floor, twist your chest area forward, and start in a youngster position. Furthermore stretch your legs while raising your chest area, and change to a downdog position. Fix your elbows and knees totally, and your look is toward the tip of your toes. Relax for 1 moment while keeping up with your stance.

4. Span all over.

Lie on your back on the mat, pull your knees, and stick your feet together. Then, at that point, press your arm to the floor and float your butt in the air. You can make the scaffold position. Keep your body corner to corner. Then, at that point, bring down your hips and lift them briefly.

5. Furrow.

Lie on the mat and totally fix your back on the floor. Support your arms and float your legs in the air. Try not to spread between your legs, and gradually raise it. Then, at that point, you can return your hair totally. Put your toes on the floor, hold your midriff with your hands, or clasp them to the floor. Hold tight briefly.

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About NFT and token

source : pixabay

As how much cash builds, the corporate share market stays unaltered.

A great representation is an adjustment of coin-related stock costs. Normally, the coin market is fluctuating, and accidental and subsidiary areas are likewise impacted in association.

​

Presently, before we proceed with the story, how about we momentarily bring up the idea.

In the first place, the distinction among coins and tokens, regularly alluded to as ought to be inspected.

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Assuming you search the distinction among coins and tokens on the Internet, you will track down that possession, decentralization, mainnet, and other extensive and troublesome words are reordered.

With that, it is hard to get what the distinction among coins and tokens is.

This is on the grounds that they are reordered to fill the post.

​

What is the distinction among coins and tokens?

​

It’s actual basic.

Coin alludes to an installment technique (cash), and token alludes to the power to utilize the administrations of a particular organization.

At the end of the day, they are clarifying this in such a troublesome manner. Whatever is troublesome, it implies that the essayist doesn’t see as expected.

​

To make it simpler to clarify as an every day model, every one of them have vanished now, yet when I was in school, I sold round-molded coins that could take transports.

This was known as a “transport token.” To get on the transport, I purchased a token in real money and paid for it.

<Transport Token>

​

It is straightforward that such substance is the contrast among coins and tokens.

The coin is utilized like money, and the token is a symbolic that can utilize the assistance.

​

Then, at that point, what is the NFT that is quickly becoming well known nowadays?

NFT represents Non-Fungible Token, which implies an indispensable symbolic when deciphered. It is indispensable, that is, a special symbolic that can’t be traded for anything more.

​

Nowadays, game-related stocks are having loads of fun with this NFT all over. This is on the grounds that NFT itself is an IT-based material that is ideal for thematization. How great is this is on the grounds that it is connected material when the stock cost is raised by making a topic that didn’t exist?

​

In the securities exchange, which has become always showing signs of change because of the flood of cash on the lookout, it is aimless in itself to gauge whether this well known topic is correct, off-base, great, or awful. Notwithstanding, assuming that you are a Joorin, you ought to be cautious about bouncing in like a fire moth without knowing anything.

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These kinds of stock stocks change without question. This is on the grounds that to get on a running pony and be protected, it is risky without most abilities and muscle strength.

​

On the off chance that you plunge, you sell this is on the grounds that you keep thinking about whether the pattern has finished, and assuming you take off, your record will recoil rapidly assuming that you rehash misrepresentation since you figure it will consume once more. Then, at that point, it is hard to endure except if there is a different pay from an external perspective.

​

Try not to trust the Internet effectively all things considered.

What amount did you procure from what? Every one individuals who talk are pre-buyers. As such, they simply get it first and catch the breeze to drift it. Consequently, rather than sneaking about the games that others take, you need to study all alone and put resources into what you are great at and know well so you can chuckle serenely while watching Netflix or Watcha even with little changes.

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tips

Tequila : How to enjoy tequila properly.

tequila

Tequila is one of the beverages that individuals like and aversion as a result of its exceptional fragrance and taste.

For the people who like tequila, I might want to give you a great nibble formula.

There are a many individuals who would rather avoid it yet to those individuals today,
I might want to acquaint how with eat tequila scrumptiously.
Most tequila is typically presented with lemon and salt when requested outside.
These two go very well with tequila. (As such, honey combination!!))
Tequila has a dry and hot taste (hot taste), so it goes very well with these invigorating fixings.

(After drink shopping, you have to delivery check from 통합택배조회)

Today, I might want to present a marginally unique mix of espresso powder and lime than the recently known bite.
It’s flavorful to eat with lemon, yet when you eat it at home, it’s truly delightful to cut and eat lime.
Leave half of the lime and make slices so that it’s not difficult to eat.
Sprinkle a great deal of sugar on top and consume it with a light.
At the point when you want something sweet while eating crude lime, it’s great to eat individually.
Assuming you add glossed over lime like this, you can appreciate tequila all the more delightfully.
Assuming you eat tequila and appreciate salt or lime sugar with lime espresso powder,
You can partake in the genuine taste of tequila.

Tequila is flavorful even with a prison.

It is a method for adding carbonic corrosive to tequila.
Since you need to place in two things, set up a marginally bigger glass than the current shot glass.

In the event that you add half of tequila and juice and drink it, it’s
It’s blended in with carbonated beverages, so it tastes less and is extremely scrumptious. I continue to eat this is on the grounds that it’s great.
I suggest eating reasonably on the grounds that you can get tipsy rapidly.

tequila formula

Presently, I’ll let you know a mixed drink formula with tequila.

It’s margarita mixed drink.

Tequila is portrayed by a spotless taste with the sharp and fragrant taste of lime and the pungent taste of salt.

Magirita, which just adds lime, can be supposed to be the equation for tidiness.
The fixings that go in are triple-sek, lime juice, tequila, and salt.
Slice the lime down the middle and squeeze it. (Cut the rimming halime a tad.)
Experience the glass with salt. You can cover the lime with salt.
Put ice in a shaker, put an ounce of tequila, and triple sex 0… 5 ounces.
Add 0.5 ounces of lime squeeze and shake it.
From that point onward, empty it into the glass and it’s finished.

Then, we will make a tequila dawn.

It is quite possibly the most delegate mixed drink made with tequila alongside margarita.
It is a mixed drink where the Grenadine syrup sinks down and is finished in a beautiful shading that ascents to the sky when the sun rises.
With squeezed orange, it tastes acrid and sweet.
It seems crude, however it is a mixed drink that joins the harsh and solid liquor aroma of tequila.
To start with, get ready ice in a glass. Add 1 ounce of tequila and 3 ounces of squeezed orange.
Gradually pour 0.5 ounces of Grenadine Syrup.
Put cherries and pineapples in a glass with embellishment to finish the mixed drink.

Also among tequila mixed drinks, Matador is a mixed drink.

It’s a tasty however extraordinary mixed drink.
Bullfighter implies a matador. Particularly toward the end, he assumes the part of wounding the cow to a ridiculous degree.
It alludes to a matador, and it is said that embellishment is utilized as a cherry to communicate the red shroud of the matador.
It is a flavorful mixed drink with pineapple squeeze that is harsh, sweet, and inconspicuous tequila fragrance.

Fixings are lime juice and tequila pineapple juice perry (decorate).

On the off chance that you add water to the crude record apple, grind it, and use it as juice, you can appreciate more delightful Matador.
It is alright to utilize financially accessible pineapple juice. In the first place, cut the lime down the middle and squeeze it.
You can utilize half. Add 1 ounce of tequila and 2 ounces of pineapple juice and 0.5 ounce of lime juice to the shaker and shake.
Add ice to the glass and pour the mixed drink.
Also finish it by putting cherry and pineapple decorate on top.

The icebreaker has grapefruit juice and grenadine syrup in it.

It’s a mixed drink that is made. Tequila and grapefruit juice are more remarkable than I suspected.
I think individuals who appreciate tequila will like this is on the grounds that it suits them well.
It is a decent mixed drink to appreciate softly in light of the fact that it is respectably sweet and new.
Elements for section can be ready in triple sek, grenadine syrup, tequila, and grapefruit juice.
1 ounce of ice, tequila, 1 ounce of grapefruit juice, 0.3 ounces of triple sex, and 1 spoon of Grenadine syrup.
Put it in and shake it. In the wake of shaking, empty it into a glass to finish the conversation starter.
For reference, the liquor content is around 22 degrees.

At last, it is a mixed drink called Slodequila utilizing.

The liquor level is 28 degrees. It’s somewhat exceptional with cucumber embellish with slojin and tequila lemon juice.
It very well may be a new mixed drink.
They appear to be unforeseen fixings, yet they go very well together.
It is a mixed drink with an exceptionally bright taste joined with solid scented fixings.
Fixings incorporate lemon juice, cucumber, and tequila.

The method for making it is likewise straightforward.
In the first place, put ice in a shaker, 0.5 ounces of tequila delayed down lemon juice (a large portion of a day), and 0.5 ounces.
Shake it. Put ice in a glass, pour mixed drinks, and embellishment with cucumbers to finish it.

Assuming that you truly disdain cucumbers, you may be hesitant outwardly,
Assuming you attempt it, you will be dependent on the unobtrusive taste.

Today, I presented five mixed drink plans with tequila.

It would be great to appreciate different mixed drinks at home with a container of tequila.
To break Tequila’s bias, did you like the sweet and scrumptious formula?