galaxy | A cache-coherent in-memory data grid | Database library
kandi X-RAY | galaxy Summary
kandi X-RAY | galaxy Summary
RAM storage and code/data co-location Application code runs on the same cluster nodes (called peer nodes), and processes the data objects which are kept in RAM. Unlike other IMDGs that partition data items and distribute them in such a way that each object is the responsibility of a single node, Galaxy nodes exchange messages to transfer ownership of objects from one node to another. This means that if the application code in one of the nodes regularly updates some data items, those items will be owned by the node, and will be available for processing and update without any network I/O. As the application runs, items will migrate from one node to another (though items can reside on several nodes at once for read-only access). This gives the application precise control over the location of the data in the cluster for maximum performance. This flexibility, however, is suitable when data access patterns can be predicted and so the data can be optimally placed. If data access is random, other IMDGs may be a better choice as they can retrieve or update any item at a cost of one network hop, while Galaxy might need to search the cluster for an unexpected item access. Because the application code is co-located with the data, and because all of the data is kept in RAM, Galaxy is suitable for low-latency applications. Consistency Galaxy stores data in a fully consistent manner, meaning that if data item B has been modified after a change to data item A, no node in the cluster will see A's new value but B's old one. Galaxy achieves consistency by using a cache-coherence protocol similar to the protocols used to coordinate memory access among CPU cores. However, as Galaxy can guarantee the ordering of coordination messages between nodes no memory-fence operations are requires (as they are in CPUs) to achieve consistency. Disk persistence and server nodes The data items can optionally be persisted to disk on one or more special server nodes. However, in order to keep latency low, Galaxy (even when configured to use a persistent server node), is not durable. This means that a failure in one or more of the nodes may result in a permanent loss of some recent updates. However, even in cases of such failures the data remains consistent, meaning the lost updates will be lost to all of the nodes (or to none). High Availability Galaxy can withstand a failure in one or more of the nodes, providing high-availability. This is achieved by either running Galaxy with a server node (which persists all of the grid data to disk) or by running a slave node (or more) for each of the peers, or both. If only a server node is used, data is not lost when a peer node fails (except for possibly some recent updates as explained above), and all the data items owned by the failed node are still accessible. However, as the server reads those items from the disk, latency might suffer until all items have been accessed by the peers and kept in RAM. Alternately, or in combination with a server, you can run one or more slave-nodes for each of the peers, that mirror the data stored in them, so that upon failure of a peer, one of its slaves will take over, already having all of the necessary data items in RAM. A server node may also have slaves that will take over when it fails. Messaging Galaxy provides a point-to-point messaging service that guarantees message delivery and ordering. A message can be sent to a known node or to the unknown (to the application) owner of a given data item. So if Galaxy's data-item migration makes moving data to code simple, Galaxy's messages make moving an operation (code) to data just as simple. The application messages are delivered by the same communication channel that delivers Galaxy's internal coherence protocol messages, so messages are also guaranteed to be ordered with data operations. Say that node A updates data item X, and then sends a message to the owner of data item Y (which happens to be node B), as a result of which node B reads the value of X. In this case node B is guaranteed to read the value of X after the update done by A before sending the message. Monitoring All of Galaxy's components are monitored to enable full diagnoses of failure or performance problems. Galaxy's aim is to give the application full control over data location and processing in the grid, and in-order to provide maximal flexibility with a simple API, it is relatively low-level. It provides no query mechanism whatsoever, imposes no structure on the data (which is kept in memory and on disk as byte arrays), and provides no locking of elements to coordinate complex transactions among different threads on a single node (although each operation is atomic by itself). All of that must be provided by the application.
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Top functions reviewed by kandi - BETA
- Initializes the node
- Set the online state of the node
- Completes the leader addition
- Process a leader
- Initialize the channel
- Adds a property to this node
- Sets the reference counter to the given value
- Initialize reference id counter
- Formats a log record
- Processes a message
- Handles the event
- Handle a node event
- Builds the pipeline to connect to all registered channels
- Broadcasts a message to all peers
- Collect and reset counters
- Allocates a number of references to the given range
- Starts the timer
- Handles a channel event
- Receive message
- Remove the owner of the node
- Initialize this channel
- Receives message
- Get the owner of a node
- Creates a node
- Process incoming message
- Send a message
galaxy Key Features
galaxy Examples and Code Snippets
Community Discussions
Trending Discussions on galaxy
QUESTION
EDIT: I have changed the question to new code that produces the same error and is more reliable in doing so.
I have been struggling to find a segmentation fault in my code for a while now and have boiled it down to the following code:
...ANSWER
Answered 2022-Mar-31 at 13:16Looks like a bug in GSL. Please report :-)
The line
QUESTION
TL;DR how can I have an Android sensor permanently running/active/registered for my app, even if I close it?
Objective:
I'm making a Flutter application that counts your steps using the pedometer package,
which uses the built-in sensor TYPE_STEP_COUNTER of Android,
which returns the # of steps taken since last boot (iOS). On Android, any steps taken before installing the app are not counted.
How I implemented it:
- When the app is actively running in the foreground, each step causes
a
myStepCountto increment by 1. - In all other cases (phone locked, went to home-screen, closed the app...), the android
TYPE_STEP_COUNTERsensor should still be running in the background, and once I open my app again, the difference between newstepCountand last savedstepCount(saved using shared_prefs) will be calculated and added tomyStepCount.
Important:
The TYPE_STEP_COUNTER sensor must be permanently running/stay registered in the background, even after I lock my phone, go to the home-screen, or close the app...
Observations:
- On my Samsung Galaxy A02s, my app works perfectly fine, as it it supposed to
(as described above). That is because on that phone I also have the
Google Fit app installed, which tracks your steps 24/7 (so the
TYPE_STEP_COUNTERsensor is permanently registered). - On my Samsung Galaxy S7, my app does not work as it's supposed to.
myStepCountgets incremented when I take steps while the app is running in the foreground. But steps taken while the app is closed will NOT be added tomyStepCountonce I open the app again.
Note: I don't have any other step-counting-apps like Google Fit on this phone.
Conclusion:
I need to find a way to register the TYPE_STEP_COUNTER sensor from my Flutter app, and keep it registered even after I close the app.
2 Attempted (but unsuccessful) Solutions:
1st Attempt:
Calling Native Android Code from my Flutter Code to register the sensor
This is my main.dart file (with the unimportant parts left out for simplicity):
ANSWER
Answered 2022-Feb-09 at 22:13Update: I've contacted one of the developers of the pedometer package, and he suggested me to use flutter_foreground_service (which is developed by the same team/company as pedometer). It works.
But I would still find it interesting, if there is another way (maybe similar to my 2 failed attempts).
QUESTION
I have implemented biometric authentication in my application with biometric level BIOMETRIC_STRONG (Class 3). The fingerprint authentication is working as expected but I couldn't able to test the face authentication on any of my devices (Samsung Galaxy S10, Oppo A3S, etc.). I think the face authentication in those devices is not falling under Class 3.
Are there any Android devices with BIOMETRIC_STRONG (Class 3) face authentication? It would be helpful if someone can provide a list.
...ANSWER
Answered 2022-Feb-02 at 10:46Pixel 4 is currently the only device with face authentication that qualifies as BIOMETRIC_STRONG (Class 3).
Face authentication was not added to pixel 5, and looks like there are no plans to add it back with Pixel 6 either.
This is true as of 5th October 2021, but there might be more devices that support in the future.
QUESTION
They know how to implement the scroll by bezel (Galaxy watch 4 Classic) in wear os 3.0 with jetpack compose
In the documentation it mentions the use of ScalingLazyListState or ScrollState but so far the scroll with the rotating bezel of my device has not been recognized.
if anyone has information or an example it would help me a lot.
...ANSWER
Answered 2022-Jan-28 at 17:27In Wear Compose Alpha 15, it is now supported.
QUESTION
I've been trying to write a simple vibration app for my Samsung Galaxy 4 watch but am having an issue. The watch will not vibrate when the screen is off. It will only vibrate when my application is open. Any ideas why this is? Here is some of my code:
...ANSWER
Answered 2022-Jan-23 at 13:20See docs here https://developer.android.com/reference/android/os/VibratorManager
The app should be in foreground for the vibration to happen.
Maybe relevant Android Play Vibration from Foreground Service
QUESTION
My app requires precise user location because it requires the user to be at specific locations to perform tasks. I have followed the documentation for the proper way to request both ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION together.
ANSWER
Answered 2022-Jan-21 at 05:14Comparing my AndroidManifest.xml to the generated file in the built app (using the "Analyze APK" feature in Android Studio), I discovered that the generated APK file had the following entry:
QUESTION
I was having a hard time figuring out how to phrase this. Sorry if this is a noob question, I'm new to responsive design and mobile web design in general.
My phone (Galaxy s10e) will render my webpage as if it's 360 pixels wide, with all elements positioned appropriately based on this width. I have several image tags on the site that are the same width. I was using src images that are 360px wide, and this looks fine on desktop because it is actually rendering my images at 360px, but on mobile the images alone appear to be rendering at a much higher resolution, causing it to look terrible due to upscaling.
If someone could explain to me what is happening here it would really help, since I can't find information on this specific behavior. Some questions I have:
- Is the browser choosing to position the elements based on a 360px width while rendering the actual content at the screen's resolution?
- How do I account for this in my design? I considered rendering the images at the higher resolution and then having the page dynamically scale those images down (so even though the actual div is 360px, the browser can use the 'extra space' allotted by max-width to render the image at a higher resolution), but I want the images to remain 360px wide on desktop, not the higher max-width for mobile rendering.
- Where can I learn all about this behavior so I know how to tackle responsive image scaling in the future?
Thank you for your time. Let me know if you have any other questions. I'm using ReactJS to develop the site.
...ANSWER
Answered 2022-Jan-08 at 01:22OK so in a nutshell pixels are relative sizes. One pixel is not literally one pixel on your phone.
What happens is PPI kicks in and basically zooms in to make things readable.
Because if you actually tried to view 360px on a phone with that pixel density you'd see nothing really.
So lets look at some phone specs:
6.1 INCH
5.90 x 2.77 x 0.31 INCH
Resolution 1440 x 3040 PX ~ 550 PIXELS PER INCH
Viewport 360 x 760 PX 138 PIXELS PER INCH
Now the viewport is what you actually see on screen. in this case it give you a pixel ratio of like 4. So that means your phone has a resolution 4 times that of it's viewport.
so for a web app where a div is set to 200px wide it will display 200px as you'd expect it based on the viewport but this div is actually 800px wide relative to your phones resolution.
Now pictures don't need this limitation. Whats the point in a high res display if your pictures only display 200px with a pixel density one fourth of your screens capability.
So a picture lives in a dual reality on your phone. It has a box size which is the size of the image relative to your viewport but the image itself inside the box lives within your resolution relative to your devices total screen pixels.
So when you have and image that's 200px in the viewport its display resolution is actually 800px. So when you put a picture that's only 200px and have it on a screen that does viewport scaling which nowadays is pretty much everything you're effectively stretching that image to four times its actual size. or what ever the screen pixel density ratio to viewport is. AKA it looks like crap.
And to answer your needs on this I'm just going to direct you here to MOZ who will go over the whys and how's as well as show you what to do to combat this.
Combating element position is pretty easy you just use :
QUESTION
I want to let the user switch the whole document between LTR and RTL. Some CSS properties have start and end values that follow the direction of the document. Most geometrical relations are though absolute.
I want to do something like this if possible, in plain CSS without Javascript and without reloading the document:
if dir is ltr
use padding-left: 65px;
if dir is rtl
use padding-right: 65px;
Edit: Here is i complete list of logical properties and values, so adding a conditional properties may not be needed altogether. Note though that some or all will not work on few years old browsers. My 4yo Galaxy s8 for instance, has never updated its native browser who did not support logical.
Edit2: See now that float: inline-start and inline-end are only supported by Firefox, so back to conditional CSS,
ANSWER
Answered 2021-Dec-23 at 17:10QUESTION
I tried to cluster my dataset using K-mean, but there is a categorical data in column 9; so when I ran k-mean it had an error like this:
...ANSWER
Answered 2021-Dec-17 at 17:31To solve your specific issue, you can generate dummy variables to run your desired clustering.
One way to do it is using the dummy_columns() function from the fastDummies package.
QUESTION
So I have multi-class classification. I want to compile my model:
...ANSWER
Answered 2021-Nov-10 at 09:26You can either convert your labels to one-hot encoded labels and use the categorical_crossentropy loss function:
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