book | Actix user guides | Caching library

 by   actix Rust Version: Current License: Apache-2.0

kandi X-RAY | book Summary

kandi X-RAY | book Summary

book is a Rust library typically used in Server, Caching applications. book has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitHub.

Actix user guides
Support
    Quality
      Security
        License
          Reuse

            kandi-support Support

              book has a low active ecosystem.
              It has 160 star(s) with 55 fork(s). There are 18 watchers for this library.
              OutlinedDot
              It had no major release in the last 6 months.
              There are 4 open issues and 7 have been closed. On average issues are closed in 29 days. There are no pull requests.
              It has a neutral sentiment in the developer community.
              The latest version of book is current.

            kandi-Quality Quality

              book has 0 bugs and 0 code smells.

            kandi-Security Security

              book has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
              book code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              book is licensed under the Apache-2.0 License. This license is Permissive.
              Permissive licenses have the least restrictions, and you can use them in most projects.

            kandi-Reuse Reuse

              book releases are not available. You will need to build from source code and install.

            Top functions reviewed by kandi - BETA

            kandi's functional review helps you automatically verify the functionalities of the libraries and avoid rework.
            Currently covering the most popular Java, JavaScript and Python libraries. See a Sample of book
            Get all kandi verified functions for this library.

            book Key Features

            No Key Features are available at this moment for book.

            book Examples and Code Snippets

            copy iconCopy
            const isEmpty = val => val == null || !(Object.keys(val) || val).length;
            
            
            isEmpty([]); // true
            isEmpty({}); // true
            isEmpty(''); // true
            isEmpty([1, 2]); // false
            isEmpty({ a: 1, b: 2 }); // false
            isEmpty('text'); // false
            isEmpty(123); // true -  
            copy iconCopy
            const geometricProgression = (end, start = 1, step = 2) =>
              Array.from({
                length: Math.floor(Math.log(end / start) / Math.log(step)) + 1,
              }).map((_, i) => start * step ** i);
            
            
            geometricProgression(256); // [1, 2, 4, 8, 16, 32, 64, 128, 2  
            copy iconCopy
            const includesAny = (arr, values) => values.some(v => arr.includes(v));
            
            
            includesAny([1, 2, 3, 4], [2, 9]); // true
            includesAny([1, 2, 3, 4], [8, 9]); // false
            
              
            Updates an existing book .
            javadot img4Lines of Code : 19dot img4License : Non-SPDX
            copy iconCopy
            public void update(Book book) throws BookNotFoundException, VersionMismatchException {
                if (!collection.containsKey(book.getId())) {
                  throw new BookNotFoundException("Not found book with id: " + book.getId());
                }
            
                var latestBook = coll  
            Book a room
            javadot img5Lines of Code : 16dot img5License : Non-SPDX
            copy iconCopy
            public void bookRoom(int roomNumber) throws Exception {
            
                var room = hotelDao.getById(roomNumber);
            
                if (room.isEmpty()) {
                  throw new Exception("Room number: " + roomNumber + " does not exist");
                } else {
                  if (room.get().isBooked()  
            Retrieves a book by title
            javadot img6Lines of Code : 12dot img6License : Non-SPDX
            copy iconCopy
            @Override
              public Book getBook(String title) {
                Book bookDTo;
                try (var session = sessionFactory.openSession()) {
                  var sqlQuery = session.createSQLQuery("SELECT b.title as \"title\","
                      + " b.price as \"price\"" + " FROM Book b wh  

            Community Discussions

            QUESTION

            how to enable comparison between Vec<_> and Vec<_,CustomAllocator>?
            Asked 2022-Mar-28 at 09:53

            I am trying to use a custom allocator, using the allocator API in Rust.

            It seems Rust considers Vec and Vec as two distinct types.

            ...

            ANSWER

            Answered 2022-Mar-28 at 09:53

            Update: Since GitHub pull request #93755 has been merged, comparison between Vecs with different allocators is now possible.

            Original answer:

            Vec uses the std::alloc::Global allocator by default, so Vec is in fact Vec. Since Vec and Vec are indeed distinct types, they cannot directly be compared because the PartialEq implementation is not generic for the allocator type. As @PitaJ commented, you can compare the slices instead using assert_eq!(&a[..], &b[..]) (which is also what the author of the allocator API recommends).

            Source https://stackoverflow.com/questions/71021633

            QUESTION

            Largest value representable by a floating-point type smaller than 1
            Asked 2022-Mar-08 at 23:51

            Is there a way to obtain the greatest value representable by the floating-point type float which is smaller than 1.

            I've seen the following definition:

            ...

            ANSWER

            Answered 2022-Mar-08 at 23:51

            You can use the std::nextafter function, which, despite its name, can retrieve the next representable value that is arithmetically before a given starting point, by using an appropriate to argument. (Often -Infinity, 0, or +Infinity).

            This works portably by definition of nextafter, regardless of what floating-point format your C++ implementation uses. (Binary vs. decimal, or width of mantissa aka significand, or anything else.)

            Example: Retrieving the closest value less than 1 for the double type (on Windows, using the clang-cl compiler in Visual Studio 2019), the answer is different from the result of the 1 - ε calculation (which as discussed in comments, is incorrect for IEEE754 numbers; below any power of 2, representable numbers are twice as close together as above it):

            Source https://stackoverflow.com/questions/71383519

            QUESTION

            Room database is not working in mac book pro m1
            Asked 2022-Mar-05 at 06:15

            Room database is not working in mac book pro m1 i have already added id 'kotlin-kapt'

            screen shoot of android studio console log

            • What went wrong: Execution failed for task ':app:kaptDebugKotlin'.

            A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptWithoutKotlincTask$KaptExecutionWorkAction java.lang.reflect.InvocationTargetException (no error message)

            Caused by: java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at org.jetbrains.kotlin.kapt3.base.AnnotationProcessingKt.doAnnotationProcessing(annotationProcessing.kt:90) at org.jetbrains.kotlin.kapt3.base.AnnotationProcessingKt.doAnnotationProcessing$default(annotationProcessing.kt:31) at org.jetbrains.kotlin.kapt3.base.Kapt.kapt(Kapt.kt:45) ... 31 more

            Caused by: java.lang.Exception: No native library is found for os.name=Mac and os.arch=aarch64. path=/org/sqlite/native/Mac/aarch64 at org.sqlite.SQLiteJDBCLoader.loadSQLiteNativeLibrary(SQLiteJDBCLoader.java:333) at org.sqlite.SQLiteJDBCLoader.initialize(SQLiteJDBCLoader.java:64) at androidx.room.verifier.DatabaseVerifier.(DatabaseVerifier.kt:71) ... 50 more

            ...

            ANSWER

            Answered 2021-Nov-28 at 16:03

            Simply use Room 2.4.0-alpha03

            Source https://stackoverflow.com/questions/68922875

            QUESTION

            Is if(A | B) always faster than if(A || B)?
            Asked 2022-Feb-11 at 05:03

            I am reading this book by Fedor Pikus and he has some very very interesting examples which for me were a surprise.
            Particularly this benchmark caught me, where the only difference is that in one of them we use || in if and in another we use |.

            ...

            ANSWER

            Answered 2022-Feb-08 at 19:57

            Code readability, short-circuiting and it is not guaranteed that Ord will always outperform a || operand. Computer systems are more complicated than expected, even though they are man-made.

            There was a case where a for loop with a much more complicated condition ran faster on an IBM. The CPU didn't cool and thus instructions were executed faster, that was a possible reason. What I am trying to say, focus on other areas to improve code than fighting small-cases which will differ depending on the CPU and the boolean evaluation (compiler optimizations).

            Source https://stackoverflow.com/questions/71039947

            QUESTION

            Docker standard_init_linux.go:228: exec user process caused: no such file or directory
            Asked 2022-Feb-08 at 20:49

            Whenever I am trying to run the docker images, it is exiting in immediately.

            ...

            ANSWER

            Answered 2021-Aug-22 at 15:41

            Since you're already using Docker, I'd suggest using a multi-stage build. Using a standard docker image like golang one can build an executable asset which is guaranteed to work with other docker linux images:

            Source https://stackoverflow.com/questions/68881023

            QUESTION

            Understanding color scales in ggplot2
            Asked 2022-Feb-03 at 17:47

            There are so many ways to define colour scales within ggplot2. After just loading ggplot2 I count 22 functions beginging with scale_color_* (or scale_colour_*) and same number beginging with scale_fill_*. Is it possible to briefly name the purpose of the functions below? Particularly I struggle with the differences of some of the functions and when to use them.

            • scale_*_binned()
            • scale_*_brewer()
            • scale_*_continuous()
            • scale_*_date()
            • scale_*_datetime()
            • scale_*_discrete()
            • scale_*_distiller()
            • scale_*_fermenter()
            • scale_*_gradient()
            • scale_*_gradient2()
            • scale_*_gradientn()
            • scale_*_grey()
            • scale_*_hue()
            • scale_*_identity()
            • scale_*_manual()
            • scale_*_ordinal()
            • scale_*_steps()
            • scale_*_steps2()
            • scale_*_stepsn()
            • scale_*_viridis_b()
            • scale_*_viridis_c()
            • scale_*_viridis_d()

            What I tried

            I've tried to make some research on the web but the more I read the more I get onfused. To drop some random example: "The default scale for continuous fill scales is scale_fill_continuous() which in turn defaults to scale_fill_gradient()". I do not get what the difference of both functions is. Again, this is just an example. Same is true for scale_color_binned() and scale_color_discrete() where I can not name the difference. And in case of scale_color_date() and scale_color_datetime() the destription says "scale_*_gradient creates a two colour gradient (low-high), scale_*_gradient2 creates a diverging colour gradient (low-mid-high), scale_*_gradientn creates a n-colour gradient." which is nice to know but how is this related to scale_color_date() and scale_color_datetime()? Looking for those functions on the web does not give me very informative sources either. Reading on this topic gets also chaotic because there are tons of color palettes in different packages which are sequential/ diverging/ qualitative plus one can set same color in different ways, i.e. by color name, rgb, number, hex code or palette name. In part this is not directly related to the question about the 2*22 functions but in some cases it is because providing a "wrong" palette results in an error (e.g. the error"Continuous value supplied to discrete scale).

            Why I ask this

            I need to do many plots for my work and I am supposed to provide some function that returns all kind of plots. The plots are supposed to have similiar layout so that they fit well together. One aspect I need to consider here is that the colour scales of the plots go well together. See here for example, where so many different kind of plots have same colour scale. I was hoping I could use some general function which provides a colour palette to any data, regardless of whether the data is continuous or categorical, whether it is a fill or col easthetic. But since this is not how colour scales are defined in ggplot2 I need to understand what all those functions are good for.

            ...

            ANSWER

            Answered 2022-Feb-01 at 18:14

            This is a good question... and I would have hoped there would be a practical guide somewhere. One could question if SO would be a good place to ask this question, but regardless, here's my attempt to summarize the various scale_color_*() and scale_fill_*() functions built into ggplot2. Here, we'll describe the range of functions using scale_color_*(); however, the same general rules will apply for scale_fill_*() functions.

            Overall Categorization

            There are 22 functions in all, but happily we can group them intelligently based on practical usage scenarios. There are three key criteria that can be used to define practically how to use each of the scale_color_*() functions:

            1. Nature of the mapping data. Is the data mapped to the color aesthetic discrete or continuous? CONTINUOUS data is something that can be explained via real numbers: time, temperature, lengths - these are all continuous because even if your observations are 1 and 2, there can exist something that would have a theoretical value of 1.5. DISCRETE data is just the opposite: you cannot express this data via real numbers. Take, for example, if your observations were: "Model A" and "Model B". There is no obvious way to express something in-between those two. As such, you can only represent these as single colors or numbers.

            2. The Colorspace. The color palette used to draw onto the plot. By default, ggplot2 uses (I believe) a color palette based on evenly-spaced hue values. There are other functions built into the library that use either Brewer palettes or Viridis colorspaces.

            3. The level of Specification. Generally, once you have defined if the scale function is continuous and in what colorspace, you have variation on the level of control or specification the user will need or can specify. A good example of this is the functions: *_continuous(), *_gradient(), *_gradient2(), and *_gradientn().

            Continuous Scales

            We can start off with continuous scales. These functions are all used when applied to observations that are continuous variables (see above). The functions here can further be defined if they are either binned or not binned. "Binning" is just a way of grouping ranges of a continuous variable to all be assigned to a particular color. You'll notice the effect of "binning" is to change the legend keys from a "colorbar" to a "steps" legend.

            The continuous example (colorbar legend):

            Source https://stackoverflow.com/questions/70942728

            QUESTION

            Why does GCC allocate more stack memory than needed?
            Asked 2022-Feb-03 at 08:12

            I'm reading "Computer Systems: A Programmer's Perspective, 3/E" (CS:APP3e) and the following code is an example from the book:

            ...

            ANSWER

            Answered 2022-Feb-03 at 04:10

            (This answer is a summary of comments posted above by Antti Haapala, klutt and Peter Cordes.)

            GCC allocates more space than "necessary" in order to ensure that the stack is properly aligned for the call to proc: the stack pointer must be adjusted by a multiple of 16, plus 8 (i.e. by an odd multiple of 8). Why does the x86-64 / AMD64 System V ABI mandate a 16 byte stack alignment?

            What's strange is that the code in the book doesn't do that; the code as shown would violate the ABI and, if proc actually relies on proper stack alignment (e.g. using aligned SSE2 instructions), it may crash.

            So it appears that either the code in the book was incorrectly copied from compiler output, or else the authors of the book are using some unusual compiler flags which alter the ABI.

            Modern GCC 11.2 emits nearly identical asm (Godbolt) using -Og -mpreferred-stack-boundary=3 -maccumulate-outgoing-args, the former of which changes the ABI to maintain only 2^3 byte stack alignment, down from the default 2^4. (Code compiled this way can't safely call anything compiled normally, even standard library functions.) -maccumulate-outgoing-args used to be the default in older GCC, but modern CPUs have a "stack engine" that makes push/pop single-uop so that option isn't the default anymore; push for stack args saves a bit of code size.

            One difference from the book's asm is a movl $0, %eax before the call, because there's no prototype so the caller has to assume it might be variadic and pass AL = the number of FP args in XMM registers. (A prototype that matches the args passed would prevent that.) The other instructions are all the same, and in the same order as whatever older GCC version the book used, except for choice of registers after call proc returns: it ends up using movslq %edx, %rdx instead of cltq (sign-extend with RAX).

            CS:APP 3e global edition is notorious for errors in practice problems introduced by the publisher (not the authors), but apparently this code is present in the North American edition, too. So this may be the author's mistake / choice to use actual compiler output with weird options. Unlike some of the bad global edition practice problems, this code could have come unmodified from some GCC version, but only with non-standard options.

            Related: Why does GCC allocate more space than necessary on the stack, beyond what's needed for alignment? - GCC has a missed-optimization bug where it sometimes reserves an additional 16 bytes that it truly didn't need to. That's not what's happening here, though.

            Source https://stackoverflow.com/questions/70953275

            QUESTION

            Why second spin in Spinlock gives performance boost?
            Asked 2022-Jan-28 at 15:23

            Here is a basic Spinlock implemented with std::atomic_flag.
            The author of the book claims that second while in the lock() boosts performance.

            ...

            ANSWER

            Answered 2022-Jan-28 at 05:13

            Reading a memory address does not clear the cache line.

            Writing does.

            So in a modern computer, there is RAM, and there are multiple layers of cache "around" the CPU (they are called L1, L2 and L3 cache, but the important part is that they are layers, and the CPU is at the middle). In a multi-core system, often the outer layers are shared; the innermost layer is usually not, and is specific to a given CPU.

            Clearing the cache line means informing every other cache holding this memory "the data you own may be stale, throw it out".

            Test and set writes true and atomically returns the old value. It clears the cache line, because it writes.

            Test does not write. If you have another thread unsynchronized with this one, it reading the cache of this memory doesn't have to be poked.

            The outer loop writes true, and exits if it replaced false. The inner loop waits until there is a false visible, then falls to outer loop. The inner loop need not clear every other cpu's cache status of the value of the atomic flag, but the outer has to (as it could change the false to true). As spinning could go on for a while, avoiding continuous cache clearing seems like a good idea.

            Source https://stackoverflow.com/questions/70887350

            QUESTION

            Ambiguous overload error when using conversion function
            Asked 2022-Jan-25 at 17:22

            I am trying to understand overloading resolution in C++ through the books listed here. One such example that i wrote to clear my concepts whose output i am unable to understand is given below.

            ...

            ANSWER

            Answered 2022-Jan-25 at 17:19

            Essentially, skipping over some stuff not relevant in this case, overload resolution is done to choose the user-defined conversion function to initialize the variable and (because there are no other differences between the conversion operators) the best viable one is chosen based on the rank of the standard conversion sequence required to convert the return value of to the variable's type.

            The conversion int -> double is a floating-integral conversion, which has rank conversion.

            The conversion float -> double is a floating-point promotion, which has rank promotion.

            The rank promotion is better than the rank conversion, and so overload resolution will choose operator float as the best viable overload.

            The conversion int -> long double is also a floating-integral conversion.

            The conversion float -> long double is not a floating-point promotion (which only applies for conversion float -> double). It is instead a floating-point conversion which has rank conversion.

            Both sequences now have the same standard conversion sequence rank and also none of the tie-breakers (which I won't go through) applies, so overload resolution is ambigious.

            The conversion int -> bool is a boolean conversion which has rank conversion.

            The conversion float -> bool is also a boolean conversion.

            Therefore the same situation as above arises.

            See https://en.cppreference.com/w/cpp/language/overload_resolution#Ranking_of_implicit_conversion_sequences and https://en.cppreference.com/w/cpp/language/implicit_conversion for a full list of the conversion categories and ranks.

            Although it might seem that a conversion between floating-point types should be considered "better" than a conversion from integral to floating-point type, this is generally not the case.

            Source https://stackoverflow.com/questions/70852103

            QUESTION

            What does 'Zero Cost Abstraction' mean?
            Asked 2021-Sep-14 at 13:39

            I came across this term when exploring Rust.

            I saw different kinds of explanations regarding this and still don't quite get the ideas.

            In The Embedded Rust Book, it said

            Type states are also an excellent example of Zero Cost Abstractions

            • the ability to move certain behaviors to compile time execution or analysis.

            These type states contain no actual data, and are instead used as markers.

            Since they contain no data, they have no actual representation in memory at runtime:

            Does it mean the runtime is faster because there is no memory in runtime?

            Appreciate it if anyone can explain it in an easy to understand way.

            ...

            ANSWER

            Answered 2021-Sep-14 at 13:11

            Zero Cost Abstractions means adding higher-level programming concepts, like generics, collections and so on do not come with a run-time cost, only compiler time cost (the code will be slower to compile). Any operation on zero-cost abstractions is as fast as you would write out matching functionality by hand using lower-level programming concepts (for loops, counters, ifs and so on).

            Source https://stackoverflow.com/questions/69178380

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network

            Vulnerabilities

            No vulnerabilities reported

            Install book

            You can download it from GitHub.
            Rust is installed and managed by the rustup tool. Rust has a 6-week rapid release process and supports a great number of platforms, so there are many builds of Rust available at any time. Please refer rust-lang.org for more information.

            Support

            For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .
            Find more information at:

            Find, review, and download reusable Libraries, Code Snippets, Cloud APIs from over 650 million Knowledge Items

            Find more libraries
            CLONE
          • HTTPS

            https://github.com/actix/book.git

          • CLI

            gh repo clone actix/book

          • sshUrl

            git@github.com:actix/book.git

          • Stay Updated

            Subscribe to our newsletter for trending solutions and developer bootcamps

            Agree to Sign up and Terms & Conditions

            Share this Page

            share link

            Explore Related Topics

            Consider Popular Caching Libraries

            caffeine

            by ben-manes

            groupcache

            by golang

            bigcache

            by allegro

            DiskLruCache

            by JakeWharton

            HanekeSwift

            by Haneke

            Try Top Libraries by actix

            actix-web

            by actixRust

            actix

            by actixRust

            examples

            by actixRust

            actix-net

            by actixRust

            actix-extras

            by actixRust