After following, you can keep track of his dynamic information in a timely manner
Observer mode realizes decoupled communication between objects through the design of Subject and Observer in C. The specific steps are as follows: 1. Define the Observer interface and declare the update method; 2. Implement the Subject class to maintain the observer list and provide methods for adding, removing and notification; 3. Use smart pointers such as std::weak_ptr to avoid memory leaks and wild pointers; 4. Pay attention to circular references, thread safety and performance issues, and can be optimized through asynchronous or throttling mechanisms; 5. Apply to GUI, event systems and other scenarios, such as button clicks to trigger multiple listening operations.
Aug 03, 2025 am 04:20 AM
Using$GLOBALScreateshiddendependencies,makingfunctionshardertotest,fragile,andunreusable;2.Itcomplicatesunittestingbyrequiringglobalstatemanipulation,leadingtoslow,fragiletests;3.Globalstateisunpredictableduetouncontrolledmodifications,causingbugsand
Aug 03, 2025 am 04:14 AM
Forhigh-performancemicroserviceswithlowlatencyandhighload,chooseFiber;2.ForstandardRESTAPIs,internaltools,orMVPs,chooseGinorEcho;3.Formaximummiddlewarecompatibility,chooseGinorEcho;4.ForExpress.js-likesyntaxandamodernfeel,chooseFiber;5.Forlong-termpr
Aug 03, 2025 am 03:57 AM
Java Optional should be mainly used to return values rather than fields or parameters, avoid blindly calling get(), and it is recommended to use safe methods such as orElseThrow(). 1. Use Optional as the return type of methods that may return null values; 2. Always check the existence or use ifPresent, orElse, orElseGet, orElseThrow; 3. Use map and flatMap chain safe conversion; 4. Avoid over-wrap Optional in streams; 5. Do not use Optional for collection return; 6. Treat Optional as a value container instead of a global null replacement. Correct use can improve code security and readability.
Aug 03, 2025 am 03:55 AM
UseappropriatedatastructureslikeSplFixedArrayfor1Dinteger-keyedarraysandavoiddeepnesting;2.Minimizememoryusagebypassingarraysbyreference,unsettinglargearrays,andusinggenerators;3.Optimizeiterationbycachingarraysizesandreorganizingdataforbetteraccessl
Aug 03, 2025 am 03:52 AM
RedisLua scripts ensure data consistency through atomic execution. The core features and precautions are as follows: 1. The script is run in a single thread, and no other commands are inserted during execution to avoid race conditions; 2. If a script occurs when it is runtime error, the executed modifications will not be rolled back, and the application layer needs to handle exceptions; 3. Syntax errors prevent the script from running, and runtime errors lead to partial execution; 4. The script should be kept short and efficient to avoid blocking other requests.
Aug 03, 2025 am 03:51 AM
Database audits need to clarify audit strategies, protect logs and establish an analysis mechanism. First, determine the audit scope, including login attempts, data modifications, permission changes and structure changes; second, store the logs in an independent encrypted storage and set access control and backup policies; finally, discover abnormal operations in a timely manner through log analysis tools and alarm mechanisms to ensure that compliance requirements are effectively met.
Aug 03, 2025 am 03:48 AM
Using RedisHash to store the critical value pairs is more appropriate because they save memory and support structured operations. 1. Hash is suitable for storing object-type data such as user information, with clear logic and easy maintenance; 2. Supports efficient acquisition of the entire object or atomic update of a single field; 3. Clear memory optimization, especially when there are few fields, compact encoding method is adopted; 4. Not suitable for scenarios where fields are not related, large fields need to be accessed separately, or single field expiration time needs to be set.
Aug 03, 2025 am 03:30 AM
ToenableWindowsAuthenticationdelegationforIISandbackendserviceslikeSQLServer,configurethreecoresteps:first,enableWindowsAuthenticationinIISwhiledisablinganonymousauthentication;second,setupKerberoswithproperSPNsfortheIISserviceaccountusingsetspncomma
Aug 03, 2025 am 03:24 AM
Yes,Notepad iscompletelyfreetouse.1.Notepad isafree,open-sourcecodeeditorandNotepadreplacementforWindows,offeringfeatureslikesyntaxhighlightingandauto-completion.2.It'sfreebecauseit'smaintainedbyanopen-sourcecommunityandsupportedbyoptionaldonations
Aug 03, 2025 am 03:16 AM
Code segmentation is a key technology to improve web page performance, which reduces the initial loading time by splitting JavaScript packages into small pieces that are loaded on demand. 1. Use React.lazy and Suspense to implement lazy loading based on routing to ensure that only the code required for the current page is loaded; 2. Lazy loading of non-critical heavy-duty components (such as charts or modal boxes) at the component level; 3. Separate third-party libraries into independent vendorchunks through splitChunks to improve caching efficiency; 4. Use webpack magic annotations to specify meaningful names for dynamically imported chunks for debugging; 5. Avoid excessive splitting, prevent too many small files from increasing HTTP overhead, and balance the split granularity and
Aug 03, 2025 am 03:07 AM
SmartFiltersinPhotoshopprovidenon-destructiveeditingbyallowingyoutoadjust,reorder,mask,andremovefilterswithoutdamagingtheoriginalimage.1.ConvertalayerintoaSmartObjecttoapplyeditablefiltersthatcanbemodifiedanytime.2.Stackandreordermultiplefiltersforcu
Aug 03, 2025 am 03:02 AM
To view the CPU usage in Linux system, you can use the following methods: 1. Use the top command to view the overall CPU usage ratio and the CPU usage of each process in real time, which is suitable for quickly checking the system load; 2. Use htop to provide a more friendly visual interface and support interactive operations, which is suitable for people who frequently monitor resources; 3. Use mpstat to obtain detailed statistical information of each CPU or core, which is suitable for performance analysis or script integration; 4. Use uptime or cat/proc/loadavg to quickly view the average load status of the system to help judge the overall busyness. These tools are suitable for different scenarios and can be selected and used according to your needs.
Aug 03, 2025 am 02:58 AM
GoisastrongfitforLinux-basedARMembeddedsystems,especiallythoserequiringnetworkingandconcurrency.1)Go’sgoroutinessimplifyhandlingmultipletaskslikesensorinputandnetworkcommunication.2)Cross-compilationallowsbuildingARMbinarieseasilyfromx86machines.3)St
Aug 03, 2025 am 02:53 AM
The key to HugePages management is to understand its mechanism and configure it correctly. 1. HugePages is a mechanism that uses larger memory pages (such as 2MB or 1GB) to improve memory access efficiency. It is suitable for high-performance scenarios such as databases and virtualization; 2. You can understand the current configuration and usage by viewing the HugePages_Total, HugePages_Free and other parameters in /proc/meminfo; 3. Configuring static HugePages requires adding relevant parameters to the GRUB configuration and updating the configuration and restarting to take effect, which is suitable for production environments; 4. Dynamic allocation depends on the total number of configured HugePages, and can be implemented with the help of libhugetlbfs or applications.
Aug 03, 2025 am 02:48 AM
Use $lookup to process one-to-many relationships, and implement orders and customer information association by adding customerInfo arrays; 2. Use let to define variables and pipeline filtering conditions to achieve conditional connections; 3. Many-to-many relationships need to be divided into two steps with the help of an intermediate table and deduplicated with $group; 4. Performance optimization requires indexing of the associated fields, matching filtering as soon as possible, avoiding large arrays, and considering embedding of static data. Mastering $lookup can efficiently handle complex association queries in MongoDB and give full play to the advantages of aggregation pipeline.
Aug 03, 2025 am 02:46 AM
When encountering the problem of slow server response, you should first check the system resources and then analyze the application logic and network links. First, check the server load and resource usage, and check whether the CPU, memory, disk I/O and network traffic exceed the limit through top/htop, free-h, iostat/iotop, iftop/nload; secondly, check the application layer and service configuration, use APM tools to monitor the interface response time, analyze logs, slow query logs, optimize SQL, and adjust connection pool and thread parameters; finally troubleshoot network problems, use ping, traceroute, and curl-w to check DNS resolution, path packet loss, interface response time, and review the firewall, reverse proxy and external API timeout settings.
Aug 03, 2025 am 02:39 AM
To correctly handle WebSocket connections in Nginx, you need to configure the following core steps in the location block: ① Set proxy_http_version1.1 and add Upgrade and Connection headers to enable protocol upgrades; ② Set Host, X-Real-IP and other headers to retain client information; ③ Adjust proxy_read_timeout and proxy_send_timeout to prevent idle disconnection; ④ If load balancing is load-balanced, enable stickysession to ensure the consistency of the session; ⑤ Set X-Forwarded-Proto to https when SSL terminates to support the wss protocol, and finally use wsc
Aug 03, 2025 am 02:32 AM
To delete elements from an array without changing the original array, you should use a method that does not modify the original array; 1. Use the filter() method to filter out specific values or elements that meet the conditions according to the conditions, such as numbers.filter(num=>num!==3) to remove elements with a value of 3; 2. To delete elements by index, you can combine slice() and extension operators, such as [...colors.slice(0,1),...colors.slice(2)], or use filter() to match the index parameters colors.filter((_,index)=>index!==indexToRemove); 3. Delete
Aug 03, 2025 am 02:30 AM
Thepackage-lock.jsonfileshouldbecommittedtoversioncontrolbecauseitensuresconsistent,reproducible,andreliabledependencyinstallationsacrossallenvironments;itlocksdowntheexactversion,location,checksum,andhierarchyofeveryinstalledpackage,preventingdiscre
Aug 03, 2025 am 02:21 AM
Javaisevolvingrapidlywithkeyprojectsenhancingconcurrency,performance,andsyntax.1.ProjectLoomintroducesvirtualthreadsforscalable,simpleconcurrentcode.2.ProjectValhallaaimstodeliverhigh-performancevaluetypesforbettermemoryefficiencyandexpressiveness.3.
Aug 03, 2025 am 02:15 AM
Higher-orderfunctionsinPHParefunctionsthatacceptotherfunctionsasargumentsorreturnthemasresults,enablingfunctionalprogrammingtechniques.2.PHPsupportspassingfunctionsasargumentsusingcallbacks,asdemonstratedbycustomfunctionslikefilterArrayandbuilt-infun
Aug 03, 2025 am 02:12 AM
Mismatchedorunclosedtagsmustbefixedbyensuringeveryopeningtaghasacorrespondingclosingtag,suchascorrectingjohn@example.comtojohn@example.com.2.Impropernestingofelementsmustbecorrectedbyclosingtagsinthereverseordertheywereopened,forexample,changingoverl
Aug 03, 2025 am 02:04 AM
To clone a specific branch rather than the entire history of a Git repository, use the gitclone-b--single-branch command. 1. This command only clons the specified branch and ignores other branches. 2. Add --depth=1 to perform shallow cloning, download only the latest submissions, further saving time and space. 3. If you need to switch to other branches in the future, you need to manually execute gitfetchorigin and then gitswitch. 4. To restore and get all branches, modify the configuration and execute gitfetchorigin. This method is suitable for CI/CD processes, bandwidth or disk-constrained scenarios, and new projects that are quickly started. However, Git does not support wildcard batch cloning branches and needs to be implemented with scripts.
Aug 03, 2025 am 02:01 AM
sar is a powerful system monitoring tool that can view the usage of CPU, memory, disk I/O, network and other resources in real time, and supports viewing historical data. 1. To view the CPU usage, sar-u15 can be used to display the user state, system state and idle rate; 2. To view the history record, sar-f/var/log/sa/saXX; 3. To monitor the memory usage, use sar-r23, combine kbcommit and %memused to judge the memory pressure; 4. To view the swap partition use, use sar-S23; 5. To view the disk I/O, pay attention to the TPS and read and write speed; 6. To view the network traffic, use sar-nDEV13, observe the network card sending and receiving speed to judge the bottleneck.
Aug 03, 2025 am 02:00 AM
undefinedmeansavariableisdeclaredbutnotassigned,2.nullisanintentionalabsenceofvalue,explicitlyassigned,3.undeclaredvariablesdonotexistandaccessingthemthrowsaReferenceError;usetypeoftosafelycheckexistence,alwaysprefer===todistinguishnullandundefined,a
Aug 03, 2025 am 01:58 AM
ExecutorService is suitable for asynchronous execution of independent tasks, such as I/O operations or timing tasks, using thread pool to manage concurrency, submit Runnable or Callable tasks through submit, and obtain results with Future. Pay attention to the risk of unbounded queues and explicitly close the thread pool; 2. The Fork/Join framework is designed for split-and-governance CPU-intensive tasks, based on partitioning and controversy methods and work-stealing algorithms, and realizes recursive splitting of tasks through RecursiveTask or RecursiveAction, which is scheduled and executed by ForkJoinPool. It is suitable for large array summation and sorting scenarios. The split threshold should be set reasonably to avoid overhead; 3. Selection basis: Independent
Aug 03, 2025 am 01:54 AM
Stackscanbeefficientlyimplementedusingarraysbyappendingandpoppingelementsfromtheend,achievingO(1)amortizedtimeforpushandpopoperations.2.QueuescanbebuiltusingacircularbufferwithfrontandrearpointerstoenableO(1)enqueueanddequeueoperations,avoidingO(n)sh
Aug 03, 2025 am 01:50 AM
HibernateisbetterforautomatedSQLgenerationandrapiddevelopmentwithhigh-levelabstraction,whileMyBatisisidealforfullSQLcontrolandperformanceoptimization.2.MyBatisofferssuperiorperformancecontrolduetohand-writtenSQLandnosessionlifecycle,whereasHibernater
Aug 03, 2025 am 01:39 AM
Use the PHP generator and yield keywords to effectively process large data sets to avoid memory overflow; 1. The generator realizes lazy evaluation by yield value, leaving only one value in memory at a time; 2. It is suitable for scenarios such as reading large files line by line, such as using fgets combined with yield line by line, and processing logs or CSV files line by line; 3. Support key-value pair output, and explicitly specify key names; 4. It has the advantages of low memory footprint, concise code, and seamless integration with foreach; 5. However, there are restrictions such as inability to rewind, do not support random access, and cannot be reused, and it needs to be recreated before iteration is performed; therefore, when it is necessary to traverse a large amount of data, the use of generators should be given priority.
Aug 03, 2025 am 01:38 AM
