locking | 易学教程

Lock a sheet when date in column > 24 hours: Google Sheets - Scripteditor?

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问题 In order to prevent data loss caused by other contributors, I'd like to lock an entire sheet for all data < today. It needs to be possible to do input and make changes for entries today. An simple example of the master file : EXAMPLE - LOCK < TODAY So, each row will lock for others when the date in column A < today. This link brought me closer but I'm having difficulties with var range = ss.getRange('1:1').getValues()[0]; which gives me an error on line 31: "TYPE-ERROR: can't find function

SemaphoreSlim.WaitAsync before/after try block

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问题 I know that in the sync world the first snippet is right, but what's about WaitAsync and async/await magic? Please give me some .net internals. await _semaphore.WaitAsync(); try { // todo } finally { _semaphore.Release(); } or try { await _semaphore.WaitAsync(); // todo } finally { _semaphore.Release(); } } 回答1: According to MSDN, SemaphoreSlim.WaitAsync may throw: ObjectDisposedException - If the semaphore has been disposed ArgumentOutOfRangeException - if you choose the overload which

How do java.util.concurrent.locks.Condition work?

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问题 Reading the Java 8 documentation about the java.util.concurrent.locks.Condition interface, the following example is given: class BoundedBuffer { final Lock lock = new ReentrantLock(); final Condition notFull = lock.newCondition(); final Condition notEmpty = lock.newCondition(); final Object[] items = new Object[100]; int putptr, takeptr, count; public void put(Object x) throws InterruptedException { lock.lock(); try { while (count == items.length) notFull.await(); items[putptr] = x; if (+

How do java.util.concurrent.locks.Condition work?

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Is Redis' set command an atomic operation?

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问题 I'm trying to use Redis' set command to implement a simplest distributed lock component, but I can't find any exact basis about atomicity through the official document, is Redis' SET key value [EX seconds] [PX milliseconds] [NX|XX] command an atomic operation? 回答1: Yes. The core is single threaded, so nothing will run until the SET has completed; that makes SET {key} {value} EX {expiry} NX ideal for simple locking. 来源： https://stackoverflow.com/questions/43259635/is-redis-set-command-an

Flask-SQLAlchemy with_for_update() row lock

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问题 I have a model called 'User', and 'User' has 'Money'. There a scenario that multiple session can read the model 'User' and update 'money' at the same time. Session 2 should read the 'money' value after session 1 updated successfully. I tried to lock the 'User' row when updating. Here's my code. user = User.query.with_for_update().filter_by(id=userid).first() print('000000') before_money = user.money print('111111') time.sleep(1) user.money -= 0.1 print('User:' + str(user.id) + '***' + str

Solution for Insert Intention Locks in MySQL

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问题 I have very simple table: CREATE TABLE `d` ( `id` int(11) DEFAULT NULL, UNIQUE KEY `id` (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 without records: select * from d; Empty set (0,01 sec) Then I try to open two transactions in different sessions: Session #1: begin; Query OK, 0 rows affected (0,00 sec) select * from d where id = 100 for update; Empty set (0,00 sec) Session #2: begin; Query OK, 0 rows affected (0,00 sec) select * from d where id = 700 for update; Empty set (0,00 sec) Now I try

ABP源码分析十五：ABP中的实用扩展方法

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类名扩展的类型方法名参数作用 XmlNodeExtensions XmlNode GetAttributeValueOrNull attributeName Gets an attribute's value from an Xml node. JsonExtensions object ToJsonString bool camelCase bool indented Converts given object to JSON string. StreamExtensions Stream GetAllBytes Get all bytes from a steam LockExtensions object Locking Action Executes given action by locking given source object. LockExtensions T Locking<T> Action<T> Executes given action by locking given source object. LockExtensions object Locking<TResult> Func<TResult> Executes given func and returns it's value by locking given source

Semaphore vs Mutex in Producer/Consumer

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问题 In the Producer-Consumer problem, why are we often suggested use to semaphores instead of using a lock/mutex? I don't see a valid reason to use a semaphore because we only have 2 threads coordinating. In this case a lock seems much easier to code and reason about because a thread will lock the buffer then free it so the other thread can do the same. There are only 2 threads so I don't see the use of signaling. Can anyone say why it is suggested to use semaphores usually for producer-consumer?

createFile() and DeviceIoControl() equivalent for volume devices in Unix/Linux

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问题 I have opened volume USB device and locked using CreateFile() and DeviceIoControl() in Windows. I want same functionality on Linux/Unix system. I am new to Unix So How to get it? My code for Windows : HANDLE handle = CreateFile(L"\\\\.\\F:", // F: drive to open GENERIC_READ, // no access to the drive FILE_SHARE_READ, // share mode NULL, // default security attributes OPEN_EXISTING, // disposition 0x1, // file attributes NULL); // do not copy file attributes DWORD lpBytesReturned; if