locking

问题 I'm performing I/O to a single file from multiple threads. Access to this shared file foo is controlled through an advisory file lock ( flock(2) with LOCK_EX ). foo was opened with fopen(3) mode a+ . a+ was chosen because of the documentation stating: Subsequent writes to the file will always end up at the then current end of file, irrespective of any intervening fseek(3) or similar. Simplified, the operations would start: FILE *fp = fopen("foo", "a+"); ...spawn threads... Writing would

问题 basically I got two threads running.. one broadcasts music via a network (let's call it broadcaster).. the other communicates with clients to know when to start broadcasting, play music etc.. (runs on main) The broadcasting thread keeps on running even while the server is talking to the client, there is only one part when I want to pause the broadcaster thread, and that's when I want to send a packet to the client to start playing music (ie i want both server and client to play in sync).. i

问题 I've got a simple VB.Net 4 WinForms application that does basic code generation. The code generation creates a DLL assembly perfectly fine, but each time the DLL is generated it needs to be registered programmatically with the GAC. The reason it must be registered is that it is a COM object that when deployed gets called via CreateObject from a VB6 application. Eww, I know. All of this works fine: the DLL generation, registering programmatically and using the generated DLL from the VB6

问题 So having simple class class mySafeData { public: mySafeData() : myData(0) { } void Set(int i) { boost::mutex::scoped_lock lock(myMutex); myData = i; // set the data ++stateCounter; // some int to track state chages myCondvar.notify_all(); // notify all readers } void Get( int& i) { boost::mutex::scoped_lock lock(myMutex); // copy the current state int cState = stateCounter; // waits for a notification and change of state while (stateCounter == cState) myCondvar.wait( lock ); } private: int

问题 I'm trying to build a nagios check to check for how long a mongoDB has been locked using fsyncLock() for backup purposes (if the iSCSI snapshotting script blows up and the mongo is not being unlocked for example) I was thinking about using a simple $currentLock->run_command({currentOp => 1}) $isLocked = $currentLock->{fsyncLock} But it seems like run_command() doesn't support currentOp yet. (As seen in there: https://github.com/MLstate/opalang/blob/master/lib/stdlib/apis/mongo/commands.opa)

问题 Assuming we have the following database tables: create table department ( id bigint not null, budget bigint not null, name varchar(255), primary key (id) ) ENGINE=InnoDB create table employee ( id bigint not null, name varchar(255), salary bigint not null, department_id bigint, primary key (id) ) ENGINE=InnoDB alter table employee add constraint FK_department_id foreign key (department_id) references department (id) And we have 2 departments : insert into department (name, budget, id) values

问题 Let's say I have a form with two buttons ( button1 and button2 ) and a resource object ( r ). The resource has its own locking and unlocking code to handle concurrency. The resource could be modified by any thread. When button1 is clicked, its handler does some modifying of r itself and then calls _IndependentResourceModifierAsync() asynchronously which does some modifying of r in a spawned task. _IndependentResourceModifierAsync() acquires r 's lock before doing this. Also because the

问题 Is there a way in postgres to lock the rows until the next select query execution from the same system.And one more thing is there will be no update process on locked rows. scenario is something like this If the table1 contains data like id | txt ------------------- 1 | World 2 | Text 3 | Crawler 4 | Solution 5 | Nation 6 | Under 7 | Padding 8 | Settle 9 | Begin 10 | Large 11 | Someone 12 | Dance If sys1 executes select * from table1 order by id limit 5; then it should lock row from id 1 to 5

问题 Intro : For synchronization, C# offers the System.Threading.Monitor class, offering thread synchronization routines such as Enter() , Exit() , TryEnter() and alike. Furthermore, there is the lock statement that makes sure a lock gets destroyed when a critical code block is left, either by normal execution flow or by an exception: private static readonly obj = new Object(); lock(obj) { ... } Problem: In C++, for this purpose, we got the RAII wrappers std::lock_guard and std::unique_lock that

问题 Is there a construct in c# that is like lock { }, but works when called from an event handler i.e. waits for the code block to complete before handling a subsequent event. The problem I am having is that lock { } only prevents other threads from obtaining a lock on the object, but if an event handler on the same thread is called, the execution of code within the lock block is interrupted, and the new event is handled before returning to the execution of the original code. object DoStuffLock =