[SERVER ONLY]
fcf.NLock.lockNamedMutex(string a_name, function a_cb)
Package: fcf-framework-lock
File: fcf-framework-lock:index.js
Available from version: 1.0.6
Performs a lock on a named mutex
Arguments
string a_name
- The mutex name
function a_cb
- The function of processing the result of the function execution.
Function signature: a_cb(Error|undefined a_error, number a_lock)
-
Error|undefined a_error - If the function executed with an error, then the argument contains an error object
-
number a_lock - Contains a lock handle to be passed to the fcf.NLock.unlockNamedMutex function to unlock the mutex.
Example: Function application
Below is an example of implementing a critical section using named mutexes. The output to the terminal is made for two instance of the program running simultaneously.
let libLock = require("fcf-framework-lock");
async function main(){
const mutexName = "TestMutexForExample"
console.log(`PID:${process.pid}: ${new Date().toISOString()}: "Wait locking ..."`);
let lock = await new Promise((a_res, a_rej)=>{
libLock.lockNamedMutex(mutexName, (a_error, a_lock)=>{
if (!a_error){
a_res(a_lock);
} else {
a_rej(a_error);
}
});
});
console.log(`PID:${process.pid}: ${new Date().toISOString()}: Start of critical section`);
await new Promise((a_res, a_rej)=>{
setTimeout(()=>{
a_res(0);
}, 1000);
});
console.log(`PID:${process.pid}: ${new Date().toISOString()}: End of critical section`);
await new Promise((a_res, a_rej)=>{
libLock.unlockNamedMutex(lock, (a_error)=>{
if (!a_error){
a_res();
} else {
a_rej(a_error);
}
});
});
console.log(`PID:${process.pid}: ${new Date().toISOString()}: Process is exit`);
}
main();
Output:
PID:9412: 2023-10-21T17:34:38.246Z: "Wait locking ..."
PID:9413: 2023-10-21T17:34:38.246Z: "Wait locking ..."
PID:9413: 2023-10-21T17:34:38.251Z: Start of critical section
PID:9413: 2023-10-21T17:34:39.253Z: End of critical section
PID:9413: 2023-10-21T17:34:39.254Z: Process is exit
PID:9412: 2023-10-21T17:34:39.254Z: Start of critical section
PID:9412: 2023-10-21T17:34:40.256Z: End of critical section
PID:9412: 2023-10-21T17:34:40.257Z: Process is exit
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