1.0.0-beta.7 • Published 5 years ago
callagain v1.0.0-beta.7
CallAgain
This package help you to deal with function that:
- should be called again with same arguments in case of some specific errors;
- should not be called more than N time in some time unit;
- should not be called simultaneously more then N times;
Installing
$ npm install callagain
Basic usage example
// Here is function, it makes direct call to some API
const {loadItemsFromRemoteServer} = requires('./lib');
// Import helper
const {CallAgain} = require('callagain');
// Create instance
const c = new CallAgain({
// Concurrency settings
maxConcurrentCalls: 10, // Extrernal API allows only 10 concurrent calls
// Retry on error settings
maxRetryAttempts: 5, // Try 5 time before throw error
delayOnRetry: 5000, // If some call fails, wait 5 sec and try again
// Rate limit settings
maxCallsPerInterval: 50, // External API allows 50 calls per minute
intervalLength: 60000 // External API allows 50 calls per minute
});
// Use helper's *wrap* method to create safe version of needed function
const safeLoadItems = c.wrap(loadItemsFromRemoteServer);
// Now we can simply call our function
for (int page=0; page<100; page++) {
safeLoadItems(page)
.then(items => {
// ...
})
.catch(e => console.error(e.message))
}
Error handling
You can specify error handlers
const c = new CallAgain({...});
// wrapping axios get call
const getItems = c.wrap(url => axios.get);
c.onError((err, next) => {
// here err is axios error
// this function must return boolean value
// indicating should CallAgain retry or not
if (err.response.status >= 500) {
// Unknown server error, retry in *delayOnRetry* milliseconds
return true
}
// if you do not know, how to deal with error, you should pass it to next handler
return next(err)
});
//handlers han be chained
c.onError(...).onError(...).onError(...)
Rejecting all
You can reject all pending calls by calling rejectAll
method
const c = new CallAgain({...});
c.wrap(() => new Promise(resolve => setTimeout(resolve, 1000)))().catch(e => {
console.log(e) // "Reject reason"
});
setTimeout(() => {
c.rejectAll("Reject reason") // optional value to pass to catch handler
}, 500)
1.0.0-beta.7
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