A simple node utility to serialize execution of asynchronous functions
A simple node utility to serialize execution of asynchronous functions.
Asynchrony in nodejs is great, except that it makes your code looks horrible because of all the callbacks. If you use synchronous functions, which give you good-looking, easy-to-read code, they will block the thread and make your server not responsive.
serailize to the rescue!
serialize converts your asynchronous functions into serialized versions. Serialized functions are executed one after another, without explicitly chaining them with callback functions.
serialize does NOT execute the function synchronously (block the thread), it just serialize the execution of asynchronous functions. So that it makes the code looks synchronous, but it is actually ascynhronous underneath.
To create a serialized version of an asynchronous function, call
serialize with it. For example, if you want to make serialized versions of
fs.mkdir, you do:
var serialize = require'serialize';fsmkdir = serializefsmkdir;fswriteFile = serializefswriteFile;
Then, you can use
fs.writeFile like they are synchronous functions:
fsmkdir'new';fsmkdir'new/folder';fswriteFile'new/folder/hello.txt' "hello world" callback;
These function will be executed one after another, but they will not block the thread as their synchronous versions do. The
callback will be invoked after the last call completes.
If you want to restore
fs.mkdir to their original version, just do:
fsmkdir = fsmkdirfree;fswriteFile = fswriteFilefree;
If an error happens, the error will be passed to the corresponding callback function, and the execution of all serialized calls after it will be aborted. If an error happens in a function call that does not have a callback, the error will be passed down to the first call that has a callback function.
For example, if the
fs.mkdir('new') call in the above code throws an error, because there's no callback attached to that call, the error will be passed down to the callback of
fs.writeFile(...). And, of course,
fs.writeFile(...) won't be executed because an error occurred before them.
If you want to serialize calls to file system, and serialize calls to database, but allow calls to file system and calls to database to happen concurrently, how to do it?
You can serialize different functions into different queues. Functions belong to the same queue will be executed in serial, but functions between different queues can run concurrently.
To serialize a function to a queue other than the default queue, give a queue name as the second argument of
connquery = serializeconnquery "db";
Current version of
serialize can only serialize a function that satisfies the following conditions:
Note: Future version of
serialize may be able to serialize a function that emits
Copyright (c) 2013 Chaoran Yang (email@example.com)
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