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shm-typed-array

0.0.12 • Public • Published

IPC shared memory for NodeJs. Use as Buffer or TypedArray.

Install

$ npm install shm-typed-array
$ npm test

Manual build:

node-gyp configure
node-gyp build
node test/example.js

Tested on Ubuntu 16, Node v6.9.1

API

shm.create (count, typeKey [, key])

Create shared memory segment.
count - number of elements (not bytes), typeKey - type of elements ('Buffer' by default, see list below), key - optional integer to create shm with specific key.
Returns shared memory Buffer or descendant of TypedArray object, class depends on param "typeKey". Or returns null if shm can't be created.
Returned object has property 'key' - integer key of created shared memory segment, to use in shm.get().

shm.get (key, typeKey)

Get created shared memory segment. Returns null if shm can't be opened.

shm.detach (key)

Detach shared memory segment.
If there are no other attaches for this segment, it will be destroyed.

shm.detachAll ()

Detach all shared memory segments.
Will be automatically called on process exit/termination.

Types:

shm.BufferType = {
	'Buffer': shm.SHMBT_BUFFER,
	'Int8Array': shm.SHMBT_INT8,
	'Uint8Array': shm.SHMBT_UINT8,
	'Uint8ClampedArray': shm.SHMBT_UINT8CLAMPED,
	'Int16Array': shm.SHMBT_INT16,
	'Uint16Array': shm.SHMBT_UINT16,
	'Int32Array': shm.SHMBT_INT32,
	'Uint32Array': shm.SHMBT_UINT32,
	'Float32Array': shm.SHMBT_FLOAT32,
	'Float64Array': shm.SHMBT_FLOAT64,
};

shm.getTotalSize()

Get total size of all shared segments in bytes.

shm.LengthMax

Max length of shared memory segment (count of elements, not bytes)
2^31 for 64bit, 2^30 for 32bit

Usage

See example.js

const cluster = require('cluster');
const shm = require('./index.js');
 
var buf, arr;
if (cluster.isMaster) {
    buf = shm.create(4096); //4KB
    arr = shm.create(1000000*100, 'Float32Array'); //100M floats
    buf[0] = 1;
    arr[0] = 10.0;
    console.log('[Master] Typeof buf:', buf.constructor.name,
        'Typeof arr:', arr.constructor.name);
    
    var worker = cluster.fork();
    worker.on('online', function() {
        this.send({ msg: 'shm', bufKey: buf.key, arrKey: arr.key });
        var i = 0;
        setInterval(function() {
            buf[0] += 1;
            arr[0] /= 2;
            console.log(+ ' [Master] Set buf[0]=', buf[0],
                ' arr[0]=', arr ? arr[0] : null);
            i++;
            if (== 5) {
                groupSuicide();
            }
        }, 500);
    });
} else {
    process.on('message', function(data) {
        var msg = data.msg;
        if (msg == 'shm') {
            buf = shm.get(data.bufKey);
            arr = shm.get(data.arrKey, 'Float32Array');
            console.log('[Worker] Typeof buf:', buf.constructor.name,
                'Typeof arr:', arr.constructor.name);
            var i = 0;
            setInterval(function() {
                console.log(+ ' [Worker] Get buf[0]=', buf[0],
                    ' arr[0]=', arr ? arr[0] : null);
                i++;
                if (== 2) {
                    shm.detach(data.arrKey);
                    arr = null; //otherwise process will drop
                }
            }, 500);
        } else if (msg == 'exit') {
            process.exit();
        }
    });
}
 
function groupSuicide() {
    if (cluster.isMaster) {
        for (var id in cluster.workers) {
            cluster.workers[id].send({ msg: 'exit'});
            cluster.workers[id].destroy();
        }
        process.exit();
    }
}

Output:

[Master] Typeof buf: Buffer Typeof arr: Float32Array
[Worker] Typeof buf: Buffer Typeof arr: Float32Array
0 [Master] Set buf[0]= 2  arr[0]= 5
0 [Worker] Get buf[0]= 2  arr[0]= 5
1 [Master] Set buf[0]= 3  arr[0]= 2.5
1 [Worker] Get buf[0]= 3  arr[0]= 2.5
2 [Master] Set buf[0]= 4  arr[0]= 1.25
2 [Worker] Get buf[0]= 4  arr[0]= null
3 [Master] Set buf[0]= 5  arr[0]= 0.625
3 [Worker] Get buf[0]= 5  arr[0]= null
4 [Master] Set buf[0]= 6  arr[0]= 0.3125
shm segments destroyed: 2

Install

npm i shm-typed-array

DownloadsWeekly Downloads

35

Version

0.0.12

License

MIT

Unpacked Size

31.1 kB

Total Files

12

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