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Extend listener removal in BusHelper #37

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merged 3 commits into from Feb 19, 2024
Merged

Extend listener removal in BusHelper #37

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fca927b
Extend listener removal in BusHelper
tuxedoxt May 27, 2022
1cc34e9
Fix re-use after listener removal in BusHelper
tuxedoxt Nov 8, 2022
1855c3b
Add test cases for BusHelper.removeListeners
tuxedoxt Nov 8, 2022
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8 changes: 8 additions & 0 deletions src/BusHelper.js
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Expand Up @@ -97,6 +97,14 @@ class BusHelper extends EventEmitter {
return this._ifaceProxy[methodName](...args)
}

removeListeners () {
this.removeAllListeners('PropertiesChanged')
if (this._propsProxy !== null) {
this._propsProxy.removeAllListeners('PropertiesChanged')
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@tuxedoxt I understand that you want to delete this listener because it generate a memory leak, but I think that if you do this in this way, you creates a different bug.
What if the user connects again this device? No code line will subscribe again on 'PropertiesChanged' events, so the library will not work correctly.

I think that this bug requires a different fix.

What do you think?

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Thanks for the feedback. I see what you mean.

As I see it, additionally setting

this._ready = false

should make _prepare reattach listener. However also does other things, like assigns completely new _propsProxy and _ifaceProxy objects. Would more clean-up be needed there or is this feasible?

this._ready = false
}
}

static buildChildren (path, nodes) {
if (path === '/') path = ''
const children = new Set()
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2 changes: 1 addition & 1 deletion src/Device.js
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Expand Up @@ -119,7 +119,7 @@ class Device extends EventEmitter {
*/
async disconnect () {
await this.helper.callMethod('Disconnect')
this.helper.removeAllListeners('PropertiesChanged') // might be improved
this.helper.removeListeners()
}

/**
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28 changes: 28 additions & 0 deletions test/BusHelper.spec.js
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Expand Up @@ -125,3 +125,31 @@ test('propsEvents', async () => {
await helper.set('VirtualProperty', buildTypedValue('string', 'bar'))
await expect(res).resolves.toMatchObject({ VirtualProperty: { signature: 's', value: 'bar' } })
})

test('removeListeners', async () => {
const helper = new BusHelper(dbus, TEST_NAME, TEST_OBJECT, TEST_IFACE, { useProps: true, usePropsEvents: true })

const dummyCb = () => {}

// Init with listener on helper (directly attached dummyCb) and _propsProxy (through method call triggered _prepare)
helper.on('PropertiesChanged', dummyCb)
await helper.callMethod('Echo', 'ping')
expect(helper.listenerCount('PropertiesChanged')).toBeGreaterThan(0)
expect(helper._propsProxy.listenerCount('PropertiesChanged')).toBeGreaterThan(0)

// Test remove
helper.removeListeners()
expect(helper.listenerCount('PropertiesChanged')).toBe(0)
expect(helper._propsProxy.listenerCount('PropertiesChanged')).toBe(0)

// Test reuse after remove (same initialization as before)
helper.on('PropertiesChanged', dummyCb)
await helper.callMethod('Echo', 'ping')
expect(helper.listenerCount('PropertiesChanged')).toBeGreaterThan(0)
expect(helper._propsProxy.listenerCount('PropertiesChanged')).toBeGreaterThan(0)

// Remove second time
helper.removeListeners()
expect(helper.listenerCount('PropertiesChanged')).toBe(0)
expect(helper._propsProxy.listenerCount('PropertiesChanged')).toBe(0)
})
1 change: 1 addition & 0 deletions test/Device.spec.js
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Expand Up @@ -13,6 +13,7 @@ jest.doMock('../src/BusHelper', () => {
this.waitPropChange = jest.fn()
this.children = jest.fn()
this.callMethod = jest.fn()
this.removeListeners = jest.fn()
}
}
})
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