Fujitsu Printer Reconnect & Power Settings #4831
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@jonahkagan normally @kofi-q has been reviewing this integration but since he's out, passing you to. Setting up the reconnect logic we talked about. |
adghayes
changed the title
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The logic in this file feels a little complex to me. There's a strategy for managing the connection state of the driver that's implemented across two methods: getDriver and getStatus, and then all of the other methods have to remember to start by calling getStatus (which feels a little brittle).
Could this code be reorganized such that in order to access the driver, each method needs to call some function that checks the connection status? A sketch:
async print(data: Buffer) {
const driverResult = await getDriver();
if (driverResult.isErr()) { // If the driver is disconnected or otherwise in a non-ready state
return driverResult;
}
const printResult = await print(driverResult.ok(), data);
...(Ideally in this scheme, there would be no this.driver - the only way to access it would be through getDriver)
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@jonahkagan I ended up not re-organizing the code, but dumbing down my assumptions. I have never seen the printer be unresponsive while still attached, which we've seen with scanners. As long as it's connected, it responds to commands. So within print and advancePaper, I'm going to assume that the driver exists and is available. getStatus is the only endpoint which handles connection and disconnection. It's not actually plausible that we would jump straight to invoke an action - the app should always be checking for device status before starting an action.
| if (!this.driver) { | ||
| this.driver = await this.getDriver(); | ||
| // if we failed to initialize the driver, the device is likely not connected | ||
| if (!this.driver) { | ||
| return { state: 'error', type: 'disconnected' }; | ||
| } | ||
| } |
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Could also write as:
this.driver ??= await this.getDriver();
// if we failed to initialize the driver, the device is likely not connected
if (!this.driver) {
return { state: 'error', type: 'disconnected' };
}which is slightly simpler for me to read
| /** | ||
| * Initializes and returns a new driver instance. | ||
| */ | ||
| private async getDriver(): Promise<Optional<FujitsuThermalPrinterDriver>> { |
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maybe rename to initializeDriver to be slightly more descriptive?
Commit 1: Currently VxScan just crashes if the printer is not attached on startup, and it cannot handle disconnects and reconnects. While this was OK for the happy path, it's not OK for the sad path and development. Changing the layers so that we are just checking for the device on every status call.
Commit 2: Finishes removing the speed setting (started in commit 1) and also specifies the print quality setting on printer connect. This is to set "Auto-Division" which we've found that we need to set to prevent spikes in power draw that go beyond our v4 PSU capabilities.