Hot reload

Some changes to DataMind Oda apply while it runs, and others wait for the next start. Hot reload is the part of Oda that applies changes in place: with it on, a plugin toggled or a settings file edited while Oda is open takes effect without a restart. This page shows which changes apply live, how Oda watches for them, and what the reload messages mean.

What applies while Oda runs

With hot reload on, these changes apply without a restart:

• Plugin changes. Toggling a plugin, installing a new bundle and the other changes you make on the Plugins page apply while Oda runs; see Plugins and bundles.
• Settings changes. Edits to the settings file a profile keeps on this computer apply while Oda runs, and the live plugin settings you change in Oda's forms reach the same file; see Live plugin settings.
• Code changes. Where a watch list covers plugin code, a change reloads the plugins whose code depends on the changed file.

Where hot reload is on

• The desktop app. DataMind Oda runs with hot reload on in the desktop app.
• The serving and one-off profiles. The automation, SDK and headless profiles start with hot reload off.
• It can be switched back on. A profile can re-enable hot reload in the settings file it keeps on this computer; Oda profiles and launchers covers the ways Oda runs.
• Off means later, not lost. With hot reload off, changes are saved and applied the next time Oda starts.

What still needs a restart

• A swapped version. Replacing a plugin or bundle that is already installed with a different version applies at the next start, from the Plugins page.
• A different package source. Changing where a plugin's package comes from, such as relinking a package folder or repointing a plugin name to a different package, applies at the next start.
• Plugin code. Reloading a plugin's code in place needs support for replacing code in the way Oda runs. Where that support is missing, code changes apply at the next start.

How Oda watches for changes

• Settings files, watched exactly. The settings files Oda manages are watched by their exact paths, even when they sit outside Oda's own folders. If a watched file does not exist yet, Oda starts watching from the nearest folder that does, so creating the file later still applies.
• Code folders, when a watch list is set. The watch list (root) names the folders watched for code changes. It defaults to the folder Oda runs from, and an empty list keeps only the exact settings watches.
• What is skipped. node_modules, dot entries (names starting with a dot), cache and data are skipped by default (the ignored list). Rapid changes are batched with a short delay: debounce defaults to 100 ms.
• When a save counts as done. A watched settings file is re-read only after its write has stopped changing for two seconds, so a file that is still being saved is never read half-written.
• Repeated saves. Creating, editing and deleting a watched file all count as changes. If you save again while a reload is running, saves do not stack up one per save: Oda applies the latest state once it can.

Reloads run one at a time

• Everything hot reload does shares a single queue: a plugin change, a code reload and a settings reload run one after another, never two at once.
• A reload cannot start inside another reload; an attempt to nest them is refused.
• The queue survives a failure: one reload that fails does not stop the next change from being applied.
• Configuration reloads wait for Oda to be ready: a change seen while Oda is still starting is applied once it has finished; see Startup and diagnostics.
• When Oda closes, hot reload closes its watches and cancels reloads that were still waiting to start.

When a reload fails

A reload that does not go through changes nothing: the version that was already running stays in place, and the previous configuration is kept until the new one applies. Reload messages use the short name HMR for hot reload.

If re-reading a watched settings file fails, Oda reports the failure and keeps the previous configuration; correct the file and save again.

Questions, answered

Why did my change not apply until I restarted Oda?

Either hot reload is off for the way Oda was running, or the change is one that always needs a restart, such as a swapped plugin version. The automation, SDK and headless profiles start with hot reload off, and with it off every change applies at the next start; see Oda profiles and launchers.

Do I need to restart Oda after changing a plugin or its settings?

Usually not. With hot reload on, plugin toggles, bundle installs and settings changes apply while Oda runs. Restart when you replace a plugin or bundle that is already installed, or change where a plugin's package comes from; see Plugins and bundles.

Why does Oda wait a moment before applying a saved settings file?

Oda re-reads a watched settings file only after its write has stopped changing for two seconds, so it never reads a file that is half-saved. If a reload is already running, your save waits its turn, and saves that land while one is running are not stacked up: the latest file state is what gets applied.

What happens to the running version when a reload fails?

Nothing changes. A failed reload keeps the version that was already running and the previous configuration; the failure is reported so you can fix it, and saving again retries the reload.

What do the file and position in a failed reload message point to?

The place in the code that failed to compile: File: <file>:<line>:<column>, followed by a short code frame. Fix the file at that position and save again to retry the reload.

What does "HMR is disposed" mean?

Hot reload had already shut down when the change arrived, so it could not be applied. Start Oda again; the change is picked up at the next start.

What does "Profile HMR requires application readiness" mean?

The change arrived before Oda had finished starting. Configuration reloads run only after Oda is ready; nothing is lost, and the change is applied once it has started.

Can two changes reload at the same time?

No. Every reload shares one queue and runs one after another, and a reload never starts inside another. A failed reload does not stop the queue: later changes are still applied.

Which folders does Oda watch for changes?

The settings files Oda manages are watched by their exact paths, wherever they sit. For code, a watch list (root) names the folders; it defaults to the folder Oda runs from, and an empty list keeps only the exact settings watches. node_modules, dot entries, cache and data are skipped by default.

If I delete a watched file, do its changes stop applying?

Yes. Creating, changing and deleting a watched file all count as changes, so when a settings file is deleted, the settings it added stop applying.

Does hot reload work in every way of running Oda?

It is on in the desktop app. The automation, SDK and headless profiles start with it off, and it can be switched back on in the settings file a profile keeps on this computer; see The profile settings file. With it off, changes apply at the next start.