Return a unique, nonempty string which identifies this storage engine.

Prioritize this engine relative to other engines.

Engines with a smaller priority number get an opportunity to write files first. Generally, lower-latency filestores should have lower priority numbers, and higher-latency filestores should have higher priority numbers. Setting priority to approximately the number of milliseconds of read latency will generally produce reasonable results.

In conjunction with filesize limits, the goal is to store small files like profile images, thumbnails, and text snippets in lower-latency engines, and store large files in higher-capacity engines.

Return true if the engine is currently writable.

Engines that are disabled or missing configuration should return false to prevent new writes. If writes were made with this engine in the past, the application may still try to perform reads.

Update the index for an abstract document.

Reconstruct the document for a given PHID. This is used for debugging and does not need to be perfect if it is unreasonable to implement it.

Execute a search query.

Does the search index exist?

Is the index in a usable state?

Do any sort of setup for the search index.