Maven Central search results should be cached #263

[vrubezhny]

Fixes: #263

[vrubezhny]

Some quick measurements:

First request for groupIDs: [Trace - 9:11:37 PM] Received response 'textDocument/completion - (103)' in 7828ms.
Next request for groupIDs: [Trace - 9:11:40 PM] Received response 'textDocument/completion - (105)' in 81ms.

First request for artifacts [for selected groupID): [Trace - 9:36:17 PM] Received response 'textDocument/completion - (649)' in 871ms.
Next request for artifacts [in selected groupID): [Trace - 9:36:22 PM] Received response 'textDocument/completion - (654)' in 37ms.

First request for versions (for selected groupID/artifactID): [Trace - 9:12:28 PM] Received response 'textDocument/completion - (206)' in 2820ms.
Next request for versions (for selected groupID/artifactID): [Trace - 9:13:07 PM] Received response 'textDocument/completion - (273)' in 20ms.

[angelozerr]

@vrubezhny for managing cache, I suggest that you use CacheBuilder from guave. We did that in LemMinx https://github.com/eclipse/lemminx/blob/d808ae7fc32f269ecdd7d737a413ab40e1671873/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/uriresolver/CacheResourcesManager.java#L144

[mickaelistria]

I'm still not sure about the probability that the same request gets processed many times in a short time frame.

[vrubezhny]

I'm still not sure about the probability that the same request gets processed many times in a short time frame.

It's not only about "the same request":

• if you get completions for <groupId>|</groupId> the cache gets filled with all the available groupId values. All the following calls to complete <groupId>|</groupId> in any document in your workspace will be fed from the cache instead of sending requests to/receiving responses from Maven Search server.
• next you'll probably select and insert some groupId and try to get completions for <artifactId>|</artifactId> - cache will be filled with all the artifacts of the selected group. All the following calls to complete ``|` in any document for that (already fetched group) in your workspace will be fed from the cache instead of sending requests to/receiving responses from Maven Search server.
• The save goes for the versions of the selected artifact - here Maven Search API has some nuances, but still at least some of the following tries to complete versions for the same group : artifact will be fed from the cache.

In any POM of the workspace for the following 15 minutes (changeable).

[vrubezhny]

@vrubezhny for managing cache, I suggest that you use CacheBuilder from guave. We did that in LemMinx https://github.com/eclipse/lemminx/blob/d808ae7fc32f269ecdd7d737a413ab40e1671873/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/uriresolver/CacheResourcesManager.java#L144

The current PR version uses guava Cache and CacheBuilder, however this still needs to be improved in order to not block on waiting for the results to be obtained from Maven Search API.