Download/Restore operations should check the http cache before making http calls to all sources

[emgarten]

Download and restore operations should check the http cache before making http calls to all sources. In many cases the package already exists in the cache, but parallel calls are still made to all http sources. The source with the cached nupkg quickly wins but feeds but the tax of these extra calls are still incurred by both the client and servers.

Actual flow today

1. Request a package id/version from all sources in parallel
2. Each call individually checks the cache in parallel
3. If the package is not found in the cache it goes online (always true for sources not containing the nupkg)

Expected flow

1. Request a package id/version from the cache for all http sources in parallel (offline only)
2. Check if any caches contained the nupkg
3. Request a package id/version from all http sources in parallel (going online this time)

[ghost]

Due to lack of recent activity, this issue has been marked as a candidate for icebox cleanup. It will be closed if no further activity occurs within 14 more days. Any new comment (by anyone, not necessarily the author) will add a Triage:NeedsTriageDiscussion label and lead to a triaging process.
This process is part of the experimental Stale icebox issues cleanup we are currently trialing. Please share any feedback you might have in the linked issue.

[ghost]

This issue will now be closed since it had been marked Icebox cleanup candidate, but received no further activity in the past 14 days.