Changes:
* Drop Users.id_to_name.
* Don't cache Users.name_to_id.
* Replace calls to name_to_id with find_by_name when possible.
* Don't autodefine creator_name in belongs_to_creator.
* Don't autodefine updater_name in belongs_to_updater.
* Instead manually define creator_name / updater_name only on models that need
to return these fields in the api.
id_to_name was cached to reduce the impact of N+1 query patterns in
certain places, especially in api responses that return creator_name /
updater_name fields. But it still meant we were doing N calls to
memcache. Using `includes` to prefetch users avoids this N+1 pattern.
name_to_id had no need be cached, it was never used in any performance-
sensitive contexts.
Avoiding caching also avoids the need to keep these caches consistent.
Fix find_by_name and name_to_id to use normalize_name properly, so that
they ignore leading/trailing whitespace. This fixes various search forms
failing to return results when the username field contains trailing
whitespace (inserted by autocomplete).
* Fix tests to run the searches for real instead of mocking everything out.
* Fix SavedSearch.populate to only use the read only database in
production because in breaks things in tests. Specifically:
the posts get created in one db connection but searched for in
another, but the second transaction doesn't see the uncommitted posts
in the first transaction, so the search doesn't work.
* Drop /posts?ro=true param (broken).
* Clean up tag_match (rescuing PG::ConnectionBad didn't do anything, we
just build the query here, we don't run it).
* Don't allow adding tags with invalid names when they already exist in
the tags table.
* If an invalid tag is added, show an warning and ignore the tag instead
of failing with a hard error.
* Move the _(cosplay) tag validation into the tag name validator.
Instead of having custom code check whether the artist name is already
in use, just enable autocomplete on the artist name field. This is an
easier and more robust way to indicate tag name conflicts.
* Clean up javascript.
* Return HTTP 422 instead of HTTP 500 on "you have already voted for
this post" errors.
* In json/xml error responses, return the error message in the `message`
field, not `reason`.
* In json/xml success responses, return the post itself instead of a
plain `{ success: true }` object.
* Simplify code.
* Show backtraces for all users, not just builders.
* Show backtraces only for unexpected server errors (status 5xx), not
for normal client errors (status 4xx).
* Log expected errors at info level (reduce noise in production logs).
Favoriting posts sometimes fails with ActiveRecord::LockWaitTimeout
errors. This happens when a user tries to favorite multiple posts in
short succession. In that case we want the lock to block and wait for
the other favorite to go through, not to immediately fail.
This causes the browser to prefetch the next page in a search, which may
make browsing seem faster to the end user, but it effectively doubles
the load on the server.
Bug: Searching for an aliased tag returns an empty page instead of
showing the results for the real tag.
Cause: The query parsing code runs the search string through
`.mb_chars.downcase` before calling `TagAlias.to_aliased`, so the input
to `to_aliased` is actually a ActiveSupport::Multibyte::Chars object.
This breaks the `aliases[name]` hash lookup because `name` is not a
plain string.
Fixup for c7bcce429.
