[fabianekc]

Summary

A check could take far longer than the start page waits for it: against a passport host that accepts connections but never answers, a check ran for about 100 s, and it kept running on the server after the page had given up. While three such checks ran, the service answered nothing else.

• Overall time limit: every check of the API (GET and POST) ends within CHECK_DEADLINE seconds, 35 by default. The limits of single requests stay (name lookup 5 s, connection 10 s, answer 20 s per redirect, links 10 s, SOyA web-cli 5 s and 30 s, didlint 10 s per request and 20 s per check), but each request waits at most the time left, connection and answer together.
• Partial result: once the time is up, no further request is sent. Criteria evaluated so far keep their results; criteria cut off are skipped with reason_code not_evaluated and the reason "the time limit of 35 s for this check was reached". A timeout counts against the host only if its own limits were not shortened by the time limit. The result has a new field timeLimit (seconds, reached) and a notice when the limit was reached.
• Nothing left behind: the parallel link requests are all joined before the check ends, and every request closes its connection when it gives up.
• One check per page: the start page waits CHECK_DEADLINE plus 5 s (40 s by default). While a check runs, the form, the example links and "Try again" send no further request.

Changes

• app/services/check_deadline.rb (new): the time limit of one check; splits the time left into connect and read limits per request.
• app/services/http_resolver.rb, passport_fetcher.rb, links_check.rb, soya_web_cli.rb, didlint.rb: limits cut to the time left; name lookup with an overall limit; link requests joined.
• app/services/passport_linter.rb, app/controllers/api/v1/validations_controller.rb: one time limit per request, partial result, timeLimit, notice.
• app/javascript/check_client.js, app/views/home/show.html.erb: one check at a time per page.
• config/initializers/dpplint.rb: CHECK_DEADLINE; CHECK_TIMEOUT follows it.
• swagger/v1/swagger.yaml, README.md: timeLimit, the limits.
• Tests: test/services/check_deadline_test.rb, test/integration/check_time_limit_test.rb, test/support_slow_server.rb (new), JavaScript tests for one check at a time, adapted page and resolver tests.

Tests

• Full suite in the image: 241 runs, 0 failures, 0 errors.
• With a time limit of 1.5 s: a hanging passport host, slow redirects (0.4 s per hop), 20 slow links, a hanging SOyA web-cli and a hanging didlint each end within 1.3 s, and no request is left open. Without the change, the same cases wait 20 s, 2.1 s (five hops), 10.3 s, 30 s and 10 s.
• Partial result: a passed criterion stays, two cut-off criteria are not_evaluated with the reason, a criterion without network access stays not_applicable; timeLimit.reached is true.
• Through the API, against a hanging passport host with a time limit of 3 s: answer after 2.9 s. Without the change: 100.5 s.
• With the default limits, three checks at the same time against a hanging host end after 34.7 s each (100.4 s without the change).
• Two starts from the same page in a browser: one API request (three without the change).