[wu-sheng]

Step 6 of retention: the page. Until now the page drew a removed step with no text, but said nothing above the conversation. Its Prompt tab could not draw a provider body landed after a removal, because the renderer rebuilds bodies in the browser from the files the page serves, and a removed file was left out.

The renderer is pinned at Horizon aff6287, apache/skywalking-horizon-ui#192.

What changes

• The files route serves a removed file as its skeleton, uncompressed, with kept:

  • bodies: the body of each record the session's store kept as a chain tip, by record id;
  • pieces: each removed piece a later body cites, by SHA-256.

  The budget counts them by the sizes the records name, only for what the store has, before anything is read. A file that does not fit the budget on its own is served alone. A file a removal deletes while the route reads is served as its skeleton. A store that cannot be read gives a 500, never an answer that keeps nothing.

• The page shows a small note in its header, "N files removed by retention". Its title says that only a receiver that accepted the files still has their text. It sits in the header row, so the conversation keeps its height. The loader hands the kept bytes to the renderer, and asks again for whatever an answer left out.

• The renderer (Horizon #192):

  • Its prompt store holds skeletons.
  • It takes a piece by the SHA-256 that a removed or too-large part keeps, from the record that landed first.
  • It says when a body was removed, is built from a removed one, or holds a piece too large to store.

• Skeletons keep an empty segment list for a body whose segments were all literal, so the renderer judges the skeleton as it judged the body.

• The OTLP exporter over HTTP keeps its own connections. It shared the process's default transport. An httptest server closing in a parallel scenario broke a push it had just started, with CloseIdleConnections called; that was the Linux CI failure. And closing the exporter closed every other HTTP client's idle connections.

.sk files and the store under provider/ stay local. They are never sent, so nothing changes on the OAP.

Tests

• tests/chain:
  • Every body landed after a removal rebuilds from the route's answer alone. This test also writes Horizon's fixtures.
  • The budget serves every file, and a file deleted while the route reads is served as its skeleton.
• internal/view:
  • Kept bytes are counted once, only for what the store has, and a store error is an error.
  • The page's helpers run under node: the note, kept bytes as typed arrays, a record id __proto__, and asking again for left-out files.
• internal/storage: lookup failures of the store.
• pkg/skeleton: a literal-only manifest keeps an empty list.

Each guard was proven by reverting it. make check, make scenarios and make conversation-view-check pass.