samiandClaude Sonnet 5
bd0a24c87a
io/sparse_file — the single O_WRONLY output file (docs/04 §4). open()
posix_fallocate's the full size (falls back to ftruncate on
EOPNOTSUPP/ENOSYS, reported via preallocated()); write_at() pwrites at an
absolute offset, looping short writes and retrying EINTR; sync() is
fdatasync (timer/pause only); advise_dontneed() is
posix_fadvise(DONTNEED); resize() trims a preallocated tail or sizes a
chunked download. errno -> vdm::Error (ENOSPC->disk_full,
EACCES->permission_denied, ENOENT/ENOTDIR/...->path_rejected). No lock on
write_at — POSIX makes each pwrite atomic for a regular file, so N
segment threads writing disjoint ranges is safe (tested, TSan-clean).
io/write_buffer — per-segment accumulate-and-flush buffer, preallocated
at construction; append() only memcpys (no allocation on the write-
callback hot path, docs/04 §8 — asserted by a global-new counter in the
test). Flushes on fill via a caller-supplied FlushFn; a chunk >= capacity
arriving on an empty buffer writes straight through. On a flush error
next_offset() stays at the last durable position. Single-threaded; the
disk-writer-thread handoff is stage 8.
Also: vtest.hpp VT_CHECK_EQ/NE now copy operands (auto, not auto&&) — an
assertion must not outlive a temporary the expression returned a
reference into (ASan caught this on Result<void>{}.error().code).
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01HPPSGhiArbvQgwC2DNiURS
Owner: lane CORE. See ../docs/agents/AGENT-CORE.md and ../docs/04-engine-design.md. No JSON, no SQL, no Qt, no RPC in this tree.