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
libveloxcore — public API
Status: M1 in progress. Only util/ is landed. The download-facing API
(DownloadSpec, DownloadTask, probe, typed callbacks) arrives with later stages and
is reviewed by DAEMON before M2 (AGENT-CORE DoD).
Layering (CLAUDE.md §3): this library knows nothing about JSON, SQL, Qt, or RPC. Input is
a spec value; output is bytes on disk plus typed callbacks. DAEMON projects engine state
onto the wire contract's TaskSummary / TaskDetail / events — see
core/docs/proto-requests-m1.md for the shapes that projection needs frozen.
Every header under core/include/vdm/ compiles standalone (-Wall -Wextra -Wpedantic -Werror, C++23). Clean under ASan/UBSan and TSan.
util/ — foundations
vdm/util/error.hpp
enum class Error — the engine-wide failure taxonomy (network / HTTP / content / local
I/O / metadata / probe / retry / internal). This is CORE's own vocabulary; it is not
a wire type. error_name(Error) gives a stable snake_case string; is_retryable(Error)
is the advisory retry hint the task policy consults.
struct ErrorInfo { Error code; std::string context; int http_status; bool retryable; Error cause; } — the payload carried by every failed Result. .to_string() renders
"<name>: <context> (HTTP <n>)".
vdm/util/result.hpp
Result<T> — return-based error channel, a thin wrapper over
std::expected<T, ErrorInfo>. Errors are returned, never thrown, on anything that
runs during a transfer.
Result<int> r = 42;/Result<int> r = Err{Error::timeout, "..."};/Result<T> r = Error::not_found;r.has_value(),explicit operator bool,r.value()/*r/r->,r.error(),r.code(),r.value_or(x)- monadic
and_then/transform/transform_error(forward tostd::expected) Result<void>specialization;vdm::ok()success sentinelVDM_TRY(expr)— return the error ifexprfailedVDM_TRY_ASSIGN(auto x, expr)— bind the value or return the error
vdm/util/bytes.hpp
Byte / ByteSpan / ConstByteSpan aliases; as_bytes(string_view) /
as_chars(span). Little-endian fixed-width codec load_le<T> / store_le<T> and a
bounds-checked sequential ByteReader (.u8/.u16/.u32/.u64, .raw(n), .lp_string(),
.overran()). Built for the .veloxpart.meta reader and the 4-byte NM framing; every
read is bounds-checked and latches on overrun (reader-first, fuzz-ready).
vdm/util/event_bus.hpp
EventBus — typed, thread-safe in-process pub/sub. subscribe<E>(fn) -> Token,
publish<E>(ev) (synchronous, calling thread, registration order), unsubscribe(Token),
and RAII subscribe_scoped<E> returning a Subscription. Handlers may (un)subscribe or
publish during dispatch. Handlers must not throw. Not a hot-path structure — progress is
coalesced to ≤4 Hz upstream.
vdm/util/thread_pool.hpp
ThreadPool — fixed-size std::jthread pool for bounded off-loop work (hashing, fsync
batches, DNS pre-resolve). submit(fn, args...) -> std::future<R>; propagates exceptions
through the future; drains already-queued tasks on destruction. Not the transfer
loop — net/ will own one curl_multi per dedicated worker.
vdm/util/log.hpp
Sink interface — core does no I/O itself. LogSink abstract base; DAEMON installs one
via set_log_sink(), default discards. CallbackSink adapter (with a min-level filter).
VDM_LOG_{TRACE,DEBUG,INFO,WARN,ERROR}(category, fmt, args...) — std::format syntax,
only formatted when a sink is installed and wants the level.