shoney.arickathil
7e3bf31d36
- wo_row_update_field: encode new value, unique re-check against a shadow BEFORE any mutation (violating update leaves the row untouched, DB_ERR_UNIQUE), index entries moved old-hash -> new-hash, old engine value freed; proven by test_table (unique refusal keeps the row, released key becomes insertable) - WAL UPDATE record: full-row re-log, replay = replace (remove + re-create same id); prefix/suffix delta recorded as later optimization; test_wal replays insert+update to the updated state - builtins 62 DB_UPDATE_FIELD (cid,id,field,value) and 63 DB_DELETE (cid,id), commit-before-ack like insert, WO_T_UNIQUE/WO_T_DB/WO_T_IO mapping; dispatch range 61..63; loader arities; runner mirror - plan Task 5 marked superseded-in-part with the recorded deviation: the language surface (reads, queries, row views, delete statement) is 9b's, where the comprehension design put it -- no interim brace- select grammar to retire later - gates: test_table 839/0, test_wal 102/0, 15 suites, oop-e2e 73/0 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
91 lines
4.1 KiB
C
91 lines
4.1 KiB
C
/* wal.h — typed-row write-ahead log + boot replay (iteration 9, Task 2).
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*
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* The c-runtime plan's shipped pattern (phases D/E), generalized to typed
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* rows. The commit order is doctrine, verbatim:
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*
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* RAM apply → wal_append (staged) → wal_commit (write + fdatasync)
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* → only then is the write ACKNOWLEDGED
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*
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* Record framing — replay-whole-or-not-at-all:
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*
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* record := len u32 | crc u32 | payload | mark u32
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* len = payload byte count (never 0; 0 = preallocated tail, stop)
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* crc = CRC32 of payload
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* mark = 0x574F4C31 "WOL1" — written LAST, so a record without its
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* mark is torn by definition
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* payload := kind u8 | class_id u32 | row_id u64 | body
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* kind : 1 insert (body = the row's fields, engine encoding below)
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* 2 remove (no body)
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* 3 update (reserved for Task 5)
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*
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* Field encoding in a body walks the class table's kinds:
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* SCALAR 8 bytes
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* TEXT u32 len | bytes (0xFFFFFFFF = nil)
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* OWNED u8 0 = nil, or u8 1 | u32 class_id | fields recursively
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* MULTI u8 0 = nil, or u8 1 | u8 elem_kind | u32 len | elements
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* MAP u8 0 = nil, or u8 1 | u8 kk | u8 vk | u32 len | k v pairs
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*
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* Replay decodes payloads STRAIGHT into engine-owned values — the VM heap
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* is never involved (boot must not depend on a VM existing yet), and rows
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* re-enter through the same choke-point row API, so Task 4's indexes are
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* rebuilt for free. A torn tail (short record, bad CRC, missing mark) drops
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* everything from the tear onward — never a partial record, never a record
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* after a tear. Little-endian on-disk, matching the .wob loader's platform
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* note.
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*
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* wo_wal_check is the offline oracle the crash battery verifies with: it
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* walks a WAL file with no engine at all and reports how many records are
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* intact and where the intact prefix ends. */
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#ifndef WO_WAL_H
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#define WO_WAL_H
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#include "table.h"
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#define WO_WAL_MARK 0x574F4C31u /* "WOL1" LE */
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enum { WO_WAL_INSERT = 1, WO_WAL_REMOVE = 2, WO_WAL_UPDATE = 3 };
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typedef struct wo_wal {
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int fd;
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uint64_t off; /* next write offset (the intact tail) */
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/* staged batch: appended by wal_append_*, flushed by wal_commit */
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uint8_t *buf;
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size_t len, cap;
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} wo_wal;
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/* Open (create if missing) and preallocate [prealloc] bytes (best-effort;
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* a filesystem without fallocate still works). Positions the write offset
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* at the end of the INTACT record prefix — an existing file is scanned the
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* same way replay scans it, so a torn tail is overwritten, not appended
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* after. 0 ok, -1 errno-style failure. */
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int wo_wal_open(wo_wal *w, const char *path, uint64_t prealloc);
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void wo_wal_close(wo_wal *w);
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/* Stage a record for the row that MUST already be applied to RAM (the
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* commit-order doctrine). Insert/update read the row via wo_row_ptr.
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* 0 ok, -1 OOM / no such row. */
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int wo_wal_append_insert(wo_wal *w, wo_db *db, uint32_t class_id, uint64_t id);
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int wo_wal_append_remove(wo_wal *w, uint32_t class_id, uint64_t id);
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/* UPDATE re-logs the whole row (KISS: replay replaces — remove + re-create
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* with the same id; the prefix/suffix delta trick from the survey is a
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* later optimization, recorded). Call AFTER the RAM update. */
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int wo_wal_append_update(wo_wal *w, wo_db *db, uint32_t class_id, uint64_t id);
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/* Write the staged batch and fdatasync — the ack line. Empty batch = ok,
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* no syscall. 0 ok, -1 write/sync failure (the batch stays staged). */
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int wo_wal_commit(wo_wal *w);
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/* Boot replay: apply every intact record to [db] in order. Ids re-enter
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* exactly as logged; each table's next_id advances past the replayed ids
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* that belong to this shard. Returns the number of records applied, or -1
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* on open failure / a record naming an unknown class (corruption beyond
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* what a torn tail explains). A torn tail is NOT an error: replay applies
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* the intact prefix and reports it. */
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int64_t wo_wal_replay(const char *path, wo_db *db);
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/* Offline verification (no engine): scan [path], count intact records.
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* *intact_bytes (optional) = where the intact prefix ends. -1 = open
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* failure. */
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int64_t wo_wal_check(const char *path, uint64_t *intact_bytes);
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#endif /* WO_WAL_H */
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