FileOpen(FILE_WRITE) truncates its target on open. CNet::Save already staged
the .nnw through a temp file + rename for that reason, but the three sidecars
written beside it did not:
.stats ExpertSignalAIBase.mqh:5918
.arrows ExpertSignalAIBase.mqh:6224
.cfg ExpertSignalAIBase.mqh:7329
Two defects followed.
1. An interrupted write published a truncated sidecar. For .cfg that is the
worst case: LoadAndCompareTopologyConfiguration() reads a short file as a
mismatch, which discards the trained model and restarts from era 0.
2. Windows file sharing is a mutual contract - a writer opened with no
FILE_SHARE_* blocks every concurrent open regardless of the reader's flags.
All three read paths carry FILE_SHARE_READ|FILE_SHARE_WRITE specifically so
a tester agent can read them while a live chart runs; an exclusive writer on
the same path defeated that.
Extracted CNet::Save's proven pattern into System\AtomicFile.mqh
(AtomicWriteBegin/AtomicWriteEnd) and routed all four writers through it. This
also encodes the FileMove gotcha once instead of per call site: the destination
location comes from FILE_COMMON inside the 4th arg, NOT inherited from the
source, and getting it wrong moves the file to the wrong sandbox silently.
Also fixed while in these functions:
- SaveTopologyConfiguration had 13 copy-pasted 6-line error blocks that each
returned WITHOUT FileClose(handle), leaking the handle on every write
failure. Collapsed to one ok-chain that closes exactly once. The on-disk
field order and types are unchanged (asserted during the rewrite) so existing
.cfg files still load.
- SaveChartSignals documented that pruning runs only after a successful write
("a failed write above leaves both the file AND the chart untouched") but
never checked any write result, so a partial write still deleted the chart
objects. Results are checked now, making the existing comment true.
Compiles 0 errors, 0 warnings.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
