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https://github.com/logos-messaging/nim-ffi.git
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825ae5af06
nim-ffi never times a handler out: a hard-cancel mid-call into the
underlying library (Waku/libp2p) can leave it half-applied. Instead, while
a request is still in flight its result callback receives a non-terminal
RET_STALE_WARN every StaleWarnInterval (5s default, Android's ANR interval;
-d:ffiStaleWarnIntervalMs to override), carrying the elapsed milliseconds as
a decimal string. The request always ends with exactly one terminal
RET_OK/RET_ERR — the dev decides what to do with a slow one, nim-ffi does
not decide for them.
This replaces the never-released per-proc {.ffi: "timeout = <ms>".} override
and the defaultRequestTimeout context field (issue #93), whose hard abort
unblocked the caller early. The stale-warn interval is an internal context
seam (staleWarnInterval), not a per-proc pragma.
Codegen: emit RET_STALE_WARN in the C/C++ headers, and guard every generated
trampoline (C, C++, Rust, and the Nim abi=c reply trampolines) to early-return
on the non-terminal code so the repeated callback can't double-free the
one-shot reply box. Typed wrappers ignore the progress signal for now; it is
delivered at the raw result-callback boundary.
Closes #126.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
54 lines
2.1 KiB
Nim
54 lines
2.1 KiB
Nim
import std/tables
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import chronos
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################################################################################
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### Exported types
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type FFICallBack* = proc(
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callerRet: cint, msg: ptr cchar, len: csize_t, userData: pointer
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) {.cdecl, gcsafe, raises: [].}
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## Result-delivery callback. `callerRet` is one of the `RET_*` codes below.
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## `RET_OK`/`RET_ERR` are *terminal*: they fire exactly once and end the
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## request. `RET_STALE_WARN` is *non-terminal*: it may fire repeatedly while a
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## handler is still running (see below) and is always followed by a terminal
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## code. Consumers that only care about the final answer should ignore it.
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const RET_OK*: cint = 0
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const RET_ERR*: cint = 1
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const RET_MISSING_CALLBACK*: cint = 2
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const RET_STALE_WARN*: cint = 3
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## Non-terminal progress signal: the request is still in flight. Delivered
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## every `StaleWarnInterval` (default 5s) for as long as the handler runs, with
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## `msg` carrying the elapsed milliseconds as a decimal ASCII string. nim-ffi
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## never times a handler out — it always ends with a terminal `RET_OK`/
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## `RET_ERR`; `RET_STALE_WARN` just lets the caller decide whether to keep
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## waiting.
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### End of exported types
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################################################################################
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################################################################################
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### FFI utils
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type FFIRequestProc* = proc(
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request: pointer, reqHandler: pointer
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): Future[Result[seq[byte], string]] {.async.}
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## The OK payload is a CBOR-encoded response body. Errors are plain UTF-8.
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template foreignThreadGc*(body: untyped) =
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when declared(setupForeignThreadGc):
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setupForeignThreadGc()
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body
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when declared(tearDownForeignThreadGc):
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tearDownForeignThreadGc()
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## Registered requests table populated at compile time and never updated at run time.
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## The key represents the request type name as cstring, e.g., "CreateNodeRequest".
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## The value is a proc that handles the request asynchronously.
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var registeredRequests*: Table[cstring, FFIRequestProc]
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### End of FFI utils
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################################################################################
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