nim-ffi/ffi/ffi_types.nim

52 lines
1.9 KiB
Nim

import std/tables
import chronos
################################################################################
### Exported types
type FFICallBack* = proc(
callerRet: cint, msg: ptr cchar, len: csize_t, userData: pointer
) {.cdecl, gcsafe, raises: [].}
## Result-delivery callback. `callerRet` is one of the `RET_*` codes below:
## `RET_OK`/`RET_ERR` fire exactly once and end the request, `RET_STALE_WARN`
## may fire repeatedly before them and should be ignored unless progress
## matters.
const RET_OK*: cint = 0
const RET_ERR*: cint = 1
const RET_MISSING_CALLBACK*: cint = 2
const RET_STALE_WARN*: cint = 3
## Non-terminal: the request is still in flight. Fires every
## `StaleWarnInterval` (default 5s) while the handler runs, `msg` carrying the
## elapsed milliseconds as decimal ASCII, and is always followed by a terminal
## code — nim-ffi never times a handler out, so the caller decides whether to
## keep waiting.
### End of exported types
################################################################################
################################################################################
### FFI utils
type FFIRequestProc* = proc(
request: pointer, reqHandler: pointer
): Future[Result[seq[byte], string]] {.async.}
## The OK payload is a CBOR-encoded response body. Errors are plain UTF-8.
template foreignThreadGc*(body: untyped) =
when declared(setupForeignThreadGc):
setupForeignThreadGc()
body
when declared(tearDownForeignThreadGc):
tearDownForeignThreadGc()
## Registered requests table populated at compile time and never updated at run time.
## The key represents the request type name as cstring, e.g., "CreateNodeRequest".
## The value is a proc that handles the request asynchronously.
var registeredRequests*: Table[cstring, FFIRequestProc]
### End of FFI utils
################################################################################