mirror of
https://github.com/logos-messaging/nim-ffi.git
synced 2026-06-21 00:40:16 +00:00
0e176bd5eb
- Call initializeLibrary() (setupForeignThreadGc) in the `.ffi.` request wrapper and in add/remove_event_listener so a foreign (Go) caller thread has an initialised Nim heap before any allocation ($reqTypeName / $eventName / registry ops). Without it such a thread segfaults in the allocator under GC pressure — the production unwrap SIGSEGV. - recycleContext resets the event registry/queue + stuck flag on park so a reused pool slot starts clean. - ffiDtor doc/cleanup for the async recycle ABI. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
69 lines
2.8 KiB
Nim
69 lines
2.8 KiB
Nim
import std/atomics
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import results
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import ./ffi_context, ./ffi_types
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const MaxFFIContexts* = 32
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## Maximum number of concurrently live FFI contexts when using FFIContextPool.
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## Each slot's threads, signals and dispatcher kqueue fds are created once and
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## reused, so this also caps the process's steady-state fd usage.
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type FFIContextPool*[T] = object
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contexts: array[MaxFFIContexts, FFIContext[T]]
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initialized: array[MaxFFIContexts, Atomic[bool]]
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## Whether the slot's worker has been built. Once true it stays true for the
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## process lifetime — destroy recycles the context rather than tearing it down.
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proc createFFIContext*[T](
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pool: var FFIContextPool[T]
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): Result[ptr FFIContext[T], string] =
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## Acquires a context from the fixed pool. The worker (threads + signals +
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## dispatcher kqueues) is built once on first use and REUSED on every later
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## acquisition — chronos never frees a dispatcher's kqueue fd, so a
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## thread-per-context model would leak fds unboundedly.
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for i in 0 ..< MaxFFIContexts:
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let ctx = pool.contexts[i].addr
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if not ctx.tryClaim():
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continue
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if pool.initialized[i].load():
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## Reused slot: a prior destroy drained and parked it; worker still alive.
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ctx.markAsActive()
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return ok(ctx)
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initContextResources(ctx).isOkOr:
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ctx.release()
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return err("createFFIContext: initContextResources failed: " & $error)
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pool.initialized[i].store(true)
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return ok(ctx)
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return err("FFI context pool exhausted (max " & $MaxFFIContexts & " contexts)")
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proc releaseFFIContext*[T](
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ctx: ptr FFIContext[T], callback: FFICallBack, userData: pointer
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): Result[void, string] =
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## Recycle/park the context for reuse without stopping its worker threads.
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## `callback` fires once the FFI thread has drained and parked it.
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ctx.requestRecycle(callback, userData)
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proc destroyFFIContext*[T](
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pool: var FFIContextPool[T], ctx: ptr FFIContext[T]
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): Result[void, string] =
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## Full teardown: stops/joins the worker threads and returns the context to the
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## pool, marking it uninitialised so a later createFFIContext rebuilds it. Only
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## for process/pool shutdown — normal destruction uses releaseFFIContext.
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ctx.stopAndJoinThreads().isOkOr:
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return err("destroyFFIContext(pool): " & $error)
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for i in 0 ..< MaxFFIContexts:
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if pool.contexts[i].addr == ctx:
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pool.initialized[i].store(false)
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break
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ctx.release()
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return ok()
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proc isValidCtx*[T](pool: var FFIContextPool[T], ctx: pointer): bool =
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## True only if ctx points to one of the pool's contexts that is currently
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## claimed (in use). Rejects nil / dangling / parked contexts at the API boundary.
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if ctx.isNil():
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return false
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for i in 0 ..< MaxFFIContexts:
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if cast[pointer](pool.contexts[i].addr) == ctx:
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return cast[ptr FFIContext[T]](ctx).isInUse()
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return false
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