mirror of
https://github.com/logos-messaging/nim-ffi.git
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a66c53a34b
Two foreign-host concurrency fixes for refc, both needed so a Go host can hammer the FFI under load without corrupting Nim's per-thread GC. 1. Compile-time request ids. ffiNewReq / the method + ctor wrappers built the request id with `$T` at runtime, allocating a Nim GC string on the foreign caller's (often transient) thread. Emit a `cstring` literal of the type name instead — no allocation on the caller thread. 2. Recycle pooled contexts instead of destroy/recreate. Restores the release/v0.1 model that v0.2 dropped: a pool slot's worker + event threads and signal fds are built once and reused. The ffiDtor now requests a synchronous recycle (drain in-flight handlers, free the lib, clear listeners, release the slot) on the FFI thread, keeping the threads alive; createFFIContext reuses an initialised slot. Without this every create/destroy churned ~6 signal fds, so fd numbers climbed past FD_SETSIZE (1024) and ThreadSignalPtr.waitSync's select() failed with EINVAL under create/destroy load. Adds CtxLifecycle (Active/RecyclePending/Recycling), ctx-level inUse/tryClaim/release/markAsActive, requestRecycle (waits on a new recycleDoneSignal), freeLib (refc GC_unref / orc =destroy of ctor-owned libs), recycleContext, FFIEventRegistry.clearListeners, and roots the ctor-stored ref lib under refc (GC_ref, balanced in freeLib). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
70 lines
2.7 KiB
Nim
70 lines
2.7 KiB
Nim
import std/atomics
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import results
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import ./ffi_context
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const MaxFFIContexts* = 32
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# Only affects upfront pool memory; fds/threads consumed per acquired slot.
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type FFIContextPool*[T] = object
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## Fixed pool. Each slot's worker + event threads and signal fds are built
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## once (on first use) and reused across create/recycle cycles — recycle keeps
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## them alive, so repeated create/destroy does not churn fds. Bounds
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## ThreadSignalPtr fds at MaxFFIContexts * (signals per ctx).
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contexts: array[MaxFFIContexts, FFIContext[T]]
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initialized: array[MaxFFIContexts, Atomic[bool]]
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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. A slot's worker is built once on
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## first use and reused (markAsActive) on every later acquisition.
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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 recycle drained and released 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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err("FFI context pool exhausted (max " & $MaxFFIContexts & " contexts)")
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proc recycleFFIContext*[T](
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pool: var FFIContextPool[T], ctx: ptr FFIContext[T]
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): Result[void, string] =
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## Normal teardown: drains in-flight handlers, frees the lib and returns the
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## slot to the pool WITHOUT stopping its threads, so a later createFFIContext
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## reuses them. Synchronous (waits for the FFI thread to finish draining).
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ctx.requestRecycle()
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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 + event threads and frees resources,
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## marking the slot uninitialised so a later createFFIContext rebuilds it.
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## Used for process-level shutdown; normal cleanup uses recycleFFIContext.
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ctx.stopAndJoinThreads().isOkOr:
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return err("destroyFFIContext(pool): " & $error)
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let deinitRes = ctx.deinitContextResources()
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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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deinitRes.isOkOr:
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return err("destroyFFIContext(pool): " & $error)
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ok()
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proc isValidCtx*[T](pool: var FFIContextPool[T], ctx: pointer): bool =
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## Rejects nil / offset-invalid / dangling pointers 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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false
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