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Fix Swift 6 async let actor isolation crash #67

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Merged
christopherkarani merged 2 commits into from
May 5, 2026
Merged

Fix Swift 6 async let actor isolation crash #67

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93ece0a
Fix Swift 6 async let actor isolation crash
shapeful May 1, 2026
c50b602
Remove redundant async try warnings
christopherkarani May 5, 2026
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24 changes: 10 additions & 14 deletions Sources/Wax/RAG/FastRAGContextBuilder.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -76,11 +76,11 @@ package struct FastRAGContextBuilder: Sendable {
&& clamped.surrogateMaxTokens > 0
&& clamped.maxContextTokens > 0
let sourceFrameIds = rankedResults.map { $0.frameId }
async let surrogateMapTask: [UInt64: UInt64] = shouldPrefetchSurrogates
? wax.surrogateFrameIds(for: sourceFrameIds)
let surrogateMapTask: [UInt64: UInt64] = shouldPrefetchSurrogates
? await wax.surrogateFrameIds(for: sourceFrameIds)
: [:]
async let sourceFrameMetasTask: [UInt64: FrameMeta] = shouldPrefetchSurrogates
? wax.frameMetas(frameIds: sourceFrameIds)
let sourceFrameMetasTask: [UInt64: FrameMeta] = shouldPrefetchSurrogates
? await wax.frameMetas(frameIds: sourceFrameIds)
: [:]

// 2) Expansion: first result with valid UTF-8 frame content
Expand Down Expand Up @@ -127,7 +127,7 @@ package struct FastRAGContextBuilder: Sendable {
)

// Batch resolve surrogate ids in a single actor hop to avoid TaskGroup churn.
let surrogateMap = await surrogateMapTask
let surrogateMap = surrogateMapTask

// Keep only the top candidates, preserving response order.
var orderedSurrogateIds: [UInt64] = []
Expand All @@ -141,7 +141,7 @@ package struct FastRAGContextBuilder: Sendable {

// Batch load surrogate contents to avoid per-frame actor hops.
// If any surrogate is corrupted, fall back to per-frame loads and skip failures.
async let surrogateContentsTask: [UInt64: Data] = {
let surrogateContents: [UInt64: Data] = await {
do {
return try await wax.frameContents(frameIds: orderedSurrogateIds)
} catch {
Expand Down Expand Up @@ -170,7 +170,7 @@ package struct FastRAGContextBuilder: Sendable {
)

// Get only source frame metas needed for timestamp access.
let frameMetaMap = await sourceFrameMetasTask
let frameMetaMap = sourceFrameMetasTask
// nowMs resolution order:
// 1. deterministicNowMs if explicitly set (always the case when called via MemoryOrchestrator.recall)
// 2. max frame timestamp — provides a stable, deterministic "now" for direct callers
Expand All @@ -181,8 +181,6 @@ package struct FastRAGContextBuilder: Sendable {
?? frameMetaMap.values.map(\.timestamp).max()
?? Int64(Date().timeIntervalSince1970 * 1000)

let surrogateContents = await surrogateContentsTask

// Parallel tier selection and tier extraction, preserving response order.
let surrogateWorkItems = rankedResults
.compactMap { result -> (result: SearchResponse.Result, surrogateFrameId: UInt64)? in
Expand Down Expand Up @@ -529,11 +527,10 @@ package struct FastRAGContextBuilder: Sendable {
) async throws -> String? {
guard maxTokens > 0, maxBytes > 0 else { return nil }

// Fetch meta and payload in parallel to reduce latency while preserving validation.
async let metaTask = wax.frameMetaIncludingPending(frameId: frameId)
async let dataTask = wax.frameContentIncludingPending(frameId: frameId)
// Fetch meta and payload sequentially to avoid Swift 6 async let actor isolation double-free crash.
let meta = try await wax.frameMetaIncludingPending(frameId: frameId)
let data = try await wax.frameContentIncludingPending(frameId: frameId)

let meta = try await metaTask
let canonicalBytes: UInt64
if meta.canonicalEncoding == .plain {
canonicalBytes = meta.payloadLength
Expand All @@ -545,7 +542,6 @@ package struct FastRAGContextBuilder: Sendable {
guard canonicalBytes > 0 else { return nil }
guard canonicalBytes <= UInt64(maxBytes) else { return nil }

let data = try await dataTask
try Self.validateExpansionPayloadSize(
expectedBytes: canonicalBytes,
actualBytes: data.count,
Expand Down