feat(wallet): stage C — off-main runtime bootstrap (SDK build + loadFromPersistor) with stall telemetry #1071
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| // | ||
| // Created by Dash Core Group. | ||
| // Copyright © 2026 Dash Core Group. All rights reserved. | ||
| // | ||
| // Licensed under the MIT License (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // https://opensource.org/licenses/MIT | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
| // | ||
|
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| import Foundation | ||
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| /// DEBUG-only main-runloop stall detector backing the wallet-lifecycle | ||
| /// performance work: it turns "the spinner froze" into a `DWLogger` line with | ||
| /// a duration, in the same rolling file the stage timings go to, so stalls | ||
| /// can be attributed to a bootstrap stage by timestamp. | ||
| /// | ||
| /// Design: a single ping-pong. The monitor thread posts ONE block to the main | ||
| /// queue and parks on a semaphore until the main thread runs it; the measured | ||
| /// round-trip IS the stall duration (a healthy runloop answers in | ||
| /// microseconds). The next ping is only posted after the previous one was | ||
| /// answered, plus a fixed pause — so at most one ping is ever pending, a | ||
| /// single long stall produces a single log line after it resolves (never a | ||
| /// burst of queued-up reports), and the log line can only underestimate a | ||
| /// stall by at most the inter-ping pause. | ||
| /// | ||
| /// Thresholds follow the Instruments/MetricKit hang convention: report from | ||
| /// 250 ms (microhang); the etap-C acceptance gate reads ≥500 ms as a hang. | ||
| @objc(DWMainThreadStallMonitor) | ||
| final class MainThreadStallMonitor: NSObject { | ||
| /// Latencies below this are a healthy runloop; from here up they are | ||
| /// logged. Matches the Instruments "microhang" floor. | ||
| static let reportThreshold: TimeInterval = 0.25 | ||
| /// Pause between an answered ping and the next one. Bounds both the | ||
| /// sampling overhead and the maximum underestimate of a stall. | ||
| static let interPingPause: TimeInterval = 0.1 | ||
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| /// Pure classification, unit-testable without threads: milliseconds to | ||
| /// report for a measured ping round-trip, or nil when the latency is | ||
| /// below the reporting threshold. | ||
| static func stallMilliseconds(forLatency latency: TimeInterval) -> Int? { | ||
| guard latency >= reportThreshold else { return nil } | ||
| return Int(latency * 1000) | ||
| } | ||
|
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| private static var started = false | ||
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| /// Idempotent; a no-op outside DEBUG builds. Called once from | ||
| /// `application(_:didFinishLaunchingWithOptions:)`. | ||
| @objc static func start() { | ||
| #if DEBUG | ||
| dispatchPrecondition(condition: .onQueue(.main)) | ||
| guard !started else { return } | ||
| started = true | ||
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| let thread = Thread { | ||
| while true { | ||
| let semaphore = DispatchSemaphore(value: 0) | ||
| let pinged = CFAbsoluteTimeGetCurrent() | ||
| DispatchQueue.main.async { | ||
| semaphore.signal() | ||
| } | ||
| semaphore.wait() | ||
| let latency = CFAbsoluteTimeGetCurrent() - pinged | ||
| if let ms = stallMilliseconds(forLatency: latency) { | ||
| DWLogger.log("⏱️ MAINSTALL ~\(ms)ms") | ||
|
Comment on lines
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There was a problem hiding this comment. 🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win Measure the main-queue completion time. Line 71 reads the clock after the utility monitor thread resumes. If that thread is delayed after Line 68 signals the semaphore, Record the completion time in the main-queue block before it signals. Pass that value safely back to the monitor thread for the latency calculation. 🤖 Prompt for AI Agents |
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| } | ||
| Thread.sleep(forTimeInterval: interPingPause) | ||
| } | ||
| } | ||
| thread.name = "org.dashfoundation.dash.main-stall-monitor" | ||
| thread.qualityOfService = .utility | ||
| thread.start() | ||
| #endif | ||
| } | ||
| } | ||
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📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win
Move
@objcto its own line.SwiftLint reports an
attributeswarning at Line 57. Put@objcon the preceding line.🧰 Tools
🪛 SwiftLint (0.65.0)
[Warning] 57-57: Attributes should be on their own lines in functions and types, but on the same line as variables and imports
(attributes)
🤖 Prompt for AI Agents
Source: Linters/SAST tools