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apps/miniprogram/pages/terminal/terminalStdoutRenderPolicy.js

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+/* global module */
+
+const MEDIUM_BACKLOG_MIN_REMAINING_BYTES = 8 * 1024;
+const MEDIUM_BACKLOG_MIN_PENDING_BYTES = 8 * 1024;
+const MEDIUM_BACKLOG_MAX_SLICES = 8;
+const MEDIUM_BACKLOG_RENDER_COOLDOWN_MS = 220;
+
+const LARGE_BACKLOG_MIN_REMAINING_BYTES = 64 * 1024;
+const LARGE_BACKLOG_MIN_PENDING_BYTES = 32 * 1024;
+const LARGE_BACKLOG_MAX_SLICES = 32;
+const LARGE_BACKLOG_RENDER_COOLDOWN_MS = 320;
+
+const CRITICAL_BACKLOG_MIN_TOTAL_BYTES = 64 * 1024;
+const CRITICAL_BACKLOG_MIN_PENDING_BYTES = 24 * 1024;
+const CRITICAL_BACKLOG_MIN_PENDING_SAMPLES = 128;
+const CRITICAL_BACKLOG_MIN_SCHEDULER_WAIT_MS = 1200;
+const CRITICAL_BACKLOG_MIN_ACTIVE_AGE_MS = 1200;
+const CRITICAL_BACKLOG_FRAME_PENDING_BYTES = 24 * 1024;
+const CRITICAL_BACKLOG_FRAME_MAX_SLICES = 20;
+const CRITICAL_BACKLOG_RENDER_COOLDOWN_MS = 520;
+
+const STDOUT_OVERLAY_SYNC_COOLDOWN_MS = 240;
+
+function normalizeNonNegativeInteger(value, fallback) {
+  const numeric = Number(value);
+  if (!Number.isFinite(numeric)) {
+    return Math.max(0, Math.round(Number(fallback) || 0));
+  }
+  return Math.max(0, Math.round(numeric));
+}
+
+function shouldUseCriticalBacklogPolicy(options) {
+  const source = options && typeof options === "object" ? options : {};
+  const totalRawBytes = normalizeNonNegativeInteger(source.totalRawBytes, 0);
+  const pendingStdoutBytes = normalizeNonNegativeInteger(source.pendingStdoutBytes, 0);
+  const pendingStdoutSamples = normalizeNonNegativeInteger(source.pendingStdoutSamples, 0);
+  const schedulerWaitMs = normalizeNonNegativeInteger(source.schedulerWaitMs, 0);
+  const activeStdoutAgeMs = normalizeNonNegativeInteger(source.activeStdoutAgeMs, 0);
+  return (
+    pendingStdoutBytes >= CRITICAL_BACKLOG_MIN_PENDING_BYTES ||
+    pendingStdoutSamples >= CRITICAL_BACKLOG_MIN_PENDING_SAMPLES ||
+    schedulerWaitMs >= CRITICAL_BACKLOG_MIN_SCHEDULER_WAIT_MS ||
+    (totalRawBytes >= CRITICAL_BACKLOG_MIN_TOTAL_BYTES &&
+      activeStdoutAgeMs >= CRITICAL_BACKLOG_MIN_ACTIVE_AGE_MS)
+  );
+}
+
+/**
+ * stdout 的真正瓶颈不是 VT 解析，而是每个 slice 都把整份 `outputRenderLines`
+ * 重新通过 `setData` 送去视图层。
+ *
+ * 这里按 backlog 做两档降频：
+ * 1. 中等 backlog：累计到 8KB 或 8 个 slice 再提交一次；
+ * 2. 大 backlog：累计到 32KB 或 32 个 slice 再提交一次。
+ *
+ * 若用户刚有输入，或当前 slice 触发了终端响应帧，则立即提交，避免交互被延后。
+ */
+function resolveTerminalStdoutRenderDecision(options) {
+  const source = options && typeof options === "object" ? options : {};
+  if (source.yieldedToUserInput) {
+    return {
+      defer: false,
+      reason: "user_input",
+      policy: "interactive"
+    };
+  }
+  if (normalizeNonNegativeInteger(source.pendingResponseCount, 0) > 0) {
+    return {
+      defer: false,
+      reason: "pending_response",
+      policy: "interactive"
+    };
+  }
+
+  const remainingBytes = normalizeNonNegativeInteger(source.remainingBytes, 0);
+  const pendingReplayBytes = normalizeNonNegativeInteger(source.pendingReplayBytes, 0);
+  const nextSlicesSinceLastRender = normalizeNonNegativeInteger(source.nextSlicesSinceLastRender, 0);
+  const timeSinceLastRenderMs = normalizeNonNegativeInteger(
+    source.timeSinceLastRenderMs,
+    Number.MAX_SAFE_INTEGER
+  );
+  const taskDone = !!source.taskDone;
+  const usingCriticalPolicy = shouldUseCriticalBacklogPolicy(source);
+
+  if (usingCriticalPolicy) {
+    if (taskDone) {
+      return {
+        defer: false,
+        reason: "task_complete",
+        policy: "critical_backlog"
+      };
+    }
+    if (
+      nextSlicesSinceLastRender > 0 &&
+      timeSinceLastRenderMs < CRITICAL_BACKLOG_RENDER_COOLDOWN_MS
+    ) {
+      return {
+        defer: true,
+        reason: "render_cooldown",
+        policy: "critical_backlog"
+      };
+    }
+    if (pendingReplayBytes >= CRITICAL_BACKLOG_FRAME_PENDING_BYTES) {
+      return {
+        defer: false,
+        reason: "pending_bytes_threshold",
+        policy: "critical_backlog"
+      };
+    }
+    if (nextSlicesSinceLastRender >= CRITICAL_BACKLOG_FRAME_MAX_SLICES) {
+      return {
+        defer: false,
+        reason: "slice_threshold",
+        policy: "critical_backlog"
+      };
+    }
+    return {
+      defer: true,
+      reason: "defer_critical_backlog",
+      policy: "critical_backlog"
+    };
+  }
+
+  const usingLargePolicy =
+    remainingBytes >= LARGE_BACKLOG_MIN_REMAINING_BYTES ||
+    pendingReplayBytes >= LARGE_BACKLOG_MIN_PENDING_BYTES;
+  const minRemainingBytes = usingLargePolicy
+    ? LARGE_BACKLOG_MIN_REMAINING_BYTES
+    : MEDIUM_BACKLOG_MIN_REMAINING_BYTES;
+  const minPendingBytes = usingLargePolicy
+    ? LARGE_BACKLOG_MIN_PENDING_BYTES
+    : MEDIUM_BACKLOG_MIN_PENDING_BYTES;
+  const maxSlicesSinceRender = usingLargePolicy ? LARGE_BACKLOG_MAX_SLICES : MEDIUM_BACKLOG_MAX_SLICES;
+  const renderCooldownMs = usingLargePolicy
+    ? LARGE_BACKLOG_RENDER_COOLDOWN_MS
+    : MEDIUM_BACKLOG_RENDER_COOLDOWN_MS;
+  const policy = usingLargePolicy ? "large_backlog" : "medium_backlog";
+
+  if (taskDone) {
+    return {
+      defer: false,
+      reason: "task_complete",
+      policy
+    };
+  }
+
+  if (
+    nextSlicesSinceLastRender > 0 &&
+    timeSinceLastRenderMs < renderCooldownMs &&
+    pendingReplayBytes < minPendingBytes &&
+    nextSlicesSinceLastRender < maxSlicesSinceRender
+  ) {
+    return {
+      defer: true,
+      reason: "render_cooldown",
+      policy
+    };
+  }
+
+  if (remainingBytes < minRemainingBytes) {
+    return {
+      defer: false,
+      reason: "remaining_below_threshold",
+      policy
+    };
+  }
+  if (pendingReplayBytes >= minPendingBytes) {
+    return {
+      defer: false,
+      reason: "pending_bytes_threshold",
+      policy
+    };
+  }
+  if (nextSlicesSinceLastRender >= maxSlicesSinceRender) {
+    return {
+      defer: false,
+      reason: "slice_threshold",
+      policy
+    };
+  }
+  return {
+    defer: true,
+    reason: "defer_backlog",
+    policy
+  };
+}
+
+function resolveTerminalStdoutOverlayDecision(options) {
+  const source = options && typeof options === "object" ? options : {};
+  if (source.isFinalRender) {
+    return {
+      sync: true,
+      reason: "task_complete"
+    };
+  }
+  if (source.yieldedToUserInput) {
+    return {
+      sync: true,
+      reason: "user_input"
+    };
+  }
+  const overlayPassCount = normalizeNonNegativeInteger(source.overlayPassCount, 0);
+  if (overlayPassCount <= 0) {
+    return {
+      sync: true,
+      reason: "first_render"
+    };
+  }
+  const timeSinceLastOverlayMs = normalizeNonNegativeInteger(
+    source.timeSinceLastOverlayMs,
+    Number.MAX_SAFE_INTEGER
+  );
+  if (timeSinceLastOverlayMs >= STDOUT_OVERLAY_SYNC_COOLDOWN_MS) {
+    return {
+      sync: true,
+      reason: "overlay_cooldown_elapsed"
+    };
+  }
+  return {
+    sync: false,
+    reason: "overlay_throttled"
+  };
+}
+
+function shouldDeferTerminalStdoutRender(options) {
+  return resolveTerminalStdoutRenderDecision(options).defer;
+}
+
+module.exports = {
+  resolveTerminalStdoutOverlayDecision,
+  resolveTerminalStdoutRenderDecision,
+  shouldDeferTerminalStdoutRender
+};