feat: add bounded task priority and fair application dispatch

internal/transport/httpserver/worker_dispatch.go

@@ -0,0 +1,60 @@
+package httpserver
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/json"
+	"time"
+
+	"git.yuntuo.hk/k2safe/orbit/internal/fault"
+	core "git.yuntuo.hk/k2safe/orbit/model"
+	"git.yuntuo.hk/k2safe/orbit/platform/auth"
+	"git.yuntuo.hk/k2safe/orbit/pulse/worker"
+)
+
+type claimResult struct {
+	assignment *worker.Assignment
+	err        error
+}
+
+func workerPollKey(ns core.ID, in worker.ConnectInput) [32]byte {
+	// 正式注册已校验；再次规范化仅取得稳定能力集合，不包含任何秘密。
+	in, _ = worker.NormalizeConnect(in)
+	raw, _ := json.Marshal(struct {
+		Namespace, Queue core.ID
+		Capabilities     []worker.Capability
+		Keys             bool
+	}{ns, in.QueueID, in.Capabilities, in.ConcurrencyKeys})
+	return sha256.Sum256(raw)
+}
+func (h *WorkerHub) claimFair(ctx context.Context, t auth.Token, b worker.Binding, key [32]byte) (out claimResult) {
+	// HTTP handler 原本具有 panic 隔离；异步领取同样不能因一次异常杀死其他连接。
+	defer func() {
+		if recover() != nil {
+			out = claimResult{err: fault.Unavailable}
+		}
+	}()
+	h.mu.Lock()
+	until := h.emptyPolls[key]
+	h.mu.Unlock()
+	if until.After(time.Now()) {
+		return out
+	}
+	call, stop := context.WithTimeout(ctx, 8*time.Second)
+	defer stop()
+	out.assignment, out.err = h.service.Claim(call, t, b)
+	if out.assignment == nil && out.err == nil {
+		h.mu.Lock()
+		now := time.Now()
+		for k, v := range h.emptyPolls {
+			if !v.After(now) {
+				delete(h.emptyPolls, k)
+			}
+		}
+		if len(h.emptyPolls) < 128 {
+			h.emptyPolls[key] = now.Add(h.poll)
+		}
+		h.mu.Unlock()
+	}
+	return out
+}