Golang StateSnapshot.Index方法代碼示例

// evaluatePlan is used to determine what portions of a plan
// can be applied if any. Returns if there should be a plan application
// which may be partial or if there was an error
func evaluatePlan(snap *state.StateSnapshot, plan *structs.Plan) (*structs.PlanResult, error) {
	defer metrics.MeasureSince([]string{"nomad", "plan", "evaluate"}, time.Now())

	// Create a result holder for the plan
	result := &structs.PlanResult{
		NodeUpdate:     make(map[string][]*structs.Allocation),
		NodeAllocation: make(map[string][]*structs.Allocation),
		FailedAllocs:   plan.FailedAllocs,
	}

	// Collect all the nodeIDs
	nodeIDs := make(map[string]struct{})
	for nodeID := range plan.NodeUpdate {
		nodeIDs[nodeID] = struct{}{}
	}
	for nodeID := range plan.NodeAllocation {
		nodeIDs[nodeID] = struct{}{}
	}

	// Check each allocation to see if it should be allowed
	for nodeID := range nodeIDs {
		// Evaluate the plan for this node
		fit, err := evaluateNodePlan(snap, plan, nodeID)
		if err != nil {
			return nil, err
		}
		if !fit {
			// Scheduler must have stale data, RefreshIndex should force
			// the latest view of allocations and nodes
			allocIndex, err := snap.Index("allocs")
			if err != nil {
				return nil, err
			}
			nodeIndex, err := snap.Index("nodes")
			if err != nil {
				return nil, err
			}
			result.RefreshIndex = maxUint64(nodeIndex, allocIndex)

			// If we require all-at-once scheduling, there is no point
			// to continue the evaluation, as we've already failed.
			if plan.AllAtOnce {
				result.NodeUpdate = nil
				result.NodeAllocation = nil
				return result, nil
			}

			// Skip this node, since it cannot be used.
			continue
		}

		// Add this to the plan result
		if nodeUpdate := plan.NodeUpdate[nodeID]; len(nodeUpdate) > 0 {
			result.NodeUpdate[nodeID] = nodeUpdate
		}
		if nodeAlloc := plan.NodeAllocation[nodeID]; len(nodeAlloc) > 0 {
			result.NodeAllocation[nodeID] = nodeAlloc
		}
	}
	return result, nil
}

//.........這裏部分代碼省略.........
			nodeIDList = append(nodeIDList, nodeID)
		}
	}

	// Setup a multierror to handle potentially getting many
	// errors since we are processing in parallel.
	var mErr multierror.Error
	partialCommit := false

	// handleResult is used to process the result of evaluateNodePlan
	handleResult := func(nodeID string, fit bool, err error) (cancel bool) {
		// Evaluate the plan for this node
		if err != nil {
			mErr.Errors = append(mErr.Errors, err)
			return true
		}
		if !fit {
			// Set that this is a partial commit
			partialCommit = true

			// If we require all-at-once scheduling, there is no point
			// to continue the evaluation, as we've already failed.
			if plan.AllAtOnce {
				result.NodeUpdate = nil
				result.NodeAllocation = nil
				return true
			}

			// Skip this node, since it cannot be used.
			return
		}

		// Add this to the plan result
		if nodeUpdate := plan.NodeUpdate[nodeID]; len(nodeUpdate) > 0 {
			result.NodeUpdate[nodeID] = nodeUpdate
		}
		if nodeAlloc := plan.NodeAllocation[nodeID]; len(nodeAlloc) > 0 {
			result.NodeAllocation[nodeID] = nodeAlloc
		}
		return
	}

	// Get the pool channels
	req := pool.RequestCh()
	resp := pool.ResultCh()
	outstanding := 0
	didCancel := false

	// Evalute each node in the plan, handling results as they are ready to
	// avoid blocking.
	for len(nodeIDList) > 0 {
		nodeID := nodeIDList[0]
		select {
		case req <- evaluateRequest{snap, plan, nodeID}:
			outstanding++
			nodeIDList = nodeIDList[1:]
		case r := <-resp:
			outstanding--

			// Handle a result that allows us to cancel evaluation,
			// which may save time processing additional entries.
			if cancel := handleResult(r.nodeID, r.fit, r.err); cancel {
				didCancel = true
				break
			}
		}
	}

	// Drain the remaining results
	for outstanding > 0 {
		r := <-resp
		if !didCancel {
			if cancel := handleResult(r.nodeID, r.fit, r.err); cancel {
				didCancel = true
			}
		}
		outstanding--
	}

	// If the plan resulted in a partial commit, we need to determine
	// a minimum refresh index to force the scheduler to work on a more
	// up-to-date state to avoid the failures.
	if partialCommit {
		allocIndex, err := snap.Index("allocs")
		if err != nil {
			mErr.Errors = append(mErr.Errors, err)
		}
		nodeIndex, err := snap.Index("nodes")
		if err != nil {
			mErr.Errors = append(mErr.Errors, err)
		}
		result.RefreshIndex = maxUint64(nodeIndex, allocIndex)

		if result.RefreshIndex == 0 {
			err := fmt.Errorf("partialCommit with RefreshIndex of 0 (%d node, %d alloc)", nodeIndex, allocIndex)
			mErr.Errors = append(mErr.Errors, err)
		}
	}
	return result, mErr.ErrorOrNil()
}