chore: implement oom/ood processing component (#16436)

Implements the processing logic as set out in the OOM/OOD RFC.

coderd/agentapi/resourcesmonitor/resources_monitor.go

@@ -0,0 +1,129 @@
+package resourcesmonitor
+
+import (
+	"math"
+	"time"
+
+	"github.com/coder/coder/v2/agent/proto"
+	"github.com/coder/coder/v2/coderd/database"
+	"github.com/coder/coder/v2/coderd/util/slice"
+)
+
+type State int
+
+const (
+	StateOK State = iota
+	StateNOK
+	StateUnknown
+)
+
+type AlertConfig struct {
+	// What percentage of datapoints in a row are
+	// required to put the monitor in an alert state.
+	ConsecutiveNOKsPercent int
+
+	// What percentage of datapoints in a window are
+	// required to put the monitor in an alert state.
+	MinimumNOKsPercent int
+}
+
+type Config struct {
+	// How many datapoints should the agent send
+	NumDatapoints int32
+
+	// How long between each datapoint should
+	// collection occur.
+	CollectionInterval time.Duration
+
+	Alert AlertConfig
+}
+
+func CalculateMemoryUsageStates(
+	monitor database.WorkspaceAgentMemoryResourceMonitor,
+	datapoints []*proto.PushResourcesMonitoringUsageRequest_Datapoint_MemoryUsage,
+) []State {
+	states := make([]State, 0, len(datapoints))
+
+	for _, datapoint := range datapoints {
+		state := StateUnknown
+
+		if datapoint != nil {
+			percent := int32(float64(datapoint.Used) / float64(datapoint.Total) * 100)
+
+			if percent < monitor.Threshold {
+				state = StateOK
+			} else {
+				state = StateNOK
+			}
+		}
+
+		states = append(states, state)
+	}
+
+	return states
+}
+
+func CalculateVolumeUsageStates(
+	monitor database.WorkspaceAgentVolumeResourceMonitor,
+	datapoints []*proto.PushResourcesMonitoringUsageRequest_Datapoint_VolumeUsage,
+) []State {
+	states := make([]State, 0, len(datapoints))
+
+	for _, datapoint := range datapoints {
+		state := StateUnknown
+
+		if datapoint != nil {
+			percent := int32(float64(datapoint.Used) / float64(datapoint.Total) * 100)
+
+			if percent < monitor.Threshold {
+				state = StateOK
+			} else {
+				state = StateNOK
+			}
+		}
+
+		states = append(states, state)
+	}
+
+	return states
+}
+
+func NextState(c Config, oldState database.WorkspaceAgentMonitorState, states []State) database.WorkspaceAgentMonitorState {
+	// If there are enough consecutive NOK states, we should be in an
+	// alert state.
+	consecutiveNOKs := slice.CountConsecutive(StateNOK, states...)
+	if percent(consecutiveNOKs, len(states)) >= c.Alert.ConsecutiveNOKsPercent {
+		return database.WorkspaceAgentMonitorStateNOK
+	}
+
+	// We do not explicitly handle StateUnknown because it could have
+	// been either StateOK or StateNOK if collection didn't fail. As
+	// it could be either, our best bet is to ignore it.
+	nokCount, okCount := 0, 0
+	for _, state := range states {
+		switch state {
+		case StateOK:
+			okCount++
+		case StateNOK:
+			nokCount++
+		}
+	}
+
+	// If there are enough NOK datapoints, we should be in an alert state.
+	if percent(nokCount, len(states)) >= c.Alert.MinimumNOKsPercent {
+		return database.WorkspaceAgentMonitorStateNOK
+	}
+
+	// If all datapoints are OK, we should be in an OK state
+	if okCount == len(states) {
+		return database.WorkspaceAgentMonitorStateOK
+	}
+
+	// Otherwise we stay in the same state as last.
+	return oldState
+}
+
+func percent[T int](numerator, denominator T) int {
+	percent := float64(numerator*100) / float64(denominator)
+	return int(math.Round(percent))
+}