Add metrics for the various ways of calculating room state (#49)

This commit is contained in:
Mark Haines 2017-03-23 14:14:25 +00:00 committed by Kegsay
parent e347aa05fe
commit e3f3eb8f3d
2 changed files with 126 additions and 11 deletions

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@ -5,6 +5,7 @@ import (
"github.com/matrix-org/dendrite/roomserver/input"
"github.com/matrix-org/dendrite/roomserver/query"
"github.com/matrix-org/dendrite/roomserver/storage"
"github.com/prometheus/client_golang/prometheus"
sarama "gopkg.in/Shopify/sarama.v1"
"net/http"
_ "net/http/pprof"
@ -71,6 +72,8 @@ func main() {
queryAPI.SetupHTTP(http.DefaultServeMux)
http.DefaultServeMux.Handle("/metrics", prometheus.Handler())
fmt.Println("Started roomserver")
// TODO: Implement clean shutdown.

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@ -6,9 +6,106 @@ import (
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
"github.com/prometheus/client_golang/prometheus"
"sort"
"time"
)
var calculateStateDurations = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_duration_microseconds",
Help: "How long it takes to calculate the state after a list of events",
},
// Takes two labels:
// algorithm:
// The algorithm used to calculate the state or the step it failed on if it failed.
// Labels starting with "_" are used to indicate when the algorithm fails halfway.
// outcome:
// Whether the state was successfully calculated.
//
// The possible values for algorithm are:
// empty_state -> The list of events was empty so the state is empty.
// no_change -> The state hasn't changed.
// single_delta -> There was a single event added to the state in a way that can be encoded as a single delta
// full_state_no_conflicts -> We created a new copy of the full room state, but didn't enounter any conflicts
// while doing so.
// full_state_with_conflicts -> We created a new copy of the full room state and had to resolve conflicts to do so.
// _load_state_block_nids -> Failed loading the state block nids for a single previous state.
// _load_combined_state -> Failed to load the combined state.
// _resolve_conflicts -> Failed to resolve conflicts.
[]string{"algorithm", "outcome"},
)
var calculateStatePrevEventLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_prev_event_length",
Help: "The length of the list of events to calculate the state after",
},
[]string{"algorithm", "outcome"},
)
var calculateStateFullStateLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_full_state_length",
Help: "The length of the full room state.",
},
[]string{"algorithm", "outcome"},
)
var calculateStateConflictLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_conflict_state_length",
Help: "The length of the conflicted room state.",
},
[]string{"algorithm", "outcome"},
)
type calculateStateMetrics struct {
algorithm string
startTime time.Time
prevEventLength int
fullStateLength int
conflictLength int
}
func (c *calculateStateMetrics) stop(stateNID types.StateSnapshotNID, err error) (types.StateSnapshotNID, error) {
var outcome string
if err == nil {
outcome = "success"
} else {
outcome = "failure"
}
endTime := time.Now()
calculateStateDurations.WithLabelValues(c.algorithm, outcome).Observe(
float64(endTime.Sub(c.startTime).Nanoseconds()) / 1000.,
)
calculateStatePrevEventLength.WithLabelValues(c.algorithm, outcome).Observe(
float64(c.prevEventLength),
)
calculateStateFullStateLength.WithLabelValues(c.algorithm, outcome).Observe(
float64(c.fullStateLength),
)
calculateStateConflictLength.WithLabelValues(c.algorithm, outcome).Observe(
float64(c.conflictLength),
)
return stateNID, err
}
func init() {
prometheus.MustRegister(
calculateStateDurations, calculateStatePrevEventLength,
calculateStateFullStateLength, calculateStateConflictLength,
)
}
// calculateAndStoreState calculates a snapshot of the state of a room before an event.
// Stores the snapshot of the state in the database.
// Returns a numeric ID for the snapshot of the state before the event.
@ -34,10 +131,13 @@ func calculateAndStoreStateBeforeEvent(
// calculateAndStoreStateAfterEvents finds the room state after the given events.
// Stores the resulting state in the database and returns a numeric ID for that snapshot.
func calculateAndStoreStateAfterEvents(db RoomEventDatabase, roomNID types.RoomNID, prevStates []types.StateAtEvent) (types.StateSnapshotNID, error) {
metrics := calculateStateMetrics{startTime: time.Now(), prevEventLength: len(prevStates)}
if len(prevStates) == 0 {
// 2) There weren't any prev_events for this event so the state is
// empty.
return db.AddState(roomNID, nil, nil)
metrics.algorithm = "empty_state"
return metrics.stop(db.AddState(roomNID, nil, nil))
}
if len(prevStates) == 1 {
@ -47,26 +147,30 @@ func calculateAndStoreStateAfterEvents(db RoomEventDatabase, roomNID types.RoomN
// have the same state, so this event has exactly the same state
// as the previous events.
// This should be the common case.
return prevState.BeforeStateSnapshotNID, nil
metrics.algorithm = "no_change"
return metrics.stop(prevState.BeforeStateSnapshotNID, nil)
}
// The previous event was a state event so we need to store a copy
// of the previous state updated with that event.
stateBlockNIDLists, err := db.StateBlockNIDs([]types.StateSnapshotNID{prevState.BeforeStateSnapshotNID})
if err != nil {
return 0, err
metrics.algorithm = "_load_state_blocks"
return metrics.stop(0, err)
}
stateBlockNIDs := stateBlockNIDLists[0].StateBlockNIDs
if len(stateBlockNIDs) < maxStateBlockNIDs {
// 4) The number of state data blocks is small enough that we can just
// add the state event as a block of size one to the end of the blocks.
return db.AddState(
metrics.algorithm = "single_delta"
return metrics.stop(db.AddState(
roomNID, stateBlockNIDs, []types.StateEntry{prevState.StateEntry},
)
))
}
// If there are too many deltas then we need to calculate the full state
// So fall through to calculateAndStoreStateAfterManyEvents
}
return calculateAndStoreStateAfterManyEvents(db, roomNID, prevStates)
return calculateAndStoreStateAfterManyEvents(db, roomNID, prevStates, metrics)
}
// maxStateBlockNIDs is the maximum number of state data blocks to use to encode a snapshot of room state.
@ -79,12 +183,15 @@ const maxStateBlockNIDs = 64
// calculateAndStoreStateAfterManyEvents finds the room state after the given events.
// This handles the slow path of calculateAndStoreStateAfterEvents for when there is more than one event.
// Stores the resulting state and returns a numeric ID for the snapshot.
func calculateAndStoreStateAfterManyEvents(db RoomEventDatabase, roomNID types.RoomNID, prevStates []types.StateAtEvent) (types.StateSnapshotNID, error) {
func calculateAndStoreStateAfterManyEvents(
db RoomEventDatabase, roomNID types.RoomNID, prevStates []types.StateAtEvent, metrics calculateStateMetrics,
) (types.StateSnapshotNID, error) {
// Conflict resolution.
// First stage: load the state after each of the prev events.
combined, err := state.LoadCombinedStateAfterEvents(db, prevStates)
if err != nil {
return 0, err
metrics.algorithm = "_load_combined_state"
return metrics.stop(0, err)
}
// Collect all the entries with the same type and key together.
@ -98,6 +205,8 @@ func calculateAndStoreStateAfterManyEvents(db RoomEventDatabase, roomNID types.R
var state []types.StateEntry
if len(conflicts) > 0 {
metrics.conflictLength = len(conflicts)
// 5) There are conflicting state events, for each conflict workout
// what the appropriate state event is.
@ -111,17 +220,21 @@ func calculateAndStoreStateAfterManyEvents(db RoomEventDatabase, roomNID types.R
resolved, err := resolveConflicts(db, notConflicted, conflicts)
if err != nil {
return 0, err
metrics.algorithm = "_resolve_conflicts"
return metrics.stop(0, err)
}
metrics.algorithm = "full_state_with_conflicts"
state = resolved
} else {
metrics.algorithm = "full_state_no_conflicts"
// 6) There weren't any conflicts
state = combined
}
metrics.fullStateLength = len(state)
// TODO: Check if we can encode the new state as a delta against the
// previous state.
return db.AddState(roomNID, nil, state)
return metrics.stop(db.AddState(roomNID, nil, state))
}
// loadStateEvents loads the matrix events for a list of state entries.
@ -191,7 +304,6 @@ func resolveConflicts(db RoomEventDatabase, notConflicted, conflicted []types.St
}
// Resolve the conflicts.
fmt.Println("Resolving", len(conflicted), "conflicts with", len(authEvents), "authEvents")
resolvedEvents := gomatrixserverlib.ResolveStateConflicts(conflictedEvents, authEvents)
// Map from the full events back to numeric state entries.