R4R: Emit Warning Events when Validator Misses Blocks

.pending/improvements/sdk/4629-Added-event-that-get

@@ -0,0 +1,2 @@
+Added warning event that gets emitted if validator misses certain number of blocks, and re-emits periodically.
+Added parameter `DowntimeWarning` to define both the threshold of missed blocks before warning is emitted and also defines granularity of subsequent warnings if validator continues missing blocks.

docs/spec/slashing/04_begin_block.md

@@ -84,7 +84,11 @@ single slashing period is capped as described in [overview.md](overview.md) unde
 
 ## Uptime tracking
 
-At the beginning of each block, we update the signing info for each validator and check if they've dipped below the liveness threshold over the tracked window.  If so, they will be slashed by `LivenessSlashAmount` and will be Jailed for `LivenessJailPeriod`.  Liveness slashes do NOT lead to a tombstombing.
+At the beginning of each block, we update the signing info for each validator and check if they've dipped below the liveness threshold over the tracked window.  If so, they will be slashed by `LivenessSlashAmount` and will be Jailed for `LivenessJailPeriod` and an event will be emitted.  Liveness slashes do NOT lead to a tombstombing.
+
+If the Validator has missed `DowntimeWarning` blocks in the last signing block window, then a warning event is emitted. The event is re-emitted for every additional `DowntimeWarning` blocks that validator misses in the same window.
+
+Ex: Let `DowntimeWindow = 5`. If a Validator misses 5 blocks, a warning event is emitted. If within the same signing block, he misses an additional 20 blocks, 4 more warning events are emitted with each event tallying the total amount of blocks Validator has missed. If in the next signing block window, Validator doesn't miss a block, no further events will be emitted.
 
 ```
 height := block.Height
@@ -108,6 +112,19 @@ for val in block.Validators:
     signInfo.MissedBlocksCounter--
   // else previous == val not in block.AbsentValidators, no change
 
+	// Start emitting events to warn about validator downtime once validator has reached
+	// downtime warning threshold. Continue emitting warnings every missed `downtimeWarning`
+	// blocks thereafter
+	if signInfo.MissedBlocksCounter >= DOWNTIMEWARNING && signInfo.MissedBlocksCounter % DOWNTIMEWARNING == 0 {
+		ctx.EventManager().EmitEvent(
+			sdk.NewEvent(
+				types.EventTypeSlash,
+				sdk.NewAttribute(types.AttributeKeyAddress, consAddr.String()),
+				sdk.NewAttribute(types.AttributeKeyMissedBlocks, fmt.Sprintf("%d", signInfo.MissedBlocksCounter)),
+			),
+		)
+	}
+
   // validator must be active for at least SIGNED_BLOCKS_WINDOW
   // before they can be automatically unbonded for failing to be
   // included in 50% of the recent LastCommits

docs/spec/slashing/06_events.md

@@ -13,6 +13,11 @@ The slashing module emits the following events/tags:
 
 - [0] Only included if the validator is jailed. 
 
+| Type  | Attribute Key | Attribute Value             |
+|-------|---------------|-----------------------------|
+| slash | address       | {validatorConsensusAddress} |
+| slash | missed_blocks | {missedBlocksCounter}       |
+
 ## Handlers
 
 ### MsgUnjail

docs/spec/slashing/08_params.md

@@ -10,3 +10,4 @@ The slashing module contains the following parameters:
 | DowntimeJailDuration    | string (time ns) | "600000000000"         |
 | SlashFractionDoubleSign | string (dec)     | "0.050000000000000000" |
 | SlashFractionDowntime   | string (dec)     | "0.010000000000000000" |
+| DowntimeWarning         | string (int64)   | "5"                    |

simapp/sim_test.go

@@ -502,6 +502,14 @@ func genSlashingGenesisState(
 					})
 				return v
 			}(r),
+			func(r *rand.Rand) int64 {
+				var v int64
+				ap.GetOrGenerate(cdc, simulation.DowntimeWarning, &v, r,
+					func(r *rand.Rand) {
+						v = simulation.ModuleParamSimulator[simulation.DowntimeWarning](r).(int64)
+					})
+				return v
+			}(r),
 		),
 		nil,
 		nil,

types/context.go

@@ -311,4 +311,4 @@ func (pst *thePast) getOp(ver int64) (Op, bool) {
 		return Op{}, false
 	}
 	return pst.ops[ver-1], true
-}
+}

x/simulation/params.go

@@ -35,6 +35,7 @@ const (
 	DowntimeJailDuration     = "downtime_jail_duration"
 	SlashFractionDoubleSign  = "slash_fraction_double_sign"
 	SlashFractionDowntime    = "slash_fraction_downtime"
+	DowntimeWarning          = "downtime_warning"
 	InflationRateChange      = "inflation_rate_change"
 	Inflation                = "inflation"
 	InflationMax             = "inflation_max"
@@ -121,6 +122,9 @@ var (
 		SlashFractionDowntime: func(r *rand.Rand) interface{} {
 			return sdk.NewDec(1).Quo(sdk.NewDec(int64(r.Intn(200) + 1)))
 		},
+		DowntimeWarning: func(r *rand.Rand) interface{} {
+			return int64(RandIntBetween(r, 1, 10))
+		},
 		InflationRateChange: func(r *rand.Rand) interface{} {
 			return sdk.NewDecWithPrec(int64(r.Intn(99)), 2)
 		},

x/slashing/keeper.go

@@ -183,6 +183,20 @@ func (k Keeper) HandleValidatorSignature(ctx sdk.Context, addr crypto.Address, p
 		// Array value at this index has not changed, no need to update counter
 	}
 
+	downtimeWarn := k.DowntimeWarning(ctx)
+	// Start emitting events to warn about validator downtime once validator has reached
+	// downtime warning threshold. Continue emitting warnings every missed `downtimeWarning`
+	// blocks thereafter
+	if signInfo.MissedBlocksCounter >= downtimeWarn && signInfo.MissedBlocksCounter%downtimeWarn == 0 {
+		ctx.EventManager().EmitEvent(
+			sdk.NewEvent(
+				types.EventTypeSlash,
+				sdk.NewAttribute(types.AttributeKeyAddress, consAddr.String()),
+				sdk.NewAttribute(types.AttributeKeyMissedBlocks, fmt.Sprintf("%d", signInfo.MissedBlocksCounter)),
+			),
+		)
+	}
+
 	if missed {
 		logger.Info(fmt.Sprintf("Absent validator %s (%v) at height %d, %d missed, threshold %d", addr, pubkey, height, signInfo.MissedBlocksCounter, k.MinSignedPerWindow(ctx)))
 	}

x/slashing/params.go

@@ -36,6 +36,12 @@ func (k Keeper) DowntimeJailDuration(ctx sdk.Context) (res time.Duration) {
 	return
 }
 
+// Downtime Warning threshold
+func (k Keeper) DowntimeWarning(ctx sdk.Context) (res int64) {
+	k.paramspace.Get(ctx, types.KeyDowntimeWarning, &res)
+	return
+}
+
 // SlashFractionDoubleSign
 func (k Keeper) SlashFractionDoubleSign(ctx sdk.Context) (res sdk.Dec) {
 	k.paramspace.Get(ctx, types.KeySlashFractionDoubleSign, &res)

x/slashing/types/events.go

@@ -4,10 +4,11 @@ package types
 var (
 	EventTypeSlash = "slash"
 
-	AttributeKeyAddress = "address"
-	AttributeKeyPower   = "power"
-	AttributeKeyReason  = "reason"
-	AttributeKeyJailed  = "jailed"
+	AttributeKeyAddress      = "address"
+	AttributeKeyPower        = "power"
+	AttributeKeyReason       = "reason"
+	AttributeKeyJailed       = "jailed"
+	AttributeKeyMissedBlocks = "missed_blocks"
 
 	AttributeValueDoubleSign       = "double_sign"
 	AttributeValueMissingSignature = "missing_signature"

x/slashing/types/params.go

@@ -14,6 +14,7 @@ const (
 	DefaultMaxEvidenceAge       time.Duration = 60 * 2 * time.Second
 	DefaultSignedBlocksWindow   int64         = 100
 	DefaultDowntimeJailDuration time.Duration = 60 * 10 * time.Second
+	DefaultDowntimeWarning      int64         = 1
 )
 
 // The Double Sign Jail period ends at Max Time supported by Amino (Dec 31, 9999 - 23:59:59 GMT)
@@ -32,6 +33,7 @@ var (
 	KeyDowntimeJailDuration    = []byte("DowntimeJailDuration")
 	KeySlashFractionDoubleSign = []byte("SlashFractionDoubleSign")
 	KeySlashFractionDowntime   = []byte("SlashFractionDowntime")
+	KeyDowntimeWarning         = []byte("DowntimeWarning")
 )
 
 // ParamKeyTable for slashing module
@@ -47,12 +49,14 @@ type Params struct {
 	DowntimeJailDuration    time.Duration `json:"downtime_jail_duration"`
 	SlashFractionDoubleSign sdk.Dec       `json:"slash_fraction_double_sign"`
 	SlashFractionDowntime   sdk.Dec       `json:"slash_fraction_downtime"`
+	DowntimeWarning         int64         `json:"downtime_warning"`
 }
 
 // NewParams creates a new Params object
 func NewParams(maxEvidenceAge time.Duration, signedBlocksWindow int64,
 	minSignedPerWindow sdk.Dec, downtimeJailDuration time.Duration,
-	slashFractionDoubleSign sdk.Dec, slashFractionDowntime sdk.Dec) Params {
+	slashFractionDoubleSign sdk.Dec, slashFractionDowntime sdk.Dec,
+	downtimeWarning int64) Params {
 
 	return Params{
 		MaxEvidenceAge:          maxEvidenceAge,
@@ -61,6 +65,7 @@ func NewParams(maxEvidenceAge time.Duration, signedBlocksWindow int64,
 		DowntimeJailDuration:    downtimeJailDuration,
 		SlashFractionDoubleSign: slashFractionDoubleSign,
 		SlashFractionDowntime:   slashFractionDowntime,
+		DowntimeWarning:         downtimeWarning,
 	}
 }
 
@@ -71,10 +76,11 @@ func (p Params) String() string {
   MinSignedPerWindow:      %s
   DowntimeJailDuration:    %s
   SlashFractionDoubleSign: %s
-  SlashFractionDowntime:   %s`, p.MaxEvidenceAge,
+  SlashFractionDowntime:   %s
+  DowntimeWarning:         %d`, p.MaxEvidenceAge,
 		p.SignedBlocksWindow, p.MinSignedPerWindow,
 		p.DowntimeJailDuration, p.SlashFractionDoubleSign,
-		p.SlashFractionDowntime)
+		p.SlashFractionDowntime, p.DowntimeWarning)
 }
 
 // Implements params.ParamSet
@@ -86,6 +92,7 @@ func (p *Params) ParamSetPairs() params.ParamSetPairs {
 		{KeyDowntimeJailDuration, &p.DowntimeJailDuration},
 		{KeySlashFractionDoubleSign, &p.SlashFractionDoubleSign},
 		{KeySlashFractionDowntime, &p.SlashFractionDowntime},
+		{KeyDowntimeWarning, &p.DowntimeWarning},
 	}
 }
 
@@ -98,5 +105,6 @@ func DefaultParams() Params {
 		DowntimeJailDuration:    DefaultDowntimeJailDuration,
 		SlashFractionDoubleSign: DefaultSlashFractionDoubleSign,
 		SlashFractionDowntime:   DefaultSlashFractionDowntime,
+		DowntimeWarning:         DefaultDowntimeWarning,
 	}
 }