refactor(leaderelection): replace hand-rolled Redis locking with redsync (#60)

* refactor(leaderelection): replace hand-rolled Redis locking with redsync

Replace manual SetNX/Lua script implementation with github.com/go-redsync/redsync/v4
for distributed mutex handling.

Changes:
- Add redsync v4.15.0 dependency
- Simplify Elector interface: remove LeadershipChannel() and GetLeaderID()
- Rewrite RedisElector using redsync.Mutex with:
  - WithSetNXOnExtend() for Redis restart resilience
  - WithDriftFactor(0.01) for clock drift safety
  - WithTries(1) for non-blocking acquisition attempts
- Update tests to use callback-based notification only
- Reduce implementation from ~374 to ~260 lines

Breaking changes:
- LeadershipChannel() removed (use OnLeadershipChange callback instead)
- GetLeaderID() removed (redsync uses opaque internal values)

* fix logging

Author: Savid

go.mod

@@ -9,10 +9,11 @@ require (
 	github.com/creasty/defaults v1.8.0
 	github.com/ethereum/go-ethereum v1.16.7
 	github.com/go-co-op/gocron v1.37.0
+	github.com/go-redsync/redsync/v4 v4.15.0
 	github.com/hibiken/asynq v0.25.1
 	github.com/lib/pq v1.10.9
 	github.com/prometheus/client_golang v1.20.5
-	github.com/redis/go-redis/v9 v9.14.0
+	github.com/redis/go-redis/v9 v9.17.2
 	github.com/sirupsen/logrus v1.9.3
 	github.com/spf13/cobra v1.10.1
 	github.com/stretchr/testify v1.11.1
@@ -60,6 +61,8 @@ require (
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.5 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/hashicorp/go-version v1.7.0 // indirect
 	github.com/holiman/uint256 v1.3.2 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect

go.sum

@@ -124,6 +124,14 @@ github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre
 github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
 github.com/go-ole/go-ole v1.3.0 h1:Dt6ye7+vXGIKZ7Xtk4s6/xVdGDQynvom7xCFEdWr6uE=
 github.com/go-ole/go-ole v1.3.0/go.mod h1:5LS6F96DhAwUc7C+1HLexzMXY1xGRSryjyPPKW6zv78=
+github.com/go-redis/redis v6.15.9+incompatible h1:K0pv1D7EQUjfyoMql+r/jZqCLizCGKFlFgcHWWmHQjg=
+github.com/go-redis/redis v6.15.9+incompatible/go.mod h1:NAIEuMOZ/fxfXJIrKDQDz8wamY7mA7PouImQ2Jvg6kA=
+github.com/go-redis/redis/v7 v7.4.1 h1:PASvf36gyUpr2zdOUS/9Zqc80GbM+9BDyiJSJDDOrTI=
+github.com/go-redis/redis/v7 v7.4.1/go.mod h1:JDNMw23GTyLNC4GZu9njt15ctBQVn7xjRfnwdHj/Dcg=
+github.com/go-redis/redis/v8 v8.11.5 h1:AcZZR7igkdvfVmQTPnu9WE37LRrO/YrBH5zWyjDC0oI=
+github.com/go-redis/redis/v8 v8.11.5/go.mod h1:gREzHqY1hg6oD9ngVRbLStwAWKhA0FEgq8Jd4h5lpwo=
+github.com/go-redsync/redsync/v4 v4.15.0 h1:KH/XymuxSV7vyKs6z1Cxxj+N+N18JlPxgXeP6x4JY54=
+github.com/go-redsync/redsync/v4 v4.15.0/go.mod h1:qNp+lLs3vkfZbtA/aM/OjlZHfEr5YTAYhRktFPKHC7s=
 github.com/gofrs/flock v0.12.1 h1:MTLVXXHf8ekldpJk3AKicLij9MdwOWkZ+a/jHHZby9E=
 github.com/gofrs/flock v0.12.1/go.mod h1:9zxTsyu5xtJ9DK+1tFZyibEV7y3uwDxPPfbxeeHCoD0=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
@@ -132,6 +140,8 @@ github.com/golang-jwt/jwt/v4 v4.5.2 h1:YtQM7lnr8iZ+j5q71MGKkNw9Mn7AjHM68uc9g5fXe
 github.com/golang-jwt/jwt/v4 v4.5.2/go.mod h1:m21LjoU+eqJr34lmDMbreY2eSTRJ1cv77w39/MY0Ch0=
 github.com/golang/snappy v1.0.0 h1:Oy607GVXHs7RtbggtPBnr2RmDArIsAefDwvrdWvRhGs=
 github.com/golang/snappy v1.0.0/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/gomodule/redigo v1.9.3 h1:dNPSXeXv6HCq2jdyWfjgmhBdqnR6PRO3m/G05nvpPC8=
+github.com/gomodule/redigo v1.9.3/go.mod h1:KsU3hiK/Ay8U42qpaJk+kuNa3C+spxapWpM+ywhcgtw=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/uuid v1.4.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
@@ -141,8 +151,13 @@ github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aN
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.5 h1:jP1RStw811EvUDzsUQ9oESqw2e4RqCjSAD9qIL8eMns=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.5/go.mod h1:WXNBZ64q3+ZUemCMXD9kYnr56H7CgZxDBHCVwstfl3s=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/errwrap v1.1.0 h1:OxrOeh75EUXMY8TBjag2fzXGZ40LB6IKw45YeGUDY2I=
+github.com/hashicorp/errwrap v1.1.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/go-bexpr v0.1.10 h1:9kuI5PFotCboP3dkDYFr/wi0gg0QVbSNz5oFRpxn4uE=
 github.com/hashicorp/go-bexpr v0.1.10/go.mod h1:oxlubA2vC/gFVfX1A6JGp7ls7uCDlfJn732ehYYg+g0=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/hashicorp/go-version v1.7.0 h1:5tqGy27NaOTB8yJKUZELlFAS/LTKJkrmONwQKeRZfjY=
 github.com/hashicorp/go-version v1.7.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
 github.com/hibiken/asynq v0.25.1 h1:phj028N0nm15n8O2ims+IvJ2gz4k2auvermngh9JhTw=
@@ -255,8 +270,12 @@ github.com/prometheus/common v0.64.0 h1:pdZeA+g617P7oGv1CzdTzyeShxAGrTBsolKNOLQP
 github.com/prometheus/common v0.64.0/go.mod h1:0gZns+BLRQ3V6NdaerOhMbwwRbNh9hkGINtQAsP5GS8=
 github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzMyRg=
 github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
-github.com/redis/go-redis/v9 v9.14.0 h1:u4tNCjXOyzfgeLN+vAZaW1xUooqWDqVEsZN0U01jfAE=
-github.com/redis/go-redis/v9 v9.14.0/go.mod h1:huWgSWd8mW6+m0VPhJjSSQ+d6Nh1VICQ6Q5lHuCH/Iw=
+github.com/redis/go-redis/v9 v9.17.2 h1:P2EGsA4qVIM3Pp+aPocCJ7DguDHhqrXNhVcEp4ViluI=
+github.com/redis/go-redis/v9 v9.17.2/go.mod h1:u410H11HMLoB+TP67dz8rL9s6QW2j76l0//kSOd3370=
+github.com/redis/rueidis v1.0.69 h1:WlUefRhuDekji5LsD387ys3UCJtSFeBVf0e5yI0B8b4=
+github.com/redis/rueidis v1.0.69/go.mod h1:Lkhr2QTgcoYBhxARU7kJRO8SyVlgUuEkcJO1Y8MCluA=
+github.com/redis/rueidis/rueidiscompat v1.0.69 h1:IWVYY9lXdjNO3do2VpJT7aDFi8zbCUuQxZB6E2Grahs=
+github.com/redis/rueidis/rueidiscompat v1.0.69/go.mod h1:iC4Y8DoN0Uth0Uezg9e2trvNRC7QAgGeuP2OPLb5ccI=
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
@@ -299,6 +318,8 @@ github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO
 github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+github.com/stvp/tempredis v0.0.0-20181119212430-b82af8480203 h1:QVqDTf3h2WHt08YuiTGPZLls0Wq99X9bWd0Q5ZSBesM=
+github.com/stvp/tempredis v0.0.0-20181119212430-b82af8480203/go.mod h1:oqN97ltKNihBbwlX8dLpwxCl3+HnXKV/R0e+sRLd9C8=
 github.com/supranational/blst v0.3.16 h1:bTDadT+3fK497EvLdWRQEjiGnUtzJ7jjIUMF0jqwYhE=
 github.com/supranational/blst v0.3.16/go.mod h1:jZJtfjgudtNl4en1tzwPIV3KjUnQUvG3/j+w+fVonLw=
 github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7 h1:epCh84lMvA70Z7CTTCmYQn2CKbY8j86K7/FAIr141uY=

pkg/leaderelection/interface.go

@@ -22,23 +22,13 @@ type Elector interface {
 	// IsLeader returns true if this node is currently the leader
 	IsLeader() bool
 
-	// LeadershipChannel returns a channel that receives leadership changes
-	// true = gained leadership, false = lost leadership
-	//
-	// Deprecated: Use OnLeadershipChange for guaranteed delivery.
-	// This channel may drop events if the buffer is full.
-	LeadershipChannel() <-chan bool
-
 	// OnLeadershipChange registers a callback for guaranteed leadership notification.
 	// The callback is invoked synchronously when leadership status changes.
 	// Multiple callbacks can be registered and will be invoked in registration order.
 	//
 	// Important: Keep callbacks fast (< 100ms) to avoid delaying leadership renewal.
 	// For long-running operations, spawn a goroutine within the callback.
 	OnLeadershipChange(callback LeadershipCallback)
-
-	// GetLeaderID returns the current leader's ID
-	GetLeaderID() (string, error)
 }
 
 // Config holds configuration for leader election.
@@ -49,7 +39,7 @@ type Config struct {
 	// RenewalInterval is how often to renew the leader lock
 	RenewalInterval time.Duration
 
-	// NodeID is the unique identifier for this node
+	// NodeID is the unique identifier for this node (for logging/metrics only)
 	// If empty, a random ID will be generated
 	NodeID string
 }