Check that advisory lock prefix fits inside four bytes

Add an extra safety check that an advisory lock prefix fits inside of
four bytes, which is all that's reserved for one.

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- Advisory lock prefixes are now checked to make sure they fit inside of four bytes. [PR #24](https://github.com/riverqueue/riverqueue-ruby/pull/24).
+
 ## [0.5.0] - 2024-07-05
 
 ### Changed

lib/client.rb

@@ -26,7 +26,7 @@ module River
   class Client
     def initialize(driver, advisory_lock_prefix: nil)
       @driver = driver
-      @advisory_lock_prefix = advisory_lock_prefix
+      @advisory_lock_prefix = check_advisory_lock_prefix_bounds(advisory_lock_prefix)
       @time_now_utc = -> { Time.now.utc } # for test time stubbing
     end
 
@@ -137,6 +137,16 @@ def insert_many(args)
       @driver.job_insert_many(all_params)
     end
 
+    private def check_advisory_lock_prefix_bounds(advisory_lock_prefix)
+      return nil if advisory_lock_prefix.nil?
+
+      # 2**32-1 is 0xffffffff (the largest number that's four bytes)
+      if advisory_lock_prefix < 0 || advisory_lock_prefix > 2**32 - 1
+        raise ArgumentError, "advisory lock prefix must fit inside four bytes"
+      end
+      advisory_lock_prefix
+    end
+
     # Default states that are used during a unique insert. Can be overridden by
     # setting UniqueOpts#by_state.
     DEFAULT_UNIQUE_STATES = [

sig/client.rbs

@@ -8,13 +8,15 @@ module River
     @driver: _Driver
     @time_now_utc: ^() -> Time
 
-    DEFAULT_UNIQUE_STATES: Array[jobStateAll]
-    EMPTY_INSERT_OPTS: InsertOpts
-
     def initialize: (_Driver driver, ?advisory_lock_prefix: Integer?) -> void
     def insert: (jobArgs, ?insert_opts: InsertOpts) -> InsertResult
     def insert_many: (Array[jobArgs | InsertManyParams]) -> Integer
 
+    private def check_advisory_lock_prefix_bounds: (Integer?) -> Integer?
+
+    DEFAULT_UNIQUE_STATES: Array[jobStateAll]
+    EMPTY_INSERT_OPTS: InsertOpts
+
     private def check_unique_job: (Driver::JobInsertParams, UniqueOpts?) { () -> InsertResult } -> InsertResult
     private def make_insert_params: (jobArgs, InsertOpts, ?is_insert_many: bool) -> [Driver::JobInsertParams, UniqueOpts?]
     private def truncate_time: (Time, Integer) -> Time

spec/client_spec.rb

@@ -173,6 +173,22 @@ class SimpleArgsWithInsertOpts < SimpleArgs
       )
     end
 
+    it "errors if advisory lock prefix is larger than four bytes" do
+      River::Client.new(mock_driver, advisory_lock_prefix: 123)
+
+      expect do
+        River::Client.new(mock_driver, advisory_lock_prefix: -1)
+      end.to raise_error(ArgumentError, "advisory lock prefix must fit inside four bytes")
+
+      # 2^32-1 is 0xffffffff (1s for 32 bits) which fits
+      River::Client.new(mock_driver, advisory_lock_prefix: 2**32 - 1)
+
+      # 2^32 is 0x100000000, which does not
+      expect do
+        River::Client.new(mock_driver, advisory_lock_prefix: 2**32)
+      end.to raise_error(ArgumentError, "advisory lock prefix must fit inside four bytes")
+    end
+
     it "errors if args don't respond to #kind" do
       args_klass = Class.new do
         def to_json = {}