Add a lock_wait_timeout setter to set a busy_handler that releases the GVL between connection retries, but also errors after the timeout passes

Author: fractaledmind

lib/sqlite3/database.rb

@@ -691,6 +691,19 @@ def readonly?
       @readonly
     end
 
+    def lock_wait_timeout=( milliseconds )
+      timeout_seconds = milliseconds.fdiv(1000)
+      retry_interval = 0.001 # 1 millisecond
+
+      busy_handler do |count|
+        @start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC) if count == 0
+
+        next sleep(retry_interval) unless (count % 100) == 0
+
+        (Process.clock_gettime(Process::CLOCK_MONOTONIC) - @start_time) <= timeout_seconds
+      end
+    end
+
     # A helper class for dealing with custom functions (see #create_function,
     # #create_aggregate, and #create_aggregate_handler). It encapsulates the
     # opaque function object that represents the current invocation. It also

test/test_integration_pending.rb

@@ -112,4 +112,33 @@ def test_busy_timeout
 
     assert time.real*1000 >= 1000
   end
+
+  def test_lock_wait_timeout
+    @db.lock_wait_timeout = 1000
+    busy = Mutex.new
+    busy.lock
+
+    t = Thread.new do
+      begin
+        db2 = SQLite3::Database.open( "test.db" )
+        db2.transaction( :exclusive ) do
+          busy.lock
+        end
+      ensure
+        db2.close if db2
+      end
+    end
+
+    sleep 1
+    time = Benchmark.measure do
+      assert_raise( SQLite3::BusyException ) do
+        @db.execute "insert into foo (b) values ( 'from 2' )"
+      end
+    end
+
+    busy.unlock
+    t.join
+
+    assert time.real*1000 >= 1000
+  end
 end