Fix Timeout interrupt handling on Ruby 2.3 and protect Mysql2::Statement#execute

Timeout::ExitException was removed in Ruby 2.3.0, 2.2.3, and 2.1.8,
in favor of Timeout::Error. Backwards compatible aliases are provided
for Ruby 2.1.x and 2.2.x, but not earlier verions.

With thanks to @jeremy for PR brianmario#671 and @yui-knk for PR brianmario#677, this commit
also protects prepared statements from being interrupted, so the compat
shim is in Mysql2::Util.

Author: sodabrew

lib/mysql2.rb

@@ -61,4 +61,22 @@ def self.key_hash_as_symbols(hash)
     Hash[hash.map { |k,v| [k.to_sym, v] }]
   end
 
+  #
+  # In Mysql2::Client#query and Mysql2::Statement#execute,
+  # Thread#handle_interrupt is used to prevent Timeout#timeout
+  # from interrupting query execution.
+  #
+  # Timeout::ExitException was removed in Ruby 2.3.0, 2.2.3, and 2.1.8,
+  # but is present in earlier 2.1.x and 2.2.x, so we provide a shim.
+  #
+  if Thread.respond_to?(:handle_interrupt)
+    require 'timeout'
+    # rubocop:disable Style/ConstantName
+    TimeoutError = if defined?(::Timeout::ExitException)
+      ::Timeout::ExitException
+    else
+      ::Timeout::Error
+    end
+  end
+
 end

lib/mysql2/client.rb

@@ -76,7 +76,7 @@ def self.default_query_options
 
     if Thread.respond_to?(:handle_interrupt)
       def query(sql, options = {})
-        Thread.handle_interrupt(Timeout::ExitException => :never) do
+        Thread.handle_interrupt(::Mysql2::Util::TimeoutError => :never) do
           _query(sql, @query_options.merge(options))
         end
       end

spec/mysql2/client_spec.rb

@@ -462,8 +462,7 @@ def connect *args
         }.should raise_error(Mysql2::Error)
       end
 
-
-      it 'should be impervious to connection-corrupting timeouts ' do
+      it 'should be impervious to connection-corrupting timeouts in #query' do
         pending('`Thread.handle_interrupt` is not defined') unless Thread.respond_to?(:handle_interrupt)
         # attempt to break the connection
         expect { Timeout.timeout(0.1) { @client.query('SELECT SLEEP(1)') } }.to raise_error(Timeout::Error)