add support for :read_timeout to be set on a connection

ext/mysql2/client.c

@@ -264,7 +264,7 @@ static VALUE rb_mysql_client_query(int argc, VALUE * argv, VALUE self) {
   fd_set fdset;
   int fd, retval;
   int async = 0;
-  VALUE opts, defaults;
+  VALUE opts, defaults, read_timeout;
   GET_CLIENT(self);
 
   REQUIRE_OPEN_DB(wrapper);
@@ -303,6 +303,23 @@ static VALUE rb_mysql_client_query(int argc, VALUE * argv, VALUE self) {
     return rb_raise_mysql2_error(wrapper->client);
   }
 
+  read_timeout = rb_iv_get(self, "@read_timeout");
+  struct timeval tv;
+  struct timeval* tvp = NULL;
+  if (!NIL_P(read_timeout)) {
+    Check_Type(read_timeout, T_FIXNUM);
+    tvp = &tv;
+    long int sec = FIX2INT(read_timeout);
+    // TODO: support partial seconds?
+    // also, this check is here for sanity, we also check up in Ruby
+    if (sec >= 0) {
+      tvp->tv_sec = sec;
+    } else {
+      rb_raise(cMysql2Error, "read_timeout must be a positive integer, you passed %d", sec);
+    }
+    tvp->tv_usec = 0;
+  }
+
   if (!async) {
     // the below code is largely from do_mysql
     // http://github.com/datamapper/do
@@ -311,7 +328,11 @@ static VALUE rb_mysql_client_query(int argc, VALUE * argv, VALUE self) {
       FD_ZERO(&fdset);
       FD_SET(fd, &fdset);
 
-      retval = rb_thread_select(fd + 1, &fdset, NULL, NULL, NULL);
+      retval = rb_thread_select(fd + 1, &fdset, NULL, NULL, tvp);
+
+      if (retval == 0) {
+        rb_raise(cMysql2Error, "Timeout waiting for a response from the last query. (waited %d seconds)", FIX2INT(read_timeout));
+      }
 
       if (retval < 0) {
         rb_sys_fail(0);

lib/mysql2/client.rb

@@ -24,6 +24,11 @@ module Mysql2
       # force the encoding to utf8
       self.charset_name = opts[:encoding] || 'utf8'
 
+      @read_timeout = opts[:read_timeout]
+      if @read_timeout and @read_timeout < 0
+        raise Mysql2::Error, "read_timeout must be a positive integer, you passed #{@read_timeout}"
+      end
+
       ssl_set(*opts.values_at(:sslkey, :sslcert, :sslca, :sslcapath, :sslciper))
 
       user     = opts[:username]

spec/mysql2/client_spec.rb

@@ -85,6 +85,12 @@ describe Mysql2::Client do
     @client.should respond_to(:query)
   end
 
+  it "should expect read_timeout to be a positive integer" do
+    lambda {
+      Mysql2::Client.new(:read_timeout => -1)
+    }.should raise_error(Mysql2::Error)
+  end
+
   context "#query" do
     it "should only accept strings as the query parameter" do
       lambda {
@@ -124,6 +130,13 @@ describe Mysql2::Client do
       }.should raise_error(Mysql2::Error)
     end
 
+    it "should timeout if we wait longer than :read_timeout" do
+      client = Mysql2::Client.new(:read_timeout => 1)
+      lambda {
+        client.query("SELECT sleep(2)")
+      }.should raise_error(Mysql2::Error)
+    end
+
     # XXX this test is not deterministic (because Unix signal handling is not)
     # and may fail on a loaded system
     if RUBY_PLATFORM !~ /mingw|mswin/