fix a warning in IOBuf::_pref_at()

src/brpc/concurrency_limiter.cpp

-// Copyright (c) 2014 Baidu, Inc.G
-// 
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Authors: Lei He (helei@qiyi.com)
-
-#include "brpc/concurrency_limiter.h"
-
-namespace brpc {
-
-ConcurrencyLimiter* ConcurrencyLimiter::CreateConcurrencyLimiterOrDie(
-    const AdaptiveMaxConcurrency& max_concurrency) {
-    const ConcurrencyLimiter* cl = 
-        ConcurrencyLimiterExtension()->Find(max_concurrency.name().c_str());
-    CHECK(cl != NULL) 
-        << "Fail to find ConcurrencyLimiter by `" 
-        << max_concurrency.name() << "'";
-    ConcurrencyLimiter* cl_copy = cl->New();
-    CHECK(cl_copy != NULL) << "Fail to new ConcurrencyLimiter";
-    if (max_concurrency == "constant") {
-        cl_copy->_max_concurrency = max_concurrency;
-    }
-    return cl_copy;
-} 
-
-}  // namespace brpc

src/butil/iobuf_inl.h

@@ -158,7 +158,7 @@ inline const IOBuf::BlockRef& IOBuf::_ref_at(size_t i) const {
 
 inline const IOBuf::BlockRef* IOBuf::_pref_at(size_t i) const {
     if (_small()) {
-        return i < (!!_sv.refs[0].block + !!_sv.refs[1].block) ? &_sv.refs[i] : NULL;
+        return i < (size_t)(!!_sv.refs[0].block + !!_sv.refs[1].block) ? &_sv.refs[i] : NULL;
     } else {
         return i < _bv.nref ? &_bv.ref_at(i) : NULL;
     }