2 * Copyright 2015 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
20 namespace folly { namespace fibers {
22 class StackCacheEntry;
25 * Stack allocator that protects an extra memory page after
26 * the end of the stack.
27 * Will only add extra memory pages up to a certain number of allocations
28 * to avoid creating too many memory maps for the process.
30 class GuardPageAllocator {
33 ~GuardPageAllocator();
36 * @return pointer to the bottom of the allocated stack of `size' bytes.
38 unsigned char* allocate(size_t size);
41 * Deallocates the previous result of an `allocate(size)' call.
43 void deallocate(unsigned char* limit, size_t size);
46 std::unique_ptr<StackCacheEntry> stackCache_;
47 std::allocator<unsigned char> fallbackAllocator_;