| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| */ |
| |
| #include "MemoryLimitController.h" |
| |
| namespace pulsar { |
| |
| MemoryLimitController::MemoryLimitController(uint64_t memoryLimit) |
| : memoryLimit_(memoryLimit), currentUsage_(0), mutex_(), condition_() {} |
| |
| bool MemoryLimitController::tryReserveMemory(uint64_t size) { |
| // Avoid CAS operation when size is 0 |
| if (size == 0) { |
| return true; |
| } |
| while (true) { |
| uint64_t current = currentUsage_; |
| uint64_t newUsage = current + size; |
| |
| // We allow one request to go over the limit, to make the notification |
| // path simpler and more efficient |
| if (current > memoryLimit_ && memoryLimit_ > 0) { |
| return false; |
| } |
| |
| if (currentUsage_.compare_exchange_strong(current, newUsage)) { |
| return true; |
| } |
| } |
| } |
| |
| void MemoryLimitController::reserveMemory(uint64_t size) { |
| if (!tryReserveMemory(size)) { |
| std::unique_lock<std::mutex> lock(mutex_); |
| |
| // Check again, while holding the lock, to ensure we reserve attempt and the waiting for the condition |
| // are synchronized. |
| while (!tryReserveMemory(size)) { |
| condition_.wait(lock); |
| } |
| } |
| } |
| |
| void MemoryLimitController::releaseMemory(uint64_t size) { |
| uint64_t oldUsage = currentUsage_.fetch_sub(size); |
| uint64_t newUsage = oldUsage - size; |
| |
| if (newUsage + size > memoryLimit_ && newUsage <= memoryLimit_) { |
| // We just crossed the limit. Now we have more space |
| std::lock_guard<std::mutex> lock(mutex_); |
| condition_.notify_all(); |
| } |
| } |
| |
| uint64_t MemoryLimitController::currentUsage() const { return currentUsage_; } |
| |
| } // namespace pulsar |