120 lines
4.6 KiB
C++
120 lines
4.6 KiB
C++
// Copyright 2019 The MediaPipe Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef MEDIAPIPE_GPU_MULTI_POOL_H_
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#define MEDIAPIPE_GPU_MULTI_POOL_H_
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#include "mediapipe/util/resource_cache.h"
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namespace mediapipe {
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struct MultiPoolOptions {
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// Keep this many buffers allocated for a given frame size.
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int keep_count = 2;
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// The maximum size of the GpuBufferMultiPool. When the limit is reached, the
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// oldest BufferSpec will be dropped.
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int max_pool_count = 10;
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// Time in seconds after which an inactive buffer can be dropped from the
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// pool. Currently only used with CVPixelBufferPool.
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float max_inactive_buffer_age = 0.25;
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// Skip allocating a buffer pool until at least this many requests have been
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// made for a given BufferSpec.
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int min_requests_before_pool = 2;
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// Do a deeper flush every this many requests.
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int request_count_scrub_interval = 50;
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};
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static constexpr MultiPoolOptions kDefaultMultiPoolOptions;
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// MultiPool is a generic class for vending reusable resources of type Item,
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// which are assumed to be relatively expensive to create, so that reusing them
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// is beneficial.
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// Items are classified by Spec; when an item with a given Spec is requested,
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// an old Item with the same Spec can be reused, if available; otherwise a new
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// Item will be created. When user code is done with an Item, it is returned
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// to the pool for reuse.
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// In order to manage this, a MultiPool contains a map of Specs to SimplePool;
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// each SimplePool manages Items with the same Spec, which are thus considered
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// interchangeable.
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// Item retention and eviction policies are controlled by options.
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// A concrete example would be a pool of GlTextureBuffer, grouped by dimensions
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// and format.
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template <class SimplePool, class Spec, class Item>
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class MultiPool {
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public:
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using SimplePoolFactory = std::function<std::shared_ptr<SimplePool>(
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const Spec& spec, const MultiPoolOptions& options)>;
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MultiPool(SimplePoolFactory factory = DefaultMakeSimplePool,
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MultiPoolOptions options = kDefaultMultiPoolOptions)
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: create_simple_pool_(factory), options_(options) {}
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explicit MultiPool(MultiPoolOptions options)
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: MultiPool(DefaultMakeSimplePool, options) {}
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// Obtains an item. May either be reused or created anew.
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Item Get(const Spec& spec);
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private:
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static std::shared_ptr<SimplePool> DefaultMakeSimplePool(
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const Spec& spec, const MultiPoolOptions& options) {
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return SimplePool::Create(spec, options);
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}
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// Requests a simple buffer pool for the given spec. This may return nullptr
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// if we have not yet reached a sufficient number of requests to allocate a
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// pool, in which case the caller should invoke CreateBufferWithoutPool.
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std::shared_ptr<SimplePool> RequestPool(const Spec& spec);
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absl::Mutex mutex_;
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mediapipe::ResourceCache<Spec, std::shared_ptr<SimplePool>> cache_
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ABSL_GUARDED_BY(mutex_);
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SimplePoolFactory create_simple_pool_ = DefaultMakeSimplePool;
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MultiPoolOptions options_;
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};
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template <class SimplePool, class Spec, class Item>
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std::shared_ptr<SimplePool> MultiPool<SimplePool, Spec, Item>::RequestPool(
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const Spec& spec) {
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std::shared_ptr<SimplePool> pool;
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std::vector<std::shared_ptr<SimplePool>> evicted;
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{
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absl::MutexLock lock(&mutex_);
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pool = cache_.Lookup(spec, [this](const Spec& spec, int request_count) {
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return (request_count >= options_.min_requests_before_pool)
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? create_simple_pool_(spec, options_)
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: nullptr;
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});
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evicted = cache_.Evict(options_.max_pool_count,
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options_.request_count_scrub_interval);
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}
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// Evicted pools, and their buffers, will be released without holding the
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// lock.
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return pool;
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}
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template <class SimplePool, class Spec, class Item>
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Item MultiPool<SimplePool, Spec, Item>::Get(const Spec& spec) {
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std::shared_ptr<SimplePool> pool = RequestPool(spec);
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if (pool) {
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// Note: we release our multipool lock before accessing the simple pool.
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return Item(pool->GetBuffer());
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} else {
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return Item(SimplePool::CreateBufferWithoutPool(spec));
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}
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}
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} // namespace mediapipe
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#endif // MEDIAPIPE_GPU_MULTI_POOL_H_
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