third_party/content_analysis_sdk/demo/request_queue.h

   1 // Copyright 2022 The Chromium Authors.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_ANALYSIS_DEMO_REQUST_QUEUE_H_
   6 #define CONTENT_ANALYSIS_DEMO_REQUST_QUEUE_H_
   7
   8 #include <condition_variable>
   9 #include <memory>
  10 #include <mutex>
  11 #include <queue>
  12
  13 #include "content_analysis/sdk/analysis_agent.h"
  14
  15 // This class maintains a list of outstanding content analysis requests to
  16 // process.  Each request is encapsulated in one ContentAnalysisEvent.
  17 // Requests are handled in FIFO order.
  18 class RequestQueue {
  19  public:
  20   using Event = content_analysis::sdk::ContentAnalysisEvent;
  21
  22   RequestQueue() = default;
  23   virtual ~RequestQueue() = default;
  24
  25   // Push a new content analysis event into the queue.
  26   void push(std::unique_ptr<Event> event) {
  27     std::lock_guard<std::mutex> lock(mutex_);
  28
  29     events_.push(std::move(event));
  30
  31     // Wake before leaving to prevent unpredicatable scheduling.
  32     cv_.notify_one();
  33   }
  34
  35   // Pop the next request from the queue, blocking if necessary until an event
  36   // is available.  Returns a nullptr if the queue will produce no more
  37   // events.
  38   std::unique_ptr<Event> pop() {
  39     std::unique_lock<std::mutex> lock(mutex_);
  40
  41     while (!abort_ && events_.size() == 0)
  42       cv_.wait(lock);
  43
  44     std::unique_ptr<Event> event;
  45     if (!abort_) {
  46       event = std::move(events_.front());
  47       events_.pop();
  48     }
  49
  50     return event;
  51   }
  52
  53   // Marks the queue as aborted.  pop() will now return nullptr.
  54   void abort() {
  55     std::lock_guard<std::mutex> lg(mutex_);
  56
  57     abort_ = true;
  58
  59     // Wake before leaving to prevent unpredicatable scheduling.
  60     cv_.notify_all();
  61   }
  62
  63  private:
  64   std::queue<std::unique_ptr<Event>> events_;
  65   std::mutex mutex_;
  66   std::condition_variable cv_;
  67   bool abort_ = false;
  68 };
  69
  70 #endif  // CONTENT_ANALYSIS_DEMO_REQUST_QUEUE_H_