Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 230 insertions, 0 deletions

diff --git a/src/rocksdb/util/timer_queue.h b/src/rocksdb/util/timer_queue.h
new file mode 100644
index 00000000..bd8a4f85
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+++ b/src/rocksdb/util/timer_queue.h
@@ -0,0 +1,230 @@
+//  Portions Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Borrowed from
+// http://www.crazygaze.com/blog/2016/03/24/portable-c-timer-queue/
+// Timer Queue
+//
+// License
+//
+// The source code in this article is licensed under the CC0 license, so feel
+// free to copy, modify, share, do whatever you want with it.
+// No attribution is required, but Ill be happy if you do.
+// CC0 license
+
+// The person who associated a work with this deed has dedicated the work to the
+// public domain by waiving all of his or her rights to the work worldwide
+// under copyright law, including all related and neighboring rights, to the
+// extent allowed by law.  You can copy, modify, distribute and perform the
+// work, even for commercial purposes, all without asking permission.
+
+#pragma once
+
+#include <assert.h>
+#include <chrono>
+#include <condition_variable>
+#include <functional>
+#include <queue>
+#include <thread>
+#include <utility>
+#include <vector>
+
+#include "port/port.h"
+#include "util/sync_point.h"
+
+// Allows execution of handlers at a specified time in the future
+// Guarantees:
+//  - All handlers are executed ONCE, even if cancelled (aborted parameter will
+// be set to true)
+//      - If TimerQueue is destroyed, it will cancel all handlers.
+//  - Handlers are ALWAYS executed in the Timer Queue worker thread.
+//  - Handlers execution order is NOT guaranteed
+//
+////////////////////////////////////////////////////////////////////////////////
+// borrowed from
+// http://www.crazygaze.com/blog/2016/03/24/portable-c-timer-queue/
+class TimerQueue {
+ public:
+  TimerQueue() : m_th(&TimerQueue::run, this) {}
+
+  ~TimerQueue() { shutdown(); }
+
+  // This function is not thread-safe.
+  void shutdown() {
+    if (closed_) {
+      return;
+    }
+    cancelAll();
+    // Abusing the timer queue to trigger the shutdown.
+    add(0, [this](bool) {
+      m_finish = true;
+      return std::make_pair(false, 0);
+    });
+    m_th.join();
+    closed_ = true;
+  }
+
+  // Adds a new timer
+  // \return
+  //  Returns the ID of the new timer. You can use this ID to cancel the
+  // timer
+  uint64_t add(int64_t milliseconds,
+               std::function<std::pair<bool, int64_t>(bool)> handler) {
+    WorkItem item;
+    Clock::time_point tp = Clock::now();
+    item.end = tp + std::chrono::milliseconds(milliseconds);
+    TEST_SYNC_POINT_CALLBACK("TimeQueue::Add:item.end", &item.end);
+    item.period = milliseconds;
+    item.handler = std::move(handler);
+
+    std::unique_lock<std::mutex> lk(m_mtx);
+    uint64_t id = ++m_idcounter;
+    item.id = id;
+    m_items.push(std::move(item));
+
+    // Something changed, so wake up timer thread
+    m_checkWork.notify_one();
+    return id;
+  }
+
+  // Cancels the specified timer
+  // \return
+  //  1 if the timer was cancelled.
+  //  0 if you were too late to cancel (or the timer ID was never valid to
+  // start with)
+  size_t cancel(uint64_t id) {
+    // Instead of removing the item from the container (thus breaking the
+    // heap integrity), we set the item as having no handler, and put
+    // that handler on a new item at the top for immediate execution
+    // The timer thread will then ignore the original item, since it has no
+    // handler.
+    std::unique_lock<std::mutex> lk(m_mtx);
+    for (auto&& item : m_items.getContainer()) {
+      if (item.id == id && item.handler) {
+        WorkItem newItem;
+        // Zero time, so it stays at the top for immediate execution
+        newItem.end = Clock::time_point();
+        newItem.id = 0;  // Means it is a canceled item
+        // Move the handler from item to newitem (thus clearing item)
+        newItem.handler = std::move(item.handler);
+        m_items.push(std::move(newItem));
+
+        // Something changed, so wake up timer thread
+        m_checkWork.notify_one();
+        return 1;
+      }
+    }
+    return 0;
+  }
+
+  // Cancels all timers
+  // \return
+  //  The number of timers cancelled
+  size_t cancelAll() {
+    // Setting all "end" to 0 (for immediate execution) is ok,
+    // since it maintains the heap integrity
+    std::unique_lock<std::mutex> lk(m_mtx);
+    m_cancel = true;
+    for (auto&& item : m_items.getContainer()) {
+      if (item.id && item.handler) {
+        item.end = Clock::time_point();
+        item.id = 0;
+      }
+    }
+    auto ret = m_items.size();
+
+    m_checkWork.notify_one();
+    return ret;
+  }
+
+ private:
+  using Clock = std::chrono::steady_clock;
+  TimerQueue(const TimerQueue&) = delete;
+  TimerQueue& operator=(const TimerQueue&) = delete;
+
+  void run() {
+    std::unique_lock<std::mutex> lk(m_mtx);
+    while (!m_finish) {
+      auto end = calcWaitTime_lock();
+      if (end.first) {
+        // Timers found, so wait until it expires (or something else
+        // changes)
+        m_checkWork.wait_until(lk, end.second);
+      } else {
+        // No timers exist, so wait forever until something changes
+        m_checkWork.wait(lk);
+      }
+
+      // Check and execute as much work as possible, such as, all expired
+      // timers
+      checkWork(&lk);
+    }
+
+    // If we are shutting down, we should not have any items left,
+    // since the shutdown cancels all items
+    assert(m_items.size() == 0);
+  }
+
+  std::pair<bool, Clock::time_point> calcWaitTime_lock() {
+    while (m_items.size()) {
+      if (m_items.top().handler) {
+        // Item present, so return the new wait time
+        return std::make_pair(true, m_items.top().end);
+      } else {
+        // Discard empty handlers (they were cancelled)
+        m_items.pop();
+      }
+    }
+
+    // No items found, so return no wait time (causes the thread to wait
+    // indefinitely)
+    return std::make_pair(false, Clock::time_point());
+  }
+
+  void checkWork(std::unique_lock<std::mutex>* lk) {
+    while (m_items.size() && m_items.top().end <= Clock::now()) {
+      WorkItem item(m_items.top());
+      m_items.pop();
+
+      if (item.handler) {
+        (*lk).unlock();
+        auto reschedule_pair = item.handler(item.id == 0);
+        (*lk).lock();
+        if (!m_cancel && reschedule_pair.first) {
+          int64_t new_period = (reschedule_pair.second == -1)
+                                   ? item.period
+                                   : reschedule_pair.second;
+
+          item.period = new_period;
+          item.end = Clock::now() + std::chrono::milliseconds(new_period);
+          m_items.push(std::move(item));
+        }
+      }
+    }
+  }
+
+  bool m_finish = false;
+  bool m_cancel = false;
+  uint64_t m_idcounter = 0;
+  std::condition_variable m_checkWork;
+
+  struct WorkItem {
+    Clock::time_point end;
+    int64_t period;
+    uint64_t id;  // id==0 means it was cancelled
+    std::function<std::pair<bool, int64_t>(bool)> handler;
+    bool operator>(const WorkItem& other) const { return end > other.end; }
+  };
+
+  std::mutex m_mtx;
+  // Inheriting from priority_queue, so we can access the internal container
+  class Queue : public std::priority_queue<WorkItem, std::vector<WorkItem>,
+                                           std::greater<WorkItem>> {
+   public:
+    std::vector<WorkItem>& getContainer() { return this->c; }
+  } m_items;
+  rocksdb::port::Thread m_th;
+  bool closed_ = false;
+};