first commit

.venv/Lib/site-packages/pyarrow/include/arrow/vendored/ProducerConsumerQueue.h

@@ -0,0 +1,217 @@
+// Vendored from git tag v2021.02.15.00
+
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed 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.
+ */
+
+// @author Bo Hu (bhu@fb.com)
+// @author Jordan DeLong (delong.j@fb.com)
+
+// This file has been modified as part of Apache Arrow to conform to
+// Apache Arrow's coding conventions
+
+#pragma once
+
+#include <atomic>
+#include <cassert>
+#include <cstdlib>
+#include <memory>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
+
+namespace arrow_vendored {
+namespace folly {
+
+// Vendored from folly/Portability.h
+namespace {
+#if defined(__arm__)
+#define FOLLY_ARM 1
+#else
+#define FOLLY_ARM 0
+#endif
+
+#if defined(__s390x__)
+#define FOLLY_S390X 1
+#else
+#define FOLLY_S390X 0
+#endif
+
+constexpr bool kIsArchArm = FOLLY_ARM == 1;
+constexpr bool kIsArchS390X = FOLLY_S390X == 1;
+}  // namespace
+
+// Vendored from folly/lang/Align.h
+namespace {
+
+constexpr std::size_t hardware_destructive_interference_size =
+    (kIsArchArm || kIsArchS390X) ? 64 : 128;
+
+}  // namespace
+
+/*
+ * ProducerConsumerQueue is a one producer and one consumer queue
+ * without locks.
+ */
+template <class T>
+struct ProducerConsumerQueue {
+  typedef T value_type;
+
+  ProducerConsumerQueue(const ProducerConsumerQueue&) = delete;
+  ProducerConsumerQueue& operator=(const ProducerConsumerQueue&) = delete;
+
+  // size must be >= 2.
+  //
+  // Also, note that the number of usable slots in the queue at any
+  // given time is actually (size-1), so if you start with an empty queue,
+  // IsFull() will return true after size-1 insertions.
+  explicit ProducerConsumerQueue(uint32_t size)
+      : size_(size),
+        records_(static_cast<T*>(std::malloc(sizeof(T) * size))),
+        readIndex_(0),
+        writeIndex_(0) {
+    assert(size >= 2);
+    if (!records_) {
+      throw std::bad_alloc();
+    }
+  }
+
+  ~ProducerConsumerQueue() {
+    // We need to destruct anything that may still exist in our queue.
+    // (No real synchronization needed at destructor time: only one
+    // thread can be doing this.)
+    if (!std::is_trivially_destructible<T>::value) {
+      size_t readIndex = readIndex_;
+      size_t endIndex = writeIndex_;
+      while (readIndex != endIndex) {
+        records_[readIndex].~T();
+        if (++readIndex == size_) {
+          readIndex = 0;
+        }
+      }
+    }
+
+    std::free(records_);
+  }
+
+  template <class... Args>
+  bool Write(Args&&... recordArgs) {
+    auto const currentWrite = writeIndex_.load(std::memory_order_relaxed);
+    auto nextRecord = currentWrite + 1;
+    if (nextRecord == size_) {
+      nextRecord = 0;
+    }
+    if (nextRecord != readIndex_.load(std::memory_order_acquire)) {
+      new (&records_[currentWrite]) T(std::forward<Args>(recordArgs)...);
+      writeIndex_.store(nextRecord, std::memory_order_release);
+      return true;
+    }
+
+    // queue is full
+    return false;
+  }
+
+  // move the value at the front of the queue to given variable
+  bool Read(T& record) {
+    auto const currentRead = readIndex_.load(std::memory_order_relaxed);
+    if (currentRead == writeIndex_.load(std::memory_order_acquire)) {
+      // queue is empty
+      return false;
+    }
+
+    auto nextRecord = currentRead + 1;
+    if (nextRecord == size_) {
+      nextRecord = 0;
+    }
+    record = std::move(records_[currentRead]);
+    records_[currentRead].~T();
+    readIndex_.store(nextRecord, std::memory_order_release);
+    return true;
+  }
+
+  // pointer to the value at the front of the queue (for use in-place) or
+  // nullptr if empty.
+  T* FrontPtr() {
+    auto const currentRead = readIndex_.load(std::memory_order_relaxed);
+    if (currentRead == writeIndex_.load(std::memory_order_acquire)) {
+      // queue is empty
+      return nullptr;
+    }
+    return &records_[currentRead];
+  }
+
+  // queue must not be empty
+  void PopFront() {
+    auto const currentRead = readIndex_.load(std::memory_order_relaxed);
+    assert(currentRead != writeIndex_.load(std::memory_order_acquire));
+
+    auto nextRecord = currentRead + 1;
+    if (nextRecord == size_) {
+      nextRecord = 0;
+    }
+    records_[currentRead].~T();
+    readIndex_.store(nextRecord, std::memory_order_release);
+  }
+
+  bool IsEmpty() const {
+    return readIndex_.load(std::memory_order_acquire) ==
+           writeIndex_.load(std::memory_order_acquire);
+  }
+
+  bool IsFull() const {
+    auto nextRecord = writeIndex_.load(std::memory_order_acquire) + 1;
+    if (nextRecord == size_) {
+      nextRecord = 0;
+    }
+    if (nextRecord != readIndex_.load(std::memory_order_acquire)) {
+      return false;
+    }
+    // queue is full
+    return true;
+  }
+
+  // * If called by consumer, then true size may be more (because producer may
+  //   be adding items concurrently).
+  // * If called by producer, then true size may be less (because consumer may
+  //   be removing items concurrently).
+  // * It is undefined to call this from any other thread.
+  size_t SizeGuess() const {
+    int ret = writeIndex_.load(std::memory_order_acquire) -
+              readIndex_.load(std::memory_order_acquire);
+    if (ret < 0) {
+      ret += size_;
+    }
+    return ret;
+  }
+
+  // maximum number of items in the queue.
+  size_t capacity() const { return size_ - 1; }
+
+ private:
+  using AtomicIndex = std::atomic<unsigned int>;
+
+  char pad0_[hardware_destructive_interference_size];
+  const uint32_t size_;
+  T* const records_;
+
+  AtomicIndex readIndex_;
+  char pad1_[hardware_destructive_interference_size - sizeof(AtomicIndex)];
+  AtomicIndex writeIndex_;
+
+  char pad2_[hardware_destructive_interference_size - sizeof(AtomicIndex)];
+};
+
+}  // namespace folly
+}  // namespace arrow_vendored