src/compiler-rt/lib/xray/xray_buffer_queue.cc

   1 //===-- xray_buffer_queue.cc -----------------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file is a part of XRay, a dynamic runtime instruementation system.
  11 //
  12 // Defines the interface for a buffer queue implementation.
  13 //
  14 //===----------------------------------------------------------------------===//
  15 #include "xray_buffer_queue.h"
  16 #include <cassert>
  17 #include <cstdlib>
  18
  19 using namespace __xray;
  20
  21 BufferQueue::BufferQueue(std::size_t B, std::size_t N)
  22     : BufferSize(B), Buffers(N), Mutex(), OwnedBuffers(), Finalizing(false) {
  23   for (auto &Buf : Buffers) {
  24     void *Tmp = malloc(BufferSize);
  25     Buf.Buffer = Tmp;
  26     Buf.Size = B;
  27     if (Tmp != 0)
  28       OwnedBuffers.insert(Tmp);
  29   }
  30 }
  31
  32 std::error_code BufferQueue::getBuffer(Buffer &Buf) {
  33   if (Finalizing.load(std::memory_order_acquire))
  34     return std::make_error_code(std::errc::state_not_recoverable);
  35   std::lock_guard<std::mutex> Guard(Mutex);
  36   if (Buffers.empty())
  37     return std::make_error_code(std::errc::not_enough_memory);
  38   Buf = Buffers.front();
  39   Buffers.pop_front();
  40   return {};
  41 }
  42
  43 std::error_code BufferQueue::releaseBuffer(Buffer &Buf) {
  44   if (OwnedBuffers.count(Buf.Buffer) == 0)
  45     return std::make_error_code(std::errc::argument_out_of_domain);
  46   std::lock_guard<std::mutex> Guard(Mutex);
  47   Buffers.push_back(Buf);
  48   Buf.Buffer = nullptr;
  49   Buf.Size = BufferSize;
  50   return {};
  51 }
  52
  53 std::error_code BufferQueue::finalize() {
  54   if (Finalizing.exchange(true, std::memory_order_acq_rel))
  55     return std::make_error_code(std::errc::state_not_recoverable);
  56   return {};
  57 }
  58
  59 BufferQueue::~BufferQueue() {
  60   for (auto &Buf : Buffers) {
  61     free(Buf.Buffer);
  62     Buf.Buffer = nullptr;
  63     Buf.Size = 0;
  64   }
  65 }