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//===-- xray_buffer_queue.cc -----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of XRay, a dynamic runtime instruementation system.
//
// Defines the interface for a buffer queue implementation.
//
//===----------------------------------------------------------------------===//
#include "xray_buffer_queue.h"
#include <cassert>
#include <cstdlib>
using namespace __xray;
BufferQueue::BufferQueue(std::size_t B, std::size_t N, bool &Success)
: BufferSize(B), Buffers(N), Mutex(), OwnedBuffers(), Finalizing(false) {
for (auto &T : Buffers) {
void *Tmp = malloc(BufferSize);
if (Tmp == nullptr) {
Success = false;
return;
}
auto &Buf = std::get<0>(T);
Buf.Buffer = Tmp;
Buf.Size = B;
OwnedBuffers.emplace(Tmp);
}
Success = true;
}
std::error_code BufferQueue::getBuffer(Buffer &Buf) {
if (Finalizing.load(std::memory_order_acquire))
return std::make_error_code(std::errc::state_not_recoverable);
std::lock_guard<std::mutex> Guard(Mutex);
if (Buffers.empty())
return std::make_error_code(std::errc::not_enough_memory);
auto &T = Buffers.front();
auto &B = std::get<0>(T);
Buf = B;
B.Buffer = nullptr;
B.Size = 0;
Buffers.pop_front();
return {};
}
std::error_code BufferQueue::releaseBuffer(Buffer &Buf) {
if (OwnedBuffers.count(Buf.Buffer) == 0)
return std::make_error_code(std::errc::argument_out_of_domain);
std::lock_guard<std::mutex> Guard(Mutex);
// Now that the buffer has been released, we mark it as "used".
Buffers.emplace(Buffers.end(), Buf, true /* used */);
Buf.Buffer = nullptr;
Buf.Size = 0;
return {};
}
std::error_code BufferQueue::finalize() {
if (Finalizing.exchange(true, std::memory_order_acq_rel))
return std::make_error_code(std::errc::state_not_recoverable);
return {};
}
BufferQueue::~BufferQueue() {
for (auto &T : Buffers) {
auto &Buf = std::get<0>(T);
free(Buf.Buffer);
}
}
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