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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 "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_libc.h"
#include <algorithm>
#include <cstdlib>
#include <tuple>
using namespace __xray;
using namespace __sanitizer;
BufferQueue::BufferQueue(std::size_t B, std::size_t N, bool &Success)
: BufferSize(B), Buffers(new std::tuple<Buffer, bool>[N]()),
BufferCount(N), Finalizing{0}, OwnedBuffers(new void *[N]()),
Next(Buffers.get()), First(Buffers.get()), LiveBuffers(0) {
for (size_t i = 0; i < N; ++i) {
auto &T = Buffers[i];
void *Tmp = malloc(BufferSize);
if (Tmp == nullptr) {
Success = false;
return;
}
auto &Buf = std::get<0>(T);
std::get<1>(T) = false;
Buf.Buffer = Tmp;
Buf.Size = B;
OwnedBuffers[i] = Tmp;
}
Success = true;
}
BufferQueue::ErrorCode BufferQueue::getBuffer(Buffer &Buf) {
if (__sanitizer::atomic_load(&Finalizing, __sanitizer::memory_order_acquire))
return ErrorCode::QueueFinalizing;
__sanitizer::SpinMutexLock Guard(&Mutex);
if (LiveBuffers == BufferCount)
return ErrorCode::NotEnoughMemory;
auto &T = *Next;
auto &B = std::get<0>(T);
Buf = B;
++LiveBuffers;
if (++Next == (Buffers.get() + BufferCount))
Next = Buffers.get();
return ErrorCode::Ok;
}
BufferQueue::ErrorCode BufferQueue::releaseBuffer(Buffer &Buf) {
// Blitz through the buffers array to find the buffer.
if (std::none_of(OwnedBuffers.get(), OwnedBuffers.get() + BufferCount,
[&Buf](void *P) { return P == Buf.Buffer; }))
return ErrorCode::UnrecognizedBuffer;
__sanitizer::SpinMutexLock Guard(&Mutex);
// This points to a semantic bug, we really ought to not be releasing more
// buffers than we actually get.
if (LiveBuffers == 0)
return ErrorCode::NotEnoughMemory;
// Now that the buffer has been released, we mark it as "used".
*First = std::make_tuple(Buf, true);
Buf.Buffer = nullptr;
Buf.Size = 0;
--LiveBuffers;
if (++First == (Buffers.get() + BufferCount))
First = Buffers.get();
return ErrorCode::Ok;
}
BufferQueue::ErrorCode BufferQueue::finalize() {
if (__sanitizer::atomic_exchange(&Finalizing, 1,
__sanitizer::memory_order_acq_rel))
return ErrorCode::QueueFinalizing;
return ErrorCode::Ok;
}
BufferQueue::~BufferQueue() {
for (auto I = Buffers.get(), E = Buffers.get() + BufferCount; I != E; ++I) {
auto &T = *I;
auto &Buf = std::get<0>(T);
free(Buf.Buffer);
}
}
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