forked from OSchip/llvm-project
125 lines
3.6 KiB
C++
125 lines
3.6 KiB
C++
//===-- xray_buffer_queue.cc -----------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of XRay, a dynamic runtime instruementation system.
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//
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// Defines the interface for a buffer queue implementation.
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//
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//===----------------------------------------------------------------------===//
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#include "xray_buffer_queue.h"
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#include "sanitizer_common/sanitizer_common.h"
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#include "sanitizer_common/sanitizer_libc.h"
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#include "sanitizer_common/sanitizer_posix.h"
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#include "xray_allocator.h"
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#include "xray_defs.h"
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#include <memory>
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#include <sys/mman.h>
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using namespace __xray;
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using namespace __sanitizer;
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BufferQueue::BufferQueue(size_t B, size_t N,
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bool &Success) XRAY_NEVER_INSTRUMENT
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: BufferSize(B),
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BufferCount(N),
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Mutex(),
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Finalizing{0},
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BackingStore(allocateBuffer(B *N)),
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Buffers(initArray<BufferQueue::BufferRep>(N)),
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Next(Buffers),
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First(Buffers),
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LiveBuffers(0) {
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if (BackingStore == nullptr) {
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Success = false;
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return;
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}
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if (Buffers == nullptr) {
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deallocateBuffer(BackingStore, BufferSize * BufferCount);
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Success = false;
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return;
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}
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for (size_t i = 0; i < N; ++i) {
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auto &T = Buffers[i];
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auto &Buf = T.Buff;
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Buf.Data = reinterpret_cast<char *>(BackingStore) + (BufferSize * i);
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Buf.Size = B;
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atomic_store(&Buf.Extents, 0, memory_order_release);
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T.Used = false;
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}
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Success = true;
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}
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BufferQueue::ErrorCode BufferQueue::getBuffer(Buffer &Buf) {
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if (atomic_load(&Finalizing, memory_order_acquire))
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return ErrorCode::QueueFinalizing;
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SpinMutexLock Guard(&Mutex);
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if (LiveBuffers == BufferCount)
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return ErrorCode::NotEnoughMemory;
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auto &T = *Next;
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auto &B = T.Buff;
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auto Extents = atomic_load(&B.Extents, memory_order_acquire);
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atomic_store(&Buf.Extents, Extents, memory_order_release);
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Buf.Data = B.Data;
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Buf.Size = B.Size;
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T.Used = true;
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++LiveBuffers;
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if (++Next == (Buffers + BufferCount))
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Next = Buffers;
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return ErrorCode::Ok;
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}
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BufferQueue::ErrorCode BufferQueue::releaseBuffer(Buffer &Buf) {
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// Check whether the buffer being referred to is within the bounds of the
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// backing store's range.
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if (Buf.Data < BackingStore ||
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Buf.Data >
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reinterpret_cast<char *>(BackingStore) + (BufferCount * BufferSize))
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return ErrorCode::UnrecognizedBuffer;
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SpinMutexLock Guard(&Mutex);
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// This points to a semantic bug, we really ought to not be releasing more
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// buffers than we actually get.
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if (LiveBuffers == 0)
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return ErrorCode::NotEnoughMemory;
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// Now that the buffer has been released, we mark it as "used".
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auto Extents = atomic_load(&Buf.Extents, memory_order_acquire);
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atomic_store(&First->Buff.Extents, Extents, memory_order_release);
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First->Buff.Data = Buf.Data;
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First->Buff.Size = Buf.Size;
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First->Used = true;
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Buf.Data = nullptr;
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Buf.Size = 0;
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atomic_store(&Buf.Extents, 0, memory_order_release);
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--LiveBuffers;
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if (++First == (Buffers + BufferCount))
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First = Buffers;
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return ErrorCode::Ok;
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}
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BufferQueue::ErrorCode BufferQueue::finalize() {
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if (atomic_exchange(&Finalizing, 1, memory_order_acq_rel))
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return ErrorCode::QueueFinalizing;
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return ErrorCode::Ok;
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}
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BufferQueue::~BufferQueue() {
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for (auto B = Buffers, E = Buffers + BufferCount; B != E; ++B)
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B->~BufferRep();
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deallocateBuffer(Buffers, BufferCount);
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deallocateBuffer(BackingStore, BufferSize * BufferCount);
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}
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