84 lines
2.2 KiB
C++
84 lines
2.2 KiB
C++
/*
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* Copyright (C) 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdint.h>
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#ifdef XP_WIN
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# include <windows.h>
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#else
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# include <time.h>
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# include <unistd.h>
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#endif
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#include "mozilla/Flow.h"
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// Some infrastructure that we use for computing a per process UUID
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// FNV-1a hasher
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// We use this to construct a randomish UUID by hashing the PID and the
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// current time.
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//
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// It's probably not the best choice of hasher but it works for Perfetto
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// so it's good enough for us.
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struct Hasher {
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static const uint64_t kOffsetBasis = 14695981039346656037ULL;
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static const uint64_t kPrime = 1099511628211ULL;
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uint64_t hash = kOffsetBasis;
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void Update(const void* data, size_t size) {
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const uint8_t* ptr = static_cast<const uint8_t*>(data);
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for (size_t i = 0; i < size; ++i) {
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hash ^= ptr[i];
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hash *= kPrime;
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}
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}
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void Update(uint64_t value) { Update(&value, sizeof(value)); }
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void Update(uint32_t value) { Update(&value, sizeof(value)); }
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uint64_t Get() const { return hash; }
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};
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static uint64_t CurrentTime() {
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#ifdef XP_WIN
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return GetTickCount64();
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#else
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timespec ts;
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clock_gettime(CLOCK_MONOTONIC, &ts);
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return ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
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#endif
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}
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static uint64_t CurrentPID() {
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#ifdef XP_WIN
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return GetCurrentProcessId();
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#else
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return getpid();
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#endif
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}
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// This is inspired by the perfetto code in TrackRegistry::ComputeProcessUuid
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uint64_t ComputeProcessUUID() {
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auto pid = CurrentPID();
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auto time = CurrentTime();
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Hasher hasher;
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hasher.Update(pid);
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hasher.Update(time);
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return hasher.Get();
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}
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MFBT_DATA uint64_t gProcessUUID;
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MFBT_API void Flow::Init() { gProcessUUID = ComputeProcessUUID(); }
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