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