You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
116 lines
3.3 KiB
116 lines
3.3 KiB
/*
|
|
* Copyright (C) 2015 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
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* 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 <err.h>
|
|
#include <inttypes.h>
|
|
#include <stdatomic.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/mman.h>
|
|
#include <unistd.h>
|
|
|
|
#include "err.h"
|
|
#include "Pointers.h"
|
|
|
|
Pointers::Pointers(size_t max_allocs) {
|
|
size_t pagesize = getpagesize();
|
|
// Create a mmap that contains a 4:1 ratio of allocations to entries.
|
|
// Align to a page.
|
|
pointers_size_ = (max_allocs * 4 * sizeof(pointer_data) + pagesize - 1) & ~(pagesize - 1);
|
|
max_pointers_ = pointers_size_ / sizeof(pointer_data);
|
|
void* memory =
|
|
mmap(nullptr, pointers_size_, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
|
|
if (memory == MAP_FAILED) {
|
|
err(1, "Unable to allocate data for pointer hash: %zu total_allocs\n", max_allocs);
|
|
}
|
|
// Set all of the pointers to be empty.
|
|
memset(memory, 0, pointers_size_);
|
|
pointers_ = reinterpret_cast<pointer_data*>(memory);
|
|
}
|
|
|
|
Pointers::~Pointers() {
|
|
if (pointers_ != nullptr) {
|
|
munmap(pointers_, pointers_size_);
|
|
pointers_ = nullptr;
|
|
}
|
|
}
|
|
|
|
void Pointers::Add(uintptr_t key_pointer, void* pointer) {
|
|
pointer_data* data = FindEmpty(key_pointer);
|
|
if (data == nullptr) {
|
|
err(1, "No empty entry found for 0x%" PRIxPTR "\n", key_pointer);
|
|
}
|
|
atomic_store(&data->key_pointer, key_pointer);
|
|
data->pointer = pointer;
|
|
}
|
|
|
|
void* Pointers::Remove(uintptr_t key_pointer) {
|
|
if (key_pointer == 0) {
|
|
err(1, "Illegal zero value passed to Remove\n");
|
|
}
|
|
|
|
pointer_data* data = Find(key_pointer);
|
|
if (data == nullptr) {
|
|
err(1, "No pointer value found for 0x%" PRIxPTR "\n", key_pointer);
|
|
}
|
|
|
|
void* pointer = data->pointer;
|
|
atomic_store(&data->key_pointer, uintptr_t(0));
|
|
|
|
return pointer;
|
|
}
|
|
|
|
Pointers::pointer_data* Pointers::Find(uintptr_t key_pointer) {
|
|
size_t index = GetHash(key_pointer);
|
|
for (size_t entries = max_pointers_; entries != 0; entries--) {
|
|
if (atomic_load(&pointers_[index].key_pointer) == key_pointer) {
|
|
return pointers_ + index;
|
|
}
|
|
if (++index == max_pointers_) {
|
|
index = 0;
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
Pointers::pointer_data* Pointers::FindEmpty(uintptr_t key_pointer) {
|
|
size_t index = GetHash(key_pointer);
|
|
for (size_t entries = 0; entries < max_pointers_; entries++) {
|
|
uintptr_t empty = 0;
|
|
if (atomic_compare_exchange_strong(&pointers_[index].key_pointer, &empty,
|
|
uintptr_t(1))) {
|
|
return pointers_ + index;
|
|
}
|
|
if (++index == max_pointers_) {
|
|
index = 0;
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
size_t Pointers::GetHash(uintptr_t key_pointer) {
|
|
return key_pointer % max_pointers_;
|
|
}
|
|
|
|
void Pointers::FreeAll() {
|
|
for (size_t i = 0; i < max_pointers_; i++) {
|
|
if (atomic_load(&pointers_[i].key_pointer) != 0) {
|
|
free(pointers_[i].pointer);
|
|
}
|
|
}
|
|
}
|