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Diffstat (limited to 'src/support/lockedpool.cpp')
| -rw-r--r-- | src/support/lockedpool.cpp | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/src/support/lockedpool.cpp b/src/support/lockedpool.cpp new file mode 100644 index 0000000000..63050f006b --- /dev/null +++ b/src/support/lockedpool.cpp @@ -0,0 +1,383 @@ +// Copyright (c) 2016 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include "support/lockedpool.h" +#include "support/cleanse.h" + +#if defined(HAVE_CONFIG_H) +#include "config/bitcoin-config.h" +#endif + +#ifdef WIN32 +#ifdef _WIN32_WINNT +#undef _WIN32_WINNT +#endif +#define _WIN32_WINNT 0x0501 +#define WIN32_LEAN_AND_MEAN 1 +#ifndef NOMINMAX +#define NOMINMAX +#endif +#include <windows.h> +#else +#include <sys/mman.h> // for mmap +#include <sys/resource.h> // for getrlimit +#include <limits.h> // for PAGESIZE +#include <unistd.h> // for sysconf +#endif + +LockedPoolManager* LockedPoolManager::_instance = NULL; +std::once_flag LockedPoolManager::init_flag; + +/*******************************************************************************/ +// Utilities +// +/** Align up to power of 2 */ +static inline size_t align_up(size_t x, size_t align) +{ + return (x + align - 1) & ~(align - 1); +} + +/*******************************************************************************/ +// Implementation: Arena + +Arena::Arena(void *base_in, size_t size_in, size_t alignment_in): + base(static_cast<char*>(base_in)), end(static_cast<char*>(base_in) + size_in), alignment(alignment_in) +{ + // Start with one free chunk that covers the entire arena + chunks.emplace(base, Chunk(size_in, false)); +} + +Arena::~Arena() +{ +} + +void* Arena::alloc(size_t size) +{ + // Round to next multiple of alignment + size = align_up(size, alignment); + + // Don't handle zero-sized chunks, or those bigger than MAX_SIZE + if (size == 0 || size >= Chunk::MAX_SIZE) { + return nullptr; + } + + for (auto& chunk: chunks) { + if (!chunk.second.isInUse() && size <= chunk.second.getSize()) { + char* base = chunk.first; + size_t leftover = chunk.second.getSize() - size; + if (leftover > 0) { // Split chunk + chunks.emplace(base + size, Chunk(leftover, false)); + chunk.second.setSize(size); + } + chunk.second.setInUse(true); + return reinterpret_cast<void*>(base); + } + } + return nullptr; +} + +void Arena::free(void *ptr) +{ + // Freeing the NULL pointer is OK. + if (ptr == nullptr) { + return; + } + auto i = chunks.find(static_cast<char*>(ptr)); + if (i == chunks.end() || !i->second.isInUse()) { + throw std::runtime_error("Arena: invalid or double free"); + } + + i->second.setInUse(false); + + if (i != chunks.begin()) { // Absorb into previous chunk if exists and free + auto prev = i; + --prev; + if (!prev->second.isInUse()) { + // Absorb current chunk size into previous chunk. + prev->second.setSize(prev->second.getSize() + i->second.getSize()); + // Erase current chunk. Erasing does not invalidate current + // iterators for a map, except for that pointing to the object + // itself, which will be overwritten in the next statement. + chunks.erase(i); + // From here on, the previous chunk is our current chunk. + i = prev; + } + } + auto next = i; + ++next; + if (next != chunks.end()) { // Absorb next chunk if exists and free + if (!next->second.isInUse()) { + // Absurb next chunk size into current chunk + i->second.setSize(i->second.getSize() + next->second.getSize()); + // Erase next chunk. + chunks.erase(next); + } + } +} + +Arena::Stats Arena::stats() const +{ + Arena::Stats r; + r.used = r.free = r.total = r.chunks_used = r.chunks_free = 0; + for (const auto& chunk: chunks) { + if (chunk.second.isInUse()) { + r.used += chunk.second.getSize(); + r.chunks_used += 1; + } else { + r.free += chunk.second.getSize(); + r.chunks_free += 1; + } + r.total += chunk.second.getSize(); + } + return r; +} + +#ifdef ARENA_DEBUG +void Arena::walk() const +{ + for (const auto& chunk: chunks) { + std::cout << + "0x" << std::hex << std::setw(16) << std::setfill('0') << chunk.first << + " 0x" << std::hex << std::setw(16) << std::setfill('0') << chunk.second.getSize() << + " 0x" << chunk.second.isInUse() << std::endl; + } + std::cout << std::endl; +} +#endif + +/*******************************************************************************/ +// Implementation: Win32LockedPageAllocator + +#ifdef WIN32 +/** LockedPageAllocator specialized for Windows. + */ +class Win32LockedPageAllocator: public LockedPageAllocator +{ +public: + Win32LockedPageAllocator(); + void* AllocateLocked(size_t len, bool *lockingSuccess); + void FreeLocked(void* addr, size_t len); + size_t GetLimit(); +private: + size_t page_size; +}; + +Win32LockedPageAllocator::Win32LockedPageAllocator() +{ + // Determine system page size in bytes + SYSTEM_INFO sSysInfo; + GetSystemInfo(&sSysInfo); + page_size = sSysInfo.dwPageSize; +} +void *Win32LockedPageAllocator::AllocateLocked(size_t len, bool *lockingSuccess) +{ + len = align_up(len, page_size); + void *addr = VirtualAlloc(nullptr, len, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE); + if (addr) { + // VirtualLock is used to attempt to keep keying material out of swap. Note + // that it does not provide this as a guarantee, but, in practice, memory + // that has been VirtualLock'd almost never gets written to the pagefile + // except in rare circumstances where memory is extremely low. + *lockingSuccess = VirtualLock(const_cast<void*>(addr), len) != 0; + } + return addr; +} +void Win32LockedPageAllocator::FreeLocked(void* addr, size_t len) +{ + len = align_up(len, page_size); + memory_cleanse(addr, len); + VirtualUnlock(const_cast<void*>(addr), len); +} + +size_t Win32LockedPageAllocator::GetLimit() +{ + // TODO is there a limit on windows, how to get it? + return std::numeric_limits<size_t>::max(); +} +#endif + +/*******************************************************************************/ +// Implementation: PosixLockedPageAllocator + +#ifndef WIN32 +/** LockedPageAllocator specialized for OSes that don't try to be + * special snowflakes. + */ +class PosixLockedPageAllocator: public LockedPageAllocator +{ +public: + PosixLockedPageAllocator(); + void* AllocateLocked(size_t len, bool *lockingSuccess); + void FreeLocked(void* addr, size_t len); + size_t GetLimit(); +private: + size_t page_size; +}; + +PosixLockedPageAllocator::PosixLockedPageAllocator() +{ + // Determine system page size in bytes +#if defined(PAGESIZE) // defined in limits.h + page_size = PAGESIZE; +#else // assume some POSIX OS + page_size = sysconf(_SC_PAGESIZE); +#endif +} +void *PosixLockedPageAllocator::AllocateLocked(size_t len, bool *lockingSuccess) +{ + void *addr; + len = align_up(len, page_size); + addr = mmap(nullptr, len, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); + if (addr) { + *lockingSuccess = mlock(addr, len) == 0; + } + return addr; +} +void PosixLockedPageAllocator::FreeLocked(void* addr, size_t len) +{ + len = align_up(len, page_size); + memory_cleanse(addr, len); + munlock(addr, len); + munmap(addr, len); +} +size_t PosixLockedPageAllocator::GetLimit() +{ +#ifdef RLIMIT_MEMLOCK + struct rlimit rlim; + if (getrlimit(RLIMIT_MEMLOCK, &rlim) == 0) { + if (rlim.rlim_cur != RLIM_INFINITY) { + return rlim.rlim_cur; + } + } +#endif + return std::numeric_limits<size_t>::max(); +} +#endif + +/*******************************************************************************/ +// Implementation: LockedPool + +LockedPool::LockedPool(std::unique_ptr<LockedPageAllocator> allocator_in, LockingFailed_Callback lf_cb_in): + allocator(std::move(allocator_in)), lf_cb(lf_cb_in), cumulative_bytes_locked(0) +{ +} + +LockedPool::~LockedPool() +{ +} +void* LockedPool::alloc(size_t size) +{ + std::lock_guard<std::mutex> lock(mutex); + // Try allocating from each current arena + for (auto &arena: arenas) { + void *addr = arena.alloc(size); + if (addr) { + return addr; + } + } + // If that fails, create a new one + if (new_arena(ARENA_SIZE, ARENA_ALIGN)) { + return arenas.back().alloc(size); + } + return nullptr; +} + +void LockedPool::free(void *ptr) +{ + std::lock_guard<std::mutex> lock(mutex); + // TODO we can do better than this linear search by keeping a map of arena + // extents to arena, and looking up the address. + for (auto &arena: arenas) { + if (arena.addressInArena(ptr)) { + arena.free(ptr); + return; + } + } + throw std::runtime_error("LockedPool: invalid address not pointing to any arena"); +} + +LockedPool::Stats LockedPool::stats() const +{ + std::lock_guard<std::mutex> lock(mutex); + LockedPool::Stats r; + r.used = r.free = r.total = r.chunks_used = r.chunks_free = 0; + r.locked = cumulative_bytes_locked; + for (const auto &arena: arenas) { + Arena::Stats i = arena.stats(); + r.used += i.used; + r.free += i.free; + r.total += i.total; + r.chunks_used += i.chunks_used; + r.chunks_free += i.chunks_free; + } + return r; +} + +bool LockedPool::new_arena(size_t size, size_t align) +{ + bool locked; + // If this is the first arena, handle this specially: Cap the upper size + // by the process limit. This makes sure that the first arena will at least + // be locked. An exception to this is if the process limit is 0: + // in this case no memory can be locked at all so we'll skip past this logic. + if (arenas.empty()) { + size_t limit = allocator->GetLimit(); + if (limit > 0) { + size = std::min(size, limit); + } + } + void *addr = allocator->AllocateLocked(size, &locked); + if (!addr) { + return false; + } + if (locked) { + cumulative_bytes_locked += size; + } else if (lf_cb) { // Call the locking-failed callback if locking failed + if (!lf_cb()) { // If the callback returns false, free the memory and fail, otherwise consider the user warned and proceed. + allocator->FreeLocked(addr, size); + return false; + } + } + arenas.emplace_back(allocator.get(), addr, size, align); + return true; +} + +LockedPool::LockedPageArena::LockedPageArena(LockedPageAllocator *allocator_in, void *base_in, size_t size_in, size_t align_in): + Arena(base_in, size_in, align_in), base(base_in), size(size_in), allocator(allocator_in) +{ +} +LockedPool::LockedPageArena::~LockedPageArena() +{ + allocator->FreeLocked(base, size); +} + +/*******************************************************************************/ +// Implementation: LockedPoolManager +// +LockedPoolManager::LockedPoolManager(std::unique_ptr<LockedPageAllocator> allocator): + LockedPool(std::move(allocator), &LockedPoolManager::LockingFailed) +{ +} + +bool LockedPoolManager::LockingFailed() +{ + // TODO: log something but how? without including util.h + return true; +} + +void LockedPoolManager::CreateInstance() +{ + // Using a local static instance guarantees that the object is initialized + // when it's first needed and also deinitialized after all objects that use + // it are done with it. I can think of one unlikely scenario where we may + // have a static deinitialization order/problem, but the check in + // LockedPoolManagerBase's destructor helps us detect if that ever happens. +#ifdef WIN32 + std::unique_ptr<LockedPageAllocator> allocator(new Win32LockedPageAllocator()); +#else + std::unique_ptr<LockedPageAllocator> allocator(new PosixLockedPageAllocator()); +#endif + static LockedPoolManager instance(std::move(allocator)); + LockedPoolManager::_instance = &instance; +} |