allocators: split allocators and pagelocker

Pagelocker is only needed for secure (usually wallet) operations, so don't make
the zero-after-free allocator depend on it.

1 files changed, 0 insertions, 268 deletions

diff --git a/src/allocators.h b/src/allocators.h
deleted file mode 100644
index 8ffe015b9..000000000
--- a/src/allocators.h
+++ /dev/null
@@ -1,268 +0,0 @@
-// Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2013 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#ifndef BITCOIN_ALLOCATORS_H
-#define BITCOIN_ALLOCATORS_H
-
-#include "support/cleanse.h"
-
-#include <map>
-#include <string>
-#include <string.h>
-#include <vector>
-
-#include <boost/thread/mutex.hpp>
-#include <boost/thread/once.hpp>
-
-/**
- * Thread-safe class to keep track of locked (ie, non-swappable) memory pages.
- *
- * Memory locks do not stack, that is, pages which have been locked several times by calls to mlock()
- * will be unlocked by a single call to munlock(). This can result in keying material ending up in swap when
- * those functions are used naively. This class simulates stacking memory locks by keeping a counter per page.
- *
- * @note By using a map from each page base address to lock count, this class is optimized for
- * small objects that span up to a few pages, mostly smaller than a page. To support large allocations,
- * something like an interval tree would be the preferred data structure.
- */
-template <class Locker>
-class LockedPageManagerBase
-{
-public:
-    LockedPageManagerBase(size_t page_size) : page_size(page_size)
-    {
-        // Determine bitmask for extracting page from address
-        assert(!(page_size & (page_size - 1))); // size must be power of two
-        page_mask = ~(page_size - 1);
-    }
-
-    ~LockedPageManagerBase()
-    {
-        assert(this->GetLockedPageCount() == 0);
-    }
-
-
-    // For all pages in affected range, increase lock count
-    void LockRange(void* p, size_t size)
-    {
-        boost::mutex::scoped_lock lock(mutex);
-        if (!size)
-            return;
-        const size_t base_addr = reinterpret_cast<size_t>(p);
-        const size_t start_page = base_addr & page_mask;
-        const size_t end_page = (base_addr + size - 1) & page_mask;
-        for (size_t page = start_page; page <= end_page; page += page_size) {
-            Histogram::iterator it = histogram.find(page);
-            if (it == histogram.end()) // Newly locked page
-            {
-                locker.Lock(reinterpret_cast<void*>(page), page_size);
-                histogram.insert(std::make_pair(page, 1));
-            } else // Page was already locked; increase counter
-            {
-                it->second += 1;
-            }
-        }
-    }
-
-    // For all pages in affected range, decrease lock count
-    void UnlockRange(void* p, size_t size)
-    {
-        boost::mutex::scoped_lock lock(mutex);
-        if (!size)
-            return;
-        const size_t base_addr = reinterpret_cast<size_t>(p);
-        const size_t start_page = base_addr & page_mask;
-        const size_t end_page = (base_addr + size - 1) & page_mask;
-        for (size_t page = start_page; page <= end_page; page += page_size) {
-            Histogram::iterator it = histogram.find(page);
-            assert(it != histogram.end()); // Cannot unlock an area that was not locked
-            // Decrease counter for page, when it is zero, the page will be unlocked
-            it->second -= 1;
-            if (it->second == 0) // Nothing on the page anymore that keeps it locked
-            {
-                // Unlock page and remove the count from histogram
-                locker.Unlock(reinterpret_cast<void*>(page), page_size);
-                histogram.erase(it);
-            }
-        }
-    }
-
-    // Get number of locked pages for diagnostics
-    int GetLockedPageCount()
-    {
-        boost::mutex::scoped_lock lock(mutex);
-        return histogram.size();
-    }
-
-private:
-    Locker locker;
-    boost::mutex mutex;
-    size_t page_size, page_mask;
-    // map of page base address to lock count
-    typedef std::map<size_t, int> Histogram;
-    Histogram histogram;
-};
-
-
-/**
- * OS-dependent memory page locking/unlocking.
- * Defined as policy class to make stubbing for test possible.
- */
-class MemoryPageLocker
-{
-public:
-    /** Lock memory pages.
-     * addr and len must be a multiple of the system page size
-     */
-    bool Lock(const void* addr, size_t len);
-    /** Unlock memory pages.
-     * addr and len must be a multiple of the system page size
-     */
-    bool Unlock(const void* addr, size_t len);
-};
-
-/**
- * Singleton class to keep track of locked (ie, non-swappable) memory pages, for use in
- * std::allocator templates.
- *
- * Some implementations of the STL allocate memory in some constructors (i.e., see
- * MSVC's vector<T> implementation where it allocates 1 byte of memory in the allocator.)
- * Due to the unpredictable order of static initializers, we have to make sure the
- * LockedPageManager instance exists before any other STL-based objects that use
- * secure_allocator are created. So instead of having LockedPageManager also be
- * static-initialized, it is created on demand.
- */
-class LockedPageManager : public LockedPageManagerBase<MemoryPageLocker>
-{
-public:
-    static LockedPageManager& Instance()
-    {
-        boost::call_once(LockedPageManager::CreateInstance, LockedPageManager::init_flag);
-        return *LockedPageManager::_instance;
-    }
-
-private:
-    LockedPageManager();
-
-    static void 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
-        // LockedPageManagerBase's destructor helps us detect if that ever happens.
-        static LockedPageManager instance;
-        LockedPageManager::_instance = &instance;
-    }
-
-    static LockedPageManager* _instance;
-    static boost::once_flag init_flag;
-};
-
-//
-// Functions for directly locking/unlocking memory objects.
-// Intended for non-dynamically allocated structures.
-//
-template <typename T>
-void LockObject(const T& t)
-{
-    LockedPageManager::Instance().LockRange((void*)(&t), sizeof(T));
-}
-
-template <typename T>
-void UnlockObject(const T& t)
-{
-    memory_cleanse((void*)(&t), sizeof(T));
-    LockedPageManager::Instance().UnlockRange((void*)(&t), sizeof(T));
-}
-
-//
-// Allocator that locks its contents from being paged
-// out of memory and clears its contents before deletion.
-//
-template <typename T>
-struct secure_allocator : public std::allocator<T> {
-    // MSVC8 default copy constructor is broken
-    typedef std::allocator<T> base;
-    typedef typename base::size_type size_type;
-    typedef typename base::difference_type difference_type;
-    typedef typename base::pointer pointer;
-    typedef typename base::const_pointer const_pointer;
-    typedef typename base::reference reference;
-    typedef typename base::const_reference const_reference;
-    typedef typename base::value_type value_type;
-    secure_allocator() throw() {}
-    secure_allocator(const secure_allocator& a) throw() : base(a) {}
-    template <typename U>
-    secure_allocator(const secure_allocator<U>& a) throw() : base(a)
-    {
-    }
-    ~secure_allocator() throw() {}
-    template <typename _Other>
-    struct rebind {
-        typedef secure_allocator<_Other> other;
-    };
-
-    T* allocate(std::size_t n, const void* hint = 0)
-    {
-        T* p;
-        p = std::allocator<T>::allocate(n, hint);
-        if (p != NULL)
-            LockedPageManager::Instance().LockRange(p, sizeof(T) * n);
-        return p;
-    }
-
-    void deallocate(T* p, std::size_t n)
-    {
-        if (p != NULL) {
-            memory_cleanse(p, sizeof(T) * n);
-            LockedPageManager::Instance().UnlockRange(p, sizeof(T) * n);
-        }
-        std::allocator<T>::deallocate(p, n);
-    }
-};
-
-
-//
-// Allocator that clears its contents before deletion.
-//
-template <typename T>
-struct zero_after_free_allocator : public std::allocator<T> {
-    // MSVC8 default copy constructor is broken
-    typedef std::allocator<T> base;
-    typedef typename base::size_type size_type;
-    typedef typename base::difference_type difference_type;
-    typedef typename base::pointer pointer;
-    typedef typename base::const_pointer const_pointer;
-    typedef typename base::reference reference;
-    typedef typename base::const_reference const_reference;
-    typedef typename base::value_type value_type;
-    zero_after_free_allocator() throw() {}
-    zero_after_free_allocator(const zero_after_free_allocator& a) throw() : base(a) {}
-    template <typename U>
-    zero_after_free_allocator(const zero_after_free_allocator<U>& a) throw() : base(a)
-    {
-    }
-    ~zero_after_free_allocator() throw() {}
-    template <typename _Other>
-    struct rebind {
-        typedef zero_after_free_allocator<_Other> other;
-    };
-
-    void deallocate(T* p, std::size_t n)
-    {
-        if (p != NULL)
-            memory_cleanse(p, sizeof(T) * n);
-        std::allocator<T>::deallocate(p, n);
-    }
-};
-
-// This is exactly like std::string, but with a custom allocator.
-typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
-
-// Byte-vector that clears its contents before deletion.
-typedef std::vector<char, zero_after_free_allocator<char> > CSerializeData;
-
-#endif // BITCOIN_ALLOCATORS_H