bb7e1236f3
This is the second attempt to purge linker block allocators. Unlike the previously reverted change which purge allocators whenever all objects are freed, we only purge right before control leaves the linker. This limits the performance impact to one munmap() call per dlopen(), in most cases. Bug: 112073665 Test: Boot and check memory usage with 'showmap'. Test: Run camear cold start performance test. Change-Id: I02c7c44935f768e065fbe7ff0389a84bd44713f0
95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#pragma once
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#include <stdlib.h>
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#include <limits.h>
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#include <android-base/macros.h>
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struct LinkerBlockAllocatorPage;
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/*
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* This class is a non-template version of the LinkerTypeAllocator
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* It keeps code inside .cpp file by keeping the interface
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* template-free.
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*
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* Please use LinkerTypeAllocator<type> where possible (everywhere).
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*/
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class LinkerBlockAllocator {
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public:
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explicit LinkerBlockAllocator(size_t block_size);
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void* alloc();
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void free(void* block);
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void protect_all(int prot);
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// Purge all pages if all previously allocated blocks have been freed.
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void purge();
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private:
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void create_new_page();
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LinkerBlockAllocatorPage* find_page(void* block);
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size_t block_size_;
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LinkerBlockAllocatorPage* page_list_;
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void* free_block_list_;
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size_t allocated_;
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DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator);
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};
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/*
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* A simple allocator for the dynamic linker. An allocator allocates instances
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* of a single fixed-size type. Allocations are backed by page-sized private
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* anonymous mmaps.
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*
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* The differences between this allocator and BionicAllocator are:
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* 1. This allocator manages space more efficiently. BionicAllocator operates in
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* power-of-two sized blocks up to 1k, when this implementation splits the
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* page to aligned size of structure; For example for structures with size
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* 513 this allocator will use 516 (520 for lp64) bytes of data where
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* generalized implementation is going to use 1024 sized blocks.
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*
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* 2. This allocator does not munmap allocated memory, where BionicAllocator does.
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*
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* 3. This allocator provides mprotect services to the user, where BionicAllocator
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* always treats its memory as READ|WRITE.
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*/
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template<typename T>
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class LinkerTypeAllocator {
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public:
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LinkerTypeAllocator() : block_allocator_(sizeof(T)) {}
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T* alloc() { return reinterpret_cast<T*>(block_allocator_.alloc()); }
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void free(T* t) { block_allocator_.free(t); }
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void protect_all(int prot) { block_allocator_.protect_all(prot); }
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private:
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LinkerBlockAllocator block_allocator_;
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DISALLOW_COPY_AND_ASSIGN(LinkerTypeAllocator);
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};
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