1// Copyright (c) 2011 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5// This file contains the implementation of the FencedAllocator class. 6 7#include "gpu/command_buffer/client/fenced_allocator.h" 8 9#include <algorithm> 10 11#include "gpu/command_buffer/client/cmd_buffer_helper.h" 12 13namespace gpu { 14 15namespace { 16 17// Allocation alignment, must be a power of two. 18const unsigned int kAllocAlignment = 16; 19 20// Round down to the largest multiple of kAllocAlignment no greater than |size|. 21unsigned int RoundDown(unsigned int size) { 22 return size & ~(kAllocAlignment - 1); 23} 24 25// Round up to the smallest multiple of kAllocAlignment no smaller than |size|. 26unsigned int RoundUp(unsigned int size) { 27 return (size + (kAllocAlignment - 1)) & ~(kAllocAlignment - 1); 28} 29 30} // namespace 31 32#ifndef _MSC_VER 33const FencedAllocator::Offset FencedAllocator::kInvalidOffset; 34#endif 35 36FencedAllocator::FencedAllocator(unsigned int size, 37 CommandBufferHelper* helper, 38 const base::Closure& poll_callback) 39 : helper_(helper), 40 poll_callback_(poll_callback), 41 bytes_in_use_(0) { 42 Block block = { FREE, 0, RoundDown(size), kUnusedToken }; 43 blocks_.push_back(block); 44} 45 46FencedAllocator::~FencedAllocator() { 47 // Free blocks pending tokens. 48 for (unsigned int i = 0; i < blocks_.size(); ++i) { 49 if (blocks_[i].state == FREE_PENDING_TOKEN) { 50 i = WaitForTokenAndFreeBlock(i); 51 } 52 } 53 54 DCHECK_EQ(blocks_.size(), 1u); 55 DCHECK_EQ(blocks_[0].state, FREE); 56} 57 58// Looks for a non-allocated block that is big enough. Search in the FREE 59// blocks first (for direct usage), first-fit, then in the FREE_PENDING_TOKEN 60// blocks, waiting for them. The current implementation isn't smart about 61// optimizing what to wait for, just looks inside the block in order (first-fit 62// as well). 63FencedAllocator::Offset FencedAllocator::Alloc(unsigned int size) { 64 // size of 0 is not allowed because it would be inconsistent to only sometimes 65 // have it succeed. Example: Alloc(SizeOfBuffer), Alloc(0). 66 if (size == 0) { 67 return kInvalidOffset; 68 } 69 70 // Round up the allocation size to ensure alignment. 71 size = RoundUp(size); 72 73 // Try first to allocate in a free block. 74 for (unsigned int i = 0; i < blocks_.size(); ++i) { 75 Block &block = blocks_[i]; 76 if (block.state == FREE && block.size >= size) { 77 return AllocInBlock(i, size); 78 } 79 } 80 81 // No free block is available. Look for blocks pending tokens, and wait for 82 // them to be re-usable. 83 for (unsigned int i = 0; i < blocks_.size(); ++i) { 84 if (blocks_[i].state != FREE_PENDING_TOKEN) 85 continue; 86 i = WaitForTokenAndFreeBlock(i); 87 if (blocks_[i].size >= size) 88 return AllocInBlock(i, size); 89 } 90 return kInvalidOffset; 91} 92 93// Looks for the corresponding block, mark it FREE, and collapse it if 94// necessary. 95void FencedAllocator::Free(FencedAllocator::Offset offset) { 96 BlockIndex index = GetBlockByOffset(offset); 97 DCHECK_NE(blocks_[index].state, FREE); 98 Block &block = blocks_[index]; 99 100 if (block.state == IN_USE) 101 bytes_in_use_ -= block.size; 102 103 block.state = FREE; 104 CollapseFreeBlock(index); 105} 106 107// Looks for the corresponding block, mark it FREE_PENDING_TOKEN. 108void FencedAllocator::FreePendingToken( 109 FencedAllocator::Offset offset, int32 token) { 110 BlockIndex index = GetBlockByOffset(offset); 111 Block &block = blocks_[index]; 112 if (block.state == IN_USE) 113 bytes_in_use_ -= block.size; 114 block.state = FREE_PENDING_TOKEN; 115 block.token = token; 116} 117 118// Gets the max of the size of the blocks marked as free. 119unsigned int FencedAllocator::GetLargestFreeSize() { 120 FreeUnused(); 121 unsigned int max_size = 0; 122 for (unsigned int i = 0; i < blocks_.size(); ++i) { 123 Block &block = blocks_[i]; 124 if (block.state == FREE) 125 max_size = std::max(max_size, block.size); 126 } 127 return max_size; 128} 129 130// Gets the size of the largest segment of blocks that are either FREE or 131// FREE_PENDING_TOKEN. 132unsigned int FencedAllocator::GetLargestFreeOrPendingSize() { 133 unsigned int max_size = 0; 134 unsigned int current_size = 0; 135 for (unsigned int i = 0; i < blocks_.size(); ++i) { 136 Block &block = blocks_[i]; 137 if (block.state == IN_USE) { 138 max_size = std::max(max_size, current_size); 139 current_size = 0; 140 } else { 141 DCHECK(block.state == FREE || block.state == FREE_PENDING_TOKEN); 142 current_size += block.size; 143 } 144 } 145 return std::max(max_size, current_size); 146} 147 148// Makes sure that: 149// - there is at least one block. 150// - there are no contiguous FREE blocks (they should have been collapsed). 151// - the successive offsets match the block sizes, and they are in order. 152bool FencedAllocator::CheckConsistency() { 153 if (blocks_.size() < 1) return false; 154 for (unsigned int i = 0; i < blocks_.size() - 1; ++i) { 155 Block ¤t = blocks_[i]; 156 Block &next = blocks_[i + 1]; 157 // This test is NOT included in the next one, because offset is unsigned. 158 if (next.offset <= current.offset) 159 return false; 160 if (next.offset != current.offset + current.size) 161 return false; 162 if (current.state == FREE && next.state == FREE) 163 return false; 164 } 165 return true; 166} 167 168// Returns false if all blocks are actually FREE, in which 169// case they would be coalesced into one block, true otherwise. 170bool FencedAllocator::InUse() { 171 return blocks_.size() != 1 || blocks_[0].state != FREE; 172} 173 174// Collapse the block to the next one, then to the previous one. Provided the 175// structure is consistent, those are the only blocks eligible for collapse. 176FencedAllocator::BlockIndex FencedAllocator::CollapseFreeBlock( 177 BlockIndex index) { 178 if (index + 1 < blocks_.size()) { 179 Block &next = blocks_[index + 1]; 180 if (next.state == FREE) { 181 blocks_[index].size += next.size; 182 blocks_.erase(blocks_.begin() + index + 1); 183 } 184 } 185 if (index > 0) { 186 Block &prev = blocks_[index - 1]; 187 if (prev.state == FREE) { 188 prev.size += blocks_[index].size; 189 blocks_.erase(blocks_.begin() + index); 190 --index; 191 } 192 } 193 return index; 194} 195 196// Waits for the block's token, then mark the block as free, then collapse it. 197FencedAllocator::BlockIndex FencedAllocator::WaitForTokenAndFreeBlock( 198 BlockIndex index) { 199 Block &block = blocks_[index]; 200 DCHECK_EQ(block.state, FREE_PENDING_TOKEN); 201 helper_->WaitForToken(block.token); 202 block.state = FREE; 203 return CollapseFreeBlock(index); 204} 205 206// Frees any blocks pending a token for which the token has been read. 207void FencedAllocator::FreeUnused() { 208 // Free any potential blocks that has its lifetime handled outside. 209 poll_callback_.Run(); 210 211 for (unsigned int i = 0; i < blocks_.size();) { 212 Block& block = blocks_[i]; 213 if (block.state == FREE_PENDING_TOKEN && 214 helper_->HasTokenPassed(block.token)) { 215 block.state = FREE; 216 i = CollapseFreeBlock(i); 217 } else { 218 ++i; 219 } 220 } 221} 222 223// If the block is exactly the requested size, simply mark it IN_USE, otherwise 224// split it and mark the first one (of the requested size) IN_USE. 225FencedAllocator::Offset FencedAllocator::AllocInBlock(BlockIndex index, 226 unsigned int size) { 227 Block &block = blocks_[index]; 228 DCHECK_GE(block.size, size); 229 DCHECK_EQ(block.state, FREE); 230 Offset offset = block.offset; 231 bytes_in_use_ += size; 232 if (block.size == size) { 233 block.state = IN_USE; 234 return offset; 235 } 236 Block newblock = { FREE, offset + size, block.size - size, kUnusedToken}; 237 block.state = IN_USE; 238 block.size = size; 239 // this is the last thing being done because it may invalidate block; 240 blocks_.insert(blocks_.begin() + index + 1, newblock); 241 return offset; 242} 243 244// The blocks are in offset order, so we can do a binary search. 245FencedAllocator::BlockIndex FencedAllocator::GetBlockByOffset(Offset offset) { 246 Block templ = { IN_USE, offset, 0, kUnusedToken }; 247 Container::iterator it = std::lower_bound(blocks_.begin(), blocks_.end(), 248 templ, OffsetCmp()); 249 DCHECK(it != blocks_.end() && it->offset == offset); 250 return it-blocks_.begin(); 251} 252 253} // namespace gpu 254