libreoffice-online/kit/Delta.hpp
Ashod Nakashian d57baeb906 wsd: reduce directives for unused variable supression
We use [[maybe_unused]] to reduce explicit supression
especially under compile-time directives.

Change-Id: Ic5f3f3227a80efe52097cb35520d05b9cdaacb42
Signed-off-by: Ashod Nakashian <ashod.nakashian@collabora.co.uk>
2024-03-09 12:37:19 -05:00

872 lines
29 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* Copyright the Collabora Online contributors.
*
* SPDX-License-Identifier: MPL-2.0
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#pragma once
#include <vector>
#include <memory>
#include <unordered_set>
#include <fstream>
#include <assert.h>
#include <zlib.h>
#include <zstd.h>
#include <Log.hpp>
#include <Common.hpp>
#include <FileUtil.hpp>
#include <Png.hpp>
#include <Simd.hpp>
#include <DeltaSimd.h>
#ifndef TILE_WIRE_ID
# define TILE_WIRE_ID
typedef uint32_t TileWireId;
#endif
/// Unique location of a tile
struct TileLocation {
// in TWIPS
int _left;
int _top;
int _size;
int _part;
int _canonicalViewId;
TileLocation(int left, int top, int size, int part,
int canonicalViewId)
: _left(left), _top(top), _size(size), _part(part),
_canonicalViewId(canonicalViewId)
{
}
size_t hash() const
{
size_t left = _left;
size_t top = _top;
size_t part = _part;
size_t size = _size;
size_t canonicalViewId = _canonicalViewId;
return (left << 20) ^ top ^ (part << 15) ^ (size << 7) ^
(canonicalViewId << 24);
}
bool operator==(const TileLocation& other) const
{
return _left == other._left && _top == other._top &&
_size == other._size && _part == other._part &&
_canonicalViewId == other._canonicalViewId;
}
};
/// A quick and dirty, thread-safe delta generator for last tile changes
class DeltaGenerator {
friend class DeltaTests;
// fast - and deltas take lots of size off.
static const int compressionLevel = -3;
static constexpr size_t _rleMaskUnits = 256 / 64;
/// Bitmap row with a CRC for quick vertical shift detection
class DeltaBitmapRow final {
size_t _rleSize;
uint64_t _rleMask[_rleMaskUnits];
uint32_t *_rleData;
public:
class PixIterator final
{
const DeltaBitmapRow &_row;
unsigned int _nMask; // which mask to operate on
uint32_t _lastPix; // last pixel (or possibly plain alpha)
uint64_t _lastMask; // holding slot for mask
uint64_t _bitToCheck; // which bit should we check.
const uint32_t *_rlePtr; // next pixel to read
const uint32_t *_endRleData; // end of pixel data
public:
PixIterator(const DeltaBitmapRow &row)
: _row(row), _nMask(0),
_lastPix(0x00000000),
_lastMask(0),
_bitToCheck(0),
_rlePtr(row._rleData),
_endRleData(row._rleData + row._rleSize)
{
next();
}
uint32_t getPixel() const
{
return _lastPix;
}
bool identical(const PixIterator &i) const
{
return _lastPix == i._lastPix;
}
void next()
{
// already at end
if (_rlePtr == _endRleData)
return;
if (!_bitToCheck)
{ // slow path
if (_nMask < 4)
_lastMask = _row._rleMask[_nMask++];
else
_lastMask = 0xffffffffffffffff;
_bitToCheck = 1;
}
// fast path
if (!(_lastMask & _bitToCheck))
_lastPix = *(_rlePtr++);
_bitToCheck <<= 1;
}
};
DeltaBitmapRow()
: _rleSize(0)
, _rleData(nullptr)
{
memset(_rleMask, 0, sizeof(_rleMask));
}
DeltaBitmapRow(const DeltaBitmapRow&) = delete;
~DeltaBitmapRow()
{
if (_rleData)
free(_rleData);
}
size_t sizeBytes()
{
return sizeof(DeltaBitmapRow) + _rleSize * 4;
}
private:
void initPixRowCpu(const uint32_t *from, uint32_t *scratch,
size_t *scratchLen, uint64_t *rleMaskBlock,
unsigned int width)
{
uint32_t lastPix = 0x00000000; // transparency
unsigned int x = 0, outp = 0;
// non-accelerated path
for (unsigned int nMask = 0; nMask < 4; ++nMask)
{
uint64_t rleMask = 0;
uint64_t bitToSet = 1;
if (width - x > 64)
{
// simplified inner loop for 64bit chunks
for (; bitToSet; ++x, bitToSet <<= 1)
{
if (from[x] == lastPix)
rleMask |= bitToSet;
else
{
lastPix = from[x];
scratch[outp++] = lastPix;
}
}
}
else
{
// even slower inner loop for odd lengths
for (; x < width; ++x, bitToSet <<= 1)
{
if (from[x] == lastPix)
rleMask |= bitToSet;
else
{
lastPix = from[x];
scratch[outp++] = lastPix;
}
}
}
rleMaskBlock[nMask] = rleMask;
}
if (x < width)
{
memcpy(scratch + outp, from + x, (width - x) * 4);
outp += width-x;
}
*scratchLen = outp;
}
public:
void initRow(const uint32_t *from, unsigned int width)
{
uint32_t scratch[width];
bool done = false;
if (simd::HasAVX2 && width == 256)
{
done = simd_initPixRowSimd(from, scratch, &_rleSize, _rleMask);
#if ENABLE_DEBUG && 0 // SIMD validation
if (done)
{
uint32_t cpu_scratch[width];
uint64_t cpu_rleMask[_rleMaskUnits];
unsigned int cpu_outp = 0;
initPixRowCpu(from, cpu_scratch, &cpu_outp, cpu_rleMask, width);
// check our result
if (memcmp(cpu_rleMask, _rleMask, sizeof (cpu_rleMask)))
{
std::cerr << "Masks differ " <<
Util::bytesToHexString(reinterpret_cast<const char *>(_rleMask), sizeof(_rleMask)) << "\n" <<
Util::bytesToHexString(reinterpret_cast<const char *>(cpu_rleMask), sizeof(_rleMask)) << "\n";
}
assert(_rleSize == cpu_outp);
if(_rleSize > 0 && memcmp(scratch, cpu_scratch, _rleSize))
{
std::cerr << "RLE pixels differ mask:\n" <<
Util::bytesToHexString(reinterpret_cast<const char *>(_rleMask), sizeof(_rleMask)) << "\n" <<
"pixels:\n" <<
Util::bytesToHexString(reinterpret_cast<const char *>(scratch), _rleSize) << "\n" <<
Util::bytesToHexString(reinterpret_cast<const char *>(cpu_scratch), _rleSize) << "\n";
}
}
#endif
}
// else CPU implementation
if (!done)
initPixRowCpu(from, scratch, &_rleSize, _rleMask, width);
if (_rleSize > 0)
{
_rleData = (uint32_t *)malloc((size_t)_rleSize * 4);
memcpy(_rleData, scratch, _rleSize * 4);
}
else
_rleData = nullptr;
}
bool identical(const DeltaBitmapRow &other) const
{
if (_rleSize != other._rleSize)
return false;
if (memcmp(_rleMask, other._rleMask, sizeof(_rleMask)))
return false;
if (!_rleData && !other._rleData)
return true;
if (!_rleData || !other._rleData)
return false;
return !std::memcmp(_rleData, other._rleData, _rleSize * 4);
}
// Create a diff from our state to new state in curRow
void diffRowTo(const DeltaBitmapRow &curRow,
const int width, const int curY,
std::vector<uint8_t> &output,
LibreOfficeKitTileMode mode) const
{
PixIterator oldPixels(*this);
PixIterator curPixels(curRow);
for (int x = 0; x < width;)
{
int same;
for (same = 0; same + x < width &&
oldPixels.identical(curPixels);)
{
oldPixels.next();
curPixels.next();
same++;
}
x += same;
uint32_t scratch[256];
int diff;
for (diff = 0; diff + x < width &&
(!oldPixels.identical(curPixels) || diff < 3)
&& diff < 254;)
{
oldPixels.next();
scratch[diff] = curPixels.getPixel();
curPixels.next();
++diff;
}
if (diff > 0)
{
output.push_back('d');
output.push_back(curY);
output.push_back(x);
output.push_back(diff);
size_t dest = output.size();
output.resize(dest + diff * 4);
copy_row(reinterpret_cast<unsigned char *>(&output[dest]),
(const unsigned char *)(scratch),
diff, mode);
LOG_TRC("row " << curY << " different " << diff << "pixels");
x += diff;
}
}
}
};
/// A bitmap tile with annotated rows and details on its location
struct DeltaData final {
// no careless copying
DeltaData(const DeltaData&) = delete;
DeltaData& operator=(const DeltaData&) = delete;
DeltaData(TileWireId wid, unsigned char* pixmap, size_t startX, size_t startY, int width,
int height, const TileLocation& loc, int bufferWidth,
[[maybe_unused]] int bufferHeight)
: _loc(loc)
, _inUse(false)
, _wid(wid)
,
// in Pixels
_width(width)
, _height(height)
, _rows(new DeltaBitmapRow[height])
{
assert (startX + width <= (size_t)bufferWidth);
assert (startY + height <= (size_t)bufferHeight);
LOG_TRC("Converting pixel data to delta data of size "
<< (width * height * 4) << " width " << width
<< " height " << height);
for (int y = 0; y < height; ++y)
{
size_t position = ((startY + y) * bufferWidth * 4) + (startX * 4);
DeltaBitmapRow &row = _rows[y];
row.initRow(reinterpret_cast<uint32_t *>(pixmap + position), width);
}
}
~DeltaData()
{
delete[] _rows;
}
void setWid(TileWireId wid)
{
_wid = wid;
}
TileWireId getWid() const
{
return _wid;
}
void setWidth(int width)
{
_width = width;
}
int getWidth() const
{
return _width;
}
void setHeight(int height)
{
_height = height;
}
int getHeight() const
{
return _height;
}
const DeltaBitmapRow& getRow(int y) const
{
return _rows[y];
}
size_t sizeBytes() const
{
size_t total = sizeof(DeltaData);
for (int i = 0; i < _height; ++i)
total += _rows[i].sizeBytes();
return total;
}
void replaceAndFree(std::shared_ptr<DeltaData> &repl)
{
assert (_loc == repl->_loc);
if (repl.get() == this)
{
assert(!"replacing with yourself should never happen");
return;
}
_wid = repl->_wid;
_width = repl->_width;
_height = repl->_height;
delete[] _rows;
_rows = repl->_rows;
repl->_rows = nullptr;
repl.reset();
}
inline void use()
{
const bool wasInUse = _inUse.exchange(true); (void)wasInUse;
assert(!wasInUse && "Error: delta was already in use by another thread");
}
inline void unuse()
{
const bool wasInUse = _inUse.exchange(false); (void)wasInUse;
assert(wasInUse && "Error: delta was already un-used by another thread");
}
TileLocation _loc;
private:
std::atomic<bool> _inUse; // thread debugging check.
TileWireId _wid;
int _width;
int _height;
DeltaBitmapRow *_rows;
};
struct DeltaHasher {
std::size_t operator()(const std::shared_ptr<DeltaData> &t) const
{
return t->_loc.hash();
}
};
struct DeltaCompare {
bool operator()(const std::shared_ptr<DeltaData> &a,
const std::shared_ptr<DeltaData> &b) const
{
return a->_loc == b->_loc;
}
};
std::mutex _deltaGuard;
/// The last several bitmap entries as a cache
std::unordered_set<std::shared_ptr<DeltaData>, DeltaHasher, DeltaCompare> _deltaEntries;
size_t _maxEntries;
void rebalanceDeltasT(bool bDropAll = false)
{
if (_deltaEntries.size() > _maxEntries || bDropAll)
{
size_t toRemove = _deltaEntries.size();
if (!bDropAll)
toRemove -= (_maxEntries * 3 / 4);
std::vector<std::shared_ptr<DeltaData>> entries;
entries.insert(entries.end(), _deltaEntries.begin(), _deltaEntries.end());
std::sort(entries.begin(), entries.end(),
[](const std::shared_ptr<DeltaData> &a,
const std::shared_ptr<DeltaData> &b)
{
return a->getWid() < b->getWid();
});
for (size_t i = 0; i < toRemove; ++i)
_deltaEntries.erase(entries[i]);
}
}
static void
copy_row (unsigned char *dest, const unsigned char *srcBytes, unsigned int count, LibreOfficeKitTileMode mode)
{
switch (mode)
{
case LOK_TILEMODE_RGBA:
std::memcpy(dest, srcBytes, count * 4);
break;
case LOK_TILEMODE_BGRA:
std::memcpy(dest, srcBytes, count * 4);
for (size_t j = 0; j < count * 4; j += 4)
std::swap(dest[j], dest[j+2]);
break;
}
}
bool makeDelta(
const DeltaData &prev,
const DeltaData &cur,
std::vector<char>& outStream,
LibreOfficeKitTileMode mode)
{
// TODO: should we split and compress alpha separately ?
if (prev.getWidth() != cur.getWidth() || prev.getHeight() != cur.getHeight())
{
LOG_ERR("mis-sized delta: " << prev.getWidth() << 'x' << prev.getHeight() << " vs "
<< cur.getWidth() << 'x' << cur.getHeight());
return false;
}
LOG_TRC("building delta of a " << cur.getWidth() << 'x' << cur.getHeight() << " bitmap " <<
"between old wid " << prev.getWid() << " and " << cur.getWid());
// let's use uint8_t instead of char to avoid implicit sign extension
std::vector<uint8_t> output;
// guestimated upper-bound delta size
output.reserve(cur.getWidth() * (cur.getHeight() + 4) * 4);
// row move/copy src/dest is a byte.
assert (prev.getHeight() <= 256);
// column position is a byte.
assert (prev.getWidth() <= 256);
// How do the rows look against each other ?
size_t lastMatchOffset = 0;
size_t lastCopy = 0;
for (int y = 0; y < prev.getHeight(); ++y)
{
// Life is good where rows match:
if (prev.getRow(y).identical(cur.getRow(y)))
continue;
// Hunt for other rows
bool matched = false;
for (int yn = 0; yn < prev.getHeight() && !matched; ++yn)
{
size_t match = (y + lastMatchOffset + yn) % prev.getHeight();
if (prev.getRow(match).identical(cur.getRow(y)))
{
// TODO: if offsets are >256 - use 16bits?
if (lastCopy > 0)
{
// check if we can extend the last copy
uint8_t cnt = output[lastCopy];
if (output[lastCopy + 1] + cnt == match &&
output[lastCopy + 2] + cnt == y &&
// make sure we're not copying from out of bounds of the previous tile
output[lastCopy + 1] + cnt + 1 < prev.getHeight())
{
output[lastCopy]++;
matched = true;
continue;
}
}
lastMatchOffset = match - y;
output.push_back('c'); // copy-row
lastCopy = output.size();
output.push_back(1); // count - updated later.
output.push_back(match); // src
output.push_back(y); // dest
matched = true;
continue;
}
}
if (matched)
continue;
// Our row is just that different:
prev.getRow(y).diffRowTo(cur.getRow(y), prev.getWidth(), y, output, mode);
}
LOG_TRC("Created delta of size " << output.size());
if (output.empty())
{
// The tile content is identical to what the client already has, so skip it
LOG_TRC("Identical / un-changed tile");
// Return a zero length delta to inform WSD we didn't need that.
// This allows WSD side TileCache to send updates to waiting subscribers.
outStream.push_back('D');
return true;
}
// terminating this delta so we can detect the next one.
output.push_back('t');
// FIXME: avoid allocation & make this more efficient.
size_t maxCompressed = ZSTD_COMPRESSBOUND(output.size());
std::unique_ptr<char, void (*)(void*)> compressed((char*)malloc(maxCompressed), free);
// compress for speed, not size - and trust to deltas.
size_t compSize = ZSTD_compress(compressed.get(), maxCompressed,
output.data(), output.size(),
compressionLevel);
if (ZSTD_isError(compSize))
{
LOG_ERR("Failed to compress delta of size " << output.size() << " with " << ZSTD_getErrorName(compSize));
return false;
}
LOG_TRC("Compressed delta of size " << output.size() << " to size " << compSize);
// << Util::dumpHex(std::string((char *)compressed.get(), compSize)));
// FIXME: should get zstd to drop it directly in-place really.
outStream.push_back('D');
size_t oldSize = outStream.size();
outStream.resize(oldSize + compSize);
memcpy(&outStream[oldSize], compressed.get(), compSize);
return true;
}
public:
DeltaGenerator()
: _maxEntries(0)
{}
/// Re-balances the cache size to fit the number of sessions
void rebalanceDeltas(ssize_t limit = -1)
{
std::unique_lock<std::mutex> guard(_deltaGuard);
if (limit > 0)
_maxEntries = limit;
rebalanceDeltasT();
}
/// Adapts cache sizing to the number of sessions
void setSessionCount(size_t count)
{
rebalanceDeltas(std::max(count, size_t(1)) * 96);
}
void dropCache()
{
std::unique_lock<std::mutex> guard(_deltaGuard);
rebalanceDeltasT(true);
}
void dumpState(std::ostream& oss)
{
oss << "\tdelta generator with " << _deltaEntries.size() << " entries vs. max " << _maxEntries << "\n";
size_t totalSize = 0;
for (auto &it : _deltaEntries)
{
size_t size = it->sizeBytes();
oss << "\t\t" << it->_loc._size << "," << it->_loc._part << "," << it->_loc._left << "," << it->_loc._top << " wid: " << it->getWid() << " size: " << size << "\n";
totalSize += size;
}
oss << "\tdelta generator consumes " << totalSize << " bytes\n";
}
/**
* Creates a delta if possible:
* if so - returns @true and appends the delta to @output
* stores @pixmap, and other data to accelerate delta
* creation in a limited size cache.
*/
bool createDelta(
unsigned char* pixmap, size_t startX, size_t startY,
int width, int height,
int bufferWidth, int bufferHeight,
const TileLocation &loc,
std::vector<char>& output,
TileWireId wid, bool forceKeyframe,
LibreOfficeKitTileMode mode)
{
if ((width & 0x1) != 0) // power of two - RGBA
{
LOG_TRC("Bad width to create deltas " << width);
return false;
}
if (width > 256 || height > 256)
{
LOG_TRC("Bad size << " << width << " x " << height << " to create deltas ");
assert(false && "shouldn't be possible to get tiles > 256x256");
return false;
}
// FIXME: why duplicate this ? we could overwrite
// as we make the delta into an existing cache entry,
// and just do this as/when there is no entry.
std::shared_ptr<DeltaData> update(
new DeltaData(
wid, pixmap, startX, startY, width, height,
loc, bufferWidth, bufferHeight));
std::shared_ptr<DeltaData> cacheEntry;
{
// protect _deltaEntries
std::unique_lock<std::mutex> guard(_deltaGuard);
auto it = _deltaEntries.find(update);
if (it == _deltaEntries.end())
{
_deltaEntries.insert(update);
return false;
}
cacheEntry = *it;
cacheEntry->use();
}
// interestingly cacheEntry may no longer be in the cache by here.
// but no other thread can touch the same tile at the same time.
assert (cacheEntry);
bool delta = false;
if (!forceKeyframe)
delta = makeDelta(*cacheEntry, *update, output, mode);
// no two threads can be working on the same DeltaData.
cacheEntry->replaceAndFree(update);
cacheEntry->unuse();
return delta;
}
/**
* Compress the relevant pixmap data either to a delta if we can
* or a plain deflated stream if we cannot.
*/
size_t compressOrDelta(
unsigned char* pixmap, size_t startX, size_t startY,
int width, int height,
int bufferWidth, int bufferHeight,
const TileLocation &loc,
std::vector<char>& output,
TileWireId wid, bool forceKeyframe,
bool dumpTiles, LibreOfficeKitTileMode mode)
{
#if !ENABLE_DEBUG
dumpTiles = false;
#endif
// Dump the tiles to the child sessions chroot jail
int dumpedIndex = 1;
if (dumpTiles)
{
std::string path = FileUtil::getSysTempDirectoryPath() + "/tiledump";
bool directoryExists = FileUtil::Stat(path).exists();
if (!directoryExists)
FileUtil::createTmpDir("tiledump");
// filename format: tile-<viewid>-<part>-<left>-<top>-<index>.png
std::ostringstream oss;
oss << "tile-" << loc._canonicalViewId << "-" << loc._part << "-" << loc._left << "-" << loc._top << "-";
std::string baseFilename = oss.str();
// find the next available filename
bool found = false;
int index = 1;
while (!found)
{
std::string filename = std::string("/") + baseFilename + std::to_string(index) + ".png";
if (!FileUtil::Stat(path + filename).exists())
{
found = true;
path += filename;
dumpedIndex = index;
}
else
{
index++;
}
}
std::ofstream tileFile(path, std::ios::binary);
std::vector<char> pngOutput;
Png::encodeSubBufferToPNG(pixmap, startX, startY, width, height,
bufferWidth, bufferHeight, pngOutput, mode);
tileFile.write(pngOutput.data(), pngOutput.size());
}
if (!createDelta(pixmap, startX, startY, width, height,
bufferWidth, bufferHeight,
loc, output, wid, forceKeyframe, mode))
{
// FIXME: should stream it in =)
size_t maxCompressed = ZSTD_COMPRESSBOUND((size_t)width * height * 4);
std::unique_ptr<char, void (*)(void*)> compressed((char*)malloc(maxCompressed), free);
if (!compressed)
{
LOG_ERR("Failed to allocate buffer of size " << maxCompressed << " to compress into");
return 0;
}
ZSTD_CCtx *cctx = ZSTD_createCCtx();
ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, compressionLevel);
ZSTD_outBuffer outb;
outb.dst = compressed.get();
outb.size = maxCompressed;
outb.pos = 0;
unsigned char fixedupLine[width * 4];
// FIXME: should we RLE in pixels first ?
for (int y = 0; y < height; ++y)
{
copy_row(fixedupLine, pixmap + ((startY + y) * bufferWidth * 4) + (startX * 4), width, mode);
ZSTD_inBuffer inb;
inb.src = fixedupLine;
inb.size = width * 4;
inb.pos = 0;
bool lastRow = (y == height - 1);
ZSTD_EndDirective endOp = lastRow ? ZSTD_e_end : ZSTD_e_continue;
size_t compSize = ZSTD_compressStream2(cctx, &outb, &inb, endOp);
if (ZSTD_isError(compSize))
{
LOG_ERR("failed to compress image: " << compSize << " is: " << ZSTD_getErrorName(compSize));
ZSTD_freeCCtx(cctx);
return 0;
}
}
ZSTD_freeCCtx(cctx);
size_t compSize = outb.pos;
LOG_TRC("Compressed image of size " << (width * height * 4) << " to size " << compSize);
// << Util::dumpHex(std::string((char *)compressed, compSize)));
// FIXME: get zstd to compress directly into this buffer.
output.push_back('Z');
size_t oldSize = output.size();
output.resize(oldSize + compSize);
memcpy(&output[oldSize], compressed.get(), compSize);
}
else
{
// Dump the delta
if (dumpTiles)
{
std::string path = FileUtil::getSysTempDirectoryPath() + "/tiledump";
std::ostringstream oss;
// filename format: tile-delta-<viewid>-<part>-<left>-<top>-<prev_index>_to_<index>.zstd
oss << "tile-delta-" << loc._canonicalViewId << "-" << loc._part << "-" << loc._left << "-" << loc._top
<< "-" << dumpedIndex - 1 << "_to_" << dumpedIndex << ".zstd";
path += oss.str();
std::ofstream tileFile(path, std::ios::binary);
// Skip first character which is a 'D' used to identify deltas
// The rest should be a zstd compressed delta
tileFile.write(output.data() + 1, output.size() - 1);
}
}
return output.size();
}
// used only by test code
static Blob expand(const Blob &blob)
{
Blob img = std::make_shared<BlobData>();
img->resize(1024*1024*4); // lots of extra space.
size_t const dSize = ZSTD_decompress(img->data(), img->size(), blob->data(), blob->size());
if (ZSTD_isError(dSize))
{
LOG_ERR("Failed to decompress blob of size " << blob->size() << " with " << ZSTD_getErrorName(dSize));
return Blob();
}
img->resize(dSize);
return img;
}
};
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */