OpenVDB 13.0.0

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StreamCompression.h
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1// Copyright Contributors to the OpenVDB Project
2// SPDX-License-Identifier: Apache-2.0
3
4/// @file points/StreamCompression.h
5///
6/// @author Dan Bailey
7///
8/// @brief Convenience wrappers to using Blosc and reading and writing of Paged data.
9///
10/// Blosc is most effective with large (> ~256KB) blocks of data. Writing the entire
11/// data block contiguously would provide the most optimal compression, however would
12/// limit the ability to use delayed-loading as the whole block would be required to
13/// be loaded from disk at once. To balance these two competing factors, Paging is used
14/// to write out blocks of data that are a reasonable size for Blosc. These Pages are
15/// loaded lazily, tracking the input stream pointers and creating Handles that reference
16/// portions of the buffer. When the Page buffer is accessed, the data will be read from
17/// the stream.
18
19#ifndef OPENVDB_TOOLS_STREAM_COMPRESSION_HAS_BEEN_INCLUDED
20#define OPENVDB_TOOLS_STREAM_COMPRESSION_HAS_BEEN_INCLUDED
21
22#include <openvdb/io/io.h>
23#include <openvdb/util/Assert.h>
24#include <tbb/spin_mutex.h>
25#include <memory>
26#include <string>
27
28
29 class TestStreamCompression;
30
31 namespace openvdb {
32 OPENVDB_USE_VERSION_NAMESPACE
33 namespace OPENVDB_VERSION_NAME {
34 namespace compression {
35
36
37// This is the minimum number of bytes below which Blosc compression is not used to
38// avoid unecessary computation, as Blosc offers minimal compression until this limit
39 static const int BLOSC_MINIMUM_BYTES = 48;
40
41// This is the minimum number of bytes below which the array is padded with zeros up
42// to this number of bytes to allow Blosc to perform compression with small arrays
43 static const int BLOSC_PAD_BYTES = 128;
44
45
46/// @brief Returns true if compression is available
47 OPENVDB_API bool bloscCanCompress();
48
49/// @brief Retrieves the uncompressed size of buffer when uncompressed
50///
51/// @param buffer the compressed buffer
52 OPENVDB_API size_t bloscUncompressedSize(const char* buffer);
53
54/// @brief Compress into the supplied buffer.
55///
56/// @param compressedBuffer the buffer to compress
57/// @param compressedBytes number of compressed bytes
58/// @param bufferBytes the number of bytes in compressedBuffer available to be filled
59/// @param uncompressedBuffer the uncompressed buffer to compress
60/// @param uncompressedBytes number of uncompressed bytes
61 OPENVDB_API void bloscCompress(char* compressedBuffer, size_t& compressedBytes,
62 const size_t bufferBytes, const char* uncompressedBuffer, const size_t uncompressedBytes);
63
64/// @brief Compress and return the heap-allocated compressed buffer.
65///
66/// @param buffer the buffer to compress
67/// @param uncompressedBytes number of uncompressed bytes
68/// @param compressedBytes number of compressed bytes (written to this variable)
69/// @param resize the compressed buffer will be exactly resized to remove the
70/// portion used for Blosc overhead, for efficiency this can be
71/// skipped if it is known that the resulting buffer is temporary
72 OPENVDB_API std::unique_ptr<char[]> bloscCompress(const char* buffer,
73 const size_t uncompressedBytes, size_t& compressedBytes, const bool resize = true);
74
75/// @brief Convenience wrapper to retrieve the compressed size of buffer when compressed
76///
77/// @param buffer the uncompressed buffer
78/// @param uncompressedBytes number of uncompressed bytes
79 OPENVDB_API size_t bloscCompressedSize(const char* buffer, const size_t uncompressedBytes);
80
81/// @brief Decompress into the supplied buffer. Will throw if decompression fails or
82/// uncompressed buffer has insufficient space in which to decompress.
83///
84/// @param uncompressedBuffer the uncompressed buffer to decompress into
85/// @param expectedBytes the number of bytes expected once the buffer is decompressed
86/// @param bufferBytes the number of bytes in uncompressedBuffer available to be filled
87/// @param compressedBuffer the compressed buffer to decompress
88 OPENVDB_API void bloscDecompress(char* uncompressedBuffer, const size_t expectedBytes,
89 const size_t bufferBytes, const char* compressedBuffer);
90
91/// @brief Decompress and return the the heap-allocated uncompressed buffer.
92///
93/// @param buffer the buffer to decompress
94/// @param expectedBytes the number of bytes expected once the buffer is decompressed
95/// @param resize the compressed buffer will be exactly resized to remove the
96/// portion used for Blosc overhead, for efficiency this can be
97/// skipped if it is known that the resulting buffer is temporary
98 OPENVDB_API std::unique_ptr<char[]> bloscDecompress(const char* buffer,
99 const size_t expectedBytes, const bool resize = true);
100
101
102////////////////////////////////////////
103
104
105// 1MB = 1048576 Bytes
106 static const int PageSize = 1024 * 1024;
107
108
109/// @brief Stores a variable-size, compressed, delayed-load Page of data
110/// that is loaded into memory when accessed. Access to the Page is
111/// thread-safe as loading and decompressing the data is protected by a mutex.
112 class OPENVDB_API Page
113{
114 private:
115 struct Info
116 {
117#ifdef OPENVDB_USE_DELAYED_LOADING
118 io::MappedFile::Ptr mappedFile;
119#endif
120 SharedPtr<io::StreamMetadata> meta;
121 std::streamoff filepos;
122 long compressedBytes;
123 long uncompressedBytes;
124 }; // Info
125
126 public:
127 using Ptr = std::shared_ptr<Page>;
128
129 Page() = default;
130
131 /// @brief load the Page into memory
132 void load() const;
133
134 /// @brief Uncompressed bytes of the Paged data, available
135 /// when the header has been read.
136 long uncompressedBytes() const;
137
138 /// @brief Retrieves a data pointer at the specific @param index
139 /// @note Will force a Page load when called.
140 const char* buffer(const int index) const;
141
142 /// @brief Read the Page header
143 void readHeader(std::istream&);
144
145 /// @brief Read the Page buffers. If @a delayed is true, stream
146 /// pointers will be stored to load the data lazily.
147 void readBuffers(std::istream&, bool delayed);
148
149 /// @brief Test if the data is out-of-core
150 bool isOutOfCore() const;
151
152 private:
153 /// @brief Convenience method to store a copy of the supplied buffer
154 void copy(const std::unique_ptr<char[]>& temp, int pageSize);
155
156 /// @brief Decompress and store the supplied data
157 void decompress(const std::unique_ptr<char[]>& temp);
158
159 /// @brief Thread-safe loading of the data
160 void doLoad() const;
161
162 std::unique_ptr<Info> mInfo = std::unique_ptr<Info>(new Info);
163 std::unique_ptr<char[]> mData;
164 tbb::spin_mutex mMutex;
165}; // class Page
166
167
168/// @brief A PageHandle holds a unique ptr to a Page and a specific stream
169/// pointer to a point within the decompressed Page buffer
170 class OPENVDB_API PageHandle
171{
172 public:
173 using Ptr = std::unique_ptr<PageHandle>;
174
175 /// @brief Create the page handle
176 /// @param page a shared ptr to the page that stores the buffer
177 /// @param index start position of the buffer to be read
178 /// @param size total size of the buffer to be read in bytes
179 PageHandle(const Page::Ptr& page, const int index, const int size);
180
181 /// @brief Retrieve a reference to the stored page
182 Page& page();
183
184 /// @brief Return the size of the buffer
185 int size() const { return mSize; }
186
187 /// @brief Read and return the buffer, loading and decompressing
188 /// the Page if necessary.
189 std::unique_ptr<char[]> read();
190
191 /// @brief Return a copy of this PageHandle
192 Ptr copy() { return Ptr(new PageHandle(mPage, mIndex, mSize)); }
193
194 protected:
195 friend class ::TestStreamCompression;
196
197 private:
198 Page::Ptr mPage;
199 int mIndex = -1;
200 int mSize = 0;
201}; // class PageHandle
202
203
204/// @brief A Paging wrapper to std::istream that is responsible for reading
205/// from a given input stream and creating Page objects and PageHandles that
206/// reference those pages for delayed reading.
207 class OPENVDB_API PagedInputStream
208{
209 public:
210 using Ptr = std::shared_ptr<PagedInputStream>;
211
212 PagedInputStream() = default;
213
214 explicit PagedInputStream(std::istream& is);
215
216 /// @brief Size-only mode tags the stream as only reading size data.
217 void setSizeOnly(bool sizeOnly) { mSizeOnly = sizeOnly; }
218 bool sizeOnly() const { return mSizeOnly; }
219
220 // @brief Set and get the input stream
221 std::istream& getInputStream() { OPENVDB_ASSERT(mIs); return *mIs; }
222 void setInputStream(std::istream& is) { mIs = &is; }
223
224 /// @brief Creates a PageHandle to access the next @param n bytes of the Page.
225 PageHandle::Ptr createHandle(std::streamsize n);
226
227 /// @brief Takes a @a pageHandle and updates the referenced page with the
228 /// current stream pointer position and if @a delayed is false performs
229 /// an immediate read of the data.
230 void read(PageHandle::Ptr& pageHandle, std::streamsize n, bool delayed = true);
231
232 private:
233 int mByteIndex = 0;
234 int mUncompressedBytes = 0;
235 std::istream* mIs = nullptr;
236 Page::Ptr mPage;
237 bool mSizeOnly = false;
238}; // class PagedInputStream
239
240
241/// @brief A Paging wrapper to std::ostream that is responsible for writing
242/// from a given output stream at intervals set by the PageSize. As Pages are
243/// variable in size, they are flushed to disk as soon as sufficiently large.
244 class OPENVDB_API PagedOutputStream
245{
246 public:
247 using Ptr = std::shared_ptr<PagedOutputStream>;
248
249 PagedOutputStream();
250
251 explicit PagedOutputStream(std::ostream& os);
252
253 /// @brief Size-only mode tags the stream as only writing size data.
254 void setSizeOnly(bool sizeOnly) { mSizeOnly = sizeOnly; }
255 bool sizeOnly() const { return mSizeOnly; }
256
257 /// @brief Set and get the output stream
258 std::ostream& getOutputStream() { OPENVDB_ASSERT(mOs); return *mOs; }
259 void setOutputStream(std::ostream& os) { mOs = &os; }
260
261 /// @brief Writes the given @param str buffer of size @param n
262 PagedOutputStream& write(const char* str, std::streamsize n);
263
264 /// @brief Manually flushes the current page to disk if non-zero
265 void flush();
266
267 private:
268 /// @brief Compress the @param buffer of @param size bytes and write
269 /// out to the stream.
270 void compressAndWrite(const char* buffer, size_t size);
271
272 /// @brief Resize the internal page buffer to @param size bytes
273 void resize(size_t size);
274
275 std::unique_ptr<char[]> mData = std::unique_ptr<char[]>(new char[PageSize]);
276 std::unique_ptr<char[]> mCompressedData = nullptr;
277 size_t mCapacity = PageSize;
278 int mBytes = 0;
279 std::ostream* mOs = nullptr;
280 bool mSizeOnly = false;
281}; // class PagedOutputStream
282
283
284} // namespace compression
285} // namespace OPENVDB_VERSION_NAME
286} // namespace openvdb
287
288#endif // OPENVDB_TOOLS_STREAM_COMPRESSION_HAS_BEEN_INCLUDED
Assert.h
OPENVDB_ASSERT
#define OPENVDB_ASSERT(X)
Definition Assert.h:41
OPENVDB_API
#define OPENVDB_API
Definition Platform.h:291
openvdb::v13_0::compression::PageHandle::read
std::unique_ptr< char[]> read()
Read and return the buffer, loading and decompressing the Page if necessary.
openvdb::v13_0::compression::PageHandle::page
Page & page()
Retrieve a reference to the stored page.
openvdb::v13_0::compression::PageHandle::Ptr
std::unique_ptr< PageHandle > Ptr
Definition StreamCompression.h:173
openvdb::v13_0::compression::PageHandle::PageHandle
PageHandle(const Page::Ptr &page, const int index, const int size)
Create the page handle.
openvdb::v13_0::compression::PageHandle::copy
Ptr copy()
Return a copy of this PageHandle.
Definition StreamCompression.h:192
openvdb::v13_0::compression::PageHandle::size
int size() const
Return the size of the buffer.
Definition StreamCompression.h:185
openvdb::v13_0::compression::Page
Stores a variable-size, compressed, delayed-load Page of data that is loaded into memory when accesse...
Definition StreamCompression.h:113
openvdb::v13_0::compression::Page::uncompressedBytes
long uncompressedBytes() const
Uncompressed bytes of the Paged data, available when the header has been read.
openvdb::v13_0::compression::Page::readHeader
void readHeader(std::istream &)
Read the Page header.
openvdb::v13_0::compression::Page::load
void load() const
load the Page into memory
openvdb::v13_0::compression::Page::isOutOfCore
bool isOutOfCore() const
Test if the data is out-of-core.
openvdb::v13_0::compression::Page::Page
Page()=default
openvdb::v13_0::compression::Page::buffer
const char * buffer(const int index) const
Retrieves a data pointer at the specific.
openvdb::v13_0::compression::Page::Ptr
std::shared_ptr< Page > Ptr
Definition StreamCompression.h:127
openvdb::v13_0::compression::Page::readBuffers
void readBuffers(std::istream &, bool delayed)
Read the Page buffers. If delayed is true, stream pointers will be stored to load the data lazily.
openvdb::v13_0::compression::PagedInputStream::setSizeOnly
void setSizeOnly(bool sizeOnly)
Size-only mode tags the stream as only reading size data.
Definition StreamCompression.h:217
openvdb::v13_0::compression::PagedInputStream::PagedInputStream
PagedInputStream(std::istream &is)
openvdb::v13_0::compression::PagedInputStream::PagedInputStream
PagedInputStream()=default
openvdb::v13_0::compression::PagedInputStream::createHandle
PageHandle::Ptr createHandle(std::streamsize n)
Creates a PageHandle to access the next.
openvdb::v13_0::compression::PagedInputStream::setInputStream
void setInputStream(std::istream &is)
Definition StreamCompression.h:222
openvdb::v13_0::compression::PagedInputStream::sizeOnly
bool sizeOnly() const
Definition StreamCompression.h:218
openvdb::v13_0::compression::PagedInputStream::read
void read(PageHandle::Ptr &pageHandle, std::streamsize n, bool delayed=true)
Takes a pageHandle and updates the referenced page with the current stream pointer position and if de...
openvdb::v13_0::compression::PagedInputStream::Ptr
std::shared_ptr< PagedInputStream > Ptr
Definition StreamCompression.h:210
openvdb::v13_0::compression::PagedInputStream::getInputStream
std::istream & getInputStream()
Definition StreamCompression.h:221
openvdb::v13_0::compression::PagedOutputStream::setSizeOnly
void setSizeOnly(bool sizeOnly)
Size-only mode tags the stream as only writing size data.
Definition StreamCompression.h:254
openvdb::v13_0::compression::PagedOutputStream::setOutputStream
void setOutputStream(std::ostream &os)
Definition StreamCompression.h:259
openvdb::v13_0::compression::PagedOutputStream::PagedOutputStream
PagedOutputStream()
openvdb::v13_0::compression::PagedOutputStream::getOutputStream
std::ostream & getOutputStream()
Set and get the output stream.
Definition StreamCompression.h:258
openvdb::v13_0::compression::PagedOutputStream::Ptr
std::shared_ptr< PagedOutputStream > Ptr
Definition StreamCompression.h:247
openvdb::v13_0::compression::PagedOutputStream::sizeOnly
bool sizeOnly() const
Definition StreamCompression.h:255
openvdb::v13_0::compression::PagedOutputStream::write
PagedOutputStream & write(const char *str, std::streamsize n)
Writes the given.
openvdb::v13_0::compression::PagedOutputStream::PagedOutputStream
PagedOutputStream(std::ostream &os)
openvdb::v13_0::compression::PagedOutputStream::flush
void flush()
Manually flushes the current page to disk if non-zero.
openvdb::v13_0::compression
Definition StreamCompression.h:34
openvdb::v13_0::compression::PageSize
static const int PageSize
Definition StreamCompression.h:106
openvdb::v13_0::compression::BLOSC_PAD_BYTES
static const int BLOSC_PAD_BYTES
Definition StreamCompression.h:43
openvdb::v13_0::compression::BLOSC_MINIMUM_BYTES
static const int BLOSC_MINIMUM_BYTES
Definition StreamCompression.h:39
openvdb::v13_0::compression::bloscCanCompress
OPENVDB_API bool bloscCanCompress()
Returns true if compression is available.
openvdb::v13_0::compression::bloscDecompress
OPENVDB_API void bloscDecompress(char *uncompressedBuffer, const size_t expectedBytes, const size_t bufferBytes, const char *compressedBuffer)
Decompress into the supplied buffer. Will throw if decompression fails or uncompressed buffer has ins...
openvdb::v13_0::compression::bloscUncompressedSize
OPENVDB_API size_t bloscUncompressedSize(const char *buffer)
Retrieves the uncompressed size of buffer when uncompressed.
openvdb::v13_0::compression::bloscCompressedSize
OPENVDB_API size_t bloscCompressedSize(const char *buffer, const size_t uncompressedBytes)
Convenience wrapper to retrieve the compressed size of buffer when compressed.
openvdb::v13_0::compression::bloscCompress
OPENVDB_API void bloscCompress(char *compressedBuffer, size_t &compressedBytes, const size_t bufferBytes, const char *uncompressedBuffer, const size_t uncompressedBytes)
Compress into the supplied buffer.
openvdb::v13_0::SharedPtr
std::shared_ptr< T > SharedPtr
Definition Types.h:95
openvdb
Definition Exceptions.h:13
io.h
OPENVDB_VERSION_NAME
#define OPENVDB_VERSION_NAME
The version namespace name for this library version.
Definition version.h.in:121
OPENVDB_USE_VERSION_NAMESPACE
#define OPENVDB_USE_VERSION_NAMESPACE
Definition version.h.in:218