1 // SPDX-License-Identifier: 0BSD 2 3 /////////////////////////////////////////////////////////////////////////////// 4 // 5 /// \file outqueue.h 6 /// \brief Output queue handling in multithreaded coding 7 // 8 // Author: Lasse Collin 9 // 10 /////////////////////////////////////////////////////////////////////////////// 11 12 #ifndef LZMA_OUTQUEUE_H 13 #define LZMA_OUTQUEUE_H 14 15 #include "common.h" 16 17 18 /// Output buffer for a single thread 19 typedef struct lzma_outbuf_s lzma_outbuf; 20 struct lzma_outbuf_s { 21 /// Pointer to the next buffer. This is used for the cached buffers. 22 /// The worker thread must not modify this. 23 lzma_outbuf *next; 24 25 /// This initialized by lzma_outq_get_buf() and 26 /// is used by lzma_outq_enable_partial_output(). 27 /// The worker thread must not modify this. 28 void *worker; 29 30 /// Amount of memory allocated for buf[]. 31 /// The worker thread must not modify this. 32 size_t allocated; 33 34 /// Writing position in the worker thread or, in other words, the 35 /// amount of finished data written to buf[] which can be copied out 36 /// 37 /// \note This is read by another thread and thus access 38 /// to this variable needs a mutex. 39 size_t pos; 40 41 /// Decompression: Position in the input buffer in the worker thread 42 /// that matches the output "pos" above. This is used to detect if 43 /// more output might be possible from the worker thread: if it has 44 /// consumed all its input, then more output isn't possible. 45 /// 46 /// \note This is read by another thread and thus access 47 /// to this variable needs a mutex. 48 size_t decoder_in_pos; 49 50 /// True when no more data will be written into this buffer. 51 /// 52 /// \note This is read by another thread and thus access 53 /// to this variable needs a mutex. 54 bool finished; 55 56 /// Return value for lzma_outq_read() when the last byte from 57 /// a finished buffer has been read. Defaults to LZMA_STREAM_END. 58 /// This must *not* be LZMA_OK. The idea is to allow a decoder to 59 /// pass an error code to the main thread, setting the code here 60 /// together with finished = true. 61 lzma_ret finish_ret; 62 63 /// Additional size information. lzma_outq_read() may read these 64 /// when "finished" is true. 65 lzma_vli unpadded_size; 66 lzma_vli uncompressed_size; 67 68 /// Buffer of "allocated" bytes 69 uint8_t buf[]; 70 }; 71 72 73 typedef struct { 74 /// Linked list of buffers in use. The next output byte will be 75 /// read from the head and buffers for the next thread will be 76 /// appended to the tail. tail->next is always NULL. 77 lzma_outbuf *head; 78 lzma_outbuf *tail; 79 80 /// Number of bytes read from head->buf[] in lzma_outq_read() 81 size_t read_pos; 82 83 /// Linked list of allocated buffers that aren't currently used. 84 /// This way buffers of similar size can be reused and don't 85 /// need to be reallocated every time. For simplicity, all 86 /// cached buffers in the list have the same allocated size. 87 lzma_outbuf *cache; 88 89 /// Total amount of memory allocated for buffers 90 uint64_t mem_allocated; 91 92 /// Amount of memory used by the buffers that are in use in 93 /// the head...tail linked list. 94 uint64_t mem_in_use; 95 96 /// Number of buffers in use in the head...tail list. If and only if 97 /// this is zero, the pointers head and tail above are NULL. 98 uint32_t bufs_in_use; 99 100 /// Number of buffers allocated (in use + cached) 101 uint32_t bufs_allocated; 102 103 /// Maximum allowed number of allocated buffers 104 uint32_t bufs_limit; 105 } lzma_outq; 106 107 108 /** 109 * \brief Calculate the memory usage of an output queue 110 * 111 * \return Approximate memory usage in bytes or UINT64_MAX on error. 112 */ 113 extern uint64_t lzma_outq_memusage(uint64_t buf_size_max, uint32_t threads); 114 115 116 /// \brief Initialize an output queue 117 /// 118 /// \param outq Pointer to an output queue. Before calling 119 /// this function the first time, *outq should 120 /// have been zeroed with memzero() so that this 121 /// function knows that there are no previous 122 /// allocations to free. 123 /// \param allocator Pointer to allocator or NULL 124 /// \param threads Number of buffers that may be in use 125 /// concurrently. Note that more than this number 126 /// of buffers may actually get allocated to 127 /// improve performance when buffers finish 128 /// out of order. The actual maximum number of 129 /// allocated buffers is derived from the number 130 /// of threads. 131 /// 132 /// \return - LZMA_OK 133 /// - LZMA_MEM_ERROR 134 /// 135 extern lzma_ret lzma_outq_init(lzma_outq *outq, 136 const lzma_allocator *allocator, uint32_t threads); 137 138 139 /// \brief Free the memory associated with the output queue 140 extern void lzma_outq_end(lzma_outq *outq, const lzma_allocator *allocator); 141 142 143 /// \brief Free all cached buffers that consume memory but aren't in use 144 extern void lzma_outq_clear_cache( 145 lzma_outq *outq, const lzma_allocator *allocator); 146 147 148 /// \brief Like lzma_outq_clear_cache() but might keep one buffer 149 /// 150 /// One buffer is not freed if its size is equal to keep_size. 151 /// This is useful if the caller knows that it will soon need a buffer of 152 /// keep_size bytes. This way it won't be freed and immediately reallocated. 153 extern void lzma_outq_clear_cache2( 154 lzma_outq *outq, const lzma_allocator *allocator, 155 size_t keep_size); 156 157 158 /// \brief Preallocate a new buffer into cache 159 /// 160 /// Splitting the buffer allocation into a separate function makes it 161 /// possible to ensure that way lzma_outq_get_buf() cannot fail. 162 /// If the preallocated buffer isn't actually used (for example, some 163 /// other error occurs), the caller has to do nothing as the buffer will 164 /// be used later or cleared from the cache when not needed. 165 /// 166 /// \return LZMA_OK on success, LZMA_MEM_ERROR if allocation fails 167 /// 168 extern lzma_ret lzma_outq_prealloc_buf( 169 lzma_outq *outq, const lzma_allocator *allocator, size_t size); 170 171 172 /// \brief Get a new buffer 173 /// 174 /// lzma_outq_prealloc_buf() must be used to ensure that there is a buffer 175 /// available before calling lzma_outq_get_buf(). 176 /// 177 extern lzma_outbuf *lzma_outq_get_buf(lzma_outq *outq, void *worker); 178 179 180 /// \brief Test if there is data ready to be read 181 /// 182 /// Call to this function must be protected with the same mutex that 183 /// is used to protect lzma_outbuf.finished. 184 /// 185 extern bool lzma_outq_is_readable(const lzma_outq *outq); 186 187 188 /// \brief Read finished data 189 /// 190 /// \param outq Pointer to an output queue 191 /// \param allocator lzma_allocator for custom allocator functions 192 /// \param out Beginning of the output buffer 193 /// \param out_pos The next byte will be written to 194 /// out[*out_pos]. 195 /// \param out_size Size of the out buffer; the first byte into 196 /// which no data is written to is out[out_size]. 197 /// \param unpadded_size Unpadded Size from the Block encoder 198 /// \param uncompressed_size Uncompressed Size from the Block encoder 199 /// 200 /// \return - LZMA: All OK. Either no data was available or the buffer 201 /// being read didn't become empty yet. 202 /// - LZMA_STREAM_END: The buffer being read was finished. 203 /// *unpadded_size and *uncompressed_size were set if they 204 /// were not NULL. 205 /// 206 /// \note This reads lzma_outbuf.finished and .pos variables and thus 207 /// calls to this function need to be protected with a mutex. 208 /// 209 extern lzma_ret lzma_outq_read(lzma_outq *restrict outq, 210 const lzma_allocator *restrict allocator, 211 uint8_t *restrict out, size_t *restrict out_pos, 212 size_t out_size, lzma_vli *restrict unpadded_size, 213 lzma_vli *restrict uncompressed_size); 214 215 216 /// \brief Enable partial output from a worker thread 217 /// 218 /// If the buffer at the head of the output queue isn't finished, 219 /// this will call enable_partial_output on the worker associated with 220 /// that output buffer. 221 /// 222 /// \note This reads a lzma_outbuf.finished variable and thus 223 /// calls to this function need to be protected with a mutex. 224 /// 225 extern void lzma_outq_enable_partial_output(lzma_outq *outq, 226 void (*enable_partial_output)(void *worker)); 227 228 229 /// \brief Test if there is at least one buffer free 230 /// 231 /// This must be used before getting a new buffer with lzma_outq_get_buf(). 232 /// 233 static inline bool 234 lzma_outq_has_buf(const lzma_outq *outq) 235 { 236 return outq->bufs_in_use < outq->bufs_limit; 237 } 238 239 240 /// \brief Test if the queue is completely empty 241 static inline bool 242 lzma_outq_is_empty(const lzma_outq *outq) 243 { 244 return outq->bufs_in_use == 0; 245 } 246 247 248 /// \brief Get the amount of memory needed for a single lzma_outbuf 249 /// 250 /// \note Caller must check that the argument is significantly less 251 /// than SIZE_MAX to avoid an integer overflow! 252 static inline uint64_t 253 lzma_outq_outbuf_memusage(size_t buf_size) 254 { 255 assert(buf_size <= SIZE_MAX - sizeof(lzma_outbuf)); 256 return sizeof(lzma_outbuf) + buf_size; 257 } 258 259 #endif 260
Indexes created Mon Oct 12 00:27:07 UTC 2026