src/liblzma/common/outqueue.h

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