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///////////////////////////////////////////////////////////////////////////////
//
/// \file outqueue.h
/// \brief Output queue handling in multithreaded coding
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "common.h"
/// Output buffer for a single thread
typedef struct lzma_outbuf_s lzma_outbuf;
struct lzma_outbuf_s {
/// Pointer to the next buffer. This is used for the cached buffers.
/// The worker thread must not modify this.
lzma_outbuf *next;
/// This initialized by lzma_outq_get_buf() and
/// is used by lzma_outq_enable_partial_output().
/// The worker thread must not modify this.
void *worker;
/// Amount of memory allocated for buf[].
/// The worker thread must not modify this.
size_t allocated;
/// Writing position in the worker thread or, in other words, the
/// amount of finished data written to buf[] which can be copied out
///
/// \note This is read by another thread and thus access
/// to this variable needs a mutex.
size_t pos;
/// Decompression: Position in the input buffer in the worker thread
/// that matches the output "pos" above. This is used to detect if
/// more output might be possible from the worker thread: if it has
/// consumed all its input, then more output isn't possible.
///
/// \note This is read by another thread and thus access
/// to this variable needs a mutex.
size_t decoder_in_pos;
/// True when no more data will be written into this buffer.
///
/// \note This is read by another thread and thus access
/// to this variable needs a mutex.
bool finished;
/// Return value for lzma_outq_read() when the last byte from
/// a finished buffer has been read. Defaults to LZMA_STREAM_END.
/// This must *not* be LZMA_OK. The idea is to allow a decoder to
/// pass an error code to the main thread, setting the code here
/// together with finished = true.
lzma_ret finish_ret;
/// Additional size information. lzma_outq_read() may read these
/// when "finished" is true.
lzma_vli unpadded_size;
lzma_vli uncompressed_size;
/// Buffer of "allocated" bytes
uint8_t buf[];
};
typedef struct {
/// Linked list of buffers in use. The next output byte will be
/// read from the head and buffers for the next thread will be
/// appended to the tail. tail->next is always NULL.
lzma_outbuf *head;
lzma_outbuf *tail;
/// Number of bytes read from head->buf[] in lzma_outq_read()
size_t read_pos;
/// Linked list of allocated buffers that aren't currently used.
/// This way buffers of similar size can be reused and don't
/// need to be reallocated every time. For simplicity, all
/// cached buffers in the list have the same allocated size.
lzma_outbuf *cache;
/// Total amount of memory allocated for buffers
uint64_t mem_allocated;
/// Amount of memory used by the buffers that are in use in
/// the head...tail linked list.
uint64_t mem_in_use;
/// Number of buffers in use in the head...tail list. If and only if
/// this is zero, the pointers head and tail above are NULL.
uint32_t bufs_in_use;
/// Number of buffers allocated (in use + cached)
uint32_t bufs_allocated;
/// Maximum allowed number of allocated buffers
uint32_t bufs_limit;
} lzma_outq;
/**
* \brief Calculate the memory usage of an output queue
*
* \return Approximate memory usage in bytes or UINT64_MAX on error.
*/
extern uint64_t lzma_outq_memusage(uint64_t buf_size_max, uint32_t threads);
/// \brief Initialize an output queue
///
/// \param outq Pointer to an output queue. Before calling
/// this function the first time, *outq should
/// have been zeroed with memzero() so that this
/// function knows that there are no previous
/// allocations to free.
/// \param allocator Pointer to allocator or NULL
/// \param threads Number of buffers that may be in use
/// concurrently. Note that more than this number
/// of buffers may actually get allocated to
/// improve performance when buffers finish
/// out of order. The actual maximum number of
/// allocated buffers is derived from the number
/// of threads.
///
/// \return - LZMA_OK
/// - LZMA_MEM_ERROR
///
extern lzma_ret lzma_outq_init(lzma_outq *outq,
const lzma_allocator *allocator, uint32_t threads);
/// \brief Free the memory associated with the output queue
extern void lzma_outq_end(lzma_outq *outq, const lzma_allocator *allocator);
/// \brief Free all cached buffers that consume memory but aren't in use
extern void lzma_outq_clear_cache(
lzma_outq *outq, const lzma_allocator *allocator);
/// \brief Like lzma_outq_clear_cache() but might keep one buffer
///
/// One buffer is not freed if its size is equal to keep_size.
/// This is useful if the caller knows that it will soon need a buffer of
/// keep_size bytes. This way it won't be freed and immediately reallocated.
extern void lzma_outq_clear_cache2(
lzma_outq *outq, const lzma_allocator *allocator,
size_t keep_size);
/// \brief Preallocate a new buffer into cache
///
/// Splitting the buffer allocation into a separate function makes it
/// possible to ensure that way lzma_outq_get_buf() cannot fail.
/// If the preallocated buffer isn't actually used (for example, some
/// other error occurs), the caller has to do nothing as the buffer will
/// be used later or cleared from the cache when not needed.
///
/// \return LZMA_OK on success, LZMA_MEM_ERROR if allocation fails
///
extern lzma_ret lzma_outq_prealloc_buf(
lzma_outq *outq, const lzma_allocator *allocator, size_t size);
/// \brief Get a new buffer
///
/// lzma_outq_prealloc_buf() must be used to ensure that there is a buffer
/// available before calling lzma_outq_get_buf().
///
extern lzma_outbuf *lzma_outq_get_buf(lzma_outq *outq, void *worker);
/// \brief Test if there is data ready to be read
///
/// Call to this function must be protected with the same mutex that
/// is used to protect lzma_outbuf.finished.
///
extern bool lzma_outq_is_readable(const lzma_outq *outq);
/// \brief Read finished data
///
/// \param outq Pointer to an output queue
/// \param out Beginning of the output buffer
/// \param out_pos The next byte will be written to
/// out[*out_pos].
/// \param out_size Size of the out buffer; the first byte into
/// which no data is written to is out[out_size].
/// \param unpadded_size Unpadded Size from the Block encoder
/// \param uncompressed_size Uncompressed Size from the Block encoder
///
/// \return - LZMA: All OK. Either no data was available or the buffer
/// being read didn't become empty yet.
/// - LZMA_STREAM_END: The buffer being read was finished.
/// *unpadded_size and *uncompressed_size were set if they
/// were not NULL.
///
/// \note This reads lzma_outbuf.finished and .pos variables and thus
/// calls to this function need to be protected with a mutex.
///
extern lzma_ret lzma_outq_read(lzma_outq *restrict outq,
const lzma_allocator *restrict allocator,
uint8_t *restrict out, size_t *restrict out_pos,
size_t out_size, lzma_vli *restrict unpadded_size,
lzma_vli *restrict uncompressed_size);
/// \brief Enable partial output from a worker thread
///
/// If the buffer at the head of the output queue isn't finished,
/// this will call enable_partial_output on the worker associated with
/// that output buffer.
///
/// \note This reads a lzma_outbuf.finished variable and thus
/// calls to this function need to be protected with a mutex.
///
extern void lzma_outq_enable_partial_output(lzma_outq *outq,
void (*enable_partial_output)(void *worker));
/// \brief Test if there is at least one buffer free
///
/// This must be used before getting a new buffer with lzma_outq_get_buf().
///
static inline bool
lzma_outq_has_buf(const lzma_outq *outq)
{
return outq->bufs_in_use < outq->bufs_limit;
}
/// \brief Test if the queue is completely empty
static inline bool
lzma_outq_is_empty(const lzma_outq *outq)
{
return outq->bufs_in_use == 0;
}
/// \brief Get the amount of memory needed for a single lzma_outbuf
///
/// \note Caller must check that the argument is significantly less
/// than SIZE_MAX to avoid an integer overflow!
static inline uint64_t
lzma_outq_outbuf_memusage(size_t buf_size)
{
assert(buf_size <= SIZE_MAX - sizeof(lzma_outbuf));
return sizeof(lzma_outbuf) + buf_size;
}
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