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xz: Make --block-list and --block-size work together in single-threaded.

Previously, --block-list and --block-size only worked together
in threaded mode. Boundaries are specified by --block-list, but
--block-size specifies the maximum size for a Block. Now this
works in single-threaded mode too.

Thanks to James M Leddy for the original patch.
This commit is contained in:
Lasse Collin 2013-11-12 16:29:48 +02:00
parent ae222fe980
commit dd750acbe2

View file

@ -514,6 +514,56 @@ coder_init(file_pair *pair)
}
/// Resolve conflicts between opt_block_size and opt_block_list in single
/// threaded mode. We want to default to opt_block_list, except when it is
/// larger than opt_block_size. If this is the case for the current Block
/// at *list_pos, then we break into smaller Blocks. Otherwise advance
/// to the next Block in opt_block_list, and break apart if needed.
static void
split_block(uint64_t *block_remaining,
uint64_t *next_block_remaining,
uint64_t *list_pos)
{
if (*next_block_remaining > 0) {
// The Block at *list_pos has previously been split up.
assert(hardware_threads_get() == 1);
assert(opt_block_size > 0);
assert(opt_block_list != NULL);
if (*next_block_remaining > opt_block_size) {
// We have to split the current Block at *list_pos
// into another opt_block_size length Block.
*block_remaining = opt_block_size;
} else {
// This is the last remaining split Block for the
// Block at *list_pos.
*block_remaining = *next_block_remaining;
}
*next_block_remaining -= *block_remaining;
} else {
// The Block at *list_pos has been finished. Go to the next
// entry in the list. If the end of the list has been reached,
// reuse the size of the last Block.
if (opt_block_list[*list_pos + 1] != 0)
++*list_pos;
*block_remaining = opt_block_list[*list_pos];
// If in single-threaded mode, split up the Block if needed.
// This is not needed in multi-threaded mode because liblzma
// will do this due to how threaded encoding works.
if (hardware_threads_get() == 1 && opt_block_size > 0
&& *block_remaining > opt_block_size) {
*next_block_remaining
= *block_remaining - opt_block_size;
*block_remaining = opt_block_size;
}
}
}
/// Compress or decompress using liblzma.
static bool
coder_normal(file_pair *pair)
@ -537,6 +587,10 @@ coder_normal(file_pair *pair)
// only a single block is created.
uint64_t block_remaining = UINT64_MAX;
// next_block_remining for when we are in single-threaded mode and
// the Block in --block-list is larger than the --block-size=SIZE.
uint64_t next_block_remaining = 0;
// Position in opt_block_list. Unused if --block-list wasn't used.
size_t list_pos = 0;
@ -551,14 +605,22 @@ coder_normal(file_pair *pair)
// If --block-list was used, start with the first size.
//
// FIXME: Currently this overrides --block-size but this isn't
// good. For threaded case, we want --block-size to specify
// how big Blocks the encoder needs to be prepared to create
// at maximum and --block-list will simultaneously cause new
// Blocks to be started at specified intervals. To keep things
// logical, the same should be done in single-threaded mode.
if (opt_block_list != NULL)
block_remaining = opt_block_list[list_pos];
// For threaded case, --block-size specifies how big Blocks
// the encoder needs to be prepared to create at maximum
// and --block-list will simultaneously cause new Blocks
// to be started at specified intervals. To keep things
// logical, the same is done in single-threaded mode. The
// output is still not identical because in single-threaded
// mode the size info isn't written into Block Headers.
if (opt_block_list != NULL) {
if (block_remaining < opt_block_list[list_pos]) {
assert(hardware_threads_get() == 1);
next_block_remaining = opt_block_list[list_pos]
- block_remaining;
} else {
block_remaining = opt_block_list[list_pos];
}
}
}
strm.next_out = out_buf.u8;
@ -622,15 +684,13 @@ coder_normal(file_pair *pair)
} else {
// Start a new Block after LZMA_FULL_BARRIER.
if (opt_block_list == NULL) {
assert(hardware_threads_get() == 1);
assert(opt_block_size > 0);
block_remaining = opt_block_size;
} else {
// FIXME: Make it work together with
// --block-size.
if (opt_block_list[list_pos + 1] != 0)
++list_pos;
block_remaining
= opt_block_list[list_pos];
split_block(&block_remaining,
&next_block_remaining,
&list_pos);
}
}