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Buflib: Handle not having enough space for new handles (fixes FS#12265).

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Handles are allocated at the end, growing downwards.
The tiny allocations from r30478 broke buflib, since it was assumed that the only shrinkable allocation (the audiobuffer) is the very last allocation.
The tiny allocations however fit into the reserve buffer for new handles, breaking the above assumption, and they can't shrink to make room for handles.

Now, move any allocations before audiobuf (or shrink audiobuf like before) to make room for handles. This also unifies some duplicated code.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30486 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Thomas Martitz 2011-09-09 13:33:22 +00:00
parent 7e3a3f491d
commit 0dcbc6cd5d
1 changed files with 40 additions and 27 deletions
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67
firmware/buflib.c
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@ -89,6 +89,9 @@
#define BDEBUGF(...) do { } while(0) #define BDEBUGF(...) do { } while(0)
#endif #endif
static union buflib_data*
find_block_before(struct buflib_context *ctx, union buflib_data* block,
bool is_free);
/* Initialize buffer manager */ /* Initialize buffer manager */
void void
buflib_init(struct buflib_context *ctx, void *buf, size_t size) buflib_init(struct buflib_context *ctx, void *buf, size_t size)
@ -227,7 +230,7 @@ buflib_compact(struct buflib_context *ctx)
int shift = 0, len; int shift = 0, len;
/* Store the results of attempting to shrink the handle table */ /* Store the results of attempting to shrink the handle table */
bool ret = handle_table_shrink(ctx); bool ret = handle_table_shrink(ctx);
for(block = ctx->first_free_block; block != ctx->alloc_end; block += len) for(block = ctx->first_free_block; block < ctx->alloc_end; block += len)
{ {
len = block->val; len = block->val;
/* This block is free, add its length to the shift value */ /* This block is free, add its length to the shift value */
@ -241,11 +244,14 @@ buflib_compact(struct buflib_context *ctx)
if (-ctx->first_free_block->val > block->val) if (-ctx->first_free_block->val > block->val)
{ {
intptr_t size = ctx->first_free_block->val; intptr_t size = ctx->first_free_block->val;
union buflib_data* next_block = block + block->val;
if (move_block(ctx, block, ctx->first_free_block - block)) if (move_block(ctx, block, ctx->first_free_block - block))
{ {
/* moving was successful. Mark the next block as the new /* moving was successful. Mark the next block as the new
* first_free_block and merge it with the free space * first_free_block and merge it with the free space
* that the move created */ * that the move created */
if (ctx->alloc_end == next_block)
ctx->alloc_end = block;
ctx->first_free_block += block->val; ctx->first_free_block += block->val;
ctx->first_free_block->val = size + block->val; ctx->first_free_block->val = size + block->val;
continue; continue;
@ -307,12 +313,16 @@ buflib_compact_and_shrink(struct buflib_context *ctx, unsigned shrink_hints)
int ret; int ret;
int handle = ctx->handle_table - this[1].handle; int handle = ctx->handle_table - this[1].handle;
char* data = this[1].handle->alloc; char* data = this[1].handle->alloc;
bool last = (this+this->val) == ctx->alloc_end;
ret = this[2].ops->shrink_callback(handle, shrink_hints, ret = this[2].ops->shrink_callback(handle, shrink_hints,
data, (char*)(this+this->val)-data); data, (char*)(this+this->val)-data);
result |= (ret == BUFLIB_CB_OK); result |= (ret == BUFLIB_CB_OK);
/* this might have changed in the callback (if /* this might have changed in the callback (if
* it shrinked from the top), get it again */ * it shrinked from the top), get it again */
this = handle_to_block(ctx, handle); this = handle_to_block(ctx, handle);
/* could also change with shrinking from back */
if (last)
ctx->alloc_end = this + this->val;
} }
} }
/* shrinking was successful at least once, try compaction again */ /* shrinking was successful at least once, try compaction again */
@ -407,26 +417,26 @@ handle_alloc:
/* If allocation has failed, and compaction has succeded, it may be /* If allocation has failed, and compaction has succeded, it may be
* possible to get a handle by trying again. * possible to get a handle by trying again.
*/ */
if (!ctx->compact && buflib_compact(ctx)) union buflib_data* last_block = find_block_before(ctx,
goto handle_alloc; ctx->alloc_end, false);
else struct buflib_callbacks* ops = last_block[2].ops;
{ /* first try to shrink the alloc before the handle table unsigned hints = 0;
* to make room for new handles */ if (!ops || !ops->shrink_callback)
int handle = ctx->handle_table - ctx->last_handle; { /* the last one isn't shrinkable
union buflib_data* last_block = handle_to_block(ctx, handle); * make room in front of a shrinkable and move this alloc */
struct buflib_callbacks* ops = last_block[2].ops; hints = BUFLIB_SHRINK_POS_FRONT;
if (ops && ops->shrink_callback) hints |= last_block->val * sizeof(union buflib_data);
{
char *data = buflib_get_data(ctx, handle);
unsigned hint = BUFLIB_SHRINK_POS_BACK | 10*sizeof(union buflib_data);
if (ops->shrink_callback(handle, hint, data,
(char*)(last_block+last_block->val)-data) == BUFLIB_CB_OK)
{ /* retry one more time */
goto handle_alloc;
}
}
return -1;
} }
else if (ops && ops->shrink_callback)
{ /* the last is shrinkable, make room for handles directly */
hints = BUFLIB_SHRINK_POS_BACK;
hints |= 16*sizeof(union buflib_data);
}
/* buflib_compact_and_shrink() will compact and move last_block()
* if possible */
if (buflib_compact_and_shrink(ctx, hints))
goto handle_alloc;
return -1;
} }
buffer_alloc: buffer_alloc:
@ -504,9 +514,10 @@ buffer_alloc:
/* Finds the free block before block, and returns NULL if it's not free */ /* Finds the free block before block, and returns NULL if it's not free */
static union buflib_data* static union buflib_data*
find_free_block_before(struct buflib_context *ctx, union buflib_data* block) find_block_before(struct buflib_context *ctx, union buflib_data* block,
bool is_free)
{ {
union buflib_data *ret = ctx->first_free_block, union buflib_data *ret = ctx->buf_start,
*next_block = ret; *next_block = ret;
/* find the block that's before the current one */ /* find the block that's before the current one */
@ -519,10 +530,12 @@ find_free_block_before(struct buflib_context *ctx, union buflib_data* block)
/* If next_block == block, the above loop didn't go anywhere. If it did, /* If next_block == block, the above loop didn't go anywhere. If it did,
* and the block before this one is empty, that is the wanted one * and the block before this one is empty, that is the wanted one
*/ */
if (next_block == block && ret < block && ret->val < 0) if (next_block == block && ret < block)
{
if (is_free && ret->val >= 0) /* NULL if found block isn't free */
return NULL;
return ret; return ret;
/* otherwise, e.g. if ret > block, or if the buffer is compact, }
* there's no free block before */
return NULL; return NULL;
} }
@ -536,7 +549,7 @@ buflib_free(struct buflib_context *ctx, int handle_num)
/* We need to find the block before the current one, to see if it is free /* We need to find the block before the current one, to see if it is free
* and can be merged with this one. * and can be merged with this one.
*/ */
block = find_free_block_before(ctx, freed_block); block = find_block_before(ctx, freed_block, true);
if (block) if (block)
{ {
block->val -= freed_block->val; block->val -= freed_block->val;
@ -652,7 +665,7 @@ buflib_shrink(struct buflib_context* ctx, int handle, void* new_start, size_t ne
/* mark the old block unallocated */ /* mark the old block unallocated */
block->val = block - new_block; block->val = block - new_block;
/* find the block before in order to merge with the new free space */ /* find the block before in order to merge with the new free space */
union buflib_data *free_before = find_free_block_before(ctx, block); union buflib_data *free_before = find_block_before(ctx, block, true);
if (free_before) if (free_before)
free_before->val += block->val; free_before->val += block->val;
else if (ctx->first_free_block > block) else if (ctx->first_free_block > block)