janwas
8371f42da9
adts: slight improvements allocators: change POOL_VARIABLE_ALLOCS to -1 for safety; fix invalid assumptions of it being 0 lib: more expressive param names file: add file_get_random_name for randomized trace generation; allow file_cache.h to declare externally visible file_buf_alloc API file_cache: zero-length file bugfix; also add several flags to the API routines allowing statistics gathering to be disabled (avoids distorting stats due to e.g. trace_entry_causes_io cache simulation) file_stats: add archive builder info; separate IO timing and seek accounting (-> correct results) trace: add random generation capability vfs: made responsible for cache hit/miss accounting (fixes cache miss rate display) This was SVN commit r3681.
115 lines
4.5 KiB
C
115 lines
4.5 KiB
C
#ifndef FILE_CACHE_H__
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#define FILE_CACHE_H__
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struct BlockId
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{
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const char* atom_fn;
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u32 block_num;
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};
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extern bool block_eq(BlockId b1, BlockId b2);
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// create an id for use with the cache that uniquely identifies
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// the block from the file <atom_fn> starting at <ofs>.
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extern BlockId block_cache_make_id(const char* atom_fn, const off_t ofs);
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extern void* block_cache_alloc(BlockId id);
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extern void block_cache_mark_completed(BlockId id);
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extern void* block_cache_find(BlockId id);
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extern void block_cache_release(BlockId id);
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enum FileCacheFlags
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{
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// indicates the buffer will not be freed immediately
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// (i.e. before the next buffer alloc) as it normally should.
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// this flag serves to suppress a warning and better avoid fragmentation.
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// caller sets this when FILE_LONG_LIVED is specified.
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//
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// also used by file_cache_retrieve because it may have to
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// 'reactivate' the buffer (transfer from cache to extant list),
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// which requires knowing whether the buffer is long-lived or not.
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FC_LONG_LIVED = 1,
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// statistics (e.g. # buffer allocs) should not be updated.
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// (useful for simulation, e.g. trace_entry_causes_io)
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FC_NO_STATS = 2,
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// file_cache_retrieve should not update item credit.
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// (useful when just looking up buffer given atom_fn)
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FC_NO_ACCOUNTING = 4
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};
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// allocate a new buffer of <size> bytes (possibly more due to internal
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// fragmentation). never returns 0.
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// <atom_fn>: owner filename (buffer is intended to be used for data from
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// this file).
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extern FileIOBuf file_buf_alloc(size_t size, const char* atom_fn, uint fc_flags = 0);
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// mark <buf> as no longer needed. if its reference count drops to 0,
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// it will be removed from the extant list. if it had been added to the
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// cache, it remains there until evicted in favor of another buffer.
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extern LibError file_buf_free(FileIOBuf buf, uint fc_flags = 0);
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// interpret file_io parameters (pbuf, size, flags, cb) and allocate a
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// file buffer if necessary.
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// called by file_io and afile_read.
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extern LibError file_buf_get(FileIOBuf* pbuf, size_t size,
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const char* atom_fn, uint flags, FileIOCB cb);
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// inform us that the buffer address will be increased by <padding>-bytes.
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// this happens when reading uncompressed files from archive: they
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// start at unaligned offsets and file_io rounds offset down to
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// next block boundary. the buffer therefore starts with padding, which
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// is skipped so the user only sees their data.
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// we make note of the new buffer address so that it can be freed correctly
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// by passing the new padded buffer.
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extern void file_buf_add_padding(FileIOBuf exact_buf, size_t exact_size, size_t padding);
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// if buf is not in extant list, complain; otherwise, mark it as
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// coming from the file <atom_fn>.
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// this is needed in the following case: uncompressed reads from archive
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// boil down to a file_io of the archive file. the buffer is therefore
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// tagged with the archive filename instead of the desired filename.
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// afile_read sets things right by calling this.
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extern LibError file_buf_set_real_fn(FileIOBuf buf, const char* atom_fn);
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// "give" <buf> to the cache, specifying its size and owner filename.
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// since this data may be shared among users of the cache, it is made
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// read-only (via MMU) to make sure no one can corrupt/change it.
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//
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// note: the reference added by file_buf_alloc still exists! it must
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// still be file_buf_free-d after calling this.
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extern LibError file_cache_add(FileIOBuf buf, size_t size, const char* atom_fn);
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// check if the contents of the file <atom_fn> are in file cache.
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// if not, return 0; otherwise, return buffer address and optionally
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// pass back its size.
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//
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// note: does not call stats_cache because it does not know the file size
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// in case of cache miss! doing so is left to the caller.
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extern FileIOBuf file_cache_retrieve(const char* atom_fn, size_t* psize, uint fc_flags = 0);
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// invalidate all data loaded from the file <fn>. this ensures the next
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// load of this file gets the (presumably new) contents of the file,
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// not previous stale cache contents.
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// call after hotloading code detects file has been changed.
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extern LibError file_cache_invalidate(const char* P_fn);
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// reset entire state of the file cache to what it was after initialization.
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// that means completely emptying the extant list and cache.
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// used after simulating cache operation, which fills the cache with
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// invalid data.
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extern void file_cache_reset();
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extern void file_cache_init();
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extern void file_cache_shutdown();
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#endif // #ifndef FILE_CACHE_H__
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