forked from mia/Aegisub
c2267bedcc
libass: Fix cache lookup problem causing memory bloat The cache code did hash lookups by storing key values in struct fields and then hashing and comparing the struct as a single memory block. In at least one case such a struct contained uninitialized padding bytes which prevented the complete memory area of the struct from matching even though the fields did. As a result the code failed to find existing objects in the cache and stored new versions of them, causing gigabytes of memory use in some circumstances. Initializing the struct memory to zero before writing the fields avoided such memory use in tests but is not guaranteed to work if I interpret the C standard correctly (the compiler is allowed to write garbage over padding bytes when changing struct member values). Change the code to use struct-specific hashing and comparison functions that work field by field to guarantee correct behavior. Create these by replacing the struct definition with a template that lists the fields and can be used the generate each of struct definition, hash function and compare function with some preprocessor magic (otherwise every field would need to be listed separately in all three). Originally committed to SVN as r2895.
98 lines
3.2 KiB
C
98 lines
3.2 KiB
C
// -*- c-basic-offset: 8; indent-tabs-mode: t -*-
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// vim:ts=8:sw=8:noet:ai:
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/*
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* Copyright (C) 2006 Evgeniy Stepanov <eugeni.stepanov@gmail.com>
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*
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* This file is part of libass.
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*
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* libass is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* libass is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with libass; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef LIBASS_CACHE_H
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#define LIBASS_CACHE_H
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#include "ass.h"
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#include "ass_font.h"
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#include "ass_bitmap.h"
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void ass_font_cache_init(void);
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ass_font_t* ass_font_cache_find(ass_font_desc_t* desc);
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void* ass_font_cache_add(ass_font_t* font);
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void ass_font_cache_done(void);
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// Create definitions for bitmap_hash_key and glyph_hash_key
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#define CREATE_STRUCT_DEFINITIONS
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#include "ass_cache_template.c"
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typedef struct bitmap_hash_val_s {
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bitmap_t* bm; // the actual bitmaps
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bitmap_t* bm_o;
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bitmap_t* bm_s;
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} bitmap_hash_val_t;
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void ass_bitmap_cache_init(void);
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void* cache_add_bitmap(bitmap_hash_key_t* key, bitmap_hash_val_t* val);
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bitmap_hash_val_t* cache_find_bitmap(bitmap_hash_key_t* key);
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void ass_bitmap_cache_reset(void);
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void ass_bitmap_cache_done(void);
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// Cache for composited bitmaps
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typedef struct composite_hash_key_s {
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int aw, ah, bw, bh;
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int ax, ay, bx, by;
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bitmap_hash_key_t a;
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bitmap_hash_key_t b;
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} composite_hash_key_t;
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typedef struct composite_hash_val_s {
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unsigned char* a;
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unsigned char* b;
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} composite_hash_val_t;
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void ass_composite_cache_init(void);
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void* cache_add_composite(composite_hash_key_t* key, composite_hash_val_t* val);
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composite_hash_val_t* cache_find_composite(composite_hash_key_t* key);
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void ass_composite_cache_reset(void);
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void ass_composite_cache_done(void);
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typedef struct glyph_hash_val_s {
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FT_Glyph glyph;
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FT_Glyph outline_glyph;
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FT_BBox bbox_scaled; // bbox after scaling, but before rotation
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FT_Vector advance; // 26.6, advance distance to the next bitmap in line
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} glyph_hash_val_t;
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void ass_glyph_cache_init(void);
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void* cache_add_glyph(glyph_hash_key_t* key, glyph_hash_val_t* val);
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glyph_hash_val_t* cache_find_glyph(glyph_hash_key_t* key);
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void ass_glyph_cache_reset(void);
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void ass_glyph_cache_done(void);
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typedef struct hashmap_s hashmap_t;
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typedef void (*hashmap_item_dtor_t)(void* key, size_t key_size, void* value, size_t value_size);
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typedef int (*hashmap_key_compare_t)(void* key1, void* key2, size_t key_size);
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typedef unsigned (*hashmap_hash_t)(void* key, size_t key_size);
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hashmap_t* hashmap_init(size_t key_size, size_t value_size, int nbuckets,
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hashmap_item_dtor_t item_dtor, hashmap_key_compare_t key_compare,
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hashmap_hash_t hash);
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void hashmap_done(hashmap_t* map);
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void* hashmap_insert(hashmap_t* map, void* key, void* value);
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void* hashmap_find(hashmap_t* map, void* key);
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#endif /* LIBASS_CACHE_H */
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