Message ID | 20240205052724.26862-1-connorbworley@gmail.com |
---|---|
State | New |
Headers | show |
Series | [FFmpeg-devel,1/2] lavu/hashtable: create generic robin hood hash table | expand |
Context | Check | Description |
---|---|---|
yinshiyou/make_loongarch64 | success | Make finished |
yinshiyou/make_fate_loongarch64 | success | Make fate finished |
andriy/make_x86 | success | Make finished |
andriy/make_fate_x86 | success | Make fate finished |
Connor Worley: > Signed-off-by: Connor Worley <connorbworley@gmail.com> > --- > libavutil/Makefile | 2 + > libavutil/hashtable.c | 172 ++++++++++++++++++++++++++++++++++++ > libavutil/hashtable.h | 62 +++++++++++++ > libavutil/tests/hashtable.c | 104 ++++++++++++++++++++++ > 4 files changed, 340 insertions(+) > create mode 100644 libavutil/hashtable.c > create mode 100644 libavutil/hashtable.h > create mode 100644 libavutil/tests/hashtable.c > > diff --git a/libavutil/Makefile b/libavutil/Makefile > index e7709b97d0..be75d464fc 100644 > --- a/libavutil/Makefile > +++ b/libavutil/Makefile > @@ -138,6 +138,7 @@ OBJS = adler32.o \ > fixed_dsp.o \ > frame.o \ > hash.o \ > + hashtable.o \ > hdr_dynamic_metadata.o \ > hdr_dynamic_vivid_metadata.o \ > hmac.o \ > @@ -251,6 +252,7 @@ TESTPROGS = adler32 \ > file \ > fifo \ > hash \ > + hashtable \ > hmac \ > hwdevice \ > integer \ > diff --git a/libavutil/hashtable.c b/libavutil/hashtable.c > new file mode 100644 > index 0000000000..fb0f0aae99 > --- /dev/null > +++ b/libavutil/hashtable.c > @@ -0,0 +1,172 @@ > +/* > + * Generic hashtable > + * Copyright (C) 2024 Connor Worley <connorbworley@gmail.com> > + * > + * This file is part of FFmpeg. > + * > + * FFmpeg is free software; you can redistribute it and/or > + * modify it under the terms of the GNU Lesser General Public > + * License as published by the Free Software Foundation; either > + * version 2.1 of the License, or (at your option) any later version. > + * > + * FFmpeg is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * Lesser General Public License for more details. > + * > + * You should have received a copy of the GNU Lesser General Public > + * License along with FFmpeg; if not, write to the Free Software > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA > + */ > + > +#include <stdint.h> > + > +#include "error.h" > +#include "mem.h" > +#include "hashtable.h" > +#include "string.h" We don't have a string.h header; the string.h from the C stdlib should of course be included via <>. > + > +#define ENTRY_OCC(entry) (entry) > +#define ENTRY_KEY(entry) (ENTRY_OCC(entry) + 1) > +#define ENTRY_VAL(entry) (ENTRY_KEY(entry) + ctx->key_size) > +#define ENTRY_PSL(entry) (size_t*) (ENTRY_VAL(entry) + ctx->val_size) Unaligned access. You need to align entry_size to the required alignment of size_t and put this at the start of it the entry to avoid this. Apart from that: The layout of your entries implies that only two members are at a fixed offset from the start, so that accessing val and psl requires actual additions. If you make it psl, occ, key, val, then only val has a variable offset. This should be beneficial given that it is the less accessed of key and val (in particular if you combine several memcpy calls as I outline below). (This is of course a good reason not to make the layout of the entries public.) > + > +#define KEYS_EQUAL(k1, k2) !memcmp(k1, k2, ctx->key_size) > + > +int av_hashtable_init(AVHashtableContext* ctx, size_t key_size, size_t val_size, size_t max_entries) > +{ > + ctx->key_size = key_size; > + ctx->val_size = val_size; > + ctx->entry_size = 1 + key_size + val_size + sizeof(size_t); > + ctx->max_entries = max_entries; > + ctx->utilization = 0; > + ctx->crc = av_crc_get_table(AV_CRC_32_IEEE); > + if (!ctx->crc) > + return AVERROR_BUG; > + ctx->table = av_mallocz(ctx->entry_size * max_entries); av_calloc() > + if (!ctx->table) > + return AVERROR(ENOMEM); > + ctx->set_key = av_malloc(key_size); > + if (!ctx->set_key) > + return AVERROR(ENOMEM); > + ctx->set_val = av_malloc(key_size); Should be val_size. Your test should test scenarios with key_size != val_size to uncover this. > + if (!ctx->set_val) > + return AVERROR(ENOMEM); > + ctx->tmp_key = av_malloc(key_size); > + if (!ctx->tmp_key) > + return AVERROR(ENOMEM); > + ctx->tmp_val = av_malloc(val_size); > + if (!ctx->tmp_val) > + return AVERROR(ENOMEM); > + return 0; > +} (There are btw issues with what happens on error here, but we can ignore this in the first round.) > + > +static size_t hash_key(const AVHashtableContext* ctx, const void* key) > +{ > + return av_crc(ctx->crc, 0, key, ctx->key_size) % ctx->max_entries; > +} > + > +int av_hashtable_get(const AVHashtableContext* ctx, const void* key, void* val) > +{ > + size_t hash = hash_key(ctx, key); > + > + if (!ctx->utilization) > + return 0; > + > + for (size_t psl = 0; psl < ctx->max_entries; psl++) { > + size_t wrapped_index = (hash + psl) % ctx->max_entries; > + uint8_t *entry = ctx->table + wrapped_index * ctx->entry_size; > + if (!*ENTRY_OCC(entry) || *ENTRY_PSL(entry) < psl) > + return 0; > + if (KEYS_EQUAL(ENTRY_KEY(entry), key)) { > + memcpy(val, ENTRY_VAL(entry), ctx->val_size); > + return 1; > + } > + } > + return 0; > +} > + > +int av_hashtable_set(AVHashtableContext* ctx, const void* key, const void* val) > +{ > + int swapping = 0; > + size_t psl = 0; > + size_t hash = hash_key(ctx, key); > + > + memcpy(ctx->set_key, key, ctx->key_size); > + memcpy(ctx->set_val, val, ctx->val_size); > + > + for (size_t i = 0; i < ctx->max_entries; i++) { > + size_t wrapped_index = (hash + i) % ctx->max_entries; > + uint8_t *entry = ctx->table + wrapped_index * ctx->entry_size; > + if (!*ENTRY_OCC(entry) || (!swapping && KEYS_EQUAL(ENTRY_KEY(entry), ctx->set_key))) { > + if (!*ENTRY_OCC(entry)) > + ctx->utilization++; > + *ENTRY_OCC(entry) = 1; > + memcpy(ENTRY_KEY(entry), ctx->set_key, ctx->key_size); > + memcpy(ENTRY_VAL(entry), ctx->set_val, ctx->val_size); > + *ENTRY_PSL(entry) = psl; > + return 1; > + } > + if (*ENTRY_PSL(entry) < psl) { > + if (ctx->utilization == ctx->max_entries) > + return 0; > + swapping = 1; > + memcpy(ctx->tmp_key, ctx->set_key, ctx->key_size); > + memcpy(ctx->tmp_val, ctx->set_val, ctx->val_size); Given that set_key/val are overwritten below, these two can be done via pointerswaps. > + memcpy(ctx->set_key, ENTRY_KEY(entry), ctx->key_size); > + memcpy(ctx->set_val, ENTRY_VAL(entry), ctx->val_size); > + memcpy(ENTRY_KEY(entry), ctx->tmp_key, ctx->key_size); > + memcpy(ENTRY_VAL(entry), ctx->tmp_val, ctx->val_size); > + FFSWAP(size_t, psl, *ENTRY_PSL(entry)); If you allocated foo_key and foo_val jointly, you can combine these memcpy's. In fact, you can allocate all four them jointly with a key-val-key-val layout and only keep one pointer in the context. You would then use an uint8_t *set, *val pointers on the stack of this function that are initialized at the beginning of this function. > + } > + psl++; > + } > + return 0; > +} > + > +int av_hashtable_delete(AVHashtableContext* ctx, const void* key) > +{ > + uint8_t *next_entry; > + size_t hash = hash_key(ctx, key); > + > + if (!ctx->utilization) > + return 0; > + > + for (size_t psl = 0; psl < ctx->max_entries; psl++) { > + size_t wrapped_index = (hash + psl) % ctx->max_entries; > + uint8_t *entry = ctx->table + wrapped_index * ctx->entry_size; > + if (!*ENTRY_OCC(entry) || *ENTRY_PSL(entry) < psl) > + return 0; > + if (KEYS_EQUAL(ENTRY_KEY(entry), key)) { > + *ENTRY_OCC(entry) = 0; > + for (psl++; psl < ctx->max_entries; psl++) { > + wrapped_index = (hash + psl) % ctx->max_entries; > + next_entry = ctx->table + wrapped_index * ctx->entry_size; > + if (!*ENTRY_OCC(next_entry) || !*ENTRY_PSL(next_entry)) { > + ctx->utilization--; > + return 1; > + } > + FFSWAP(uint8_t, *ENTRY_OCC(entry), *ENTRY_OCC(next_entry)); > + memcpy(ENTRY_KEY(entry), ENTRY_KEY(next_entry), ctx->key_size); > + memcpy(ENTRY_VAL(entry), ENTRY_VAL(next_entry), ctx->val_size); These two memcpy can be combined (if one lays out key and val sequentially in entry. Can even be combined with occ if you change the entry layout as I outlined above. > + *ENTRY_PSL(entry) = *ENTRY_PSL(next_entry) - 1; > + entry = next_entry; > + } > + } > + }; > + return 0; > +} > + > +void av_hashtable_clear(AVHashtableContext* ctx) > +{ > + memset(ctx->table, 0, ctx->entry_size * ctx->max_entries); > +} > + > +void av_hashtable_destroy(AVHashtableContext* ctx) > +{ > + av_freep(&ctx->table); > + av_freep(&ctx->set_key); > + av_freep(&ctx->set_val); > + av_freep(&ctx->tmp_key); > + av_freep(&ctx->tmp_val); > +} > \ No newline at end of file > diff --git a/libavutil/hashtable.h b/libavutil/hashtable.h > new file mode 100644 > index 0000000000..aac31ee922 > --- /dev/null > +++ b/libavutil/hashtable.h > @@ -0,0 +1,62 @@ > +/* > + * Generic hashtable > + * Copyright (C) 2024 Connor Worley <connorbworley@gmail.com> > + * > + * This file is part of FFmpeg. > + * > + * FFmpeg is free software; you can redistribute it and/or > + * modify it under the terms of the GNU Lesser General Public > + * License as published by the Free Software Foundation; either > + * version 2.1 of the License, or (at your option) any later version. > + * > + * FFmpeg is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * Lesser General Public License for more details. > + * > + * You should have received a copy of the GNU Lesser General Public > + * License along with FFmpeg; if not, write to the Free Software > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA > + */ > + > +#ifndef AVUTIL_HASHTABLE_H > +#define AVUTIL_HASHTABLE_H > + > +#include <stddef.h> > + > +#include "crc.h" > + > +/* Implements a hash table using Robin Hood open addressing. > + * See: https://cs.uwaterloo.ca/research/tr/1986/CS-86-14.pdf > + * > + * Entry slots are layed out in memory as follows: > + * - [1 byte] occupancy flag that indicates whether a slot if occupied. > + * - [key_size bytes] entry key. > + * - [val_size bytes] entry value. > + * - [sizeof(size_t) bytes] PSL (probe sequence length), used by the Robin Hood > + * algorithm. Such things should not be made public. Even if sizeof(AVHashtableContext) were part of the ABI. > + */ > + > +typedef struct AVHashtableContext { > + size_t key_size; > + size_t val_size; > + size_t entry_size; > + size_t max_entries; > + size_t utilization; > + const AVCRC *crc; You don't need the complete type here, so by using struct AVCRC *crc you can avoid the crc.h inclusion. > + uint8_t *table; > + /* used for swaps during insertion */ > + uint8_t *set_key; > + uint8_t *set_val; > + uint8_t *tmp_key; > + uint8_t *tmp_val; > +} AVHashtableContext; In patch 2/2 you are using this in a way that makes sizeof(AVHashtableContext) part of the ABI. Is this intended? Even if it is, the user should be forbidden from accessing anything in it. > + > +int av_hashtable_init(AVHashtableContext* ctx, size_t key_size, size_t val_size, size_t max_entries); We generally use > +int av_hashtable_get(const AVHashtableContext* ctx, const void* key, void* val); > +int av_hashtable_set(AVHashtableContext* ctx, const void* key, const void* val); > +int av_hashtable_delete(AVHashtableContext* ctx, const void* key); > +void av_hashtable_clear(AVHashtableContext* ctx); > +void av_hashtable_destroy(AVHashtableContext* ctx); > + > +#endif > \ No newline at end of file > diff --git a/libavutil/tests/hashtable.c b/libavutil/tests/hashtable.c > new file mode 100644 > index 0000000000..1cdbd7afd3 > --- /dev/null > +++ b/libavutil/tests/hashtable.c > @@ -0,0 +1,104 @@ > +/* > + * Generic hashtable tests > + * Copyright (C) 2024 Connor Worley <connorbworley@gmail.com> > + * > + * This file is part of FFmpeg. > + * > + * FFmpeg is free software; you can redistribute it and/or > + * modify it under the terms of the GNU Lesser General Public > + * License as published by the Free Software Foundation; either > + * version 2.1 of the License, or (at your option) any later version. > + * > + * FFmpeg is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * Lesser General Public License for more details. > + * > + * You should have received a copy of the GNU Lesser General Public > + * License along with FFmpeg; if not, write to the Free Software > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA > + */ > + > +#include "libavutil/avassert.h" > +#include "libavutil/hashtable.h" > + > +int main(void) > +{ > + AVHashtableContext ctx; > + int k, v; > + > + // hashtable can store up to 3 int->int entries > + av_assert0(!av_hashtable_init(&ctx, sizeof(int), sizeof(int), 3)); > + > + // unsuccessful deletes return 0 > + k = 1; > + av_assert0(!av_hashtable_delete(&ctx, &k)); > + > + // unsuccessful gets return 0 > + k = 1; > + av_assert0(!av_hashtable_get(&ctx, &k, &v)); > + > + // successful sets returns 1 > + k = 1; > + v = 1; > + av_assert0(av_hashtable_set(&ctx, &k, &v)); > + > + // get should now contain 1 > + k = 1; > + v = 0; > + av_assert0(av_hashtable_get(&ctx, &k, &v)); > + av_assert0(v == 1); > + > + // updating sets should return 1 > + k = 1; > + v = 2; > + av_assert0(av_hashtable_set(&ctx, &k, &v)); > + > + // get should now contain 2 > + k = 1; > + v = 0; > + av_assert0(av_hashtable_get(&ctx, &k, &v)); > + av_assert0(v == 2); > + > + // fill the table > + k = 2; > + v = 2; > + av_assert0(av_hashtable_set(&ctx, &k, &v)); > + k = 3; > + v = 3; > + av_assert0(av_hashtable_set(&ctx, &k, &v)); > + > + // inserting sets on a full table should return 0 > + k = 4; > + v = 4; > + av_assert0(!av_hashtable_set(&ctx, &k, &v)); > + > + // updating sets on a full table should return 1 > + k = 1; > + v = 4; > + av_assert0(av_hashtable_set(&ctx, &k, &v)); > + v = 0; > + av_assert0(av_hashtable_get(&ctx, &k, &v)); > + av_assert0(v == 4); > + > + // successful deletes should return 1 > + k = 1; > + av_assert0(av_hashtable_delete(&ctx, &k)); > + > + // get should now return 0 > + av_assert0(!av_hashtable_get(&ctx, &k, &v)); > + > + // sanity check remaining keys > + k = 2; > + v = 0; > + av_assert0(av_hashtable_get(&ctx, &k, &v)); > + av_assert0(v == 2); > + k = 3; > + v = 0; > + av_assert0(av_hashtable_get(&ctx, &k, &v)); > + av_assert0(v == 3); > + > + av_hashtable_destroy(&ctx); > + > + return 0; > +} > \ No newline at end of file You should add these newlines, they are AFAIK required by the spec.
On Mon, Feb 5, 2024 at 3:58 AM Andreas Rheinhardt < andreas.rheinhardt@outlook.com> wrote: > Connor Worley: > > + memcpy(ctx->tmp_key, ctx->set_key, ctx->key_size); > > + memcpy(ctx->tmp_val, ctx->set_val, ctx->val_size); > > Given that set_key/val are overwritten below, these two can be done via > pointerswaps. I don't quite follow, can you elaborate on this part?
NVM, I see what you mean by pointerswaps. On Mon, Feb 5, 2024 at 9:00 PM Connor Worley <connorbworley@gmail.com> wrote: > On Mon, Feb 5, 2024 at 3:58 AM Andreas Rheinhardt < > andreas.rheinhardt@outlook.com> wrote: > >> Connor Worley: >> > + memcpy(ctx->tmp_key, ctx->set_key, ctx->key_size); >> > + memcpy(ctx->tmp_val, ctx->set_val, ctx->val_size); >> >> Given that set_key/val are overwritten below, these two can be done via >> pointerswaps. > > > I don't quite follow, can you elaborate on this part? > -- > Connor Worley >
diff --git a/libavutil/Makefile b/libavutil/Makefile index e7709b97d0..be75d464fc 100644 --- a/libavutil/Makefile +++ b/libavutil/Makefile @@ -138,6 +138,7 @@ OBJS = adler32.o \ fixed_dsp.o \ frame.o \ hash.o \ + hashtable.o \ hdr_dynamic_metadata.o \ hdr_dynamic_vivid_metadata.o \ hmac.o \ @@ -251,6 +252,7 @@ TESTPROGS = adler32 \ file \ fifo \ hash \ + hashtable \ hmac \ hwdevice \ integer \ diff --git a/libavutil/hashtable.c b/libavutil/hashtable.c new file mode 100644 index 0000000000..fb0f0aae99 --- /dev/null +++ b/libavutil/hashtable.c @@ -0,0 +1,172 @@ +/* + * Generic hashtable + * Copyright (C) 2024 Connor Worley <connorbworley@gmail.com> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <stdint.h> + +#include "error.h" +#include "mem.h" +#include "hashtable.h" +#include "string.h" + +#define ENTRY_OCC(entry) (entry) +#define ENTRY_KEY(entry) (ENTRY_OCC(entry) + 1) +#define ENTRY_VAL(entry) (ENTRY_KEY(entry) + ctx->key_size) +#define ENTRY_PSL(entry) (size_t*) (ENTRY_VAL(entry) + ctx->val_size) + +#define KEYS_EQUAL(k1, k2) !memcmp(k1, k2, ctx->key_size) + +int av_hashtable_init(AVHashtableContext* ctx, size_t key_size, size_t val_size, size_t max_entries) +{ + ctx->key_size = key_size; + ctx->val_size = val_size; + ctx->entry_size = 1 + key_size + val_size + sizeof(size_t); + ctx->max_entries = max_entries; + ctx->utilization = 0; + ctx->crc = av_crc_get_table(AV_CRC_32_IEEE); + if (!ctx->crc) + return AVERROR_BUG; + ctx->table = av_mallocz(ctx->entry_size * max_entries); + if (!ctx->table) + return AVERROR(ENOMEM); + ctx->set_key = av_malloc(key_size); + if (!ctx->set_key) + return AVERROR(ENOMEM); + ctx->set_val = av_malloc(key_size); + if (!ctx->set_val) + return AVERROR(ENOMEM); + ctx->tmp_key = av_malloc(key_size); + if (!ctx->tmp_key) + return AVERROR(ENOMEM); + ctx->tmp_val = av_malloc(val_size); + if (!ctx->tmp_val) + return AVERROR(ENOMEM); + return 0; +} + +static size_t hash_key(const AVHashtableContext* ctx, const void* key) +{ + return av_crc(ctx->crc, 0, key, ctx->key_size) % ctx->max_entries; +} + +int av_hashtable_get(const AVHashtableContext* ctx, const void* key, void* val) +{ + size_t hash = hash_key(ctx, key); + + if (!ctx->utilization) + return 0; + + for (size_t psl = 0; psl < ctx->max_entries; psl++) { + size_t wrapped_index = (hash + psl) % ctx->max_entries; + uint8_t *entry = ctx->table + wrapped_index * ctx->entry_size; + if (!*ENTRY_OCC(entry) || *ENTRY_PSL(entry) < psl) + return 0; + if (KEYS_EQUAL(ENTRY_KEY(entry), key)) { + memcpy(val, ENTRY_VAL(entry), ctx->val_size); + return 1; + } + } + return 0; +} + +int av_hashtable_set(AVHashtableContext* ctx, const void* key, const void* val) +{ + int swapping = 0; + size_t psl = 0; + size_t hash = hash_key(ctx, key); + + memcpy(ctx->set_key, key, ctx->key_size); + memcpy(ctx->set_val, val, ctx->val_size); + + for (size_t i = 0; i < ctx->max_entries; i++) { + size_t wrapped_index = (hash + i) % ctx->max_entries; + uint8_t *entry = ctx->table + wrapped_index * ctx->entry_size; + if (!*ENTRY_OCC(entry) || (!swapping && KEYS_EQUAL(ENTRY_KEY(entry), ctx->set_key))) { + if (!*ENTRY_OCC(entry)) + ctx->utilization++; + *ENTRY_OCC(entry) = 1; + memcpy(ENTRY_KEY(entry), ctx->set_key, ctx->key_size); + memcpy(ENTRY_VAL(entry), ctx->set_val, ctx->val_size); + *ENTRY_PSL(entry) = psl; + return 1; + } + if (*ENTRY_PSL(entry) < psl) { + if (ctx->utilization == ctx->max_entries) + return 0; + swapping = 1; + memcpy(ctx->tmp_key, ctx->set_key, ctx->key_size); + memcpy(ctx->tmp_val, ctx->set_val, ctx->val_size); + memcpy(ctx->set_key, ENTRY_KEY(entry), ctx->key_size); + memcpy(ctx->set_val, ENTRY_VAL(entry), ctx->val_size); + memcpy(ENTRY_KEY(entry), ctx->tmp_key, ctx->key_size); + memcpy(ENTRY_VAL(entry), ctx->tmp_val, ctx->val_size); + FFSWAP(size_t, psl, *ENTRY_PSL(entry)); + } + psl++; + } + return 0; +} + +int av_hashtable_delete(AVHashtableContext* ctx, const void* key) +{ + uint8_t *next_entry; + size_t hash = hash_key(ctx, key); + + if (!ctx->utilization) + return 0; + + for (size_t psl = 0; psl < ctx->max_entries; psl++) { + size_t wrapped_index = (hash + psl) % ctx->max_entries; + uint8_t *entry = ctx->table + wrapped_index * ctx->entry_size; + if (!*ENTRY_OCC(entry) || *ENTRY_PSL(entry) < psl) + return 0; + if (KEYS_EQUAL(ENTRY_KEY(entry), key)) { + *ENTRY_OCC(entry) = 0; + for (psl++; psl < ctx->max_entries; psl++) { + wrapped_index = (hash + psl) % ctx->max_entries; + next_entry = ctx->table + wrapped_index * ctx->entry_size; + if (!*ENTRY_OCC(next_entry) || !*ENTRY_PSL(next_entry)) { + ctx->utilization--; + return 1; + } + FFSWAP(uint8_t, *ENTRY_OCC(entry), *ENTRY_OCC(next_entry)); + memcpy(ENTRY_KEY(entry), ENTRY_KEY(next_entry), ctx->key_size); + memcpy(ENTRY_VAL(entry), ENTRY_VAL(next_entry), ctx->val_size); + *ENTRY_PSL(entry) = *ENTRY_PSL(next_entry) - 1; + entry = next_entry; + } + } + }; + return 0; +} + +void av_hashtable_clear(AVHashtableContext* ctx) +{ + memset(ctx->table, 0, ctx->entry_size * ctx->max_entries); +} + +void av_hashtable_destroy(AVHashtableContext* ctx) +{ + av_freep(&ctx->table); + av_freep(&ctx->set_key); + av_freep(&ctx->set_val); + av_freep(&ctx->tmp_key); + av_freep(&ctx->tmp_val); +} \ No newline at end of file diff --git a/libavutil/hashtable.h b/libavutil/hashtable.h new file mode 100644 index 0000000000..aac31ee922 --- /dev/null +++ b/libavutil/hashtable.h @@ -0,0 +1,62 @@ +/* + * Generic hashtable + * Copyright (C) 2024 Connor Worley <connorbworley@gmail.com> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef AVUTIL_HASHTABLE_H +#define AVUTIL_HASHTABLE_H + +#include <stddef.h> + +#include "crc.h" + +/* Implements a hash table using Robin Hood open addressing. + * See: https://cs.uwaterloo.ca/research/tr/1986/CS-86-14.pdf + * + * Entry slots are layed out in memory as follows: + * - [1 byte] occupancy flag that indicates whether a slot if occupied. + * - [key_size bytes] entry key. + * - [val_size bytes] entry value. + * - [sizeof(size_t) bytes] PSL (probe sequence length), used by the Robin Hood + * algorithm. + */ + +typedef struct AVHashtableContext { + size_t key_size; + size_t val_size; + size_t entry_size; + size_t max_entries; + size_t utilization; + const AVCRC *crc; + uint8_t *table; + /* used for swaps during insertion */ + uint8_t *set_key; + uint8_t *set_val; + uint8_t *tmp_key; + uint8_t *tmp_val; +} AVHashtableContext; + +int av_hashtable_init(AVHashtableContext* ctx, size_t key_size, size_t val_size, size_t max_entries); +int av_hashtable_get(const AVHashtableContext* ctx, const void* key, void* val); +int av_hashtable_set(AVHashtableContext* ctx, const void* key, const void* val); +int av_hashtable_delete(AVHashtableContext* ctx, const void* key); +void av_hashtable_clear(AVHashtableContext* ctx); +void av_hashtable_destroy(AVHashtableContext* ctx); + +#endif \ No newline at end of file diff --git a/libavutil/tests/hashtable.c b/libavutil/tests/hashtable.c new file mode 100644 index 0000000000..1cdbd7afd3 --- /dev/null +++ b/libavutil/tests/hashtable.c @@ -0,0 +1,104 @@ +/* + * Generic hashtable tests + * Copyright (C) 2024 Connor Worley <connorbworley@gmail.com> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "libavutil/avassert.h" +#include "libavutil/hashtable.h" + +int main(void) +{ + AVHashtableContext ctx; + int k, v; + + // hashtable can store up to 3 int->int entries + av_assert0(!av_hashtable_init(&ctx, sizeof(int), sizeof(int), 3)); + + // unsuccessful deletes return 0 + k = 1; + av_assert0(!av_hashtable_delete(&ctx, &k)); + + // unsuccessful gets return 0 + k = 1; + av_assert0(!av_hashtable_get(&ctx, &k, &v)); + + // successful sets returns 1 + k = 1; + v = 1; + av_assert0(av_hashtable_set(&ctx, &k, &v)); + + // get should now contain 1 + k = 1; + v = 0; + av_assert0(av_hashtable_get(&ctx, &k, &v)); + av_assert0(v == 1); + + // updating sets should return 1 + k = 1; + v = 2; + av_assert0(av_hashtable_set(&ctx, &k, &v)); + + // get should now contain 2 + k = 1; + v = 0; + av_assert0(av_hashtable_get(&ctx, &k, &v)); + av_assert0(v == 2); + + // fill the table + k = 2; + v = 2; + av_assert0(av_hashtable_set(&ctx, &k, &v)); + k = 3; + v = 3; + av_assert0(av_hashtable_set(&ctx, &k, &v)); + + // inserting sets on a full table should return 0 + k = 4; + v = 4; + av_assert0(!av_hashtable_set(&ctx, &k, &v)); + + // updating sets on a full table should return 1 + k = 1; + v = 4; + av_assert0(av_hashtable_set(&ctx, &k, &v)); + v = 0; + av_assert0(av_hashtable_get(&ctx, &k, &v)); + av_assert0(v == 4); + + // successful deletes should return 1 + k = 1; + av_assert0(av_hashtable_delete(&ctx, &k)); + + // get should now return 0 + av_assert0(!av_hashtable_get(&ctx, &k, &v)); + + // sanity check remaining keys + k = 2; + v = 0; + av_assert0(av_hashtable_get(&ctx, &k, &v)); + av_assert0(v == 2); + k = 3; + v = 0; + av_assert0(av_hashtable_get(&ctx, &k, &v)); + av_assert0(v == 3); + + av_hashtable_destroy(&ctx); + + return 0; +} \ No newline at end of file
Signed-off-by: Connor Worley <connorbworley@gmail.com> --- libavutil/Makefile | 2 + libavutil/hashtable.c | 172 ++++++++++++++++++++++++++++++++++++ libavutil/hashtable.h | 62 +++++++++++++ libavutil/tests/hashtable.c | 104 ++++++++++++++++++++++ 4 files changed, 340 insertions(+) create mode 100644 libavutil/hashtable.c create mode 100644 libavutil/hashtable.h create mode 100644 libavutil/tests/hashtable.c